Understanding Heat Exchanger Reading 03a The ARAMCO Std.

My Reading on Heat Exchanger 

Reading 03- The ARAMCO Std. 

Part 1 of 2 

for my Aramco AOC’s QM31 Exam Preparations 

27 th May 2018 

http://satorp.com/ 

Charlie Chong/ Fion Zhang

闭门练功 


闭门练功 


Charlie Chong/ Fion Zhang 

Fion Zhang at Shanghai 

Damuqiao 大木桥路 

27 th May 2018


http://greekhouseoffonts.com/

The Magical Book of Heat Exchanger Reading 



有 

书 

真 

幸 

福 

无事小神仙 


Parts: 

1. API660/ ISO 16812:2007 

Shell-and-tube Heat Exchangers 

2. Materials System Specification 

32-SAMSS-007 

Manufacture of Shell and Tube Heat Exchangers 



American Petroleum Institute API 600 Std.

Part 1: 

Shell-and-tube Heat Exchangers 

ANSI/API STANDARD 660 

EIGHTH EDITION, AUGUST 2007 

ISO 16812:2007 (Identical), Petroleum, petrochemical 

and natural gas industries-Shell-and-tube Heat 

Exchangers 


Contents 

1. Scope 

2. Normative references 

3. Terms and definitions 

4. General 

5. Proposals 

6. Drawings and other required 

7. Design 

8. Materials 

9. Fabrication 

10. Inspection and testing 

11. Preparation for shipment 

12. Supplemental requirements 

Annex A (informative) Recommended practices 

Annex B (informative) Shell-and-tube heat exchanger checklist 

Annex C (informative) Shell-and-tube heat exchanger data sheets 

Annex 0 (informative) Responsibility data sheet 


Foreword 

ISO (the International Organization for Standardization) is a worldwide 

federation of national standards bodies (ISO member bodies). The work of 

preparing International Standards is normally carried out through ISO 

technical committees. Each member body interested in a subject for which a 

technical committee has been established has the right to be represented on 

that committee. 

International organizations, governmental and non-governmental, in liaison 

with ISO, also take part in the work. ISO collaborates closely with the 

International Electrotechnical Commission (IEC) on all matters of 

electrotechnical standardization. International Standards are drafted in 

accordance with the rules given in the ISO/IEC Directives, Part 2. 

The main task of technical committees is to prepare International Standards. 

Draft International Standards adopted by the technical committees are 

circulated to the member bodies for voting. Publication as an International 

Standard requires approval by at least 75 % of the member bodies casting a 

vote. 


Attention is drawn to the possibility that some of the elements of this 

document may be the subject of patent rights. ISO shall not be held 

responsible for identifying any or all such patent rights. 

ISO 16812 was prepared by Technical Committee ISO/TC 67, Materials, 

equipment and offshore structures for petroleum, petrochemical and natural 

gas industries, Subcommittee SC 6, Processing equipment and systems. This 

second edition cancels and replaces the first edition (ISO 16812:2002), which 

has been technically revised. 


ISO collaborates closely with the 

International Electrotechnical 

Commission (IEC) on all matters 

of electrotechnical 

standardization. International 

Standards are drafted in 

accordance with the rules given 

in the ISO/IEC Directives, Part 2. 


ISO Publication as an International 

Standard requires approval by at 

least 75 % of the member bodies 

casting a vote. 


Introduction 

Users of this International Standard should be aware that further or differing 

requirements may be needed for individual applications. This International 

Standard is not intended to inhibit a vendor from offering, or the purchaser 

from accepting, alternative equipment or engineering solutions for the 

individual application. This may be particularly applicable where there is 

innovative or developing technology. Where an alternative is offered, the 

vendor should identify any variations from this International Standard and 

provide details. 

Annex A provides some optional recommended practices. 

A bullet (•) at the beginning of a clause or sub-clause indicates a requirement 

for the purchaser to make a decision or provide information (see checklist in 

Annex B). 

In this International Standard, where practical, US Customary (USC) units are 

included in parentheses for information. 


A bullet (•) 

at the beginning of a clause or 

sub-clause indicates a 

requirement for the purchaser to 

make a decision or provide 

information (see checklist in 

Annex B). 


A bullet (•) 

at the beginning of a clause or sub-clause indicates a requirement for the 

purchaser to make a decision or provide information (see checklist in Annex B). 


In this International Standard, where practical, US Customary (USC) units are 

included in parentheses for information. 


Petroleum, petrochemical and natural gas industries - Shelland-tube 

heat exchangers 

1 Scope 

This International Standard specifies requirements and gives 

recommendations for the: 

1. mechanical design, 

2. material selection, 

3. fabrication, inspection, testing and 

4. preparation for shipment of shell-and-tube heat exchangers for the 

petroleum, petrochemical and natural gas industries. 

This International Standard is applicable to the following types of shell-andtube 

heat exchangers: 

• heaters, condensers, coolers and reboilers. 

This International Standard is not applicable to vacuum-operated steam 

surface condensers and feed-water heaters. 


Vacuum-operated Steam Surface Condensers 



Vacuum 

operated 

Steam 

Surface 

Condensers

Power Plant- Vacuumoperated 

Steam Surface 

Condensers 



2 Normative references 

The following referenced documents are indispensable for the application of 

this document. For dated references, only the edition cited applies. For 

undated references, the latest edition of the referenced document (including 

any amendments) applies. 

• ISO 15156 (all parts) (NACE MR0175), Petroleum and natural gas 

industries- Materials for use in H 2 S-containing environments in oil and 

gas production 

• ASME B 16.5, Pipe Flanges and Flanged Fittings 

• ASME B 16.11, Forged Fittings, Socket-Welding and Threaded 

• ASME B 1.20.1, Pipe Threads, General Purpose (Inch) 

• EJMA, Standards of the Expansion Joint Manufacturers Association 

• NACE MR0103 -Materials Resistant to Sulfide Stress Cracking in 

Corrosive Petroleum Refining Environments 

• TEMA Standards Set, 8th Edition, Standards of the Tubular Exchanger 

Manufacturers Association 

Normative : of or relating to a norm, especially an assumed norm regarded 

as the standard of correctness in behavior, speech, writing, etc. ( 规范的 ; 标准的 ) 


The following NACE referenced documents are indispensable for the 

application of this document. 

• ISO 15156 (all parts) (NACE MR0175), Petroleum and natural gas industries- Materials for 

use in H2S-containing environments in oil and gas production 

• NACE MR0103 -Materials Resistant to Sulfide Stress Cracking in Corrosive Petroleum 

Refining Environments 


3 Terms and definitions 

For the purposes of this document, the following terms and definitions apply. 

3.1 

annular distributor 

additional chamber incorporated into a shell side nozzle to more evenly 

distribute shell side fluids entering or exiting the tube bundle 


Annular Distributor 


3.2 

category A welded joint 

longitudinal welded joint within the main shell, communicating chambers, 

nozzles or transitions in diameter; or any welded joint within a sphere or 

within a formed or flat head; or circumferential welded joint connecting 

hemispherical heads to main shells, to transitions in diameters or to 

communicating chambers 

3.3 

category B welded joint 

circumferential welded joint within the main shell, communicating chambers, 

nozzles or transitions in diameter, including joints between the transitions and 

a cylinder at either the large or small end; or circumferential welded 

joint connecting formed heads, other than hemispherical, to main shells, to 

transitions in diameter, to nozzles or to communicating chambers 


Cat “B” includes most circumferential 

welded joints including formed heads (other 

than hemispherical) to main shells welds. 

FIG. UW-3 ILLUSTRATION OF WELDED JOINT LOCATIONS 

TYPICAL OF CATEGORIES A, B, C, and D 


ASME VIII-UW-03

Cat “A” includes all longitudinal welds and 

critical circumferential welds such as 

hemispherical head to shell welds. 

FIG. UW-3 ILLUSTRATION OF WELDED JOINT LOCATIONS 

TYPICAL OF CATEGORIES A, B, C, and D 


ASME VIII-UW-03

• Cat “A” includes all longitudinal welds and critical 

circumferential welds such as hemispherical head to shell 

welds. 

• Cat “B” includes most circumferential welded joints including 

formed heads (other than hemispherical) to main shells welds. 

• Cat “C” includes welded joints connecting: . flanges to 

nozzles or shell components. one side plate to another in a 

flat-sided vessel. 

• Cat “D” includes welded joints connecting nozzles to shells, 

heads or flat-sided vessels. 

Fion Zhang/ Charlie Chong 

ASME VIII-UW-03

• Cat “A” includes all longitudinal welds and critical circumferential welds 

such as hemispherical head to shell welds. 

• Cat “B” includes most circumferential welded joints including formed heads 

(other than hemispherical) to main shells welds 

Cat A 


Cat B 

Except 

Hemispherical Head 

ASME VIII-UW-03

Exercise: 


Exercise: 

D 

C 

D 

? 

D 

C 

? 

B 

B 

D 

A 

A 

D 

D 


Exercise: 

D 

C 

D 

? 

D 

C 

? 

B 

B 

D 

A 

A 

D 

D 


Exercise: 


Why Hemispherical Head fall under Cat “A” and 

What is RT1 and RT2? 

ASME Pressure Vessel Joint Efficiencies 

The ASME Pressure Vessel Joint Efficiencies article provides you with information about pressure vessel joint efficiency 

requirements and their connection with radiography testing. 

You may know Pressure Vessel Joint Efficiencies are linked to the radiography testing grades and there is a concession for full 

radiography testing as per the UW-11(a) (5) (b) clause which it is a little bit confusing. 

This article provides you the ASME pressure vessel joint efficiencies requirements and guidelines for the above clause. 

Based on the ASME Code requirement, manufacturers have to mark the type of RT i.e. RT1, RT2, RT3 and RT4 in the pressure 

vessel name plate and state the same in Pressure Vessel Data Report. 

We have seen many professionals, from inspectors to quality control engineers who are confused between RT1 and RT2, 

specifically when they see ASME Pressure Vessel Joint Efficiencies for both RT1 and RT2 is the same and equal to 1(E=1). 

They say both RT1 and RT2 are categorized in the “Full Radiography” part in UW-11 clause ... 

So why are some joints in RT2 radiographed in spots? 

We are making spot radiography, but it is categorized in full radiography!!! 

So in this "ASME Pressure Vessel Joint Efficiencies" article we want to answer this question in very simple way, but before this, 

we need review joint categories and summarize them as below: 

Category A: 

All longitudinal welds in shell and nozzles 

All welds in heads, Hemispheric-head to shell weld joint 

Category B: 

All circumferential welds in shell and nozzles 

Head to shell joint (other than Hemispheric.) 

Category C and D are flange welds and nozzle attachment welds respectively 


http://www.inspection-for-industry.com/asme-pressure-vessel-joint-efficiencies.html

Do you know why? Why ASME considered the stringent rule for 

Category “A” weld than Category “B” weld? 

Longitudinal welds (Category A) are more critical than Circumferential welds (Category B) because they are under double stress. 

This the reason why in different part of ASME code we have stringent rules in category A joint compared to category B joint. 

See the following Fig. for joint categories: 

Now let's get back to the ASME Pressure Vessel Joint Efficiencies subject, to remove the above confusion about RT1 and RT2. 

We need to know: 



When and where is there a code requirement for full radiography? 

Item 1: All butt welds in vessels used to contain a lethal substance (UW-11(a)).Lethal substances have specific definitions in 

ASME Code in UW-2 and it is the responsibility of the end user to determine if they ordered a vessel that contains lethal 

substances. 

Item 2: All butt welds in vessels in which the nominal thickness exceeds specified values (UW-11(a). You can find these values in 

subsection C, in UCS-57, UNF-57, etc. For example, this value for P-No.1 in UCS-57 is 1 ¼ inch. 

Item 3: All butt welds in an unfired steam boiler with design pressure > 50 psi (UW-11(a)). 

Item 4: All category A and D butt welds in vessel when “Full Radiography” optionally selected from table UW-12(column (a) in this 

table is selected); and categories B and C which intersect Category A shall meet the spot radiography requirement (UW-11(a) (5) 

(b)). 

The point is this: items 1, 2 and 3 are similar, but item 4 is completely different. In items 1, 2 and 3 it is mandated by code; to do 

full radiography in all butt welds in vessel so it means it is mandatory for designer to select column (a) in UW-12 table. 

But in item 4, there is no mandating rule. A manufacturer with its own decision has chosen to use column (a) in table UW-12 for 

full radiography. 

So here there is a concession or bonus to manufacturers for categories B and C. 



What is concept behind this concession or bonus in pressure vessel RT2? 

If you review item 1, 2 and 3 one more time, you will see that the pressure vessel RT tests are related to the type of welds and 

services. 

You can see the pressure vessels in these items are critical from a safety point of view, one contains a lethal substance, the other one 

has a high thickness, which implicates high pressure, and the last one is an unfired steam boiler. But item 4 has no criticality like the 

other items have. 

But you should note all 4 items have been categorized in full radiography clause( U-11(a)), so to differentiate item 1, 2 and 3 from item 

4, the RT symbols are used in Code (UG-116). 

RT 1: Items 1, 2 and 3, (E=1), All butt welds-full length radiography 

RT 2: Item 4 (E=1), Category A and D butt welds full length radiography and category B and C butt welds spot Radiography 

RT 3: (E=0.85), Spot radiography butt welds 

RT 4: (E=0.7), Partial / No radiography 

You need to consider the hemispherical head joint to shell as category A, but ellipsoidal and torispherical head joint to shell as 

category B; 

Do you know why? Why ASME considered the stringent rule for pressure 

vessel RT test in hemispherical head joint? 

It is because this joint is more critical, because the thickness obtained from the formula for hemispherical head approximately would 

be half of the shell thickness; It means if the shell thickness is 1 inch, the hemispherical head thickness would be 0.5 inch. 

For more detail, you may review the Pressure Vessel Heads http://www.inspection-for-industry.com/pressure-vessel-heads.html 

article. 



Do you know why? Why ASME considered the stringent rule for 

Category “A” weld than Category “B” weld? 

Longitudinal welds (Category A) are more critical than Circumferential welds (Category B) because they are under double stress. 

This the reason why in different part of ASME code we have stringent rules in category A joint compared to category B joint. 

Weld Types: 

Here is some clarification about the different type of welds that have specific definitions in ASME Code SEC VIII DIV 1 and related 

to the pressure vessel RT test. 

The concept is to define the different types and then introduce some restriction for using them. 

For example, a Type 1 weld is defined as a full penetration weld, typically double welded and Type 2 is welds with backing strips. 

So when you go to service restriction for a vessel containing a lethal substance, you see there is a restriction there that says all 

category A joints shall be weld Type 1 and Category B and C shall be type 1 or type 2. 

You should take this point in to account, which is this: the same joint category with different weld types have different joint 

efficiencies. 

Summary of weld types: 

Type 1: Full penetration welds (Typically Double welded) 

Type 2: Welds with backing strip 

Type 3: Single welded partial penetration welds 

Type 4, 5 and 6: Various Lap welds (rarely used) 





UW-11 RADIOGRAPHIC AND ULTRASONIC 

EXAMINATION 

(a) Full Radiography. The following welded joints 

shall be examined radiographically for their full 

length in the manner prescribed in UW-51: 

1. (1) all butt welds in the shell and heads of vessels 

used to contain lethal substances [see UW-2(a)]; 

2. (2) all butt welds in the shell and heads of vessels in 

which the nominal thickness [see (g) below] at the 

welded joint exceeds 11/2 in. (38 mm), or exceeds the 

lesser thicknesses prescribed in UCS-57, UNF-57, 

UHA-33, UCL-35, or UCL-36 for the materials covered 

therein, or as otherwise prescribed in UHT-57, ULW- 

51, ULW-52(d), ULW-54, or ULT-57; 

3. (3) all butt welds in the shell and heads of unfired 

steam boilers having design pressures 

(-a) exceeding 50 psi (350 kPa) [see UW-2(c)]; 

(-b) not exceeding 50 psi (350 kPa) [see UW-2(c)] 

but with nominal thickness at the welded joint 

exceeding the thickness specified in (2) above; 

4. (4) all butt welds in nozzles, communicating chambers, 

etc., with the nominal thickness at the welded joint that 

exceeds the thickness in (2) above or attached to the 

shell or heads of vessels under (1), (2), or (3) above 

that are required to be fully radiographed; however, 

except as required by UHT-57(a), Categories B and C 

butt welds in nozzles and communicating chambers 

that neither exceed NPS 10 (DN 250) nor 11/8 in. (29 

mm) wall thickness do not require any radiographic 

examination; 


UW-11(a) Full Radiography. The following 

welded joints shall be examined 

radiographically for their full length in the 

manner prescribed in UW-51: 

(5) all Category A and D butt welds in the 

shell and heads of vessels where the design 

of the joint or part is based on a joint 

efficiency permitted by UW-12(a), in 

which case: 

(-a) Category A and B welds connecting the 

shell or heads of vessels shall be of Type 

No. (1) or Type No. (2) of Table UW-12; 

(-b) Category B or C butt welds [but not including 

those in nozzles and communicating chambers except as 

required in (4) above] which intersect the Category 

A butt welds in the shell or heads of 

vessels or connect seamless vessel shell 

or heads shall, as a minimum, meet the 

requirements for spot radiography in 

accordance with UW-52. Spot radiographs 

required by this paragraph shall not be 

used to satisfy the spot radiography rules 

as applied to any other weld increment. 


Table UW-12 

Maximum ALLowabLe Joint Efficiencies for Arc and Gas Welded Joints 

Degree of Radiographic 

Examination 

(a) Full (b) Spot (c) 

Type No. Joint Description Limitations Joint Category [Note (1)] [Note (2)] None 

[1) Butt joints as attained by double welding or by None A, B, C & D 1.00 0.85 0.70 

other means which will obtain the same 

quality of deposited weld metal on the inside 

and outside weld surfaces to agree with the 

requirements of UW 35. Welds using metal 

backing strips which remain in place are 

excluded. 

(2) Single welded butt joint with backing strip (a) None except as in (b) below A, B, C & D 0.90 0.80 0.65 

other than those included under (1) (b)Circumferential butt joints with one plate offset; see A, B & C 0.90 0.80 0.65 

UW 13(b)[4) and Figure UW 13.1, sketch [i) 

[3) Single welded buttjointwithoutuse ofbacking Circumferential butt joints only, not over% in. [16 mm) A, B & C NA NA 0.60 

strip 

thick and not over 24 in. [600 mm) outside diameter 

(4) Double full fillet lap joint (a) Longitudinal joints not over % in. (10 mm) thick A NA NA 0.55 

(b) Circumferential joints not over % in. (16 mm) thick B & C [Note (3)] NA NA 0.55 

(5) Single full fillet lap joints with plug welds (a) Circumferential joints [Note (4)] for attachment of heads B NA NA 0.50 

conforming to UW 17 

not over 24 in. (600 mm) outside diameter to shells not 

over "/ 2 in. [13 mm) thick 

(b) Circumferential joints for the attachment to shells of c NA NA 0.50 

jackets not over % in. [16 mm) in nominal thickness 

where the distance from the center of the plug weld to the 

edge of the plate is not less than 1 1 h times the diameter of 

the hole for the plug. 

(6) Single full fillet lap joints without plug welds (a) For the attachment of heads convex to pressure to shells A&B NA NA 0.45 

not over % in. (16 mm) required thickness, only with use 

of fillet weld on inside of shell; or 

(b) for attachment of heads having pressure on either side, A&B NA NA 0.45 

to shells not over 24 in. [600 mm) inside diameter and 

not over % in. [ 6 mm) required thickness with fillet weld 

on outside of head flange only 

(7) Corner joints, full penetration, partial As limited by Figure UW 13.2 and Figure UW 16.1 C & D [Note (5)] NA NA NA 

penetration, and/ or fillet welded 

(8) Angle joints Design Eer U 2 (g) for Category B and C joints B, C & D NA NA NA 

GENERAL NOTES: 

(a} The single factor shown for each combination of joint category and degree of radiographic examination replaces both the stress reduction factor and the joint efficiency 

factor considerations previously used in this Division. 

(b) E" 1.0 for butt joints in compression. 


115 

Table UW-12 

Maximum Allowable Joint Efficiencies for Arc and Gas Welded Joints 

Degree of Radiographic 

Examination 

Type No. Joint Description Limitations Joint Category 

(a) Full 

[Note (1)] 

(b) Spot 

[Note (2)] 

None A, B, C & D 1.00 0.85 0.70 

(1) Butt joints as attained by double welding or by 

other means which will obtain the same 

quality of deposited weld metal on the inside 

and outside weld surfaces to agree with the 

requirements of UW 35. Welds using metal 

backing strips which remain in place are 

excluded. 

(2) Single welded butt joint with backing strip 

other than those included under (1) 

(3) Single welded butt joint without use of backing 

strip 

(a) None except as in (b) below A, B, C & D 0.90 0.80 0.65 

(b)Circumferential butt joints with one plate offset; see 

UW 13(b)(4) and Figure UW 13.1, sketch (i) 

A, B & C 0.90 0.80 0.65 

Circumferential butt joints only, not over 5 / 8 in. (16 mm) 

A, B & C NA NA 0.60 

thick and not over 24 in. (600 mm) outside diameter 

(4) Double full fillet lap joint (a) Longitudinal joints not over 3 / 8 in. (10 mm) thick A NA NA 0.55 

(b) Circumferential joints not over 5 / 8 in. (16 mm) thick B & C [Note (3)] NA NA 0.55 

(5) Single full fillet lap joints with plug welds 

conforming to UW 17 

(a) Circumferential joints [Note (4)] for attachment of heads 

not over 24 in. (600 mm) outside diameter to shells not 

over 1 / 2 in. (13 mm) thick 

(b) Circumferential joints for the attachment to shells of 

jackets not over 5 / 8 in. (16 mm) in nominal thickness 

where the distance from the center of the plug weld to the 

edge of the plate is not less than 1 1 / 2 times the diameter of 

the hole for the plug. 

(c) 

None 

B NA NA 0.50 

C NA NA 0.50 

(6) Single full fillet lap joints without plug welds (a) For the attachment of heads convex to pressure to shells 

A & B NA NA 0.45 

not over 5 / 8 in. (16 mm) required thickness, only with use 

of fillet weld on inside of shell; or 

(b) for attachment of heads having pressure on either side, 

A & B NA NA 0.45 

to shells not over 24 in. (600 mm) inside diameter and 

not over 1 / 4 in. (6 mm) required thickness with fillet weld 

on outside of head flange only 

(7) Corner joints, full penetration, partial 

As limited by Figure UW 13.2 and Figure UW 16.1 C&D[Note (5)] NA NA NA 

penetration, and/or fillet welded 

(8) Angle joints Design per U 2(g) for Category B and C joints B, C & D NA NA NA 

GENERAL NOTES: 

(a) The single factor shown for each combination of joint category and degree of radiographic examination replaces both the stress reduction factor and the joint efficiency 

factor considerations previously used in this Division. 

(b) E = 1.0 for butt joints in compression. 

2013 SECTION VIII - DIVISION 1 UW-13

UW-11 RADIOGRAPHIC AND ULTRASONIC EXAMINATION 

(a) Full Radiography. The following welded joints shall be examined radiographically for their 

full length in the manner prescribed in UW-51: 

1. (1) all butt welds in the shell and heads of vessels used to contain lethal substances [see UW-2(a)]; 

2. (2) all butt welds in the shell and heads of vessels in which the nominal thickness [see (g) below] at the welded joint exceeds 

11/2 in. (38 mm), or exceeds the lesser thicknesses prescribed in UCS-57, UNF-57, UHA-33, UCL-35, or UCL-36 for the 

materials covered therein, or as otherwise prescribed in UHT-57, ULW-51, ULW-52(d), ULW-54, or ULT-57; 

3. (3) all butt welds in the shell and heads of unfired steam boilers having design pressures 

(-a) exceeding 50 psi (350 kPa) [see UW-2(c)]; 

(-b) not exceeding 50 psi (350 kPa) [see UW-2(c)] 

but with nominal thickness at the welded joint exceeding the thickness specified in (2) above; 

4. (4) all butt welds in nozzles, communicating chambers, etc., with the nominal thickness at the welded joint that exceeds the 

thickness in (2) above or attached to the shell or heads of vessels under (1), (2), or (3) above that are required to be fully 

radiographed; however, except as required by UHT-57(a), Categories B and C butt welds in nozzles and communicating 

chambers that neither exceed NPS 10 (DN 250) nor 11/8 in. (29 mm) wall thickness do not require any radiographic 

examination; 

5. (5) all Category A and D butt welds in the shell and heads of vessels where the design of the joint or part is based on a joint 

efficiency permitted by UW-12(a), in which case: 

(-a) Category A and B welds connecting the shell or heads of vessels shall be of Type No. (1) or Type No. (2) of Table UW-12; 

(-b) Category B or C butt welds [but not including those in nozzles and communicating chambers except as required in (4) 

above] which intersect the Category A butt welds in the shell or heads of vessels or connect seamless vessel shell or heads 

shall, as a minimum, meet the requirements for spot radiography in accordance with UW-52. Spot radiographs required by this 

paragraph shall not be used to satisfy the spot radiography rules as applied to any other weld increment. 

6. (6) all butt welds joined by electrogas welding with any single pass greater than 11/2 in. (38 mm) and all butt welds joined by 

electroslag welding; 

7. (7) ultrasonic examination in accordance with UW-53 may be substituted for radiography for the final closure seam of a 

pressure vessel if the construction of the vessel does not permit interpretable radiographs in accordance with Code 

requirements. The absence of suitable radiographic equipment shall not be justification for such substitution. 

8. (8) exemptions from radiographic examination for certain welds in nozzles and communicating chambers as described in (2), 

(4), and (5) above take precedence over the radiographic requirements of Subsection C of this Division. 


(b) Spot Radiography. Except when spot radiography is required for Category B or C butt welds by (a)(5)(-b) above, butt 

welded joints made in accordance with Type No. (1) or (2) of Table UW-12 which are not required to be fully radiographed by (a) 

above, may be examined by spot radiography. Spot radiography shall be in accordance with UW-52. If spot radiography is 

specified for the entire vessel, radiographic examination is not required of Category B and C butt welds in nozzles and 

communicating chambers that exceed neither NPS 10 (DN 250) nor 11/8 in. (29 mm) wall thickness. 

NOTE: This requirement specifies spot radiography for butt welds of Type No. (1) or No. (2) that are used in a vessel, but does 

not preclude the use of fillet and/or corner welds permitted by other paragraphs, such as for nozzle and manhole attachments, 

welded stays, flat heads, etc., which need not be spot radiographed. 

(c) No Radiography. Except as required in (a) above, no radiographic examination of welded joints is required when the 

vessel or vessel part is designed for external pressure only, or when the joint design complies with UW-12(c). 


UG-116 REQUIRED MARKING 

(e) When radiographic or ultrasonic examination has been performed on a vessel in accordance 

with UW-11, marking shall be applied under the Certification Mark as follows: 

1. “RT 1” when all pressure‐retaining butt welds, other than Category B and C butt welds 

associated with nozzles and communicating chambers that neither exceed NPS 10 (DN 250) 

nor 11/8 in. (29 mm) wall thickness [except as required by UHT-57(a)], satisfy the full 

radiography requirements of UW-11(a) for their full length; full radiography of the above 

exempted Category B and C butt welds, if performed, may be recorded on the 

Manufacturer’s Data Report; or 

2. “RT 2” when the complete vessel satisfies the requirements of UW-11(a)(5) and when the 

spot radiography requirements of UW-11(a)(5)(-b) have been applied; or 

3. “RT 3” when the complete vessel satisfies the spot radiography requirements of UW-11(b); 

or 

4. “RT 4” when only part of the complete vessel has satisfied the radiographic requirements of 

UW-11(a) or where none of the markings “RT 1,” “RT 2,” or “RT 3” are applicable. 

The extent of radiography and the applicable joint efficiencies shall be noted on the 

Manufacturer’s Data Report. 


Vessel 

for a specified service that may 

Radiography 

include alternative operating conditions 

UW-11 

UW-51 

RT1: Full Radiography 

mandatory by code 

based on Service, 

thickness, toxicity 

UW-11(a)1,2,3,4 

Extent of 

radiography to be 

selected as 

permitted by code 

for conveniences or for desired 

joint efficiency factor 

UW-51 

UW-52 


RT2: Full 

radiography 

complying to 

UW-11(a) 5 

RT3: Spot 

radiography 

complying to 

UW-11(b) 

RT4: No 

radiography 

complying to 

UW-11(c)

3.4 

communicating chamber 

heat-exchanger appurtenance that intersects the shell or heads of the heat 

exchanger and forms an integral part of the pressure-containing envelope 

EXAMPLES Sump, annular distributor. 

Communicating 

Chamber 


3.5 

effective surface 

outside surface area of the tubes that contributes to heat transfer 

3.6 

full-penetration weld 

welded joint that results in weld metal through the entire thickness of the 

components being joined 

3.7 

heat-exchanger unit 

one or more heat exchangers for a specified service that may include 

alternative operating conditions 


3.8 

hydrogen service 

service that contains hydrogen at a partial pressure exceeding 700 kPa (100 

psi) absolute 

700 kPa? 


Hydrogen Service 

service that contains 

hydrogen at a partial 

pressure exceeding 700 

kPa (100 psi) absolute 

0.7MPa? 


3.9 

item number 

purchaser's identification number for a heat-exchanger unit 

3.10 

nubbin 

projection on the flange gasket surface, positioned at the centre of the gasket, 

used to concentrate the bolt load 

on the gasket 

3.11 

pressure design code 

recognized pressure vessel standard specified or agreed by the purchaser 


Nubbin 




Nubbin 



Nubbin 

projection on the flange 

gasket surface, 

positioned at the centre 

of the gasket, used to 

concentrate the bolt load 


Nubbin 

Double-jacketed gaskets are probably the most commonly used style of gaskets in heat exchanger applications. They are available in virtually any material 

that is commercially available in 26-gauge sheet. They are also extensively used in standard flanges where the service is not critical. Since most doublejacketed 

gaskets are custom made, there is virtually no limit to size, shape or configuration in which these gaskets can be made. 

In some cases nubbins are provided on heat exchanger designs to provide an intermediate seal. This nubbin is normally 1/64" high by 1/8" wide. Experience 

has indicated, however, that there is little advantage to this particular design. The primary seal is still dependent on the inner lap of the gasket doing the 

brute work and the secondary seal, when applicable, would be provided by the outer lap. 

Nubbin 

projection on the flange 

gasket surface, 

positioned at the centre 

of the gasket, used to 

concentrate the bolt load 


3.12 

seal-welded 

tube-to-tubesheet joint weld of unspecified strength applied between the 

tubes and tubesheets for the sole purpose of reducing the potential for 

leakage 

3.13 

strength-welded 

tube-to-tubesheet joint welded so that the design strength is equal to, or 

greater than, the axial tube strength specified by the pressure design code 


4 General 

• 4.1 The pressure design code shall be specified or agreed by the purchaser. 

Pressure components shall comply with the pressure design code and the 

supplemental requirements given in this International Standard. 

4.2 Heat-exchanger construction shall conform to TEMA (8th edition), Class R, 

unless another TEMA class is specified. 

• 4.3 The vendor shall comply with the applicable local regulations specified 

by the purchaser. 

4.4 Annex A includes some recommended mechanical and design details for 

information. 

4.5 Annex B provides a checklist that can be used by the purchaser to ensure 

that bulletted items in this International Standard are addressed. 

4.6 Annex C provides examples of data sheets. 

4. 7 Annex D includes a recommended division of responsibility for 

completing the data sheet. 


TEMA 

(Mechanical Design) 

Heat-exchanger construction 

shall conform to TEMA (8th 

edition), Class R, unless 

another TEMA class is 

specified. 


http://www.tema.org/

5 Proposals 

5.1 The vendor's proposal shall include, for each heat exchanger unit, 

completed data sheets such as those given in Annex C or, if a data sheet is 

included in the inquiry, a statement indicating complete compliance with that 

data sheet. 

5.2 Designs that are not fully defined by the nomenclature in TEMA (8th 

edition), Section 1, shall be accompanied by sketches that are sufficient to 

describe the details of construction. 

5.3 If an annular distributor is provided, the vendor shall define the type of 

construction proposed. 

5.4 The vendor shall determine the need for, and if required, include 

expansion joints based on all conditions supplied by the purchaser. The 

vendor shall state the type of construction proposed. 

5.5 The proposal shall include a detailed description of all exceptions to the 

requirements of the purchaser's inquiry. 


5.6 For stacked heat exchangers, the vendor shall supply the following 

components unless otherwise specified by the purchaser: 

a. bolts, nuts and gaskets for interconnecting nozzles; 

b. shims and bolting for interconnecting supports. 

5. 7 The vendor shall provide a separate quotation for the following items 

unless otherwise specified by the purchaser: 

a. a test component consisting of a test ring and gland, in accordance with 

TEMA (8th edition), Figure E-4.13-2 or equivalent, for each heat 

exchanger or group of similar heat exchangers with floating heads; 

b. one spare set of gaskets per heat-exchanger unit. 


Stacked Heat Exchangers, 

the vendor shall supply the following components unless otherwise specified by the purchaser: 

a. bolts, nuts and gaskets for interconnecting nozzles; 

b. shims and bolting for interconnecting supports. 


TEMA- FIGURE E-4.13-2 

Test Ring 

Floating Tubesheet 

Shell Flange- Rear Head End 

Packing 

Packing Gland 

Gaskket 


Stacked Heat Exchangers 










Break 

20180528-1043hrs 


Break 

20180528-1043hrs 



20180531 May

有书真幸福 , 无事小神仙 



Charlie Chong/ Fion Fion Zhang Zhang

Understanding Heat Exchanger Reading 03a The ARAMCO Std.

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