Dr. Winfried Heimann - Fischer Group

TKp

• Dr. Winfried Heimann
• was heading varios division of R+D, quality control and application engineering in Thyssen Edelstahlwerke and
ThyssenKrupp Nirosta
• was being Senior Manager with Outokumpu Stainless
• after retirement he is acting as Consultant in this field
• Christian Behrle
• is heading the Technical Department for R+D in Fischer-group
• specialised in SS-tubes for desalinations
• DME – Member of the Board
• Member of IDA
• Member of EDS
TKp

Corrosion Resistance
Typical Relation of Corrosion Resistance und Mechanical
Strength of some Stainless Steel Grades
Austenitic grades
1.4539
1.4404
1.4547
1.4565
1.4521
1.4362
1.4162
Superferritic grades
28 Cr
+ Mo
+ Ni
1.4410
Ferritic grades
Mechanical Strength
Ferritic-Austenitic
(Duplex)-Grades
TKp

Stainless Steel Grades for Seawater Desalination Plants
EN
10088
ASTM
A 240
Cr
%
Ni
%
Mo
%
Others PRE 1
1.4162 S32101 21 1,5 0,3 N 26 19
1.4362 S32304 23 4,8 0,3 N 26 25
1.4410 S32750 25 7 4,0 N 43 85
1.4521 S44400 18 87
1 PRE= %Cr + 3,3%Mo + 16x%N (Pitting Resistance Equivalent)
2 Critical Pitting Temperature acc. ASTM G 150
Duplex stainless steel grades Austenitic stainless steel grades
Ferritic stainless steel grades
CPT 2
°C
Ref.: Mikael Willför, Outokumpu:
Materials selection for thermal plants
DME-Workshop 2008, Duisburg
TKp

Mechanical properties of Stainless Steel Cold rolled Strip
Minimum Values
EN
10088
ASTM
A 240
Yield Strength
Rp0,2
MPa
EN(ASTM)
Tensile
Strength
Rm
MPa
EN(ASTM)
Elongation
A5
%
EN(ASTM)
1.4162 S32101 (530) (700) (30)
1.4362 S32304 450(420) 650(600) 20(20)
1.4410 S32750 550(550) 750(750) 20(15)
1.4521 S44400 320(275) 420(415) 20(20)
1.4404 S31603 240 530 40
1.4547 S31254 320(310) 650(690) (35)
1.4565 S34565 420 800 30
Duplex stainless steel grades Ferritic stainless steel grades
Austenitic stainless steel grades
TKp

Physical Properties of Stainless Steel grades
(Average values according to EN 10088 or ASTM A240)
Ferritic grades
17Cr 28Cr
2Mo 1-4Mo
0-2Ni
(Superferritics)
Duplex grades Austenitic grades
1.4404 1.4547
1.4565
(Superaustenitics)
Density g/cm³ 7,7 7,7 7,8 8,0 8,1
Modulus of
Elasticity GPa
Thermal
Conductivity
Thermal
Expansion
W/mK
RT - 300°C
10 -6 /K
Specific Heat
J/kg°C
220 200 200 200 195
23 17,5 15 15 12
11 10 14,0 17,0 16,5
430 500 500 500 450
TKp

Corrosion of Materials in Sea Water Desalination Plants
Forms of corrosion
• General corrosion
• Pitting and crevice corrosion
• Erosion corrosion
• Galvanic corrosion
TKp

Corrosion Resistance of Stainless Steel in Sea Water
• Stainless Steels have negligible thinning in sea water
• Chromium oxide film (passive layer) forms immediately
on steel surface with exposure to air
• Oxygen levels as low as 20 ppb are still sufficient to
repair itself after being damaged
TKp

Corrosion Resistance of Stainless Steel in Sea Water
• Pitting and Crevice Corrosion
• Under certain conditions the protective surface film
on stainless steels can break down locally:
oxyginated water
high chloride
too high chlorination level
low pH-value
pitting and crevice corrosion
more resistant grade has to be selected
acc. to PRE = %Cr + 3,3% Mo + 30 (16)% N
ranking of alloys can be carried out
TKp

Temperature [°C]
Critical Pitting and Crevice Corrosion Temperatures
of Stainless Steel Grades
100
80
60
40
20
1.4404
1.4404
According to ASTM G 48
Pitting
Crevice Corrosion
1.4462
1.4439
1.4462
1.4439
1.4539
1.4547
1.4539
1.4547
1.4410
1.4410
1.4565
0
25 35 45 55
PRE (%Cr + 3.3 %Mo + 30 %N)
1.4565
TKp

Critical Pitting Temperature of Stainless Steel Grades
(Values determined according to ASTM G 150)
Critical Pitting Temperature
Duplex Stainless Steel Grades Austenitic Stainless Steel Grades
Ref.: Outokumpu Stainless
Corrosion Handbook
Ninth Edition, 2004
TKp

Influence of PRE (Pitting Resistance Equivalent)
%Cr + 3,3x%Mo on the CPT (Critical Pitting Temperature)
of welded and unwelded Stainless Steels
Critical Pitting Temperature
90
°C
80
70
60
50
40
30
20
10
unwelded
TIG-welded,
without filler
TIG-welded,
overalloyed filler
(THERMANIT ® 625)
Laser-welded tubes
(0,3x30)mm,
minimum value
1.4438
1.4404
1.4439 1.4539
1.4462
1.4529
0
25 30 35 40
PRE = % Cr + 3.3 • % Mo
1.4565
20 Cr / 6,6
Mo
Test according to ASTM G48
20 Cr / 6,1 Mo
TKp

Erosion Corrosion in Sea Water Desalination Plants
Erosion corrosion is the most common failure, e.g. in the heat rejection
• Copper alloys, brasses and bronzes are prone to impingement attack,
at sea water velocities above 3m/s.
• In sea water polluted with solids copper based alloys suffer
severe erosion corrosion even at very low flow rates (< 0,5 m/s)
• Stainless steels and especially high alloyed grades like Duplex and
Superaustenitics are much better resistant to erosion corrosion than
copper based alloys.
There is no risk of erosion corrosion with special stainless steels
at velocities up 20 m/s even up to 40 m/s with high nitrogen containing
Superaustenitic steel UNS S34565.
TKp

Corrosion Resistance of Stainless Steel in Sea Water
• Erosion and Erosion Corrosion
• The passive layer is maintained at
very high flow rates and
• Sea water velocities in excess of 40 m/s can
be accommodated (in praxis usually below 10m/s)
TKp

Corrosion rate [g/m² d]
1000
100
10
1
Corrosion of Stainless Steels
in Contaminated (Solids) Flowing Sea Water
Ferritic Cr-Steels
Duplex Stainless Steels
Austenitic
Mn-Steels
Austenitic
Steel
Superaustenitic Steels
UNS S34565
0 20 40 60
Flow velocity [m/s]
TKp

Galvanic Corrosion in Sea Water Desalination Plants
Multi-metal systems: Stainless steels, titanium, copper aloys
• Titanium is cathodic to most of other metals.
• Stainless steels are towards the more noble end of
the galvanic series.
• Superaustenitic stainless steels are compatible with titanium
because their free corrosion potential is close together.
• Galvanic corrosion occurs when using titanium or stainless steel
tubing together with copper based alloy tube sheets, increasing
corrosion attack to the tube sheet to a point where cathodic
protection is required in the water boxes.
TKp

Chlorination – Performance of Stainless Steel
• Chlorination is used to control microbiological films.
To prevent the build-up of biofilms and remove settled biological species.
• Practice of chlorination is the addition of a hypochloride solution
to the sea water
• Chlorination can be either continuous or
intermittent (Chlorine is added for shorter periods
e.g. twice a day 15 minutes)
• Chlorination level
- continuous: 0,1 - 0,4 ppm
- intermittent: several ppm
total amount of chlorine is less than with systems
using continuous systems
• The objective: Keep the residual chlorine level < 0,5 ppm
• Stainless steel perform well up to 2ppm
TKp

Condenser tubes UNS S34565
TKp

Weld shape of TIG and Laser welded Stainless Steel –
thin walled tubes, welded from 1,5 mm cold rolled strip
Tungsten inert gas welding - TIG
Welding root sag < 0,2 mm
Laser welding
Welding root planed
Welding root sag
< 0,15 mm
TKp

Corrosion Tests in Simulated MSF Desalination
Plant Evironments
Tests carried out by Cortest Laboratories, Sheffield
Experimental Test Program
Material:
• UNS S34565, laser welded tube with
0,35 mm wall thickness,
20 mm and 30 mm diameter
• UNS S31603, S31803, S32760, and S34565,
plate material
Test Environment:
• Alloy C276 autoclave
• Syntetic sea water heated to 90°C
• Three oxigen levels, 750, 150, and 65 ppb
Test Duration: 30 days
Tube assembly specimen
Methodes of joining:
• Welding to the tube plate
• Rolling into the tube plate
Ref.: NACE Corrosion 2001, Paper No. 01484
NACE Corrosion 2002, Paper No. 02190
TKp

Corrosion Tests in Simulated MSF Desalination
Plant Evironments
Tests carried out by Cortest Laboratories, Sheffield
Results:
• UNS S34565 thin walled, laser welded tubing did not
corrode in any of the tests
• No corrosion occurred at the welds of any
tubeplate material studied.
UNS S34565, S32760, S31603
• Some corrosion was observed at non welded joints.
Greatest on S32760 and least on S34565.
• The extend of corrosion on the non-welded assemblies
was not great. In particular for the S34565 the corrosion is
insignificant at the lowest oxigen level tested of 65 ppb.
Conclusions:
• UNS S34565 thin walled laser welded tubes when welded to S34565, S32760 or S31603
tubeplates would be suitable for MSF plant evaporators.
• UNS S34565 thin walled laser welded tubes when rolled into S34565 tubeplate
would be suitable for MSF plant evaporators.
Ref.: NACE Corrosion 2001, Paper No. 01484
NACE Corrosion 2002, Paper No. 02190
TKp

Stainless Steel grades for Condenser Tubes
for MSF-Desalination Plants
Superaustenitic stainless steels:
1.4565 (S34565)
Superduplex stainless steels:
1.4410 (S32750)
1.4501 (S32760)
Superferritic stainless steels:
Seacure(S44660)
1.4592 (S44735)
TKp

Stainless Steel grades for Condenser Tubes
for MED-Desalination Plants
Austenitic stainless steels:
1.4404 (S31603)
Duplex stainless steels:
1.4162 (S32101)
1.4362 (S32304)
Ferritic stainless steels:
1.4521 (S44400)
TKp

Stainless Steel thin walled Tubes for Desalination Plants
MSF Plants:
• Heat recovery stages
• Heat reject stages
• Brine heater
• Vacuum systems
MED Plants
• Evaporator shell
• Tube and Tube support plates
• Vacuum ejectors
• Condenser tubes
TKp

1,4 Million Meters
Condenser Tubes of 1.4565
(UNS S34565)
Producer: Fischer Edelstahlrohre GmbH
Technical Data:
MED - HTE Multi Effect Distillation
Horizontal Tube Evaporation
Capacity:
2 x 12.000 m³ / d
Operating Temperature: 95 %
TKp

Stainless Steels in the Sea-Water-Desalination
Condenser Tubes made of 1.4565
Source:
VA TECH WABAG
TKp

Stainless Steels in the Sea-Water-Desalination
Technology Heat-Exchanger Tubes
made of 1.4565
Windpowered seawater desalination Plant
TKp

MSF and MED condenser tubing
Historically titanium and copper alloys
Trends and options
• Poor availability of titanium
• Environmental impact of toxic copper ions
• Decreasing use of copper alloys
• Use of corrosion resistant stainless steels
Duplex stainless steels
Austenitic and superaustenitic stainless steels
Ferritic and superferritic stainless steels
• Reduction of wall thickness, e.g.
heat exchanger tubes with 0,3 to 0,1 mm,
UNS S34565 Ref. AVR Rotterdam
Ref.: DME-Seminar Materials and Corrosion in
Desalination Plants, June 2007
Heike Glade, Bremen
Jan Olsson, Outokumpu Stainless
TKp

Reference List
Fischer Edelstahlrohre GmbH
Rügen Evaporator-Condenser Tubes of UNS S34565
in Operation since 1998 at about 80°C
St. Martin Testing of Condenser Tubes of UNS S34565
since 1998
Rotterdam MED-Plant of AVR Rotterdam, NL
in Operation since Dez. 1999,
1,4 Mio m Tubes of UNS S34565
Al-Taweelah A1 Condenser tubes of 316 L (1.4404) / MED
Creek Island Evaporator-Condenser Tubes of UNS S34565
will start up in 2009 at about 80°C
South Korea Evaporator-Condenser Tubes of UNS S34565
Installation in a MED test plant
Sharjah U.A.E. Layyah Station for Power Generation & Water
Desalination – Intake Pump Cooling Coil
TKp