Understanding API ICP653 Reading 8-Worksheet-05 Part2a

Understanding APIICP653 

Reading 8 Worksheet-05 Part 2a of 2 

My Pre-exam Self Study Notes 

26 th February 2015 

Charlie Chong/ Fion Zhang

AST Tanks 


API 653 Exam Administration -- Publications 

Effectivity Sheet FOR: November 2015, March 

2016 and July 2016 

Listed below are the effective editions of the publications required for this 

exam for the date(s) shown above. 

API Recommended Practice 571, Damage Mechanisms Affecting Fixed Equipment in 

the Refining Industry, Second Edition, April 2011 


API 653 Exam Administration -- Publications 

Effectivity Sheet FOR: November 2015, March 

2016 and July 2016 

Listed below are the effective editions of the publications required for this 

exam for the date(s) shown above. 

API Recommended Practice 571, Damage Mechanisms Affecting Fixed Equipment in 

the Refining Industry, Second Edition, April 2011 


ATTENTION: Only the following sections / mechanisms from RP 571 are 

included on the exam: 

Section 3, Definitions Par. 

4.2.7 Brittle Fracture 

4.2.16 Mechanical Fatigue 

4.3.2 Atmospheric Corrosion 

4.3.3 Corrosion Under insulation (CUI) 

4.3.8 Microbiologically Induced Corrosion (MIC) 

4.3.9 Soil Corrosion 

4.3.10 Caustic Corrosion 

4.5.1 Chloride Stress Corrosion Cracking (Cl-SCC) 

4.5.3 Caustic Stress Corrosion Cracking (Caustic Embrittlement) 

5.1.1.10 Sour Water Corrosion (Acidic) 

5.1.1.11 Sulfuric Acid Corrosion 


• API Recommended Practice 575, Inspection of Atmospheric and Low- 

Pressure Storage Tanks, Third Edition, April 2014 

• API Recommended Practice 577 – Welding Inspection and Metallurgy, 

Second Edition, December 2013 

• API Standard 650, Welded Tanks for Oil Storage, Twelfth Edition, March 

2013 with Addendum 1 (September 2014), Errata 1 (July 2013), and Errata 

2 (December 2014). 

• API Recommended Practice 651, Cathodic Protection of Aboveground 

Petroleum Storage Tanks, Fourth Edition, September 2014. 

• API Recommended Practice 652, Lining of Aboveground Petroleum 

Storage Tank Bottoms, Fourth Edition, September 2014 

• API Standard 653, Tank Inspection, Repair, Alteration, and 

Reconstruction, Fifth Edition, November 2014. 


• American Society of Mechanical Engineers (ASME), Boiler and Pressure 

Vessel Code, 2013 Edition 

i. ASME Section V, Nondestructive Examination, Articles 1, 2, 6, 7 and 

23 (section SE-797 only) 

ii. Section IX, Welding and Brazing Qualifications (Welding Only) 

See end of this study note for API Official BOK 


http://independent.academia.edu/CharlieChong1 

http://www.yumpu.com/zh/browse/user/charliechong 

http://issuu.com/charlieccchong 


Charlie Chong/ Fion Zhang 

http://greekhouseoffonts.com/

The Magical Book of Tank Inspection ICP 



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Fion Zhang at Xitang 

26 th February 2016

Subject API Standard 650 


API650 

Welded Tanks for Oil Storage API STANDARD 

650 TWELFTH EDITION, MARCH 2013 


API650 Section 1 

Scope 


Q1. API 650 covers the design, materials, fabrication, erection, and testing of 

aboveground steel storage tanks. What is the maximum internal pressure for 

tanks not covered by appendix F of this standard? 

a) Maximum pressure shall not exceed 15 psig 

b) Maximum pressure shall not exceed 15 psia 

c) Maximum pressure shall not exceed the weight of the roof plates 

d) Maximum pressure shall not exceed the weight of the floor plates 

ANS: c 

Q2. API-650 applies only to tanks whose entire bottom is uniformly supported 

and tanks in ___ that have a maximum operating temperature of _____°F. 

a) Any petrochemical service and temperature not exceeding 120°F 

b) Non-refrigerated service and temperature not exceeding 200°F 

c) Non-refrigerated service and temperature not exceeding 120°F 

d) Any petrochemical service and temperature not exceeding 200°F 

ANS: b 


Q3. An aboveground storage tank is to be subjected to a small internal 

service pressure. To which standard or Code may the tank be designed? 

a) API-650 providing the requirements of Appendix F are met 

b) API-653 providing the requirements of Appendix F are met 

c) ASME-Section VIII, Div. 1 providing the requirements of Appendix F 

are met 

d) ASME-Section VIII, Div. 2 providing the requirements of Appendix F 

are met 

ANS: a 

Q4. According to Table 1-1, what is the status of Appendix O? 

a) This Appendix is a Recommendation 

b) This Appendix is a Requirement 

c) This Appendix is Mandatory 

d) This Appendix is Purchaser’s option 

ANS: d 


Q5. What is the purpose of the (•) next to a paragraph number? 

a) The paragraph requires a decision or action by the API 

b) The paragraph requires a decision or action by the Inspector 

c) The paragraph requires a decision or action by the purchaser 

d) The paragraph requires a decision or action by the fabricator 

ANS: c 

Others 

F.1.3 Internal pressures that exceed the nominal weight of the shell, roof, and 

framing but do not exceed 18 kPa (21/2 lbf/in.2) gauge when the shell is 

anchored to a counterbalancing weight, such as a concrete ringwall, are 

covered in F.2 and F.7. 


Answers to API-Standard 650 Section 1, Scope 



Materials 


Q1. API-650 lists materials to be used in the construction of tanks covered by 

the standard. Is it permissible to use materials other than those listed in the 

standard? 

a) No only materials listed in API-650 may be used in tank fabrication 

b) Yes as long as the manufacturer accepts full liability for tank failure 

c) Yes providing it is certified as meeting all requirements of a material 

listed in API-650 and is approved by the API-653 Inspector 

d) Yes providing it is certified as meeting all the requirements of a 

material listed in API-650 and is approved by the purchaser 

ANS: d 


Q2. If a new or unused plate cannot be completely identified, may it still be 

used in the construction of tanks within the scope of API-650? 

a) Yes only if the material passes the tests prescribed in Appendix S 

b) Yes only if the material passes the tests prescribed in Appendix N 

c) Yes only if the material passes the tests prescribed in ASME Section V 

d) Yes only if the material passes the tests prescribed in ASME Section 

VIII, Div. 2 

ANS: b 

Q3. What is the maximum permitted underrun for shell, roof, and bottom 

plates? 

a) 0.10 inch from the computed design thickness or minimum permitted 

thickness 

b) 0.01 inch from the computed design thickness or minimum permitted 

thickness 

c) 0.001 inch from the computed design thickness or minimum permitted 

thickness 

d) 0.02 inch from the computed design thickness or minimum permitted 

thickness 

ANS: b 


Q4. Shell plates are limited to what maximum thickness? 

a) Shell plates are limited to a maximum thickness of 1.250 inches 

b) Shell plates are limited to a maximum thickness of 1.875 inches 

c) Shell plates are limited to a maximum thickness of 1.750 inches 

d) Shell plates are limited to a maximum thickness of 1.075 inches 

ANS: c 

Q5. Which of the following is not a requirement for shell plates that are thicker 

than 1.5 inches? 

a) Plates thicker than 1.5 inches shall be free of mill scale and painted 

b) Plates thicker than 1.5 inches shall be made to fine-grain practice 

c) Plates thicker than 1.5 inches shall be impact tested 

d) Plates thicker than 1.5 inches shall be normalized or quench tempered 

ANS: a 


Q6. What is the maximum shell plate thickness permitted for a tank fabricated 

of ASTM A 36 material? 

a) This plate material is limited to 1.750 inches 

b) This plate material is limited to 1.075 inches 

c) This plate material is limited to 1.050 inches 

d) This plate material is limited to 1.500 inches 

ANS: d 

Q7. What is the maximum shell plate thickness permitted for a tank fabricated 

of ASTM A 285, Grade C material? 

a) This plate material is limited to 1.000 inches 

b) This plate material is limited to 1.250 inches 

c) This plate material is limited to 1.500 inches 

d) This plate material is limited to 1.750 inches 

ANS: a 


Q8. All welding to repair surface defects shall be done with ______. 

a) Cellulose coated electrode 

b) High nickel content electrode 

c) Low-hydrogen electrode 

d) Gas tungsten process 

ANS: c 

Q9. When conducting impact tests, how many specimens are required from a 

single test coupon? 

a) Impact tests shall be performed on a single specimen taken from a 

single test coupon 

b) Impact tests shall be performed on two specimens taken from a single 

test coupon 

c) Impact tests shall be performed on three specimens taken from a 

single test coupon 

d) Impact tests shall be performed on four specimens taken from a single 

test coupon 

ANS: c 


Q10. In situations where it is not possible to obtain full size specimens, what 

is the required width along the notch for subsize specimens? 

a) 60% of the material thickness 

b) 80% of the material thickness 

c) 90% of the material thickness 

d) 75% of the material thickness 

ANS: b 

Q11. Unless data is available to justify a different temperature, what must the 

design metal temperature be for an aboveground storage tank to be installed 

in Birmingham, Alabama? (0°F) 

a) The design temperature shall be assumed to be 25°F 

b) The design temperature shall be assumed to be 15°F 

c) The design temperature shall be assumed to be 20°F 

d) The design temperature shall be assumed to be 10°F 

ANS: b 


Q12. Unless data is available to justify a different temperature, what must the 

design metal temperature be for an aboveground storage tank to be installed 

in Indianapolis, Indiana? (-15°F) 

a) The design temperature shall be assumed to be 5°F 

b) The design temperature shall be assumed to be -5°F 

c) The design temperature shall be assumed to be 0°F 

d) The design temperature shall be assumed to be 10°F 

ANS: c 

Q13. What is the required average longitudinal impact value of three 

specimens taken from a 1.375 inch thick A 516M-60(415) normalized Group 

IIIA test coupon? 

a) 30 foot-pounds 

b) 20 foot-pounds 

c) 15 foot-pounds 

d) 13 foot-pounds 

ANS: c 


Indianapolis: -10°F or -15°F? 

— Design Metal Temperature*: Enter either lowest 1-day mean temperature 

plus 8°C (15°F) or a lower temperature as specified by the Purchaser if 

operating conditions and/or local atmospheric conditions control fracture 

toughness issues. 


Q14. What is the required average longitudinal impact value of three 

specimens taken from a 1.5 inch thick A 516M-70(485) as rolled Group V test 

coupon? 

a) 35 foot-pounds 

b) 25 foot-pounds 

c) 20 foot-pounds 

d) 30 foot-pounds 

ANS: d 


Q15. Longitudinal impact tests are performed on three specimens, taken from 

a 1.5 inch thick A 516M-70(485) as rolled test coupon with the following 

results: 

Specimen #1 – 42 foot-pounds, 

Specimen #2 – 18 foot-pounds, 

Specimen # 3 – 31 foot-pounds. 

Is the impact test acceptable? 

a) Yes the average impact value exceeds 30 foot-pounds 

b) Yes only one specimen is less than 2/3 the specified minimum value 

c) No the average impact value of Specimen # 1 exceeds 2/3 the required 

average impact value and one specimen is less than 2/3 the specified 

minimum value 

d) No Specimen #2 is less than 2/3 the specified minimum 

ANS: d 


Answers to API-Standard 650 Section 2, Materials 



Designs 


Q1. According to API-650, tack welds _______ 

a) May be installed by welders who need practice 

b) Can be considered as adding to the strength of a welded joint 

c) Are not considered as having any strength value in the finished 

structure 

d) Have strength value in the finished structure provided they are 

performed by a qualified welder to a qualified welding procedure 

ANS: c 

Q2. What is the minimum size fillet weld permitted when joining a 1” thick 

plate to a ¾” thick plate? 

a) 3/16” 

b) 1/4” 

c) 3/8” 

d) 1/2” 

ANS: b 

5.1.3.3 The minimum size of fillet welds shall be as follows: On plates 5 mm 

(3/16 in.) thick, the weld shall be a full- fillet weld, and on plates more than 5 

mm (3/16 in.) thick, the weld thickness shall not be less than one-third the 

thickness of the thinner plate at the joint and shall be at least 5 mm (3/16 in.). 


Q3. For lap-welded joints that are tack welded, what is the minimum amount 

of lap permitted? 

a) The lap need not exceed 2” (double lapped) 

b) The lap need not exceed 1” (single lapped) 

c) The joint shall be lapped at least 5 times the minimum required 

thickness of the thinner plate 

d) The joint shall be lapped at least 5 times the nominal thickness of the 

thinner plate 

ANS: d 

Q4. The welded joint pictured here is defined as what type of joint? 

a) Double-V butt joint 

b) Square-groove butt joint 

c) Double-U butt joint 

d) Double-square butt joint 

ANS: a 


Q5. Vertical shell joints may be partial penetration groove welds welded from 

both sides. 

a) True 

b) False 

ANS: b 

Q6. API 650 requires the vertical joints in adjacent shell courses to be offset. 

What is the minimum required offset between the first course of an AST, 

which is 1.25” thick and the second course which is 1” thick? 

a) The minimum offset shall be 5 times the second shell course height 

b) The minimum offset shall be 5 times the thickness of the second 

course 

c) The minimum offset shall be 5 times the first shell course height 

d) The minimum offset shall be 5 times the thickness of the first shell 

course 

ANS: d 


Q7. Three-plate laps in tank bottoms shall be at least ____ from each other, 

from the tank shell, from butt-welded annular-plate joints, and from joints 

between annular plates and the bottom. 

a) 1.2 inches 

b) 12 inches 

c) 1.2 feet 

d) 12 feet 

ANS: b 

Q8. What is the maximum size of fillet weld permitted in the attachment 

between the lowest course shell plate and the bottom plate? 

a) 3/8 inch 

b) 5/16 inch 

c) 1/2 inch 

d) 1/4 inch 

ANS: c 


Q9. What is the minimum size fillet weld required on each side of the shell 

plate attaching shell plate to the annular plate? The shell plate is 1.25” thick. 

a) 3/8 inch 

b) 3/16 inch 

c) 1/4 inch 

d) 5/16 inch 

ANS: d 

Q10. A 110 ft diameter tank shall have a top angle not less than ____ inches. 

a) 2 X 2 X 3/8 

b) 2 X 3 X 3/8 

c) 3 X 3 X 3/8 

d) 3 X 2 X 3/8 

ANS: c 


Q11. The ______ shall state the design metal temperature, the design 

specific gravity, the corrosion allowance, and the design wind velocity. 

a) The purchaser 

b) The fabricator 

c) The Inspector 

d) Erector 

ANS: a 

Q12. According to API-650, tanks meeting the minimum requirements of the 

standard may be subjected to a partial vacuum of _____. 

a) One inch of mercury 

b) One inch of water pressure 

c) One pound per square inch absolute 

d) One centimeter of water pressure 

ANS: b 


Q13. An AST is 116 ft in diameter and constructed of A 516M-70(485) Group 

V as rolled material. How many hardness tests are required on one 

circumferential weld? 

a) One 

b) Two 

c) Three 

d) Four 

ANS: πD = 4 (round up) D 

Q14. The purchaser orders an aboveground storage tank and insists on a 

corrosion allowance in the bottom plates of .125 inches. What is the minimum 

thickness permitted for bottom plates in this tank? 

a) Minimum thickness of bottom plate is 1/4 inch 

b) Minimum thickness of bottom plate is 1/2 inch 

c) Minimum thickness of bottom plate is 3/8 inch 

d) Minimum thickness of bottom plate is 5/16 inch 

ANS: 0.236+ 0.125 = 0.361 used C 


Q15. What is the minimum projection, of trimmed bottom plates, beyond the 

outside edge of the weld attaching bottom to the shell? 

a) Minimum projection is 0.01 inch 

b) Minimum projection is 0.10 inch 

c) Minimum projection is 1.00 inch (2”) 

d) Minimum projection is 10.0 inch 

ANS: c 

5.4.2 Bottom plates of sufficient size shall be ordered so that, when trimmed, 

at least a 50 mm (2 in.) width will project outside the shell or meet 

requirements given in 5.1.5.7 d whichever is greater. 

Q16. Annular bottom plates shall have a radial width that provides at least 

____ between the inside of the shell and any lap-welded joint in the 

remainder of the bottom. 

a) 12 inches 

b) 24 inches 

c) 1.2 inches 

d) 2.4 inches 

ANS: b 


Q17. How far must annular bottom plates project outside the shell? 

a) Annular bottom plates shall project at least 1 inch when trimmed 

b) Annular bottom plates shall project at least 1/2 inch beyond the edge of 

the weld 

c) Annular bottom plates shall project at least 2 inches outside the shell 

d) Annular bottom plates shall project at least 5t (t = thickness of the shell 

course) outside the shell 

ANS: c 

Q18. The thickness of the first shell course of an aboveground storage tank is 

1 5/8th inches. The hydrostatic test stress in the first shell course is 33,000 

psi. What is the minimum permissible thickness of the annular bottom plates? 

a) Minimum permitted thickness is 5/8th inch 

b) Minimum permitted thickness is 9/16th inch 

c) Minimum permitted thickness is 3/4 inch 

d) Minimum permitted thickness is 11/16th inch 

ANS: c 


Table 5.1b—Annular Bottom-Plate Thicknesses (tb) (USC) 


Q19. According to API-650, what is the minimum allowable nominal shell 

thickness of an AST that is 86 feet in diameter? 

a) Minimum nominal shell thickness is 3/16th inch 

b) Minimum nominal shell thickness is 1/4 inch 

c) Minimum nominal shell thickness is 9/32nd inch 

d) Minimum nominal shell thickness is 5/16th inch 

ANS: b 

Q20. Unless otherwise agreed to by the purchaser, what is the minimum 

nominal width of shell plates? 

a) Minimum width of shell plates is 84 inches 

b) Minimum width of shell plates is 96 inches 

c) Minimum width of shell plates is 72 inches 

d) Minimum width of shell plates is 120 inches 

ANS: c 


Q21. Aboveground storage tank manufacturers are required to furnish a 

drawing to the purchaser listing all but which of the following for each course? 

a) The material specification 

b) The allowable stress 

c) The nominal thickness used 

d) The nominal thickness of coatings 

ANS: d 

Q22. In calculating the net plate thickness for an AST fabricated of A 516M 

Grade 450(60) material, what would be the product design stress value used 

in the calculation? 

a) 24,000 

b) 21,300 

c) 32,000 

d) 23,300 

ANS: b 


Q23. The fabricator of an AST obtains the approval of the purchaser to use 

the alternative shell design permitted in Appendix A in the design of a 60 foot 

diameter tank using 3/8th inch A 516M Grade 450(60) plate. What allowable 

stress would be used in the design calculations? 

a) 21,300 

b) 24,000 

c) 21,000 

d) 32,000 

ANS: c 

Q24. What is the maximum diameter of tank that permits the 1-foot method of 

calculation for required thickness? 

a) Tanks 50 feet in diameter and less 

b) Tanks 120 feet in diameter and less 

c) Tanks 180 feet in diameter and less 

d) Tanks 200 feet in diameter and less 

ANS: d 


Q25. Openings in tank shells, larger than that required to accommodate a 

____ flanged or threaded nozzle shall be reinforced. 

a) 2 inch 

b) 2.5 inch 

c) 3 inch 

d) 3.5 inch 

ANS: a 

Q26. When installing openings in a shell plate, the edge of the fillet weld 

around the periphery of the reinforcing pad shall be spaced at least the 

greater of _______ from the centerline of any butt-welded shell joints. 

a) Eight inches or ten times the weld size 

b) Eight times the weld size or ten inches 

c) Eight times the weld size or six inches 

d) Eight inches or six times the weld size 

ANS: c 


5.7.3.1 For non-stress-relieved welds on shell plates over 13 mm (1/2 in.) 

thick, the minimum spacing between penetration connections and adjacent 

shell-plate joints shall be governed by the following. 

a) The toe of the fillet weld around a non-reinforced penetration or around the 

periphery of a reinforcing plate, and the outer edge of a butt-weld around the 

periphery of a thickened insert plate or insert plate, shall be spaced at least 

the greater of eight times the weld size or 250 mm (10 in.) from the centerline 

of any butt-welded shell joints, as illustrated in Figure 5.6, dimensions A or B. 

b) The toe of the fillet weld around a non-reinforced penetration or around the 

periphery of a reinforcing plate, and the outer edge of a butt-weld around the 

periphery of a thickened insert plate or insert plate, shall be spaced at least 

the greater of eight times the larger weld size or 150 mm (6 in.) from each 

other, as illustrated in Figure 5-6, dimension E. 




Q27. When installing openings adjacent to each other, how much space must 

there be between the welds around the periphery of the reinforcing plate? 

a) Eight times the larger weld or ten inches from each other 

b) Eight inches or six times the larger weld from each other 

c) Eight times the larger weld or six inches from each other 

d) Eight times the larger weld or eight inches from each other 

ANS: c 

Q28. A minimum distance of ____ shall be maintained between the toe of a 

weld around a non-reinforced penetration and the toe of the shell-to-bottom 

weld. 

a) Ten inches 

b) Eight inches 

c) Six inches 

d) Three inches 

ANS: a 



Q29. Subject to the acceptance of the purchaser, the manufacture may locate 

a circular shell opening in a horizontal butt-welded shell joint provided ______. 

a) Minimum spacing dimensions are met and a liquid penetrant 

examination of the welded joint is conducted 

b) Minimum spacing dimensions are met and a radiographic examination 

of the welded joint is conducted 

c) Minimum spacing dimensions are met and an ultrasonic examination of 

the welded joint is conducted 

d) Minimum spacing dimensions are met and a magnetic particle 

examination of the welded joint is conducted 

ANS: b 


Q30. All flush-type clean-out fittings and flush-type shell connections shall be 

thermally stress relieved after assembly and prior to installation in the tank. 

What are the temperature range and time requirements for this stress relief 

activity? 

a) 1100°F to 1200°F for 1 hour per inch of reinforcing plate thickness 

b) 1100°F to 1200°F for 1/2 hour per inch of shell thickness 

c) 1100°F to 1200°F for 1 hour per inch of shell thickness 

d) 1100°F to 1200°F for 1 & 1/2 hour per inch of shell thickness 

ANS: c 

Q31. Subject to the acceptance of the purchaser, the fabricator may stress 

relieve at a temperature of 1000°F when it is impractical to stress relieve at a 

minimum temperature of 1100°F providing _____. 

a) The shell plate is first pre-heated to 300°F 

b) The holding time is increased to 2 hours per inch of thickness 

c) The holding time is increased to 4 hours per inch of thickness 

d) The holding time is increased to 10 hours per inch of thickness 

ANS: c 


Q32. What is the minimum required thickness for a manhole cover plate to be 

used with a 24 inch manhole? The maximum design liquid level of the tank is 

45 feet. 

a) Minimum thickness of cover plate is 9/16th inch 

b) Minimum thickness of cover plate is 5/8th inch 

c) Minimum thickness of cover plate is 1/2 inch 

d) Minimum thickness of cover plate is 11/16th inch 

ANS: b 

Q33. What is the bolt circle diameter for a cover plate used with a 30 inch 

diameter manhole? 

a) 32 ¾ inch 

b) 36 ¼ inch 

c) 38 ¾ inch 

d) 42 ¼ inch 

ANS: b 


Table 5.3b—Thickness of Shell Manhole Cover Plate and Bolting Flange 

(USC) 


Q34. The purchaser has ordered a 36 inch manhole to be installed in the first 

course of an AST. The thickness of the shell plate and the reinforcing plate is 

1.375 inches. What is the required hole diameter that must be cut in the tank 

to accommodate this manhole? 

a) 36 & 1/4 inch 

b) 36 & 1/2 inch 

c) 36 & 3/4 inch 

d) 36 & 5/8 inch 

ANS: c 

Q35. API 650 requires telltale holes in reinforcing plates. What is the required 

dimension of this hole and what should be done with it after the initial re-pad 

pressure test? 

a) The hole shall be 3/8 inch diameter and shall be left open to the 

atmosphere 

b) The hole shall be 1/4 inch diameter and shall be left open to the 

atmosphere 

c) The hole shall be 3/8 inch diameter and shall be closed after testing 

d) The hole shall be 1/4 inch diameter and shall be closed after testing 

ANS: b 


Q36. What is the maximum size un-reinforced opening permitted in flat cover 

plates without increasing the thickness of the cover plate? 

a) 4 inch pipe size providing the edge of the opening is not more than ¼ 

the height or diameter of the opening closer to the center of the cover 

plate 

b) 3 inch pipe size providing the edge of the opening is not more than ¼ 


plate 

c) 2 inch pipe size providing the edge of the opening is not more than ¼ 


plate 

d) 1 & ½ inch pipe size providing the edge of the opening is not more 

than ¼ the height or diameter of the opening closer to the center of the 

cover plate 

ANS: c 


Q37. What is the maximum size opening that may be placed in a cover plate? 

a) 12 inches pipe size 

b) 8 inches pipe size 

c) 6 inches pipe size 

d) 3 inches pipe size 

ANS: a 

Q38. An aboveground storage tank has a design liquid height of 40 feet. The 

purchaser intends to install product mixing equipment in the cover plate of a 

30 inch manhole. What is the required minimum thickness of the cover plate? 

a) The minimum thickness shall be at least .625 inches 

b) The minimum thickness shall be at least .75 inches 

c) The minimum thickness shall be at least .9375 inches 

d) The minimum thickness shall be at least .875 inches 

ANS: c 


Q39. A 24 inch manhole is to be installed in a roof plate and it is anticipated 

that work may be carried on through the manhole while the tank is in use. 

What is the diameter of the opening to be cut in the roof plate and what is the 

outside diameter of the reinforcing plate? 

a) The diameter of the opening is 24.625” and the OD of the reinforcing 

plate is 42” 

b) The diameter of the opening is 24.625” and the OD of the reinforcing 


c) The diameter of the opening is 24.750” and the OD of the reinforcing 


d) The diameter of the opening is 24.750” and the OD of the reinforcing 


ANS: b 


Q40. What is the minimum thickness permitted for rectangular roof opening 

cover plates? 

a) Minimum thickness shall not be less than .875 inches 

b) Minimum thickness shall not be less than .750 inches 

c) Minimum thickness shall not be less than .625 inches 

d) Minimum thickness shall not be less than .500 inches 

ANS: D 

5.8.6.2 The cover plate thickness and/or structural support shall be designed 

to limit maximum fiber stresses in accordance with this standard, however, 

cover plate thickness shall not be less than 5 mm (3/16 in.). In addition to 

other expected design loads, consider a 112 kg (250 lb) person standing in 

the center of the installed/closed cover. The designer shall consider wind in 

the design of hinged openings and how removed covers will be handled 

without damage (adequate rigidity). 


Q41. Stiffening ring splice welds shall be located at least _____ from any 

vertical shell weld. 

a) 24 inches 

b) 18 inches 

c) 12 inches 

d) 6 inches 

ANS: d 

Q42. When stiffening rings are to be used as walkways, what is the required 

width of the stiffening ring? 

a) The width shall be not less than 36 inches clear of the projecting curb 

angle on the top of the tank shell 

b) The width shall be not less than 3 feet 6 inches clear of the projecting 

curb angle on the top of the tank shell 

c) The width shall be not less than 24 inches clear of the projecting curb 

angle on the top of the tank shell 

d) The width shall be not less than 2 feet 4 inches clear of the projecting 

curb angle on the top of the tank shell 

ANS: d 


Q43. How far below the top of the curb angle should a stiffening ring, that is to 

be used as a walkway, be located? 

a) 3 feet 6 inches 

b) 36 inches 

c) 6 feet 3 inches 

d) 63 inches 

ANS: a 

Q44. All roofs and supporting structures shall be designed to support dead 

loads plus a uniform live load of not less than _____ of projected area 

a) 25 pounds per square inch 

b) 25 pounds per square foot 

c) 25 pounds per square yard 

d) 25 pounds per square meter 

ANS: b 


Q45. What is the minimum nominal thickness permitted for roof plates? 

a) 3/16 inch or 5.76 pounds per square foot 

b) 3/16 inch or 6.75 pounds per square foot 

c) 3/16 inch or 7.65 pounds per square foot 

d) 3/16 inch or 12-gauge sheet (7-gauge?) 

ANS: d 

Q46. A roof where the continuous fillet weld between the roof plates and the 

top angle does not exceed 3/16", the slope at the top angle attachment does 

not exceed 2" in 12", and the shell-to-roof compression ring details are limited 

to Figure F-2 (a)-(d) may be considered what type of roof? 

a) A 1 in 6 roof 

b) A dangerous roof design and should be avoided 

c) A roof with inherent compensation 

d) A frangible roof 

ANS: d 


API650: 5.10.2.2 Roof Plate Thickness: Roof plates shall have a nominal 

thickness of not less than 5 mm (3/16 in.) or 7- gauge sheet. Increased 

thickness may be required for supported cone roofs (see 5.10.4.4). Any 

required corrosion allowance for the plates of self-supporting roofs shall be 

added to the calculated thickness unless otherwise specified by the 

Purchaser. Any corrosion allowance for the plates of supported roofs shall be 

added to the greater of the calculated thickness or the minimum thickness or 

[5 mm (3/16 in.) or 7-gauge sheet]. For frangible roof tanks, where a corrosion 

allowance is specified, the design must have frangible characteristics in the 

nominal (uncorroded) condition. 

API650: C.3.3.2 Unless otherwise specified by the Purchaser, all deck plates 

shall have a minimum nominal thickness of 4.8 mm (3/16 in.) (permissible 

ordering basis—37.4 kg/m2, 7.65 lbf/ft 2 of plate, 0.180-in. plate, or 7-gauge 

sheet). 


API653: 9.11.2 Supported Cone Roofs 

9.11.2.1 The minimum thickness of new roof plates shall be 3/16 in. plus any 

corrosion allowance as specified in the repair specifications. In the event roof 

live loads in excess of 25 lbf/ft 2 are specified (such as insulation, operating 

vacuum, high snow loads), the plate thickness shall be based on analysis 

using the allowable stresses in conformance with API 650, Section 5.10.3 

(see 9.11.2.2). 

9.11.2.2 The roof supports (rafters, girders, columns, and bases) shall be 

repaired or altered such that under design conditions the resulting stresses do 

not exceed the stress levels given in API 650, Section 5.10.3. 


Q47. Rafters shall be spaced so that in the outer ring, their centers are not 

more than _____ apart measured along the circumference of the tank. 

a) 3π feet or 9.42 feet 

b) 2π feet or 6.28 feet 

c) 4π feet or 12.56 feet 

d) 2.5π feet or 7.85 feet 

ANS: b 


Answers to API-Standard 650 Section 3, Design 


Roasted Duck 烤鸭 






Stewed Duck 卤鸭 


Stewed Duck 卤鸭 


番鸭 



Fabrications 


Q1. What method(s) is/are permitted for straightening material? 

a) Pressing or other non-injurious method prior to layout or shaping 

b) Heating and hammering after layout or shaping 

c) Jacking into shape after final assembly 

d) Jacking into shape and holding with tack welds 

ANS: a 

Q2. When plates are to be butt-welded, shearing is limited to what maximum 

thickness? 

a) 5/8th inch 

b) 3/8th inch (9.5mm) 

3/8´´ 

c) 3/16th inch 

d) Shearing is not permitted 

ANS: b 


Q3. When plates are to be used in lap-welded joints, shearing is limited to 

what maximum thickness 

a) 3/16th inch 

b) 3/8th inch 

5/8´´ 

c) 1/2 inch 

d) 5/8th inch (15.88mm) 

ANS: D 

Q4. What are the requirements regarding mill test reports according to API- 

650? 

a) No material shall be used in the construction of an AST unless it is 

accompanied by a mill test report 

b) Mill test reports are required only on shell plate material 

c) Mill test reports shall be furnished to the purchaser only when specified 

in the original purchase order 

d) Mill test reports shall be furnished to the purchaser prior to final 

acceptance of the AST 

ANS: c 


Q5. Mill and shop inspection releases the manufacturer from responsibility for 

replacing defective material. 

a) True 

b) False 

ANS: b 


Answers to API-Standard 650 Section 4, Fabrication 



Erection 


Q1. What welding process is not permitted when impact testing of the 

material is required? 

a) Shielded metal-arc 

b) Gas metal-arc 

c) Oxyfuel 

d) Submerged arc 

ANS: c 

Q2. Welding may be performed manually, automatically, or semiautomatically 

according to the procedures described in ____ of the ASME 

Code. 

a) Section VIII, Division 1 

b) B31.3 

c) Section VIII, Division 2 

d) Section IX 

ANS: d 


Q3. No welding of any kind shall be performed when the temperature of the 

base metal is less than ____°F 

a) Sixty 

b) Thirty-two 

c) Zero 

d) Negative fifteen 

ANS: c 

Q4. When base metal thickness is greater than 1.25 inches or the base metal 

temperature is 0°F -32°F, what requirement must be met? 

a) The base metal within 3 inches of the starting point of the welding shall 

be heated to a temperature warm to the hand 

b) The base metal within 3 inches of the starting point of the welding shall 

be heated to a temperature of not less than 200°F 

c) The base metal within 3 inches of the starting point of the welding shall 


d) The base metal within 3 inches of the starting point of the welding shall 


ANS: a 


Q5. What is the maximum acceptable undercut for horizontal butt joints? 


b) 1/32nd inch 

c) 3/64th inch 

d) 3/32nd inch 

ANS: b 

Q6. What is the maximum acceptable undercut for vertical butt joints? 

a) 3/32nd inch 

b) 3/64th inch 

c) 1/32nd inch 

d) 1/64th inch 

ANS: d 

b) Maximum permissible undercut is 0.4 mm (1/64 in.) in depth for vertical 

butt joints, vertically oriented permanent attachments, attachment welds for 

nozzles, manholes, flush-type openings, and the inside shell-to-bottom welds. 

For horizontal butt joints, horizontally oriented permanent attachments, and 

annular-ring butt joints, the maximum permissible undercut is 0.8 mm (1/32 in.) 

in depth. 


Q7. What is the maximum permissible weld reinforcement for a vertical joint in 

plate thickness 1.25”? 


b) 1/8th inch 

c) 1/4th inch 

d) 3/32nd inch 

ANS: a 

Q8. When tack welds are used during the assembly of vertical joints, what 

requirement is stipulated by API-650? 

a) Tack welds that are to be removed do not require a qualified procedure 

or welder 

b) Tack welds that are to be left in place shall be made using a qualified 

procedure only 

c) Tack welds that are to be removed may be made using a welder in 

training 

d) Tack welds that are to be left in place shall be made using a qualified 

procedure and welder 

ANS: d 


Q9. What is the requirement when protective coatings are used on surfaces 

to be welded? 

a) The coating must be removed prior to welding 

b) The coating shall be included in the welder’s performance qualification 

tests 

c) The coating shall be included in the welding procedure qualification 

d) The coating shall be identified on the purchase order 

ANS:c 

Q10. The welding of the ____ shall be practically complete prior to weldingout 

the bottom joints. 

a) Nozzle reinforcement periphery welds 

b) Shell-to-bottom weld 

c) All vertical and horizontal shell welds 

d) All external attachment welds 

ANS: b 


Q11. In a vertical joint of an AST, what is the maximum misalignment of 1.5” 

thick plate? 

a) Maximum misalignment is .150 inch 

b) Maximum misalignment is .145 inch 

c) Maximum misalignment is .135 inch 

d) Maximum misalignment is .125 inch 

ANS: d 

Q12. In a horizontal joint of an AST, what is the maximum projection of an 

upper plate beyond the face of the plate below it? The plate thickness is .25 

inch. 

a) Maximum projection is .0625 inch 

b) Maximum projection is .0500 inch 

c) Maximum projection is .1250 inch 

d) Maximum projection is .09375 inch 

ANS: a 


Q13. Multi-pass weld procedures are required for circumferential and vertical 

joints in tank shell courses constructed of material that is more than 1.5 

inches thick. What is the maximum weld pass size permitted and what is the 

minimum pre-heat temperature? 

a) No weld pass over ¾ inch with a minimum pre-heat of 300°F 

b) No weld pass over ½ inch with a minimum pre-heat of 200°F 

c) No weld pass over ¾ inch with a minimum pre-heat of 200°F 

d) No weld pass over ½ inch with a minimum pre-heat of 300°F 

ANS: c 

Q14. The initial weld pass inside the shell of the shell-to-bottom weld shall be 

cleaned and examined for its entire circumference. This examination shall be 

visually and by which of the following? 

a) Magnetic particle or ultrasonic or suitable liquid penetrant process 

b) Magnetic particle or suitable liquid penetrant process or a vacuum box 

and bubble method 

c) Magnetic particle or radiography or vacuum box and bubble method 

d) Magnetic particle or acoustic emission or eddy current 

ANS: b 


Q15. The required examination of the initial weld pass as described in API- 

650 may be waived subject to agreement between the purchaser and the 

AST manufacturer provided all but which of the following examinations are 

performed on the entire circumference of the weld(s) 

a) Examine either side of the finished weld by MT, PT, or right angle 

vacuum box 

b) Visually examine the initial weld (inside and outside) 

c) Visually examine the finished joint welded surfaces (inside and outside 

the shell) 

d) Examine either side of the finished weld by MT, PT, UT, or RT 

ANS: a 

Q16. What are the dimensions of a standard vacuum testing box? 

a) 6” wide by 30” long 

b) 6” wide by 24” long 

c) 6” wide by 36” long 

d) 6” wide by 32” long 

ANS: a 


API650: 7.2.4 Shell-to-Bottom Welds 7.2.4.1 The initial weld pass inside the 

shell shall have all slag and non-metals removed from the surface of the weld 

and then examined for its entire circumference both visually and by one of the 

following methods to be agreed to by Purchaser and the Manufacturer. If 

method “a” is applied, either inside or outside weld may be deposited first. If 

method b, c, d, or e is applied, the inside weld shall be deposited first: -------- 

7.2.4.3 By agreement between the Purchaser and the Manufacturer, the 

examinations of 7.2.4.1 may be waived if the following examinations are 

performed on the entire circumference of the weld(s). a) Visually examine the 

initial weld pass (inside or outside). b) Visually examine the finished joint 

welded surfaces, both inside and outside the shell. c) Examine either side of 

the finished joint weld surfaces by magnetic particle, or liquid penetrant, or 

right angle vacuum box. 


Q17. In an examination of a tank’s bottom weld seams by vacuum box testing, 

what is the required partial vacuum pressure? 

a) At least 1 lbf/in2 gauge (psig) 

b) At least 2 lbf/in2 gauge (psig) 

c) At least 3 lbf/in2 gauge (psig) 

d) At least 4 lbf/in2 gauge (psig) 

ANS: c 

Q18. If an alternative to vacuum box testing is used, whose approval is 

required? 

a) The Manufacturer 

b) The API-653 Inspector 

c) The local jurisdiction 

d) The purchaser 

ANS: d 


Q19. After fabrication is completed but prior to filling an aboveground storage 

tank with test water, reinforcing plates shall be tested. What method of test 

and pressure shall be used? 

a) A hydrostatic pressure test at up to 15 lbf/in2 (psig) 

b) A pneumatic pressure test at up to 15 lbf/in2 (psig) 

c) A vacuum test at a partial pressure of 2 lbf/in2 (psig) 

d) A pneumatic pressure test at up to 25 lbf/in2 (psig) 

ANS: b 

Q20. A new aboveground storage tank must be tested. If water is available for 

testing the shell, the tank shall be filled to any of the following levels except? 

a) To the maximum design liquid level 

b) Tanks with tight roofs, to 2 inches above the weld connecting the roof 

plate of compression bar to the top angle of the shell 

c) To overflowing to ensure all air is vented from the tank 

d) To a level lower than specified in a) or b) when restricted by overflows 

or freeboard agreement between the manufacturer and the purchaser 

ANS: c 


Q21. The purchaser of an AST that is designed to be gas tight required the 

roof to be tested pneumatically. What maximum pressure would be applied to 

a tank with ¼” thick roof plates? 

a) The maximum pneumatic pressure permitted is .053 psi 

b) The maximum pneumatic pressure permitted is .071 psi 

c) The maximum pneumatic pressure permitted is .083 psi 

d) The maximum pneumatic pressure permitted is .091 psi 

ANS: 

Solution: 3/16” thick plate = 7.65 lb/ft ∴1/16” = 2.55 lb/ft 

Q22. During the filling of an aboveground storage tank for testing, leakage 

was observed in a horizontal seam. Repairs are to be completed with the test 

water in the tank. The tank is 61 feet high and the leak is discovered 29 feet 

below the top of the tank. Where must the water level be during the repair? 

a) The water level shall be not less than 30 feet from the top of the tank 

b) The water level shall be not more than 32 feet from the bottom of the 

tank 

c) The water level shall be at the maximum design liquid level 

d) The water shall be removed from the tank ANS: d 


API650: 7.4.4 Repairs of defects discovered after the tank has been filled 

with water for testing shall be made with the water level at least 0.3 m (1 ft) 

below any point being repaired or, if repairs have to be made on or near the 

tank bottom, with the tank empty. Welding shall not be done on any tank 

unless all connecting lines have been completely blinded. Repairs shall not 

be attempted on a tank that is filled with oil or that has contained oil until the 

tank has been emptied, cleaned, and gas freed. Repairs on a tank that has 

contained oil shall not be attempted by the Manufacturer unless the manner 

of repair has been approved in writing by the Purchaser and the repairs are 

made in the presence of the Purchaser’s inspector. 

61 

water level 

30’ 

29’ 

leak 


Q23. A 60 foot high aboveground storage tank is designed with an internal 

floating roof. What is the maximum out-of-plumbness permitted on the 54.5 

foot fixed roof columns? 

a) 2.94 inches 

b) 3.27 inches 

c) 1.31 inches 

d) 1.18 inches 

ANS: b 

Q24. What is the maximum roundness tolerance (radius tolerance) permitted 

on an AST that is 110 feet in diameter and where is this tolerance applied? 

a) ¾” measured 10 feet above the bottom corner weld 

b) ¾” measured 1 foot below the top shell angle joint 

c) ¾” measured 1 foot above the bottom corner weld 

d) ¾” measured 10 feet below the top shell angle joint 

ANS: c 


Q25. Peaking at vertical welds and banding at horizontal welds shall not 

exceed ____. 

a) 1 inch 

b) ¾ inch 

c) ½ inch 

d) ¼ inch 

ANS: c 

Q26. Peaking and banding are determined using a horizontal sweep board for 

peaking and a straight edge vertical sweep board for banding. What is the 

required length of these sweep boards? 

a) 48 inches 

b) 24 inches 

c) 42 inches 

d) 36 inches 

ANS: d 


Q27. The top of the concrete ringwall (where installed) of an AST must be 

level within ± 1/8” in any 30 feet of circumference. What is the total 

circumferential tolerance measured from the average elevation? 

a) ±1/8” b) ±3/16” 

c) ±1/2” d) 1/4” 

ANS: d 

Q28. Where a concrete ringwall is not provided, the foundation under the 

shell shall be level to within what tolerances? 

a) ±1/8” in any 30’ of the circumference and ±1/2” in the total 

circumference measured from the average elevation 

b) ±1/8” in any 10’ of the circumference and ±1/2” in the total 


c) ±1/8” in any 10’ of the circumference and ±1/4” in the total 


d) ±1/8” in any 30’ of the circumference and ±1/4” in the total 


ANS: b 


Q29. For foundations specified to be sloped from a horizontal plane, the 

actual elevation shall not deviate from the calculated differences by more than 

which of the following where concrete ringwalls are provided? 




circumference 



d) ±1/8” in any 30’ of the circumference and ±1/4” in the total 

circumference 

ANS: d 

Q30. For foundations specified to be sloped from a horizontal plane, the 

actual elevation shall not deviate from the calculated differences by more than 

which of the following where concrete ringwalls are not provided? 




circumference 



Answers to API-Standard 650 Section 5, Erection 



Method of Inspection Joints 


Q1. With regards to radiographic examination of welded joints, API-650 

considers plates to be the same thickness when the difference in their 

specified or design thickness is not greater than ____. 

a) 1/32nd inch 

b) 1/16th inch 

c) 3/32nd inch 

d) 1/8th inch 

ANS: d 

Q2. Which of the following joints do not require radiographic examination? 

a) Bottom-plate welds 

b) Shell butt welds 

c) Flush-type connections with butt welds 

d) Annular-plate butt welds 

ANS: a 


Q3. Vertical butt welds in plates not greater than 3/8th inch thick, require one 

spot radiograph to be taken in the first _____ of completed vertical joint of 

each type and thickness by each welder or welding operator. 

a) 100 feet 

b) 50 feet 

c) 25 feet 

d) 10 feet 

ANS: d 

Q4. One additional spot radiograph shall be taken in each additional ____ of 

vertical joint of the same type and thickness. 

a) 10 feet 

b) 200 feet 

c) 100 feet 

d) 25 feet 

ANS: c 


Q5. What percentage of the selected spot radiographs must be at junctions of 

vertical and horizontal welded joints? 

a) 25 percent 

b) 50 percent 

c) 75 percent 

d) 15 percent 

ANS:a 

Q6. For butt welded joints in plates over 3/8” to not over 1” in thickness are 

required to be radiographically examined to the same extent as plates 3/8” 

and less. What additional spot examination does API-650 require for these 

welded joints? 

a) 50 percent of all vertical and horizontal junctions 

b) 75 percent of all vertical and horizontal junctions 

c) 100 percent of all vertical and horizontal junctions 

d) 25 percent of all horizontal joints between the first and second course 

ANS: c 


Q7. The radiographic film for all junctions of vertical and horizontal joints shall 

show at least ____ of weld length on each side of the vertical intersection. 

a) 3 inches 

b) 2 inches 

c) 1 inch 

d) 4 inches 

ANS: b 

Q8. The butt weld around the periphery of an insert manhole or nozzle shall 

be ____. 

a) Completely examined by liquid penetrant methods 

b) Completely examined by ultrasonic methods 

c) Completely examined by magnetic particle methods 

d) Completely examined by radiographic methods 

ANS: d 


Q9. After the initial spot radiograph in the first 10 feet of horizontal butt joint, 

additional spot radiographs shall be taken at what increment? 

a) One radiograph shall be taken in each additional 200 feet 

b) One radiograph shall be taken in each additional 100 feet 

c) One radiograph shall be taken in each additional 300 feet 

d) One radiograph shall be taken in each additional 150 feet 

ANS: a 

Q10. What is the minimum weld length that must be clearly shown on each 

radiograph? 

a) 2 inches 

b) 3 inches 

c) 6 inches 

d) 8 inches 

ANS: c 


Q11. Personnel who perform and evaluate radiographic examinations 

according to API-650 shall be qualified and certified by the manufacturer as 

meeting the requirements as generally outlined in _____. 

a) Level II or Level III of ASNT SNAT-TC-1B 

b) Level II or Level III of ASNT SNT-TC-1B 

c) Level II or Level III of ASNT SNAT-TC-1A 

d) Level II or Level III of ASNT SNT-TC-1A 

ANS: d 

Q12. The acceptance standards for radiographic examinations shall be in 

accordance with which of the following? 

a) Paragraph UW-51(b) in Section VIII of the ASME Code 

b) Paragraph PW-51(b) in Section I of the ASME Code 

c) Paragraph 341.3.2 in B31.3 Process Piping of the ASME Code 

d) Paragraph RB-3233 in the National Board Inspection Code (NBIC) 

ANS: a 


Q13. If a section of weld is shown by a radiograph to be unacceptable under 

the provisions of API-650, paragraph 6.1.5 or the radiograph does not define 

the limits of the deficient welding, which of the following requirements apply? 

a) One additional spot shall be taken and at least 3” of weld shall be 

represented 

b) Two spots adjacent to the section shall be examined by radiography 

c) Two spots ten feet from each side of the original radiography shall be 

examined 

d) Two spots, chosen randomly by the purchaser’s inspector, shall be 

examined by radiography 

ANS: a 

Q14. After an aboveground storage tank is completed, what shall be done 

with the radiographs? 

a) They shall become the property of the insurance company 

b) They shall become the property of the manufacturer 

c) They shall become the property of the purchaser 

d) They shall become the property of the API 

ANS: c 


Q15. According to API-650, magnetic particle examination shall be performed 

to a written procedure. The examiner shall have his/her vision checked and 

be able to read which of the following? 

a) The magnetic particle written procedure at a distance not less than 12 

inches 

b) A Jaeger Type 3 standard chart at a distance not less than 12 inches 

c) A Jaeger Type 1 standard chart at a distance not less than 12 inches 

d) A Jaeger Type 2 standard chart at a distance not less than 12 inches 

ANS: d 

Q16. Ultrasonic examination shall be performed in accordance with a written 

procedure. Examiners shall be qualified and certified by the manufacturer as 

meeting the requirements of certification as generally outlined in which of the 

following? 

a) Level II or Level III of ASNT SNAT-TC-1B 

b) Level II or Level III of ASNT SNT-TC-1B 

c) Level II or Level III of ASNT SNAT-TC-1A 

d) Level II or Level III of ASNT SNT-TC-1A 

ANS: d 


Q17. Liquid penetrant examination shall be performed in accordance with a 

written procedure. The examiner shall have his/her vision checked and be 

able to read which of the following? 

a) The liquid penetrant written procedure at a distance not less than 12 

inches 

b) A Jaeger Type 2 standard chart at a distance not less than 12 inches 

c) A Jaeger Type 1 standard chart at a distance not less than 12 inches 

d) A Jaeger Type 3 standard chart at a distance not less than 12 inches 

ANS: b 

Q18. Undercutting of welds attaching nozzles, manholes, cleanout openings, 

and permanent attachments shall not exceed which of the following? 

a) Undercutting shall not exceed 1/64th inch 

b) Undercutting shall not exceed 3/32nd inch 

c) Undercutting shall not exceed 1/32nd inch 

d) Undercutting shall not exceed 3/64th inch 

ANS: a 


Answers to API-Standard 650 Section 6, Methods of Inspecting Joints 



Welding Procedure and Welder Qualifications 


Q1. Who is responsible for preparing the welding procedure specification, 

performing the qualification tests, and preparing the procedure qualification 

record? 

a) The welding operator or welder 

b) The purchaser’s inspector 

c) The purchaser’s welding engineer 

d) The erection manufacturer or the fabrication manufacturer if other than 

the erection manufacturer 

ANS: d 

Q2. The manufacturer has the approval of the purchaser to use a material 

listed in API-650 but not included in the applicable table of ASME Section IX. 

What Group number would this material be included in if the minimum tensile 

strength is specified at 73,000 psi? 

a) This material would be included in Group number 2 

b) This material would be included in Group number 1 

c) This material would be included in Group number 3 

d) This material can not be used in AST construction 

ANS: a 


Q3. When impact tests of the heat-affected zone are required, how shall this 

requirement be treated? 

a) Heat treated condition of the base metal shall be a non-essential 

variable 

b) Heat treated condition of the base metal shall be an essential variable 

c) Heat treated condition of the base metal shall be a supplementary 

essential variable 

d) Heat treated condition of the base metal does not need to be 

addressed on the welding procedure specification 

ANS: c 

Q4. If a protective coating has been applied to weld edge preparations, how is 

this condition treated on the welding procedure specification? 

a) The coating shall be removed and does not affect the weld and 

therefore does not need to be addressed 

b) The coating shall be included as an essential variable 

c) The coating shall be included as a non-essential variable 

d) The coating shall be included as a supplementary essential variable 

ANS: b 


Q5. Materials to be used at a design metal temperature below ____, the 

qualification of the welding procedure for vertical joints shall include impact 

tests of the weld metal. 

a) 50°F 

b) 32°F 

c) 60°F 

d) 0°F 

ANS: a 

Q6. Welder qualification tests conducted by one manufacturer shall not 

qualify a welder or welding operator to do work for another manufacturer. 

a) True 

b) False 

ANS: a 


Q7. Traceability to a welder or welding operator, either by welder’s 

identification stamp or “weld map”, is required on all but which of the following? 

a) Shell horizontal weld joints 

b) Shell vertical weld joints 

c) Annular plate butt welds (when annular plates are required) 

d) Roof plate welds and flange-to-nozzle neck welds 

ANS: d 


Answers to API-Standard 650 Section 7, Welding Procedure and Welder 

Qualifications 



Marking 


Q1. A nameplate shall identify aboveground storage tanks made in 

accordance with API-650. Where must this nameplate be located on the 

completed tank? 

a) This nameplate shall be attached to the tank shell adjacent to a 

manhole or to a manhole reinforcing plate immediately to the right of the 

manhole 

b) This nameplate shall be attached to the tank shell adjacent to a vertical 

weld joint at least 48” above the shell-to-bottom weld joint 

c) This nameplate shall be attached to the tank shell adjacent to a 

manhole or to a manhole reinforcing plate immediately above the 

manhole 

d) This nameplate shall be attached to the tank shell adjacent to a 

manhole or to a manhole reinforcing plate immediately below the 

manhole 

ANS: a 


Q2. The manufacturer of an AST is required to certify to the purchaser that 

the tank has been constructed in accordance with API-650. How is this 

certification accomplished? 

a) The manufacturer shall provide the purchaser with a U-1 Data Report 

form 

b) The manufacturer shall provide the purchaser with letter 

c) The manufacturer shall provide the purchaser with an ASME 

acceptable “Certificate of Compliance” 

d) The manufacturer shall provide the purchaser with a notarized 

certificate of compliance 

ANS: b 

10.3 Certification The Manufacturer shall certify to the Purchaser, by a letter 

such as that shown in Figure 10.2, that the tank has been constructed in 

accordance with the applicable requirements of this standard. An as-built data 

sheet in accordance with Annex L shall be attached to the certification letter. 


Answers to API-Standard 650 Section 8, Marking 


API650 Appendix A 

Optional Design Basis for Small Tanks 


Q1. What is the maximum shell thickness including corrosion allowance 

permitted for tanks that comply Appendix A of API-650? 

a) 7/8th inch 

b) 3/4th inch 

c) 5/8th inch 

d) 1/2 inch 

ANS: d 

Q2. What is the maximum tensile strength, before the joint efficiency is 

applied, permitted in the design of small tanks in accordance with Appendix A 

of API-650? 

a) 21000 psi 

b) 21500 psi 

c) 21000 ksi 

d) 21500 ksi 

ANS: a 


Q3. When computing the tension in each ring (course) of a small tank 

designed in accordance with Appendix A of API-650, where is this tension 

computed? 

a) The tension shall be computed 12 inches above the centerline of the 

course in question 

b) The tension shall be computed 12 inches above the centerline of the 

lower horizontal joint of the course in question 

c) The tension shall be computed 12 inches above the centerline of the 

tank in question 

d) The tension shall be computed 12 inches below the centerline of the 

upper horizontal joint of the course in question 

ANS: b 


Q4. What joint efficiency factor shall be used in the design of small tanks 

designed in accordance with Appendix A of API-650 when spot radiographic 

examination is applied? 

a) 1.00 

b) 0.90 

c) 0.85 

d) 0.70 

ANS: c 

Q5. What joint efficiency factor shall be used in the design of small tanks 

designed in accordance with Appendix A of API-650 when spot radiographic 

examination is omitted? 

a) 1.00 

b) 0.90 

c) 0.85 

d) 0.70 

ANS: d 


Answers to API-Standard 650 

Appendix A - Optional Design Basis for Small Tanks 


API650 Appendix B – Recommendations for Design 

and Construction of Foundations for Aboveground Oil 

Storage Tanks 


Q1. If the owner does not specify an alternative grade slope, the finished tank 

grade shall be crowned from its outer periphery to its center at a slope of 

_____. 

a) The slope shall be one inch in twelve feet 

b) The slope shall be one inch in ten feet (1:120) 

c) The slope shall be one inch in eight feet 

d) The slope shall be one inch in six feet 

ANS: 

Q2. The owner decides that an earth foundation will be installed under a new 

tank installation. According to API-650 Appendix B, there are specific items 

that an earth foundation should accomplish. Of the following, which is not one 

of those items? 

a) Earth foundations should provide a stable plane for support of the tank 

b) Earth foundations should limit settlement to values used in the design 

of the connecting piping 

c) Earth foundations should not settle excessively at the perimeter due to 

the weight of the tank 

d) Earth foundations should reinforced with steel reinforcing bar to 

prevent sagging 

ANS: 


Q3. When does Appendix B of API-650 recommend the use of a concrete 

ringwall foundations? 

a) When there is some doubt whether the foundation will be able carry 

the shell load directly 

b) When there will be an area in the foundation open for passing cathodic 

protection equipment through 

c) When the tank is located in an area that is easily accessible for pouring 

the concrete 

d) When the tank erector decides a concrete foundation will be easier to 

install 

ANS: a 

Q4. When a concrete ringwall is designed, what is the minimum thickness 

permitted? 

a) The ringwall shall not be less than 8 inches 

b) The ringwall shall not be less than 10 inches 

c) The ringwall shall not be less than 12 inches 

d) The ringwall shall not be less than 14 inches 

ANS: 


Q5. How far below the lowest adjacent finish grade must the bottom of the 

ringwall, if founded on soil, be located? 

a) The bottom of the ringwall shall be located 1 foot below grade 

b) The bottom of the ringwall shall be located 1.5 feet below grade 

c) The bottom of the ringwall shall be located 2.5 feet below grade 

d) The bottom of the ringwall shall be located 2 feet below grade 

ANS: 

12 in.? 

ringwall 

adjacent finish grade 

2 feet 


B.4.2.2 When a concrete ringwall is designed, it shall be proportioned so that 

the allowable soil bearing is not exceeded. The ringwall shall not be less than 

300 mm (12 in.) thick. The centerline diameter of the ringwall should equal the 

nominal diameter of the tank; however, the ringwall centerline may vary if 

required to facilitate the placement of anchor bolts or to satisfy soil bearing 

limits for seismic loads or excessive uplift forces. The depth of the wall will 

depend on local conditions, but the depth must be sufficient to place the 

bottom of the ringwall below the anticipated frost penetration and within the 

specified bearing strata. As a minimum, the bottom of the ringwall, if founded 

on soil, shall be located 0.6 m (2 ft) below the lowest adjacent finish grade. 

Tank foundations must be constructed within the tolerances specified in 7.5.5. 

Recesses shall be provided in the wall for flush-type cleanouts, drawoff 

sumps, and any other appurtenances that require recesses. 


Answers to API-Standard 650 Appendix B - Recommendations for 

Design of Foundations for Aboveground Oil Storage Tanks 


API650 Appendix C 

External Floating Roofs 








Q1. Unless otherwise specified by the purchaser, all deck plates shall have a 

minimum nominal thickness of _____. 

a) 1/4 inch 

b) 1/8 inch 

c) 3/16 inch (4.76mm) 

d) 3/32 inch 

ANS: c 

Q2. What is the minimum slope required for the top decks of double-deck 

roofs and of pontoon sections? 

a) 3/16 inch in 12 inches (1:64) 

b) 3/16 inch in 12 feet 

c) 3/16 inch in 10 inches 

d) 3/16 inch in 10 feet 

ANS: a 


Q3. Pontoon type floating roofs shall have sufficient buoyancy to remain 

afloat on a liquid with a specific gravity of ____. 

a) 1.0 

b) .87 

c) .85 

d) .70 

ANS: d 

Q4. What is the minimum size of roof drain required for a pan-type floating 

roof that is 110 feet in diameter. 

a) NPS 4 

b) NPS 3 

c) NPS 2 

d) NPS 2.5 

ANS: 


Q5. Floating roof support legs and attachments shall be designed to support 

the roof and a uniform live load of at least _____ per square foot. 

a) 100 pounds 

b) 75 pounds 

c) 50 pounds 

d) 25 pounds 

ANS: 

Q6. Manholes are required in floating roofs for access to the tank interior and 

for ventilation. What is the minimum nominal diameter of these manholes? 

a) 24 inches 

b) 20 inches 

c) 18 inches 

d) 15 inches 

ANS: 


Q7. If the sealing device between the outer periphery of the roof and the tank 

shell employs steel shoes, what material shall these shoes be made of and 

what is the minimum nominal thickness permitted? 

a) The shoes shall be made from galvanized sheet ASTM A 924 with a 

minimum thickness of 14 gauge 

b) The shoes shall be made from galvanized sheet ASTM A 924 with a 


c) The shoes shall be made from galvanized sheet ASTM A 924 with a 


d) The shoes shall be made from galvanized sheet ASTM A 924 with a 


ANS: 


Q8. Drainpipe and hose systems of primary drains shall be tested with water 

at a pressure of ___. 

a) 0.5 psig 

b) 5.0 psig 

c) 50 psig 

d) 50 ksig 

ANS: 


Drainpipe and hose systems of primary drains 


Answers to API-Standard 650 Appendix C - External Floating Roofs 


API650 Appendix G – Structurally 

Supported Aluminum Dome Roofs 






Q1. Aluminum dome roofs may be added to an existing tank. Who has the 

responsibility for providing reinforcement to enable the tank to support the 

roof? 

a) The fabricator if other than the erector 

b) The erector if other than the manufacturer 

c) The manufacturer 

d) The purchaser 

ANS: 

Q2. Aluminum dome roof shall be supported only from the rim of the tank. 

The design of the connection shall allow for thermal expansion. What is the 

minimum temperature range that must be used for the design? 

a) ±110°F 

b) ±120°F (67°C) 

c) ±125°F 

d) ±130°F 

ANS: 


Q3. Aluminum panels shall be designed in accordance with ___ and 

Appendix G of API-650. 

a) AA ASM-35 

b) AA ASM-135 

c) AA ASM-53 

d) AA ASM-315 

ANS: 

Q4. The internal pressure of tanks with aluminum dome roofs shall not 

exceed the weight of the roof. In no case shall the maximum design pressure 

exceed ____ 

a) 9 psig 

b) 9 inches of mercury column 

c) 0.9 psig 

d) 9 inches of water column 

ANS: 


Q5. The maximum dome radius shall be ____ times the diameter of the tank. 

The minimum dome radius shall be ___ times the diameter of the tank unless 

other wise specified by the purchaser. 

a) 1.2 and 0.9 

b) 1.2 and 0.5 

c) 1.2 and 0.7 

d) 1.2 and 0.8 

ANS: 


Answers to API-Standard 650 Appendix G - Structurally Supported 

Aluminum Dome Roofs 


API650 Appendix H – Internal Floating 

Roofs 


Internal Floating Roofs 


Q1. Internal floating roofs may be designed and built to float and rest in a 

reasonably flat position. A rim or skirt shall be provided around the roof 

periphery and all columns, ladders, and other roof openings. How far must 

this rim extend above the liquid? 

a) 3 inches 

b) 6 inches 

c) 9 inches 

d) 12 inches 

ANS: 

Q2. Internal floating roofs shall be designed to safely support at least _____. 

a) 500 pounds over 1 square foot 

b) 500 pounds over 1 square inch 

c) 500 pounds over 1 square yard 

d) 500 pounds over 1 square meter 

ANS: 


Q3. What is the minimum required thickness, excluding corrosion allowance, 

for a steel internal floating roof in contact with vapor? 

a) The minimum thickness shall be 0.094 inches 

b) The minimum thickness shall be 9 gauge 

c) The minimum thickness shall be 0.07 inches 

d) The minimum thickness shall be 7 gauge 

ANS: 

Q4. A peripheral seal shall be designed to accommodate ____ of local 

deviation between the floating roof and the shell. 

a) ±2 inches 

b) ±3 inches 

c) ±4 inches 

d) ±5 inches 

ANS: 


Q5. Which of the following is not permitted as a design for internal floating 

roofs in contact with the liquid? 

a) Double deck 

b) Pontoon 

c) Metallic Pan 

d) Metallic on floats 

ANS: 

Q6. Metallic internal roofs on floats shall be designed to be buoyant enough 

to support how much weight? 

a) Twice its dead weight 

b) Twice the weight of two men 

c) 500 pounds per square foot 

d) Three times its dead weight 

ANS: 


Q7. The maximum spacing between circulation vents shall be _____. 

a) 24 feet 

b) 32 feet 

c) 28 feet 

d) 30 feet 

ANS: 

Q8. What is the minimum number of circulation vents that must be located on 

the shell or fixed roof above the seal of the floating roof when the tank is full? 

a) 8 

b) 4 

c) 6 

d) 2 

ANS: 


Q9. How many and what size manholes must be provided in a fixed roof for 

access to the tank interior? 

a) At least two with a nominal diameter of 24 inches each 

b) At least three with a nominal diameter of 24 inches each 

c) At least one with a nominal diameter of 24 inches 

d) At least four with a nominal diameter of 24 inches each 

ANS: 

Q10. When specified by the purchaser, inspection hatches shall be located 

on the fixed roof to permit visual inspection of the seal region. What is the 

maximum spacing between these hatches? 

a) 32 feet 

b) 50 feet 

c) 75 feet 

d) 100 feet 

ANS: 


Answers to API-Standard 650 Appendix H - Internal Floating Roofs 


API650 

Remaining Appendixes 


Remaining Appendixes 

Appendix D – Technical Inquiries 

This appendix provides guidance for requesting interpretations of API 

Standard 650. The inquiry format is specific must be followed. Basically 

inquiries shall be formulated in such a way that they can be answered “yes” or 

“no”. 

Appendix E – Seismic Design of Storage Tanks 

According the “Body of Knowledge”, question pertaining to this Appendix will 

be excluded on the API-653 examination. 

Appendix F – Design of Tanks for Small Internal Pressures 




Appendix I – Under-tank Leak Detection and Sub-grade Protection 

This appendix provides basic recommendations, which may be specified by 

the purchaser, for design and construction of tank and foundation systems 

that provide leak detection and sub-grade protection in the event of tank 

bottom leakage, and provides for tanks supported by grillage. Typically, this 

appendix would only be used as a guide. The body of knowledge states that 

questions pertaining to tanks supported by grillage will be excluded on the 

examination. 

Appendix J – Shop Assembled Storage Tanks 

This appendix presents requirements covering the complete assembly of 

tanks that do not exceed 20 feet in diameter. 

Appendix K – Application of the Variable-Design- Point Method 




Appendix L – API Standard 650 Storage Tank Data Sheets 

This appendix provides data sheets to be used by the purchaser in ordering a 

storage tank and by the manufacturer upon completion of construction of the 

tank. 

Appendix M – Requirements for Tanks Operating at Elevated 

Temperatures 

This appendix provides additional requirements for tanks with maximum 

operating temperatures from 200°F to 500°F. 

Appendix N – Use of New Materials That Are Not Identified 

This appendix provides requirements for the use of new or unused plate and 

pipe materials that are not completely identified by this standard as complying 

with any listed specification. 

Appendix O – Recommendations for Under-Bottom Connections 

This appendix contains recommendations for the design and construction of 

under-bottom connections for storage tanks 


Appendix P – Allowable External Loads on Tank Shell Openings 

This appendix presents minimum recommendations for design of shell 

openings that conform to Table 3 – 8 that are subject to external piping loads. 

The purchaser or manufacturer may agree upon an alternative or 

supplemental design. According to the body of knowledge, questions 

pertaining to this appendix will not be asked on the examination. 

Appendix S – Austenitic Stainless Steel Tanks 




API RP 651 

Cathodic Protection of Aboveground 

Petroleum Storage Tanks 

API RECOMMENDED PRACTICE 651 

FOURTH EDITION, SEPTEMBER 2014 


Section 4 - Corrosion of Above Ground 

Steel Storage Tanks 


Q1. According to API Recommended Practice - 651, there are four 

components in each corrosion cell. Theses components are an anode and all 

but which of the following? 

a) DC current supplied by batteries 

b) A cathode 

c) A metallic path connecting the anode and cathode 

d) An electrolyte 

ANS: a 

Q2. The base metal goes into solution (corrodes) by releasing electrons and 

forming positive metal ions. This statement describes what takes place at 

what component of a corrosion cell? 

a) The cathode 

b) The electrolyte 

c) The metallic connection between the cathode and the anode 

d) The anode 

ANS: d 


Q3. Which of the following is the most correct statement regarding the 

cathode? 

a) Moderate corrosion takes place at the cathode 

b) No corrosion takes place at the cathode 

c) All corrosion takes place at the cathode 

d) A chemical reaction takes place using electrons released at the 

electrolyte 

ANS: b 

Q4. The electrolyte contains ions and conducts positive current from the 

anode to the cathode. The most common electrolyte for external tank bottom 

surfaces is _______, while the most common for internal surfaces is 

_________. 

a) Water, sludge and moist soil 

b) Moist soil, water and sludge 

c) Acidic soil, water and sludge 

d) Moist soil, product and sludge 

ANS: b 


Q5. The two most common types of corrosion to tank bottoms are ______ 

and ______. 

a) Stress corrosion and galvanic 

b) Erosion and erosion/corrosion 

c) General and pitting 

d) Stray current and bimetallic 

ANS: c 

Q6. Which type of corrosion results in relatively uniform metal loss? 

a) Erosion and erosion/corrosion 

b) Stray current 

c) General 

d) Pitting 

ANS: c 


Q7. Which type of corrosion may only affect relatively small areas, while 

substantial areas of the surface are unaffected by corrosion? 

a) Galvanic 

b) General 

c) Brittle 

d) Pitting 

ANS: d 

Q8. Composition of the metal is a factor in determining which areas become 

anodes and which become cathodes. What else can cause corrosion? 

a) Differences between weld metal, heat affected zone, and parent metal 

b) Differences in thickness between adjacent plates 

c) Improper fit-up of the welded joint 

d) Slag inclusion in the weld metal 

ANS: a 


Q9. Which of the following is a correct statement regarding oxygen 

concentration of the electrolyte. 

a) Oxygen concentration in the electrolyte has no impact on the corrosion 

cell 

b) Areas of lower oxygen concentrations become anodic and areas of 

higher concentrations become cathodic. 

c) Areas of lower oxygen concentrations become cathodic and areas of 

higher concentrations become anodic 

d) Areas of lower oxygen concentrations become acidic and areas of 

higher concentrations become alkaline 

ANS: b 

Q10. Soil characteristics substantially affect what? 

a) What type of product may be stored in the tank 

b) What the maximum fill height of the tank is 

c) The type and rate of corrosion on a structure in contact with soil 

d) Perk rate for dissipation of small leaks from the tank bottom 

ANS: c 


Q11. What is another term used for "stray currents"? 

a) Short circuits 

b) Positive currents 

c) Impressed currents 

d) Interference currents 

ANS: d 

Q12. The most common and potentially the most damaging stray currents are: 

a) Direct currents 

b) Alternating currents 

c) Intermittent currents 

d) Close proximity alternating currents 

ANS: a 


Q13. Which of the following is not likely to be a source of stray currents? 

a) Static electricity 

b) Welding machines 

c) Impressed current cathodic protection systems 

d) Railroads 

ANS: a 

Q14. Two metals with different compositions connected in an electrolyte is a 

general description of: 

a) A battery 

b) A current suppressor 

c) A short circuit 

d) Galvanic corrosion 

ANS: d 


Q15. All but one of the following is listed as major factors which influence the 

severity of internal corrosion. Which is not a factor? 

a) The pH level of the fluid in contact with the steel bottom 

b) The amount of nitrogen in the fluid in contact with the steel bottom 

c) Suspended solids in the fluid in contact with the steel bottom 

d) Conductivity of the fluid in contact with the steel bottom 

ANS: b 

Q16. Three major types of internal corrosion to be considered are general 

corrosion, pitting corrosion, and to a lesser extent in tanks, environmental 

cracking. 

a) True 

b) False 

ANS: a 


Answers to API-651 Section 4, corrosion of Aboveground Steel Storage 

Tanks 


Section 5 - Determination of Need for 

Cathodic Protection 


Q1. API Recommended Practice 651 states that the need for cathodic 

protection must be determined for all storage facilities. Decisions governing 

the need for cathodic protection should be based on all but which of the 

following? 

a) Data from corrosion surveys and operating records 

b) National Board and ASME recommendations 

c) Prior test results with similar systems in similar environments 

d) National, state, and local code requirements and the recommendations 

in API-651 

ANS: b 

Q2. When should corrosion control by cathodic protection for new ASTs be 

provided? 

a) After final welding and before hydrostatic testing 

b) After all stress relief has been carried out 

c) In the initial design 

d) After the tank is in service for 6 months 

ANS: c 


Q3. Generally tanks in petroleum service use ______ on the internal surfaces 

to control internal corrosion. 

a) AC Current instead of DC current cathodic protection systems 

b) Coatings 

c) Cathodic protection in conjunction with coatings 

d) Since pure hydrocarbon fluids are usually not corrosive experience 

shows that internal corrosion will never occur therefore, corrosion control 

is not necessary 

ANS: b 

Q4. Cathodic protection is an effective means of corrosion control only if it is 

possible to pass electrical current between what two components? 

a) Anode and cathode 

b) Tank shell and roof support system 

c) Roof to bottom through roof support structures 

d) Tank shell and tank bottom 

ANS: a 


Q5. A full evaluation of tank history should be performed prior to _______. 

a) Filling the tank for the 25th time 

b) Painting the exterior surface of the tank 

c) Temporarily removing the tank from service 

d) Determining the need for cathodic protection 

ANS: d 

Q6. Such items as site plan, soil properties, previous repairs, existing 

cathodic protection of nearby structures, maintenance history, and expected 

life should be investigated and determined when conducting the 

____________. 

a) Evaluation of the location of a refinery 

b) Probability study of tank settlement 

c) Evaluation of tank design/construction history 

d) Evaluation of tank repairs and alterations 

ANS: c 


Q7. Of the following items which is not an item that should be investigated 

and determined in the evaluation of types of service? 

a) Type of product stored 

b) Product temperature 

c) Ambient temperature 

d) Presence and depth of water bottoms 

ANS: c 

Q8. Such items as tank inspections per API Standard 653, corrosion rate 

records, stray current problems, design and performance of previous 

protection systems, and structure-to-soil potential surveys should be 

investigated and determined when conducting the ______. 

a) Evaluation of tank repair/alteration/construction history 

b) Evaluation of tank design/construction history 

c) Evaluation of types of service 

d) Evaluation of inspection/corrosion history 

ANS: d 


Q9. The cushion material under the tank has a significant effect on external 

corrosion of the tank bottom. The material can also influence: 

a) The effectiveness and applicability of external cathodic protection 

b) The effectiveness and applicability of internal cathodic protection 

c) The decision to use or not use a rectifier or DC generator set to supply 

current 

d) The type of product that may be stored in the tank 

ANS: a 

Q10. What is an advantage of using fine particles for the cushion material? 

a) The fine particles should be uniform which makes it easier to transport 

b) Fine particles provide a more dense cushion to help reduce the influx 

and outflow of oxygen 

c) Fine particles will not permit the passage of product should a leak 

occur in the tank bottom 

d) Fine particles will hold moisture longer permitting it to stabilize and 

prevent acid from forming in the electrolyte 

ANS: b 


Q11. What is the main disadvantage in using large size particles in the soil 

cushion material? 

a) The large particles may puncture the tank bottom 

b) The large particles may trap moisture and allow general corrosion to 

form 

c) If large particles are used, differential aeration corrosion may result 

where the particles contact the tank bottom 

d) The large particles are more difficult to transport 

ANS: c 

Q12. A soil resistivity of about 1250 OHM-CM would indicate the soil is 

probably ____. 

a) Mildly corrosive 2000-10000 

b) Very corrosive

Table 1—General Classification of Resistivity 


Q13. The results of soil resistivity surveys can be used to determine 

________. 

a) When it is time to replace the cushion material under the tank bottom 

b) The need for cathodic protection 

c) The amount of compression of the cushion material under the tank 

d) The best place to install a corrosion test bed 

ANS: b 

Q14. A properly designed concrete tank cushion constructed on stable, 

properly prepared subsoil may be effective in all but which of the following? 

a) Cracks in the tank bottom weld seams 

b) Intrusion of groundwater 

c) Soil-side corrosion 

d) The need for cathodic protection 

ANS: d 


Q15. Cracks through the concrete cushion may permit water and 

contaminants to permeate to the steel tank bottom and provide a path for 

proper electrical current flow. 

a) True 

b) False 

ANS: b 

Q16. Corrosion of the steel tank bottom installed on a concrete cushion may 

result from moisture accumulation caused by all but which of the following? 

a) Condensation 

b) Blowing snow or rain 

c) Humidity in the air surrounding the tank 

d) Flooding 

ANS: c 


Q17. Why would it be more important to provide proper support under 

cushions of new asphalt than for concrete? 

a) Asphalt is inherently alkaline and therefore does not have the potential 

of preventing corrosion 

b) Asphalt is not inherently alkaline and therefore does not have the 

potential of preventing corrosion 

c) Asphalt may degrade and become a corrosive substance 

d) Asphalt may crack allowing moisture to reach the tank bottom where it 

will react violently with the asphalt and the steel tank bottom 

ANS: d 

Q18. How can the condition of the external surface of tank bottom and the 

asphalt cushion be determined? 

a) Raise the entire tank and inspect the tank bottom and the asphalt 

b) Take a core sample from the asphalt for testing. This test will reveal 

the amount of steel that has gone into solution and been trapped in the 

asphalt 

c) Conduct a soil resistivity survey around the periphery of the tank 

containment 

d) By cutting coupons from the tank bottom 

ANS: d 


Q19. A soil analysis reveals the pH of a native soil cushion to be 6.25. This 

soil is considered to be: 

a) Moderately corrosive 

b) Mildly corrosive 

c) Corrosive 

d) Very corrosive 

ANS: b 

Q20. A soil analysis reveals the sulfates level of a native soil cushion to be 

5525ppm. This soil is considered to be 

a) Moderately corrosive 

b) Mildly corrosive 

c) Corrosive 

d) Very corrosive 

ANS: d 


5.3.2.1 Sand Pad Material 

• Measuring pH indicates the hydrogen ion content of a soil. Corrosion of 

steel is fairly independent of pH when it is in the range of 5.0 to 8.0. The 

rate of corrosion increases appreciably when pH is < 5.0 and decreases 

when pH is > 8.0. pH may be determined in accordance with ASTM G51 or 

equivalent. 

• Chlorides will affect the resistivity of soil, and act as a depolarizing agent 

which will increase the current requirement for cathodic protection of steel. 

Pitting corrosion on steel can begin at chloride levels of 10 ppm. Chloride 

content may be determined in accordance with ASTM D512 or equivalent. 

There is currently no industry consensus on an acceptable range for 

chloride levels, therefore the tank owner/operator should specify the 

acceptable chloride level. There are practical and possible economic 

limitations in achieving minimum levels of chloride content. 


i) Sulfate levels > 200 ppm frequently indicate high concentrations of organic 

matter. Sulfate content may be determined in accordance with ASTM 

D516 or equivalent. There iscurrently no industry consensus on an 

acceptable range for sulfate levels, therefore the tank owner/operator 

should specify the acceptable sulfate level. There are practical and 

possible economic limitations in achieving minimum levels of sulfate 

content. 

ii) Sulfide levels > 0.10 ppm, may indicate that sulfates have been reduced 

by bacteria. Sulfide content may be determined in accordance with EPA 

0376.1 or equivalent. There is currently no industry consensus on an 

acceptable range for sulfide levels, therefore the tank owner/operator 

should specify the acceptable sulfide level. There are practical and 

possible economic limitations in achieving minimum levels of sulfide 

content. 


5.3.7 Native Soil Pad 

5.3.7.1 Soil analysis is often a useful test for helping to determine whether the 

potential corrosion activity will be high enough to make cathodic protection 

necessary and whether cathodic protection will be a practical application to 

prevent corrosion. Determination of aggressive ions such as chlorides and 

sulfates along with measurement of pH and resistivity are helpful for further 

corrosion analysis. The variety of particle sizes and chemical and electrical 

differences as discussed in 5.3.1.1and 5.3.2.1 should also be considered in 

the effectiveness of a cathodic protection system. 


Q21. What is the most common material used as a cushion beneath storage 

tank bottoms? 

a) Clean concrete 

b) Clean sand 

c) Clean Asphalt 

d) Clean modified aggregate 

ANS: b 

Q22. The use of oiled sand beneath tank bottoms does not eliminate the need 

for cathodic protection and in fact may cause cathodic protection to be less 

effective because: 

a) The oiled sand has higher resistivity 

b) The sand is unable to conduct electrical current 

c) The oil acts as an insulator and blocks all current flow 

d) The oil creates a vapor bearer entrapping water and contaminants next 

to the tank bottom 

ANS: c 


Q23. There are several ways the tank cushion can become contaminated. 

Three of the following are methods of cushion contamination, which one is 

not? 

a) In coastal areas salt spay may be washed down the side of the tank 

b) Fertilizer from spraying operations in rural areas 

c) Airborne chemicals from industrial operations 

d) Residual build-up of electrons in the sand cushion 

ANS: d 

Q24. Leakage of product from the tank bottom can cause accelerated 

corrosion by creating ____. 

a) Stray current corrosion 

b) Corrosion cells where none existed before 

c) More positively charged electrons 

d) A film that would block electrical current flow 

ANS: d 


Q25. When a layer of crushed-limestone or clam-shell is used for the tank 

cushion, why is it important to ensure the particles are fine and uniform? 

a) Large particles could puncture the tank bottom 

b) Differential aeration corrosion cells will cause pitting at contact areas 

between the large particles and the metal 

c) Large particles may allow the formation of dissolved gas pockets which 

could become a hazard if hot tap work is performed on the tank bottom 

d) Large particle will eventually fracture and create voids in the tank 

cushion 

ANS: b 

Q26. What is an advantage of using crushed-limestone or clam-shell under 

tank bottoms? 

a) This material is plentiful and relatively inexpensive 

b) Contamination is easier to detect because of discoloration 

c) Water from rain or groundwater makes the environment under the tank 

alkaline, which may reduce corrosion 

d) The use of this material eliminates the need for cathodic protection 

ANS: c 


Q27. Heated tanks or tanks storing hot product can cause: 

a) Increased water intrusion due to causing snow to melt and run down 

the tank sides 

b) Excessive drying out of concrete foundations resulting in premature 

deterioration and failure 

c) Accelerated corrosion on the internal surface especially in tanks with 

water bottoms 

d) Accelerated corrosion on the external surface due to elevated 

temperature is the area is wet 

ANS: c 

Q28. There are a variety of methods for secondary containment, which of the 

following is not an accepted method of secondary containment. 

a) Dual bottom tank design 

b) Sand bags 

c) Use of impervious clay pad in tank dike 

d) Impervious nonmetallic membrane 

ANS: b 


5.4 Other Factors Affecting Cathodic Protection 

5.4.1 Contents of Tank 

Aboveground storage tank temperature can influence corrosion on tank 

bottoms. Accelerated corrosion can occur on the external surface of the 

bottom of heated tanks due to elevated temperatures if the area is wet. 

NOTE The corrosion rate of steel may double with every 18 °F (10 °C) 

increase in temperature above 77 °F (25 °C). 


Q29. During the installation of a new steel bottom over an existing steel 

bottom, which has been repaired, if water or other electrolyte intrudes into the 

annulus, what can happen? 

a) A galvanic cell may form which will cause the new steel tank bottom to 

corrode at an accelerated rate 

b) An electrochemical reaction may take place creating hazardous 

gasses 

c) A galvanic cell may form which will cause the old tank bottom to 

corrode at an accelerated rate 

d) A galvanic cell may form which will turn the old tank bottom into an 

anode 

ANS: a 


Q30. With the installation of _____ in a diked area prior to new tank 

construction, most cathodic protection systems are rendered ineffective. 

a) A secondary containment system utilizing a perforated impervious 

membrane 

b) A secondary containment system utilizing an impervious membrane 

c) A secondary containment system utilizing a metallic impregnated 

screen membrane 

d) A secondary containment system utilizing a non-impervious membrane 

ANS: b 


Answers to API-651 Section 5, Determination of Need for Cathodic 

Protection 


Section 6- Methods of Cathodic 

Protection for Corrosion Control 


Q1. What is the basic principle that makes cathodic protection effective. 

a) Cathodic protection is a technique for preventing corrosion by making 

the entire surface of the metal to be protected act as the rectifier 

b) Cathodic protection is a technique for preventing corrosion by making 

the entire surface of the metal to be protected act as the corrosion cell 

c) Cathodic protection is a technique for preventing corrosion by making 

the entire surface of the metal to be protected act as the cathode 

d) Cathodic protection is a technique for preventing corrosion by making 

the entire surface of the metal to be protected act as the anode 

ANS: c 

Q2. What are the two systems of cathodic protection? 

a) Galvanic and repressed current 

b) Galvanic and impressed current 

c) Galvanic and reversed current 

d) Galvanic and induced current 

ANS: b 


Q3. Galvanic cathodic protection systems use a metal, that is more active 

than the structure to be protected, to supply the current required to stop 

corrosion. What is another term(s) used to describe this material? 

a) Anode, commonly referred to as a galvanic or sacrificial anode 

b) Cathode, commonly referred to as a galvanic or sacrificial cathode 

c) Ribbon cathode, commonly referred to as a sacrificial ribbon cathode 

d) Impressed current anode, commonly referred to as the impressed 

anode 

ANS: a 

Q4. Where on the galvanic series is clean and shiny mild steel? 

a) Clean and shiny mild steel has a value of –1.1 volts 

b) Clean and shiny mild steel has a value of –1.0 volts 

c) Clean and shiny mild steel has a value of –0.8 volts 

d) Clean and shiny mild steel has a value of –0.5 to -0.8 volts 

ANS: d 


Q5. The most common metals used as galvanic anodes in soil are: 

a) Lead and copper 

b) Aluminum alloy (5% zinc) and Mild steel (clean and shiny) 

c) Magnesium and zinc 

d) Mild steel in concrete and cast iron 

ANS: c 

Q6. Of the following, which is not an advantage of galvanic cathodic 

protection systems? 

a) No external power is needed 

b) Capital investment is low for small-diameter tanks 

c) Method is limited to use in low-resistivity soils 

d) Interference problems (stray currents) are rare 

ANS: c 


Q7. Impressed current cathodic protection systems use: 

a) Alternating current 

b) Direct current usually provided by a rectifier 

c) Direct current usually provided by a dry cell battery 

d) Either direct current or alternating current depending upon which is 

available 

ANS: b 

Q8. Of the following, which is not a disadvantage of impressed current 

cathodic protection systems? 

a) High current output 

b) High maintenance costs 

c) High operating costs 

d) High capital cost for small installations 

ANS: a 


Q9. A cathodic protection rectifier has two major components; what are they? 

a) A step-down transformer to reduce the AC supply voltage and 

rectifying elements to convert DC to AC output 

b) A step-down transformer to reduce the AC supply voltage and 

rectifying elements to convert AC to DC output 

c) A step-down transformer to reduce the DC supply voltage and 

rectifying elements to convert DC to AC output 

d) A step-down transformer to reduce the AC supply voltage and 

rectifying elements to regulate the AC output 

ANS: b 

Q10. Impressed current anodes used in soil are not made of: 

a) Graphite 

b) High silicon cast iron 

c) Zinc 

d) Mixed metal oxides on titanium 

ANS: c 


Q11. Impressed current anodes may be installed underneath the tank. 

a) True 

b) False 

ANS: a 


Table 2—Partial Galvanic Series 


Answers to API-651 Section 6, Methods of Cathodic Protection for 

Corrosion Control 


Section 7 – Design of Cathodic Protection 

Systems 


Q1. It has been decided to install an impervious membrane under a new 

storage tank being installed in a diked area. Cathodic protection of the tank 

bottom is required. Where must the anodes be placed? 

a) Anodes shall be placed outside the diked area 

b) Directly under the membrane beneath the tank 

c) As close as possible to the rectifier 

d) Between the membrane and the tank bottom 

ANS: d 

Q2. Inspection experience has disclosed the need for cathodic protection for 

an existing tank in a diked area. There is a membrane installed under the tank. 

What would be an option for installing anodes under this tank? 

a) Jack the tank up on the side opposite the fill and discharge lines and 

slide the ribbon anodes under 

b) Bore under the tank at a very shallow angle and install the anodes 

c) Bore under the membrane at a very shallow angle and install the 

anodes 

d) Install deep ground bed anodes in coke breeze backfill outside the 

diked area 

ANS: b 


Q3. If an existing tank bottom is protected by cathodic protection and/or if 

cathodic protection is planned for the new bottom (by deep or shallow 

groundbeds), what should be done with the old bottom? 

a) The old tank bottom should be electrically connected to the cathodic 

protection system to now act as an anode 

b) The old tank bottom should be painted with a corrosion resistant 

coating and left in place 

c) The old tank bottom should be completely removed 

d) Nothing needs to be done with the old tank bottom 

ANS: c 


Q4. It has been decided to install a new tank bottom in a tank with cathodic 

protection. What would be the result of leaving the old bottom in place and not 

properly prepared? 

a) The old bottom forms a shield that collects the cathodic current 

(cations) flowing through the ground and prevents cathodic protection of 

the new tank bottom 

b) The old bottom forms a shield that collects the anodic current flowing 

through the ground and prevents cathodic protection of the new tank 

bottom 

c) The old bottom forms a shield that collects the galvanic current flowing 


bottom 

d) The old bottom forms a shield that collects the stray current flowing 


bottom 

ANS: a 


Q5. Industry experience has shown that if a conductive electrolyte exists 

between an old and a new tank bottom: 

a) The current flow and metal loss will be from the old bottom 

b) The current flow and metal loss will be from the new bottom 

c) The current flow will be from the old bottom and metal loss will be from 

the new bottom 

d) The current flow will be from the new bottom and metal loss will be 

from the old bottom 

ANS: c 

Q6. There are several advantages to installing a secondary containment. Of 

the following, which would not be considered an advantage? 

a) Provides a means of detecting and containing leaks and preventing 

ground contamination 

b) Prevents the natural current flow between the old bottom and the new 

bottom 

c) Permits the addition of cathodic protection at a later date 

d) May reduce the entry of groundwater into the space between the 

bottoms 

ANS: c 


7.2.4.3 If an existing tank bottom is protected by cathodic protection and/or if 

cathodic protection is planned for the new bottom (by means of deep or 

shallow anode beds), the old bottom will have to be completely removed. 

As shown in Figure 8, if it is not removed, the old bottom forms a shield that 

collects the cathodic current flowing through the ground and prevents 

cathodic protection of the new bottom. Unless the anodes are installed 

between the two steel bottoms (see Figure 8), or the old bottom is removed, 

electrically isolated, or coated with a nonconductive material, a galvanic cell 

can develop between the old and new bottom. Industry experience has 

shown that if a conductive electrolyte exists between bottoms, the current flow 

and metal loss will be from the new bottom, resulting in premature failure of 

the new bottom. 


Corrosion Cell Current (metallic path) 

current flow 


Q7. There are several disadvantages to installing a secondary containment. 

Of the following, which would not be considered a disadvantage 

a) The membrane may act as a basin to contain water or any other 

electrolyte that might wet the sand between the bottoms 

b) The membrane could entrap hydrocarbon products, which would 

require extra care for hot work 

c) Makes the future addition of cathodic protection virtually impossible 

d) Acts as a barrier to groundwater 

ANS: d 


Q8. When an external cathodic protection system is being designed, there are 

several items to be considered. Of the following four items, which one would 

not be a consideration? 

a) Selection and design of the cathodic protection system for optimum 

economy of installation, maintenance, and operation 

b) Specification of materials and installation practices that meet 

applicable codes, such as National Electrical Manufacturers Association 

standards, NACE recommended practices, and federal, state, and local 

regulations 

c) Provisions for monitoring the cathodic protection system 

d) Specification of materials and installation practices that meet 

applicable codes, such as American Society of Mechanical Engineers 

standards, NACE recommended practices, and federal, state, and local 

regulations 

ANS: d 


Q9. Information that is useful for design of an external cathodic protection 

system can be divided into three categories: 

a) Specifications, site conditions, and jurisdictional requirements 

b) Specifications and practices, site conditions, and U.S. Geological 

survey reports 

c) Specifications and practices, site conditions, and field survey, corrosion 

test data, and operating experience 

d) Specifications and practices, tank shell conditions, and field surveys 

ANS: a 

Q10. What are the two types of cathodic protection systems most commonly 

used? 

a) Galvanic cathode system and impressed voltage system 

b) Galvanic anode system and impressed current system 

c) Galvanic anode system and interference current system 

d) Galvanic anode system and interference voltage system 

ANS: b 


Q11. Galvanic cathodic protection systems are more economical on: 

a) Small-diameter tanks 

b) Large-diameter tanks 

c) Bare, poorly coated structures 

d) Multiple large tanks in a diked area 

ANS: a 

Q12. The three most common galvanic anode materials used for soil 

installations are: 

a) High potential magnesium alloys, zinc, and pure aluminum 

b) High potential magnesium alloys, Standard magnesium, and Copper 

c) High potential magnesium alloys, standard magnesium, and zinc 

d) High potential magnesium alloys, standard magnesium, and stainless 

steel 

ANS: c 


Q13. What are the advantages of using a special backfill with anodes for 

installation in soil environments? 

a) Reduces the possibility of contaminating the environment and 

promotes anode efficiency 

b) Promotes anode efficiency, lengthens the life of the anode, dissipates 

stray currents 

c) Promotes anode efficiency, lengthens anode life, and keeps anode 

environment moist 

d) Promotes anode efficiency, keeps anode environment moist, and 

prevents total deterioration of the anode 

ANS: c 


Q14. The number of anodes required to provide cathodic protection depends 

upon what two factors? 

a) The distance from the galvanic anode to the tank bottom and soil 

discharge rate 

b) Total current requirements and the expected individual anode 

discharge rate in the soil 

c) Total stray currents expected and the total current requirements 

d) Total current requirements and the expected individual cathode 

discharge rate in the soil 

ANS: b 


Q15. In placing the anodes, how is better current distribution and more 

uniform polarization obtained? 

a) By distributing anodes uniformly around the tank or under the 

membrane for new construction 

b) By distributing anodes uniformly around the diked area or under the 

tank for new construction 

c) By distributing the cathodes uniformly around the tank or under the 

tank for new construction 

d) By distributing the anodes uniformly around the tank or under the tank 

for new construction 

ANS: d 

Q16. How are impressed current anodes installed? 

a) These anodes are installed either fully coated or in special backfill 

material 

b) These anodes are installed either bare or in special backfill material 

c) These anodes are installed either directly on the tank bottom or in 

special backfill material 

d) These anodes are installed either bare or in special liquid filled 

cylinders 

ANS: b 


Q17. Impressed current anodes are connected with an insulated conductor: 

a) Singly to the positive terminal of a DC source 

b) In groups to the positive terminal of a DC source 

c) Either singly or in groups to the negative terminal of an DC source 

d) Either singly or in groups to the positive terminal of an DC source 

ANS: d 

Q18. Of the following, which is not the preferred material for impressed 

current anodes used in soil installations? 

a) Graphite 

b) Zinc 

c) High silicon cast iron 

d) Mixed metal oxide 

ANS: b 


Q19. Of the following, which is not the best material for impressed current 

anodes used in water installations 

a) Titanium 

b) Tantalum 

c) Copper 

d) Platinized niobium 

ANS: c 

Q20. In an impressed current cathodic protection system, proper groundbed 

design should do which of the following? 

a) Avoid physical interference with existing facilities, provide uniform 

current distribution, and avoid stray current interference with off-site 

structures 

b) Provide for direct connection with existing facilities, provide uniform 


structures 

c) Avoid physical interference with existing facilities, provide random 


structures 

d) Avoid physical interference with existing facilities, provide uniform 

current distribution, and intercept stray current interference with off-site 


Q21. In an impressed current system why would additional anodes be 

considered in the distributed anode design? 

a) To provide uniform current distribution and provide back-up anodes for 

replacement 

b) To provide uniform current distribution and provide allowance in case 

of isolated cathode connection failure or partial cathode depletion 

c) To provide uniform current distribution and provide allowance in case 

of isolated anode connection failure or partial anode depletion 

d) To provide random current distribution and provide allowance in case 

of isolated anode connection failure or partial anode depletion 

ANS: c 


Q22. The current required for cathodic protection should be calculated using 

the results of current requirement tests. In lieu of this test, what is the 

generally accepted protective current density? 

a) Between –0.5 and +0.5 milliamps per square foot at ambient conditions 

b) Between 0.01 and 0.1 milliamps per square foot at ambient conditions 

c) Between 0.1 and 0.2 milliamps per square foot at ambient conditions 

d) Between 1 and 2 milliamps per square foot at ambient conditions 

ANS: d 

Q23. The current requirement test can only be performed on existing tanks 

using a temporary groundbed and an appropriate source of direct current. 

Depending on the current required, the power source can vary by how much? 

a) From a 24 volt storage battery to a 300-amp welding unit 

b) From a 12 volt storage battery to a 300-amp welding unit 

c) From a 6 volt storage battery to a 300-amp welding unit 

d) From a 1.2 volt solar panel to a 300-amp welding unit 

ANS: 


Q24. During the current requirement test, how is maximum contact of the tank 

bottom with the cushion material ensured? 

a) The tank is filled to an adequate liquid level to ensure maximum 

bottom contact 

b) The tank is pressurized with an inert gas to ensure maximum bottom 

contact 

c) The tank is completely filled and subjected to a hydrostatic pressure 

d) The tank is emptied and concrete weights are installed and the tank 

filled to half design liquid level 

ANS: a 

Q25. The voltage necessary to drive the required amount of current depends 

largely on what two factors? 

a) The type of power source available and the resistivity of the soil 

b) The number and location of anodes and the resistivity of the soil 

c) The number and location of cathodes and the resistivity of the soil 

d) The number and location of the anodes and the resistivity of the 

special backfill 

ANS: b 


Q26. In an impressed current system, rectifiers with a moderated excess 

capacity should be selected to allow for adjustments during the life of the 

cathodic protection system and to prevent damage due to overloads. What is 

the typical excess capacity of such rectifiers? 

a) 40% to 50% 

b) 30% to 50% 

c) 20% to 50% 

d) 10% to 50% 

ANS: 

Q27. Electrical grounding of electrical equipment is an essential element in 

personnel safety. 

a) True 

b) False 

ANS: a 


Q28. Condition and type of coating (if any), minimum and maximum water 

level in tank, compatibility of stored liquid with anodes and cables, and 

internal inspection interval of tank which affects design life are all factors that: 

a) Influence the design of an external cathodic protection system 

b) Influence the design of a depressed current cathodic protection system 

c) Influence the design of an internal cathodic protection system 

d) Influence the design of the rectifier used in a cathodic protection 

system 

ANS: c 


Answers to API-651 Section 7, Design of Cathodic Protection Systems 


Section 8 – Criteria for Cathodic 

Protection 


Q1. API-651 provides criteria for determining the adequacy of cathodic 

protection of aboveground storage tanks. What document is referenced for a 

more detailed description? 

a) ASME Section V, Nondestructive Examination 

b) API-Standard 650, Welded Steel Tanks for Oil Storage 

c) API-Standard 653, Tank Inspection, Repair, Alteration, and 

Reconstruction 

d) NACE RP-01-69 

ANS: d 

Q2. In determining if adequate cathodic protection is being achieved, which of 

the following would be correct? 

a) A negative (cathodic) potential of at least 850 mV with cathodic current 

applied 

b) A positive (cathodic) potential of at least 850 mV with cathodic current 

applied 

c) A negative (cathodic) potential of at least 85.0 mV with cathodic current 

applied 

d) A positive (cathodic) potential of at least 85.0 mV with cathodic current 

applied 

ANS: a 


Q3. How must the required negative potential be measured? 

a) This potential shall be measured with respect to a saturated 

copper/copper sulfate reference electrode (CSE) contacting the metal 

tank bottom 

b) This potential shall be measured with respect to a saturated 

copper/copper sulfate reference electrode (CSE) contacting the 

electrolyte 

c) This potential shall be measured with respect to a saturated 

copper/copper sulfate reference electrode (CSE) contacting the metal 

casing of the rectifier 

d) This potential shall be measured with respect to a saturated 

copper/copper sulfate reference electrode (CSE) contacting the positive 

terminal of the power source 

ANS: b 



a) Negative polarized potential of at least 8.50 mV relative to a CSE 

b) Negative polarized potential of at least 85.0 mV relative to a CSE 

c) Negative polarized potential of at least 850 mV relative to a CSE 

d) Negative polarized potential of at least .850 mV relative to a CSE 


Q5. Name a common method of measuring polarized potential. 

a) Measuring the distance between the tank bottom and the anode 

b) Measuring the AC current relative to the DC current 

c) Using the “instant on” method 

d) Using the “instant off” method 

ANS: d 




a) A minimum of 1000 mV of cathodic polarization measured between the 

tank bottom metallic surface and a standard reference electrode 

contacting the electrolyte 

b) A minimum of 850 mV of cathodic polarization measured between the 



c) A minimum of 100 mV of cathodic polarization measured between the 



d) A minimum of -0.85 mV of cathodic polarization measured between the 



ANS: d 



8.2.2.2 A negative polarized potential of at least 850 mV relative to a CSE. 

(One common method of measuring polarized potential is by using the 

“instant off” technique.) This criterion may be excessive and not practical for 

bare steel tank bottoms. 

8.2.2.3 A minimum of 100 mV of cathodic polarization measured between the 

tank bottom metallic surface and a stable reference electrode contacting the 

electrolyte. The formation or decay of this polarization can be measured to 

satisfy this criterion. 


Q7. The standard method of determining the effectiveness of cathodic 

protection on a tank bottom is the __________ measurement 

a) Resistivity 

b) DC current 

c) Tank-to-soil (potential?) 

d) Interference current 

ANS: 

Q8. How is the tank-to-soil potential measurement performed? 

a) This measurement is performed using a low-impedance voltmeter and 

a stable, reproducible reference electrode contacting the electrolyte 

b) This measurement is performed using a high-impedance voltmeter and 

a stable, regenerative reference electrode contacting the electrolyte 

c) This measurement is performed using a high-impedance voltmeter and 

a stable, reproducible reference electrode contacting the electrolyte 

d) This measurement is performed using a high-impedance voltmeter and 

an unstable, non-reproducible reference electrode contacting the 

electrolyte 

ANS: c 


Q9. Tank-to-soil potential measurements are typically taken with current 

applied; however, corrections for ______ in the soil must be made. 

a) IW drop(s) 

b) IR drop(s) 

c) ER drop(s) 

d) IE drop(s) 

ANS: b 

Q10. Correction for IR drop in the soil is often necessary for measurements 

made at the tank perimeter even if the reference electrode is placed 

immediately adjacent to the tank. This is especially true if ______ is/are close 

to the tank. 

a) Distributed anodes 

b) The cathodic protection power supply rectifier 

c) The sacrificial anode 

d) The DC power supply (battery) 

ANS: a 


Q11. Monitoring the actual structure-to-soil potential under the tank should be 

considered. How can this be accomplished? 

a) Permanently installed reference electrode or by burying reference 

electrode every 20 feet around the perimeter of the tank 

b) Inserting a reference electrode under the tank through a perforated 

tube or attaching a reference electrode to the tank shell 

c) Permanently installed reference electrode or by inserting a reference 

electrode under the tank through a perforated tube 

d) Permanently installed bare copper wire connected to the tank bottom 

or by inserting a reference electrode under the tank through a perforated 

tube 

ANS: c 

Q12. Other standard reference electrodes may be substituted for the 

saturated copper/copper sulfate reference electrode. Which of the following is 

not a common substitute? 

a) Reference electrode Zinc, Voltage +0.25 

b) Reference electrode Saturated KCI calomel Voltage -0.78 

c) Reference electrode Silver/silver chloride Voltage -0.80 

d) Reference electrode Aluminum alloy (5% zinc) Voltage +0.08 

ANS: d 


Answers to API-651 Section 8, Criteria for Cathodic Protection 


Section 9 - Installation of Cathodic 

Protection Systems 


Q1. Installation of cathodic protection systems shall be in strict accordance 

with the drawings and specifications. Exceptions may be made only with the 

approval of which of the following? 

a) The API-653 Inspector or personnel qualified and trained by the 

Inspector 

b) The National Board Inspector or personnel qualified and trained by the 

Inspector 

c) The owner, operator, or personnel qualified by the owner or operator 

d) The manufacturer of the tank or the authorized representative of the 

tank manufacturer 

ANS: c 

Q2. Packaged galvanic anodes should be back-filled with ______. 

a) Compacted special backfill material such as coke breeze 

b) Compacted sand 

c) Compacted limestone or clam shell backfill material 

d) Compacted native soil 

ANS: a 


Packaged galvanic anodes 










Q3. How may galvanic anodes, used to protect the internal surfaces of tank 

bottoms, be installed? 

a) Bolted or welded to the tank bottom 

b) Laid on the tank bottom at specific intervals around the perimeter and 

in the center 

c) Held in place with a special adhesive or welded 

d) Held in place by epoxy coating that will adhere to the tank bottom 

ANS: b 

Q4. When installing galvanic anodes, care must be taken during the 

backfilling operation to 

a) Ensure the limestone or clamshell backfill is not disturbed 

b) Prevent damage to the lead wires and connections 

c) Ensure the proper impervious membrane has been installed under the 

anode 

d) Prevent damage to the AC/DC rectifier 

ANS: b 


Q5. Which if the following is a true statement with regards to installing 

galvanic anodes? 

a) It is customary to carry the anode to the site by the lead wire to ensure 

its tightness 

b) The lead wire should only be long enough to reach the tank bottom 

with no slack 

c) Anodes should not be carried or lowered into the excavation by the 

lead wires 

d) The anode should be stored in a container of water until it is placed in 

the excavation 

ANS: c 


Q6. In an impressed current cathodic protection system, care must be taken 

not to crack or damage the anode during handling and installation. Of the 

following, which would be a true statement? 

a) Anodes with very small cracks near the bottom of the anode may be 

used without repair 

b) Cracked anodes should be inspected to ensure the insulation on the 

lead wires is not damaged before installing the anode 

c) Anodes with cracks greater than 0.0625“ (1.6mm) in width shall not be 

used 

d) Cracked anodes should not be used 

ANS: a 


Q7. How can the life of an impressed current anode be increased? 

a) By installing a timing device that activates the current at thirty-second 

intervals 

b) Properly installing the backfill material 

c) Use a substitute anode material 

d) Using AC current instead of DC current 

ANS: b 

Q8. Of the following, which is not a principal point that needs to be observed 

in the installation of impressed current anodes? 

a) The anode should be installed so that at least one side is in contact 

with the soil 

b) Buried connections must be protected against the entrance of moisture 

c) Anodes and cable should be installed at a sufficient depth to protect 

against accidental damage 

d) Care should be taken to protect the cable connection to the anode 

ANS: a 


Q9. For a typical vertical anode installation, the hole is excavated _8-12”___ 

inches in diameter by approximately _10-20’_____ feet deep. 

a) Six to ten, five to ten 

b) Eight to twelve, ten to twenty 

c) Twelve to eighteen, twelve to twenty-four 

d) Eighteen to twenty-four, eighteen to thirty 

ANS: b 

Q10. When it is necessary to install an impressed current anode in the 

horizontal position, a layer of crushed coke breeze is laid in the trench and 

the anode is laid on top of the coke breeze. Compacted native soil is then 

filled in on top of the anode. 

a) True 

b) False 

ANS: 


9.3.2 Shallow Anode Bed Installation 

9.3.2.1 Figure 12 shows an example of a shallow anode bed installation. For 

a typical vertical anode installation, the hole is excavated 8 in. to 12 in. (20 cm 

to 30 cm) in diameter by approximately 10 ft to 20 ft (304 cm to 366 cm) deep. 

Power auger equipment is used where available if both the terrain and right of 

way will permit. The anode is centered in the opening and properly installed 

anode backfill is carefully tamped when necessary. Many anodes also come 

prepackaged in carbonaceous backfill. 

9.3.2.2 Sometimes it is necessary to install an anode in a location where rock 

is encountered at a shallow depth, or where soil resistivity increases markedly 

with depth. Such sites can be coped with by a horizontal installation of 

anodes. A ditch is excavated to whatever depth is practical, and a horizontal 

column of coke breeze is laid therein, usually square in cross section. The 

anode is laid horizontally in the center of this column. Groundbed resistances 

tend to be higher for horizontally installed groundbeds. Additional anodes or 

increased rectifier voltage should be considered with horizontally installed 

groundbeds. 


Q11. For impressed current cathodic protection systems, when would 

installation of the anode in the horizontal position be acceptable or practical? 

a) Where rock is encountered at a shallow depth or where soil resistivity 

decreases markedly with depth 

b) Where sand is encountered at a shallow depth or where soil resistivity 

decreases markedly with depth 

c) Where rock is encountered at a shallow depth or where soil resistivity 

increases markedly with depth 

d) Where sand is encountered at a shallow depth or where soil resistivity 

increases markedly with depth 

ANS: c 


Q12. To improve current distribution to the center of the tank in an impressed 

current cathodic protection system, it may be desirable to do which of the 

following? 

a) Install fifty percent more anodes 

b) Extend the shallow groundbed an additional twenty-five percent 

greater diameter around the tank 

c) Use AC current instead of DC current 

d) Install anodes in holes drilled at an angle under the perimeter of the 

tank bottom 

ANS: d 


Q13. In situations where a deep groundbed installation is required, why is it 

important to consider the environmental aspects of this type of installation? 

a) The groundbed may be located in contaminated soil, which could allow 

contamination of the atmosphere 

b) The groundbed installation may fracture bedrock and permit the 

release of radon contamination 

c) The groundbed installation may be located through underground 

aquifers 

d) The groundbed installation may cause cracking of foundations of 

nearby structures during the drilling process 

ANS: c 


Q14. An impressed current cathodic protection system is installed; the 

installing contractor connected the positive connection of the rectifier to the 

tank. Is this a satisfactory installation? 

a) Yes it does not matter how the leads are connected 

b) No the positive lead should have been connected to anode so the tank 

bottom would be the anode 

c) Yes the connection is correct the tank bottom will act as the anode as 

intended 

d) No the connection is incorrect, the tank bottom will now act as the 

anode resulting in rapid corrosion of the tank bottom 

ANS: d 


Q15. What is the preferred means of connecting the negative rectifier lead 

wire to the structure to be protected? 

a) A powder weld connection (Cadweld, Thermite, or equivalent) 

b) Brazed 

c) Soldered 

d) Any arc welding process 

ANS: a 

Q16. All positive cable connections and wire splices should be waterproofed 

and covered with electrical insulating material. What should be done if 

mechanical connections are used? 

a) Mechanical connections should be buried to protect them from 

vandalism 

b) Mechanical connections should not be buried 

c) Mechanical connections should be buried to protect them from 

accidental damage 

d) Mechanical connections should not be used for rectifier installation 

ANS: d 


Mechanical 

connections should 

not be buried 


Mechanical 


not be buried 


Mechanical 


not be buried 


Q17. Underground splices of the positive lead wire to the groundbed should 

be ______. 

a) Braided and soldered 

b) Made up with mechanical splices 

c) Avoided 

d) Close to the surface for ease of maintenance 

ANS: c 


Q18. One of the problems with monitoring cathodic protection systems on the 

tank bottom is the inability to place a portable reference electrode in close 

proximity to the underside. How can this situation be remedied during new 

construction of a tank? 

a) Permanently installed reference electrodes and lead wires to the roof 

support structure where provided 

b) Installing polyvinyl chloride or fiber reinforced plastic pipe for use in 

profiling the tank-to-soil potential from the perimeter to the center 

c) Installing polyvinyl chloride or terracotta pipe for use in profiling the 

tank-to-soil potential from the perimeter to the center 

d) Installing perforated polyvinyl chloride or fiber reinforced plastic pipe 

for use in profiling the tank-to-soil potential from the perimeter to the 

center 

ANS: d 


Q19. For existing tanks, not scheduled for bottom repair or replacement, how 

can installation of permanent reference electrodes be accomplished? 

a) Air lance or mechanical procedures 

b) Water jetting or mechanical procedures 

c) Steam blast or mechanical procedures 

d) Controlled explosives or mechanical procedures 

ANS: b 

Q20. Why is it a good practice to install permanent test leads, grounding lugs, 

or short pieces of cable for measuring tank-to-soil potential? 

a) Repeated contact with the tank by a knife or ice pick will eventually 

puncture the tank 

b) Repeated contact with the tank by a knife or ice pick can cause short 

circuiting of the cathodic protection system 

c) Repeated contact with the tank by a knife or ice pick can cause early 

failure of the tank's paint system. 

d) Repeated contact with the tank by a knife or ice pick can cause stress 

risers due to cutting the tank surface 

ANS: c 


Answers to API-651 Section 9, Installation of Cathodic Protection 

Systems 


Section 10 

Interference Currents 


Q1. What can be a problem caused by the installation of a new impressed 

current cathodic protection system? 

a) A new impressed cathodic protection system may cause an 

unacceptable drain on the electrical substation for the refinery 

b) A new impressed cathodic protection system may cause interference 

with neighboring structures 

c) A new impressed cathodic protection system may cause interference 

with certain radio signals 

d) A new impressed cathodic protection system may cause interference 

with operating controls of nearby process units 

ANS: b 

Q2. What is the most common source of "constant current" interference 

currents? 

a) Rectifiers energizing nearby cathodic protection systems 

b) Electromagnetic fields set up by the operation of very large motors 

close to the cathodic protection system 

c) Electromagnetic fields caused by transformers in nearby substations 

d) Electromagnetic fields caused by overhead high tension wire 

ANS: a 


Q3. With regard to "fluctuating current", which of the following is not a normal 

source for this type of stray current? 

a) Underground mining electrical systems 

b) Electric railways 

c) Rapid transit systems 

d) AC to DC rectifiers 

ANS: d 

Q4. During a corrosion control survey, the inspector noticed a positive shift of 

the structure-to-soil potential on the affected structure at a point where current 

may be discharged from the affected structure. What would this indicate? 

a) Interference from the cathodic protection system rectifier (own) 

b) Interference from a nearby lighting circuit 

c) Interference from a neighboring source 

d) Interference from a galvanic anode system 

ANS: a 


Q5. Interference currents have been detected. How could this problem be 

resolved? 

a) Design, proper bonding, and use of sacrificial anodes 

b) Design, relocation of the tank, use of sacrificial anodes 

c) Design, proper bonding, removal of cathodic protection system 

d) Design, proper bonding, different choice of coating on the structure 

ANS: a 


Stray Current 


Answers to API-651 Section 10, Interference Currents 


Section 11 - Operation and Maintenance 

of Cathodic Protection Systems 


Q1. Why is it important to conduct potential surveys when there is an 

adequate liquid level in a tank? 

a) Bottom-to-electrolyte potential readings may indicate adequate 

protection for the portion of the tank in contact with the soil but when the 

tank is full and all of the bottom is in contact, protection may not be 

sufficient 

b) Bottom-to-anode potential readings may indicate adequate protection 

for the portion of the tank in contact with the soil but when the tank is full 

and all of the bottom is in contact, protection may not be sufficient 

c) Bottom-to-cathode potential readings may indicate adequate protection 

for the portion of the tank in contact with the soil but when the tank is full 

and all of the bottom is in contact, protection may not be sufficient 

d) Bottom-to-electrolyte potential readings may indicate adequate 

protection for the portion of the tank in contact with the soil but when the 

tank is full and all of the bottom is in contact, protection may be far more 

than necessary 

ANS: a 


Q2. Measurements of the native structure-to-soil potential should be made 

________. 

a) Immediately after any cathodic protection system is energized 

b) Within two days after any cathodic protection system is energized 

c) Within 6 months after any cathodic protection system is energized 

d) Prior to energizing a new cathodic protection system 

ANS: a 

Q3. After a system has been energized, it may take _____ for polarization to 

a steady state to take place. 

a) Two and a half years 

b) One year 

c) Several months 

d) Fifteen minutes 

ANS: c 


Q4. To ensure the effectiveness of cathodic protection, how often should 

cathodic protection surveys be taken? 

a) Every two years 

b) Annually 

c) Bi-annually 

d) Quarterly 

ANS: b 

Q5. How often should all sources of impressed current be checked? 

a) At intervals not exceeding two years 

b) At intervals not exceeding one year 

c) At intervals not exceeding two months 

d) At intervals not exceeding two weeks 

ANS: c 


Q6. Tank bottoms shall be examined for evidence of corrosion at least once 

each year by conducting an internal inspection and taking coupon cutouts. 

a) True 

b) False 

ANS: b 

Q7. Records to demonstrate the need for corrosion control measures should 

be retained for 

a) 5 years 

b) 10 years 

c) 15 years 

d) As long as the facility remains in service 

ANS: d 


Q8. Records related to the effectiveness of cathodic protection should be 

retained for a ______ period unless a shorter period is specifically permitted 

by regulation 

a) 5 years 

b) 10 years 

c) 15 years 

d) As long as the facility remains in service 

ANS: a 


Answers to API-651 Section 11, Operation and Maintenance of Cathodic 

Protection Systems 


API RECOMMENDED PRACTICE 652 

Linings of Aboveground Petroleum 

Storage Tank Bottoms 

Fourth Edition, September 2014 


Section 4 – 

Corrosion Mechanisms 


Q1. Several common mechanisms of internal storage tank bottom corrosion 

are listed in API-652. Which of the following is not a common corrosion 

mechanism? 

a) Galvanic cell corrosion 

b) Concentration cell corrosion 

c) Chloride stress corrosion 

d) Corrosion caused by sulfate-reducing bacteria 

ANS: c 

Q2. Product cleanup tanks, chemical storage tanks, and wastewater 

treatment tanks may be susceptible to which type of corrosion? 

a) Galvanic cell corrosion 

b) Chemical corrosion 

c) Erosion-corrosion 

d) Concentration cell corrosion 

ANS: d 


Q3. Concentration cell corrosion will most likely result in which of the 

following conditions? 

a) Pitting and possibly significant localized metal loss 

b) Pitting and possibly uniform metal loss over a large area 

c) Pitting and possibly the loss of external cathodic protection 

d) Pitting and possibly grooving of the outer perimeter of the tank bottom 

ANS: a 

Q4. Pitting caused by concentration cell corrosion of a bare steel tank bottom 

may be as high as 

a) 20 mils per year 

b) 40 mils per year 

c) 60 mils per year 

d) 80 mils per year (2.032mm) 

ANS: a 


Q5. What is another name for the thin layer of oxide found on the surface of 

hot-rolled carbon steel, typically used for the construction of petroleum 

storage tanks? 

a) Patina 

b) Iron oxide 

c) Mill scale 

d) Rust 

ANS: c 

Q6. With regard to galvanic cell corrosion, what adverse affect could the large 

differences in the microstructure of steel bottom plates caused by welding 

have? 

a) They can provide a built in area of localized cracking 

b) They can provide a built in stress concentration 

c) They can provide a built in break in the external cathodic protection 

d) They can provide a built in galvanic couple 

ANS: d 


Q7. Sulfate-reducing bacteria (SRB) corrosion is universally recognized. The 

physical presence of bacterial deposits can promote aggressive _________ 

mechanism. 

a) Uniform metal loss over a wide area similar to erosion-corrosion 

b) Pitting by corrosion similar to concentration cell corrosion 

c) Pitting by corrosion similar to Chemical corrosion 

d) Pitting by corrosion similar to galvanic cell corrosion 

ANS: b 

Q8. SRB colonies derive energy from the reduction of sulfates to sulfide 

which _______. 

a) Promotes the appearance of a non-corrosive coating 

b) Promotes the natural corrosion inhibitors of the steel plates 

c) Is corrosive to steel 

d) Is non-corrosive to steel 

ANS: c 


Q9. Iron sulfide corrosion is _____ to the base steel and may promote pitting 

by a galvanic corrosion mechanism. 

a) An anode 

b) Ionic 

c) Cationic 

d) Cathodic 

ANS: d 

Q10. Erosion-corrosion may occur in wastewater treating or mixing tanks 

where ___ is present 

a) Sulfate-reducing bacteria and anaerobic condition 

b) Soil or small abrasive aggregate 

c) Sulfuric acid or ballast water 

d) An anode or cathode 

ANS: b 


Q11. Erosion-corrosion causes ______. 

a) Scattered pitting in a random pattern 

b) High localized metal loss in a random pattern 

c) Scattered pitting in a well defined pattern 

d) High localized metal loss in a well defined pattern 

ANS: d 


Answers to API-652 Section 4, Corrosion Mechanisms 


Section 5 - Determination of the Need for 

Tank Bottom Lining 


Q1. Aboveground storage tank bottoms are usually fabricated from ____ inch 

thick carbon steel plate. 

a) 1 

b) 3/4 

c) 1/2 

d) 1/4 

ANS: a 

Q2. Annular floor plates of storage tanks are frequently ____ to ___ inch thick. 

a) 1/4 to 1/2 

b) 1/2 to 3/4 

c) 3/4 to 1 

d) 1 to 1-1/4 

ANS: a 


Q3, The need for an internal tank bottom lining in an aboveground storage 

tank is generally based upon several considerations. Which of the following 

would not be a consideration in determining the need for tank bottom lining? 

a) Tank design 

b) Environmental considerations 

c) Method of external cathodic protection employed 

d) Federal, state, and local regulations 

ANS: c 

Q4. Internal tank bottom lining may be necessary if the minimum thickness is 

less than: 

a) 0.010 inch 

b) 0.100 inch 

c) 1.000 inch 

d) 0.1875 inch 

ANS: b 


Q5. Of the following what would not be considered important to consider 

when determining the need for tank bottom lining? 

a) Where is the corrosion 

b) What type of corrosion is occurring 

c) How high is the design fill level 

d) What is the corrosion rate 

ANS: c 

Q6. Flexing of the steel tank bottom may cause ______. 

a) An internal bottom lining to fail by cracking 

b) An internal bottom lining to fail by tearing 

c) An internal bottom lining to fail by blistering 

d) An internal bottom lining to fail by separating from the bottom plate 

ANS: a 


Q7. In old tanks, which of the following may complicate the problem of poor 

coverage? 

a) The diameter of the tank 

b) The thickness of the tank bottom 

c) Uneven settlement of the tank bottom 

d) Chemical contaminants 

ANS: c 

Q8. A properly applied internal bottom lining provides leak prevention by 

_______. 

a) Creating a cathodic protection barrier on the internal surface 

b) Enhancing the effectiveness of the external cathodic protection system 

c) Limiting internal corrosion of the steel tank bottom 

d) Limiting internal corrosion of the support columns and landing pads 

ANS: c 


Q9. In setting priorities for the application of linings to the bottom of 

aboveground storage tanks, which of the following does not need to be 

considered? 

a) The potential for groundwater contamination 

b) Type of external cathodic protection system 

c) Presence of secondary containment and leak detection systems 

d) Location of facility 

ANS: d 

Q10. A properly applied tank bottom lining may provide ___ years of service 

life in a particular product. 

a) 20 to 30 

b) 10 to 20 

c) 5 to 10 

d) 1 to 5 

ANS: b 


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Q11. A lining that has provided adequate protection in one product may not 

provide the same level of protection for another product. 

a) True 

b) False 

ANS: a 


Answers to API-652 Section 5, Determination of the Need for Tank 

Bottom Lining 


Section 6 – 

Tank Bottom Lining Selection 


Q1. Thin film linings are typically what thickness? 

a) 20 mils or less 

b) 30 mils or less 

c) 40 mils or less 

d) 50 mils or less 

ANS: a 

Q2. Thick film linings are typically what thickness? 

a) Greater than 20 mils 

b) Greater than 30 mils 

c) Greater than 40 mils 

d) Greater than 50 mils 

ANS: a 


Q3. Why must all linings be resistant to water? 

a) Water must be present at the tank bottom to act as a shield between 

the stored product and the lining 

b) Water must be present at the tank bottom to prevent contamination of 

the soil should a leak occur. The water will be detect before any product 

leakage 

c) Water must be present at the tank bottom for electrochemical corrosion 

to occur 

d) Water must be present at the tank bottom for electromotive corrosion 

to occur 

ANS: c 

Q4. Which of the following type of lining would be used for a tank bottom 

containing water, distillates, crude, and gasoline at 195ºF 

a) Thin-film Coal tar epoxy 

b) Thick film isophthalic polyester 

c) Thick film epoxy 

d) Thin film epoxy with an amine curative 

ANS: d 


Q5. What are two advantages of thin-film linings? 

a) Lower cost and can be used to cover very irregular surfaces 

b) Lower cost and ease of application 

c) Lower cost and surface preparation is not critical 

d) Requires no special training and lower cost 

ANS: b 

Q6. Which of the following type of lining would be used for a tank bottom 

containing water, crude oil, distillates, and gasoline at 150ºF 

a) Thin film coal tar 

b) Thick film vinyl ester 

c) Thin film epoxy with a polyamide curative 

d) Thick film isophthalic polyester 

ANS: b 


Q7 Thick-film linings are commonly reinforced with which of the following? 

a) Sand and small diameter gravel 

b) Copper wire, stainless steel wire, and low alloy steel mesh fabric 

c) Chopped PVC piping, copped ABS piping, and Resin beads 

d) Glass flake, chopped glass fibers, and organic fibers 

ANS: d 

Q8. One advantage of thick-film lining is _________. 

a) It can provide a good surface to attach internal corrosion monitoring 

devices 

b) It can provide sufficient strength to bridge over large perforations in the 

tank bottom 

c) It can provide sufficient strength to bridge over small perforation in the 

tank bottom 

d) It can provide sufficient strength to prevent leakage should the tank 

bottom completely corrode away 

ANS: c 


Q9. Special consideration must be given to what area of the tank bottom with 

regard to thick-film lining? 

a) The center because this is the area that will be subjected to the most 

stress 

b) The critical zone 

c) Any butt weld joints in the tank bottom 

d) The coving at the transition from the tank bottom to the shell 

ANS: d 

Q10. What are two disadvantages of thick-film linings? 

a) They are more expensive than thin-film linings and require more time 

to apply 

b) They are available in only one color and require more time to apply 

c) They are more expensive and require a curative 

d) They are more expensive and require high temperature airflow for curing 

ANS: d 


Q11. Storage tank bottom linings generally cover the entire tank bottom and 

extend ________ up the shell of the tank. 

a) 12 to 18 inches 

b) 18 to 24 inches 

c) 24 to 30 inches 

d) 30 to 36 inches 

ANS: a 

Q12. For thin-film lining systems, application of ______ coats is often required 

to achieve the desired film thickness 

a) 7 to 8 

b) 5 to 6 

c) 1 to 4 

d) 2 to 3 

ANS: d 


Q13. For thick-film lining systems, ______ coats may be required to obtain 

the thickness of the desired lining. 

a) 5 to 8 

b) 2 to 3 

c) 1 to 4 

d) 3 to 7 

ANS: b 

Q14. When only internal corrosion is taking place, regardless of the age of the 

tank, ______ thick linings may be used. 

a) 80 to 120 mil 

b) 55 to 80 mil 

c) 35 to 55 mil (0.9~1.3mm) 

d) 10 to 35 mil 

ANS: d 


Q15. What type and thickness of lining can be used for older tank bottoms 

that have corroded both internally and externally? 

a) Glass reinforced - 80 to 120 mil (2-3mm) 

b) Glass reinforced - 55 to 80 mil 

c) Glass reinforced - 35 to 55 mil 

d) Glass reinforced - 10 to 35 mil 

ANS: b 

Q16. Besides the corrosion history and the potential for corrosion, what two 

exceptional circumstances must be taken into account during the selection o 

a tank bottom lining? 

a) Specific gravity of the product and elevated temperature 

b) Product purity and fill/empty cycles 

c) Elevated temperatures and product purity 

d) Elevated temperatures and product viscosity 

ANS: c 


Answers to API-652 Section 6, Tank Bottom Lining Selection 


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Section 7 – 

Surface Preparation 


Q1. What is meant by "anchor pattern" as it pertains to surface preparation for 

tank bottom lining? 

a) The grid pattern of mechanical fixtures that hold the lining in place 

b) The grid pattern of adhesive use to hold the lining to the tank bottom 

c) The surface profile or roughness 

d) The grid pattern of the bottom plate to plate welds 

ANS: c 

Q2. Abrasive blast cleaning to a ______ finish is often specified as the 

minimum degree of surface cleanliness. 

a) White metal 

b) Near white metal 

c) Smooth metal 

d) Rough 

ANS: b 


Q3. To facilitate inspection and to ensure good adhesion of the lining, surface 

preparation should extend _______ beyond the area to be lined. 

a) Several inches 

b) Several feet 

c) Not less than 6 inches 

d) Not less than 12 inches 

ANS: a 

Q4. What is the preferred technique for the repair of perforations of the tank 

bottom? 

a) Thread the perforation and install a suitable pipe plug 

b) Install an entirely new tank bottom over the old bottom 

c) Fill the perforation with amber acrylic 

d) Welding of steel patches 

ANS: d 


Q5. Abrasive blasting should not be performed if the temperature of the steel 

surface is less than _____ above the dew point or if the humidity is greater 

than ______ percent. 

a) 10ºF - 80 

b) 5ºF - 80 (2.7ºC) 

c) 15ºF - 80 

d) 25ºF - 80 

ANS: b 

Q6. The anchor pattern typically required for linings is ____ and generally 

increases with the thickness of the lining. 

a) 3.5 to 6 mils 

b) 2.5 to 5 mils 

c) 1.5 to 4 mils 

d) 0.5 to 3 mils 

ANS: c 


Q7. What is the problem with having small mounts of contaminants such as 

dirt, clay, water-soluble salts, or oil in the abrasive used for storage tank 

bottom cleaning? 

a) This contamination in small amounts will not affect the quality and 

service life of the lining 

b) This contamination in small amounts will cause ripples in the lining 

surface 

c) This contamination in small amounts will cause the abrasive material to 

stick together and clog the cleaning equipment 

d) This contamination in small amounts will reduce the useful life of the 

lining 

ANS: d 


Answers to API-652 Section 7, Surface Preparation 


Section 8 – 

Lining Application 


Q1. For thick-film linings, the manufacturer may specify that the prime coat be 

applied at a film thickness less than that of the anchor pattern. Why is it 

important to follow these requirements? 

a) Failure to follow these requirements could result in the nullification of 

the lining warranty 

b) Failure to follow these requirements could result in the lining cracking 

at the first filling of the tank 

c) Failure to follow these requirements could result in disbonding or 

delamination of the lining 

d) Failure to follow these requirements could result in pitting of the lining 

surface 

ANS: c 


Q2. What should be done if there are differences between the owner's 

specifications and the lining manufacturer's recommendations? 

a) These differences should be resolved prior to beginning the job 

b) These differences should be resolved at each step to see which is 

more advantageous 

c) Disregard the manufacturer's recommendations 

d) Disregard the owner's specifications 

ANS: a 


Q3. As a general rule, the temperature of the steel surface should be ____ 

and the humidity should be _______ during the application and curing of the 

lining. 

a) 25ºF above the dew point - below 80% 

b) 5ºF above the dew point - below 80% 

c) 5ºF below the dew point - above 80% 

d) 5ºF above the dew point - above 80% 

ANS: b 

Q4. What is a common cause of failure of thick-film lining systems? 

a) Abrasive blasting to a white metal finish 

b) Abrasive blasting to a near white metal finish 

c) Primer coating at a thickness less than the anchor pattern 

d) Excess primer thickness 

ANS: d 


Q5. What two factors are the major causes of premature lining failure? 

a) Forced curing and improper application 

b) Improper application and inadequate curing 

c) Abrasive blasting to white metal finish and inadequate curing 

d) Abrasive blasting to white metal finish and improper application 

ANS: b 


Answers to API-652 Section 8, Lining Application 


Section 9 – 

Inspection 


Q1. To ensure the lining meets the specification, it should be inspected during 

___ and ___. 

a) Application and at the next scheduled internal inspection; not to 

exceed 20 years 

b) Application and at the next scheduled internal inspection; not to 

exceed 10 years 

c) Application and at the next scheduled internal inspection; not to exceed 

5 years 

d) Application and upon completion of the work 

ANS: d 

Q2. All lining inspectors should demonstrate a thorough knowledge of lining 

and coating practices or be _____ certified. 

a) National Board 

b) API-510 

c) NACE 

d) API-653 

ANS: c 


Q3. How is holiday testing of thick film linings accomplished? 

a) Holiday testing of thick film linings shall be carried out with a lowvoltage 

detector in accordance with NACE RP-01-88 

b) Holiday testing of thick film linings shall be carried out with a highvoltage 


c) Holiday testing of thick film linings shall be carried out with a lowwattage 


d) Holiday testing of thick film linings shall be carried out with an infrared 


ANS: b 


Answers to API-652 Section 9, Inspection 


Section 10 - Repair of Tank Bottom 

Linings 


Q1. A service life of ______ years should be expected from a properly 

selected and applied lining system. 

a) 10 to 20 

b) 15 to 30 

c) 20 to 30 

d) 25 to 30 

ANS: a 

Q2. When should repairs to the tank be accomplished when it is necessary to 

make repairs to the lining? 

a) All repairs to the tank should be completed immediately after lining 

repairs to permit proper curing 

b) All repairs to the tank should be completed only after the lining repair 

has had time to cure 

c) All repairs to the tank should be completed prior to any repair of the 

lining 

d) All repairs to the tank should be started before the repair of the lining 

and finished as soon as the work on the lining is complete. 

ANS: c 


Q3. Before deciding how to repair a lining, the cause and extent must be 

established. In addition, what three possible failure modes must be 

considered as possible causes of lining failure? 

a) Environmental, mechanical, cathodic protection 

b) Mechanical, improper installation, environmental 

c) Improper installation, wrong inspection technique, environmental 

d) Mechanical, environmental, placement of galvanic anodes 

ANS: 

Q4. Of the following, which is not one of the three basic types of lining repair? 

a) Top-coating of an existing lining 

b) Complete relining 

c) Spot repairs 

d) Installing metallic plugs in lining breaks 

ANS: d 


Q5. Who should be consulted to access the compatibility of new coats with 

existing lining in the top-coating repair method? 

a) The API-653 Inspector 

b) The owner or operator 

c) The lining manufacturer 

d) NACE RP-01-84 

ANS: c 


Answers to API-652 Section 10, Repair of Tank Bottom Linings 


Section 11 – 

Safety 


Q1. In addition to proper safe work procedures and training of employees, 

what else is required prior to the application of internal tank linings? 

a) Provision of the necessary supervision and/or inspection before and 

after the job is done 

b) Provision of the necessary supervision and/or inspection prior to the 

start of the lining application 

c) Provision of the necessary supervision and/or inspection throughout 

the progress of the job 

d) Provision of the necessary supervision and/or inspection provided by 

the employee with the most experience 

ANS: c 

Q2. All necessary precautions to protect _____ shall be taken prior to entry of 

and while working in a storage tank. 

a) The thick film tank bottom lining 

b) Personnel 

c) Any cathodic protection system 

d) The environment 

ANS: b 


Q3. Working in a petroleum storage tank presents certain hazards. Which of 

the following would not be a hazard associated with this activity? 

a) Drowning 

b) Respiratory 

c) Fire 

d) Explosion 

ANS: a 

Q4. In order to properly protect themselves, employees should consult 

______. 

a) Their immediate supervisor 

b) The owner/operator's specifications 

c) Previous inspection reports 

d) Material Safety Data Sheets (MSDS) 

ANS: d 


General note to participants: The purpose of an MSDS is to tell the 

worker: 

a) A material's physical properties which make is hazardous to handle 

b) The type of personal protective equipment needed 

c) The first aid treatment is exposed to a hazard 

d) The planning needed for safely handling normal operation, as well as 

emergencies such as spills and fires 

e) The appropriate response to accidents 

The applicable MSDS should be consulted prior to conducting any work 


Answers to API-652 Section 11, Safety 


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API PUBLICATION 2207 

Preparing Tank Bottoms 

for Hot Work - 1998 






Preparing Tank Bottoms 

for Hot Work 


Fifth Edition, September 1998 


Section 1 – 

General 


Q1. An operation that can produce a spark or flame hot enough to ignite 

flammable vapors is the definition, used by API 2207, for _____. 

a) Flame work 

b) Hot work 

c) Flash work 

d) Burning work 

ANS: b 

Q2. Tanks that have contained flammable or combustible liquids must be 

inspected and proven safe for hot work. These inspections include gas testing 

to determine an oxygen content of between ____ and _____ is present. 

a) 19.5 and 22.5 ppm 

b) 19.5 and 22.5 ppb 

c) 19.5 and 22.5 percent 

d) 19.5 and 22.5 ml per cubic foot 

ANS: c 


Section 3 – 

Precautions 


Q1. During the entry and hot work activity, a/an ______ should be in 

operation. 

a) Electrical light stationed at the tank entrance 

b) Electrical air mover 

c) Cathodic protection system 

d) Gasoline powered air mover 

ANS: b 

Q2. Tank surfaces that have been in contact with leaded gasoline should be: 

a) Scraped down to bare metal 

b) Thoroughly flushed with potable water 

c) Steam cleaned 

d) Air lanced and cleaned with a solvent 

ANS: a 


Q3. As an alternative to scraping down to bare metal, welders should: 

a) Preheat the area to be welded to a minimum of 200°F 

b) Wear chemical and gasoline resistant shoes and gloves 

c) Take frequent breaks by leaving the area at least every 15 minutes 

d) Use supplied-air respiratory equipment 

ANS: d 

Q4. Grounding leads from welding machines should be attached to: 

a) The rectifier for the tank where hot work is being performed 

b) A bared surface on a tank in close proximity to the one in which hot 

work is being performed 

c) A bared surface on the tank shell on which hot work is to be performed 

d) A grounding rod driven deep in the ground out side the diked area of 

the tank in which hot work is being performed 

ANS: c 


Q5. Compressed gas cylinders used for cutting operations should be kept: 

a) Inside the tank to prevent tampering 

b) Outside the tank next to the opening 

c) Outside the tank at a safe distance from open manholes 

d) Inside the tank as long as there is at least 20 feet separating the 

cylinder from the hot work area 

ANS: c 


Section 4 – Inspection Procedures / 

Section 5 – Safe Work Procedures 


Q1. In preparation for performing hot work on a tank bottom, the repair 

organization places small openings in the tank bottom. Why would these 

openings be cut into the tank bottom? 

a) These openings facilitate inspection and complete draining of the tank 

b) These openings facilitate inspection and freeing the interior from gas 

c) These openings facilitate installation of jigs for alignment 

d) These openings facilitate inspection and testing the soil under the tank 

ANS: b 


Q1. Minor welded repairs, if the tank bottom is not in good shape, may be 

made using which of the following procedures? 

a) Drill and tap a hole for ½” pipe, connect a supply of inert gas to the tap, 

establish a flow of inert gas before starting the hot work, ensure oxygen 

content of atmosphere of 19.5 to 22.5 percent, plug the hole and back 

weld. 

b) Drill and tap a hole for 1/4” pipe, connect a supply of inert gas to the 

tap, establish a flow of inert gas before starting the hot work, ensure 

oxygen content of atmosphere of 19.5 to 22.5 percent, plug the hole and 

back weld. 

c) Drill and tap a hole for ½” pipe, connect a supply of inert gas to the tap, 

establish a flow of inert gas immediately after starting the hot work, 

ensure oxygen content of atmosphere of 19.5 to 22.5 percent, plug the 

hole and back weld. 

d) Drill and tap a hole for ½” pipe, connect a supply of inert gas to the tap, 

establish a flow of inert gas before starting the hot work, ensure oxygen 

content of atmosphere of 16.5 to 29.5 percent, plug the hole and back 

weld. 

ANS: a 


Q2. Major repairs involving most of the tank bottom can be accomplished by 

constructing a dike around the tank’s outer shell and flooding beneath the 

tank bottom with: 

a) Solution of soap and water 

b) Solution of soda ash and water 

c) Light diesel oil 

d) Water 

ANS: d 

Q3. When it is necessary to perform welded repairs around the perimeter of a 

tank, excavation for a minimum of ____ beyond the point of any hot work area 

should be made. 

a) Twelve feet 

b) Twelve inches 

c) Six feet 

d) Six inches 

ANS: b 


Q4. When a tank double bottom is constructed, how much sand or other 

sealing material should be placed over the existing floor. 

a) Approximately 12 inches 

b) Approximately 8 inches 

c) Approximately 6 inches 

d) Approximately 4 inches 

ANS: 





API RP 575 

Inspection Practices for Atmospheric 

and Low-Pressure Storage Tanks 

Third Edition, April 2014 


Section 3 – Selected Nondestructive 

Examination Methods 


Q1. In ultrasonic thickness measurements, dual-element transducers have 

the ability to operate from thin sections of ____ inch 

a) 0.500 – 1.000 

b) 0.050 – 0.100 

c) 0.050 – 1.000 (1.27mm-25.4mm) 

d) 0.005 – 1.000 

ANS: 

Q2. In performing ultrasonic thickness measurements _____ transducers are 

recommended for measurements on penetrations and floors and _____ 

transducers are recommended on shells where coating thickness may not be 

uniform. 

a) Dual-element, Single crystal contact 

b) Single crystal contact, Dual-element 

c) High-temperature, Low-temperature 

d) Low-temperature, High-temperature 

ANS: a 


Q3. What is the minimum overlap for ultrasonic thickness readings according 

to the ASME? 

a) 10 percent based on the thickness of the part being examined 

b) 10 percent based on the diameter of the transducer 

c) 10 percent based on the thickness of the calibration block 

d) 10 percent based on the diameter of the transducer cable 

ANS: b 

Q4. What ultrasonic method can be used to assist in the discrimination 

between inclusions in the metal and laminations? 

a) A scan 

b) B scan 

c) Straight beam 

d) Shear wave 

ANS: a 


Q5. The primary advantage of magnetic floor testing using a floor scanner is 

the ability to detect topside pitting and underside corrosion. Additional 

inspection is required to quantify flaws detected above certain thresholds. 

Generally, what method of examination is used for this purpose? 

a) Liquid penetrant 

b) Eddy current 

c) Ultrasonic 

d) Radiography 

ANS: c 


Answers to API-RP-575 Section 3, Selected Nondestructive Examination 

Methods 


Section 4 – 

Types of Storage Tanks 


Q1. API-575 states that atmospheric storage tanks are used for fluids having 

a true vapor pressure at the storage temperature that is _____. 

a) equal to or greater than atmospheric pressure 

b) at least 2.5 psi above atmospheric 

c) at least 2.5 pounds per square foot above atmospheric 

d) substantially below atmospheric 

ANS: a 

Q2. What type of tank does API-575 consider the simplest type of 

atmospheric storage tank? 

a) Cone-roof 

b) Dome-roof 

c) Umbrella-roof 

d) Pan-type floating roof 

ANS: a 


3.3 

atmospheric pressure 

When referring to (vertical) tanks, the term “atmospheric pressure” usually 

means tanks designed to API 650, although API 620 uses the term 

atmospheric pressure to describe tanks designed to withstand an internal 

pressure not exceeding the weight of the roof plates. API 650 also provides 

for rules to design tanks for “higher internal pressure” up to 2.5 lbf/in.2 (18 

kPa). API 653 uses the generic meaning for atmospheric pressure to describe 

tanks designed to withstand an internal pressure up to, but not exceeding 2.5 

lbf/in.2 (18 kPa) gauge. 

4 Types of Storage Tanks 4.1 General Storage tanks are used to store 

fluids such as crude oil, intermediate and refined products, gas, chemicals, 

waste products, water, and water/product mixtures. Important factors such as 

the volatility of the stored fluid and the desired storage pressure and 

temperature result in tanks being built of various types, sizes, and materials of 

construction. In this document, only atmospheric and low-pressure storage 

tanks are considered. Guidelines for inspection of pressure vessels operating 

at pressures greater than 15 lbf/in2 (103 kPa) gauge are covered in API 572. 


Q3. The floating roof atmospheric storage tank is designed to do which of the 

following? 

a) Allow the tank to filled completely to the top rim and provide selfventing 

b) Prevent personnel for falling into the tank and keep birds out of the 

storage area 

c) Eliminate or minimize the vapor space above the stored liquid 

d) Create or maximize the vapor space above the stored liquid 

ANS: c 

Q4. The pan-type floating roof is the simplest type of floating roof design. 

Which of the following is the most correct? 

a) This design is susceptible to collapse 

b) This design is susceptible to sinking 

c) This design is more susceptible to corrosion 

d) This design is not suited for hydrocarbon storage tanks 

ANS: b 


Q5. Storage tanks that are designed to operate at pressures, in their gas or 

vapor spaces, exceeding 2.5 psi but not more than 15 psi are described as 

which of the following? 

a) Atmospheric storage tanks 

b) High-pressure storage tanks 

c) Intermediate pressure storage tanks 

d) Low-pressure storage tanks 

ANS: d 


Answers to API-RP-575 Section 4, Types of Storage Tanks 


Section 5 – Reasons for Inspection and 

Causes of Deterioration 


Q1. In general, why are storage tanks inspected? 

a) To determine their physical condition and cycles of use 

b) To determine their physical condition and rate of deterioration 

c) To determine their physical dimensions and rate of deterioration 

d) To determine their physical condition and type of design 

ANS: b 

Q2. What is the prime cause of deterioration of steel storage tanks and 

accessories? 

a) Erosion 

b) Upset 

c) Settlement 

d) Corrosion 

ANS: d 


Q3. A sand pad beneath a tank bottom is found to be contaminated with 

gravel and crushed stones. What type of problem could this contamination 

cause? 

a) Pitting corrosion at points of contact 

b) Punctures of the tank bottom at points of contact 

c) Air spaces which provide even corrosion 

d) Cracking at the point of contact 

ANS: a 

Q4. If soil movement raises the grade level to cover the lower portion of the 

shell, what would you as the inspector look for? 

a) Severe external corrosion of the shell beneath the soil level 

b) Severe external corrosion of the shell just above the soil line 

c) Severe internal corrosion of the shell beneath the soil level 

d) Severe internal corrosion of the shell just above the soil line 

ANS: a 


Q5. Atmospheric corrosion can occur on all external parts of a tank. During 

your inspection, you notice considerable damage to the protective coating 

and accelerated corrosion rates. What would you suspect the cause to be? 

a) Hydrogen and oxygen rich atmosphere 

b) Nitrogen and oxygen rich atmosphere 

c) Sulfurous or acidic atmosphere 

d) Carbon dioxide and nitrogen rich atmosphere 

ANS: c 

Q6. Internal corrosion in the vapor space above the liquid of crude oil and 

petroleum product tanks is commonly caused by _________. 

a) Hydrogen sulfide vapor, water vapor, caustic vapors or any 

combination of the three 

b) Hydrogen sulfide vapor, nitrogen vapors, oxygen or any combination of 

the three 

c) Hydrogen sulfide vapor, water vapor, oxygen or any combination of the 

three 

d) Hydrogen sulfide vapor, water vapor, nitrogen or any combination of 

the three 

ANS: c 


Q7. Of the following, which is not a point where cracks are most likely to 

occur? 

a) Around nozzle connections 

b) Around rivet holes 

c) Bottom-to-shell connections 

d) In the roof rafters 

ANS: d 

Q8. Why is inspection for cracking of the lower-shell-to-sketch-plate weld 

critical? 

a) This area is more susceptible to cracking because it is subjected to 

internal and external atmosphere 

b) This area is critical because in relatively large or hot tanks, it has more 

potential for cracking 

c) This area is critical because in relatively large or hot tanks, it has more 

potential for corrosion 

d) This area is critical because in relatively small or cold tanks, it has 

more potential for cracking 

ANS: b 


Q9. Why is it important to check roof drains? 

a) Plugged drains can cause enough rainwater to accumulate on the roof 

to prevent the tank from being pumped full 

b) Plugged drains can cause enough rainwater to accumulate on the roof 

to increase the vapor pressure enough to cause the tank to rupture 

c) Plugged drains can cause enough rainwater to accumulate on the roof 

to force product out of the vents creating an environmental hazard 

d) Plugged drains can cause enough rainwater to accumulate on the roof 

to sink a pan-type or pontoon-type floating roof 

ANS: d 


Answers to API-RP-575 Section 5, Reasons for Inspection and Causes 

of Deterioration 


Section 7 – Methods of Inspection and 

Inspection Scheduling 


Q1. Some of the first items to inspect when conducting an internal inspection 

of a storage tank should be which of the following? 

a) The tank bottom and the annular ring plate if one is installed 

b) The water draw-off pipe and product drain 

c) The base of all roof support structures 

d) Overhead parts and all supports 

ANS: d 

Q2. Where should the recommended inspection of overhead parts and 

supports be conducted from? 

a) A bosun’s chair suspended through the roof vent after the tank has 

been gas freed 

b) The entry point or other observations points before entering the tank 

c) From the very center of the tank bottom with a powerful sealed beam 

portable light 

d) From ladders or scaffolding 

ANS: b 


Q3. The inspector should thoroughly review __________ prior to conducting 

internal or external inspections. 

a) The repair plan and/or re-commissioning plan 

b) The operating history of the tank and list of products that have been in 

the tank 

c) The inspection and maintenance records 

d) The tank entry permit and qualification of the entry attendant 

ANS: c 

Q4. When any work is being done on the outside or close to the tank, 

especially on the roof, during inspection ________ should be kept 

informed. 

a) The owner/operator 

b) The qualified person 

c) Personnel working inside the tank 

a) Personnel working under the tank 

ANS: c 


Q5. When should the majority of external inspection activity be conducted? 

a) As soon as the tank is taken out of service and is drained 

b) Six months before the tank is removed from service for the internal 

inspection 

c) While the tank is being drained 

d) While the tank is in service 

ANS: d 

Q6. During the external in-service inspection, ladder and stair treads should 

be checked. What condition(s) would you be looking for? 

a) Missing rungs and wear 

b) Corrosion or broken parts 

c) Corrosion and missing rungs 

d) Tread-to-tread distance and handrail height 

ANS: b 


Q7. Inspection of pipe connections to the tank should include bolting at 

flanged joints. Piping that enters the ground should be inspected at the soilto-air 

interface by excavating ___ to ___ inches to permit visual and ultrasonic 

thickness examination. 

a) 18 to 24 

b) 12 to 18 

c) 6 to 12 

d) 4 to 8 

ANS: b 

Q8. If during your inspection, you find distortion around a nozzle connection, 

what additional action would you recommend? 

a) All seams and the shell in this area should be examined 

b) All horizontal welds around the tank in the course that contains the 

nozzle should be examined 

c) All vertical welds within 36 inches of the nozzle should be examined 

d) An area measuring two nozzle diameters square should be examined 

around the nozzle 

ANS: a 


Q9. Grounding connections should be visually checked for corrosion at the 

point where they enter the earth. What is the approximate total resistance 

from the tank to earth? 

a) Should not exceed 100 ohms 

b) Should not exceed 75 ohms 

c) Should not exceed 50 ohms 

d) Should not exceed 25 ohms 

ANS: d 

Q10. Where would you expect to find paint blisters? 

a) On the roof and on the side of the tank on the north side 

b) On the roof and on the side of the tank subjected to mist over-spray 

from cooling towers 

c) On the roof and on the side of the tank adjacent to another tank 

d) On the roof and on the side of the tank receiving the most sunlight 

ANS: d 


Q11. Why is it recommended that inspectors not walk on insulated roof? 

a) The inspector may damage the insulation 

b) The insulation may contain hazardous substances 

c) The roof plates may not be strong enough to support the inspector’s 

weight 

d) The inspector may cause indentations in the insulation where water 

can collect 

ANS: c 

Q12. The inspector finds corrosion during the shell inspection and requires 

ultrasonic thickness measurements to be taken. How many measurements 

would normally be taken? 

a) At least one thickness measurement on each shell ring 

b) At least two thickness measurements on each shell ring 

c) At least three thickness measurements on each shell ring 

d) At least one thickness measurement in the immediate area of the 

corrosion 

ANS: d 


Q13. In obtaining shell thickness measurements, special attention should be 

given to the upper __ inches of un-coated shells of floating-roof tanks. 

a) Twelve 

b) Twenty-four 

c) Eighteen 

d) Thirty-six 

ANS: 

Q14. Where would you expect to find caustic stress corrosion cracking 

(caustic embrittlement) during an inspection of a storage tank used to store 

amine? 

a) At the liquid to vapor interface 

b) At the roof supports on the tank bottom 

c) Around connections for internal heating coils or units 

d) At the shell-to-bottom connection 

ANS: c 


Q15. What should be done if an indication of leakage through a crack is 

discovered on an in-service tank? 

a) A soft patch should be applied over the crack and the area observed 

for 24 hours 

b) It may be possible to caulk the crack to stop the leakage 

c) The tank shall immediately be removed from service, drained, opened, 

and repaired 

d) The tank should be removed from service as soon as possible and a 

complete inspection with subsequent repairs made 

ANS: d 

Q16. Welded tanks that have significant distortions may cause the weld 

seams to be over-stressed. In addition to the bottom-to-shell joint, what other 

welds are susceptible to cracking? 

a) Horizontal shell seams 

b) Vertical shell seams 

c) Wind girder attachment welds 

d) Reinforcement pad peripheral welds 

ANS: b 


Q17. When a tank is of welded construction and has significant distortion, 

weld seams may crack. When cracking is suspected, what is the preferred 

method of nondestructive examination? 

a) Radiography 

b) Ultrasonic 

c) Liquid Penetrant 

d) Magnetic Particle 

ANS: b 

Q18. When conducting a tank roof inspection on a floating roof, in addition to 

the recommendation that the inspector walk on weld seams, what other 

precaution should be taken? 

a) The tank should be empty and the roof siting on the lower support 

stops 

b) The roof should be in the high-gauge position if volatile liquid is in the 

tank 

c) Inert gas should be applied under the roof if volatile liquid is in the tank 

d) The roof vent(s) should be plugged to prevent vapor escape while the 

inspector is on the roof 

ANS: 


When conducting a tank roof inspection on a floating roof, The roof should be 

in the high-gauge position if volatile liquid is in the tank 


When conducting a tank roof inspection on a floating roof, The roof should be 

in the high-gauge position if volatile liquid is in the tank 


Q19. External corrosion on roof surfaces will usually be most severe at 

depressions where water can remain until it evaporates. 

a) True 

b) False 

ANS: a 

Q20. Which of the following is the correct procedure for pressure testing roof 

drain lines and joints? 

a) First test at about 1.5 times design pressure for approximately ½ hour 

then reduce pressure to ½ design pressure and hold for another ½ hour 

b) First test at about 15 psi for approximately ½ hour then reduce 

pressure to 5 psi and hold for another ½ hour 

c) First test at about 30 psi for approximately ½ hour then reduce 

pressure to 5 psi and hold for another ½ hour 

d) First test at about 3.0 times design pressure for approximately ½ hour 

then reduce pressure to ½ design pressure and hold for another ½ hour 

ANS: c 


Q21. In conducting a preliminary internal visual inspection, what is the 

recommended sequence of the inspection? 

a) The bottom, shell, internal supports, and roof in that order 

b) The shell, bottom, internal supports, and roof in that order 

c) The internal supports, roof, shell, and bottom in that order 

d) The roof, internal supports, shell, and bottom in that order 

ANS: c 

Q22. An inspector should be aware of the possibility of accumulation of dry 

pyrophoric deposits that could ignite during the inspection. What should be 

done with these deposits if they can not be removed prior to the inspection? 

a) These deposits should be kept moist 

b) These deposits should be kept dry 

c) These deposits should be covered with foam 

d) These deposits should be left alone and the inspector should stay at 

least 12 feet from them 

ANS: a 


Q23. Where would you expect to find significant internal corrosion in a tank in 

sour refinery fluid service? 

a) On the surfaces of the bottom plates 

b) In vapor space above the stored liquid 

c) Adjacent to the product drain nozzle 

d) Adjacent to the manway entrance nozzle 

ANS: b 

Q24. Caustic stress corrosion cracking (caustic embritlement) is prevalent 

when the temperature rises above ____°F. 

a) 100 

b) 125 

c) 150 (65°C) 

d) 175 

ANS: d 


Q25. When the statistical methods are used to assess the probable condition 

of a tank bottom, what is the typical amount of the floor that should be 

randomly scanned? 

a) 30 to 50 percent 

b) 20 to 30 percent 

c) 10 to 20 percent 

d) 5 to 10 percent 

ANS: 

Q26. Tanks with a bottom angle between the shell and the bottom should be 

checked for cracks in the shell adjacent to any welded butt joints in this angle. 

What method of examination should be used? 

a) Ultrasonic or radiography 

b) Liquid penetrant or magnetic particle 

c) Eddy current or acoustic emission 

d) Light diesel oil or vacuum box 

ANS: b 


statistical methods are used to assess the probable condition of a tank bottom, 

what is the typical amount of the floor that should be randomly scanned? d) 5 

to 10 percent 


Q27. To test for leaks through shell plates, sometimes a penetrating oil can 

be sprayed or brushed on one side and the other side observed for leakage. 

What period of time might be required to conduct this type of test? 

a) 48 hours 

b) 36 hours 

c) 24 hours 

d) 72 hours 

ANS: c 


Q28. API-575 discusses several methods of inspecting the bottoms of tanks 

that are resting on pads or on the soil. The methods require a temporary clay 

dam to be placed around the outside of the tank bottom. Which of the 

following is not one of the methods discussed? 

a) Cover the inside surface with a soap solution and inject air at not more 

than 3 inches of water pressure under the tank 

b) Inject a solution of light diesel oil under the tank at a pressure not more 

that 3 psi and observe the tank bottom from the inside for wicking of the 

oil 

c) Pump about 6 inches of water into the tank and then place air at not 

more than 9 inches of water pressure under the tank 

d) Pump water under the tank to depth of about 6 inches above the level 

of the highest point of the tank bottom and holding the water with the clay 

dam 

ANS: d 


Cover the inside surface with a soap solution and inject air at not more than 3 

inches of water pressure under the tank 

inject air at not 

more than 3 

inches of water 

pressure 

soap solution 

air 

air 

air 

air 

air 


Pump about 6 inches of water into the tank and then place air at not more 

than 9 inches of water pressure under the tank 

inject air at not 

more than 9 

inches of water 

pressure 

water 

6 inches 

air 

air 

air 

air 

air 


Pump water under the tank to depth of about 6 inches above the level of the 

highest point of the tank bottom and holding the water with the clay dam 

water 

6 inches 


Q29. Atmospheric tanks that are designed for not more than 0.5 psig over the 

static pressure of the liquid contained in the tank are normally tested: 

a) By filling the tank with the liquid to be stored 

b) By filling the tank with an inert gas 

c) By filling the tank with water 

d) By filling the tank with a soap solution 

ANS: c 

Q30. What should be the deciding factor(s) in determining the need for tank 

repair or renewal? 

a) Structural integrity and leak avoidance 

b) Economics 

c) Age of the tank 

d) Product stored in the tank 

ANS: a 


Answers to API-RP-575 Section 7, Reasons for Inspection and Causes 

of Deterioration 


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Understanding API ICP653 Reading 8-Worksheet-05 Part2a

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