Transcript Surprising Corrosion Issues in Hydrogen Production

Plenary Lecture:
Corrosion Standards- Who
Needs Them?
Sheldon W. Dean, Jr.
Dean Corrosion Technology, Inc
www.deancorrtech.com
Corrosion 2010, San Antonio, TX
NACE International
What is a Standard?
• Document that provides specific
procedures or set of requirements for a
commercial product or process that
attains a consensus of knowledgeable
people.
• Compliance with standards is voluntary
unless mandated by law.
History of Standards
• International Society of Testing
Materials- 1880’s.
• ASTM founded ~1898.
• NACE founded 1948.
• ISO ~1960.
History of Corrosion
Standards
• ASTM- 1904
- Steel vs. wrought iron in atmosphere
• ASTM-1939
- Salt Spray Test, B117
• NACE- Cathodic protection issues
History of Corrosion
Standards, Continued
• ASTM Reorganization 1964- Created
Committee G-1 on Corrosion of Metals
• NACE ~1960s Created Technical
Practices Committee
• ISO 1978 Created TC156 on Corrosion
of Metals
– 11 Working Groups
3 Examples of Standards
• ASTM G 5 Potentiodynamic Polarization
• NACE SP0294 Sulfuric Acid Storage
Tanks
• ASTM G186/G188 Leak Detection
Fluids
Potentiodynamic Polarization
• Corrosion is electrochemical
• Potentiostats became available (1960s)
• Passive-active behavior of stainless
steels revealed with potentiostat
• Issues with reliability and reproducibility
ASTM G5 Reference Method
1969
• 430 stainless steel in 1.0 N H2SO4
• Single lot of stainless steel
• Carefully designed procedure
– 10 mV per min from Ecorr
• Many participants
• Reproducibility range shown
ASTM G 5 Potentiodynamic
Composite
FIG.5- Potentiodynamic Polarization Plot for UNS S43000 Stainless Steel in 1 N Sulfuric
Acid at 30º C Showing Range of Data from Interlaboratory Program from ASTM G 5
ASTM G 5 Crevice Effect
FIG. 6- Potentiostatic Polarization Plot of UNS S43000 Stainless Steel in 1 N Sulfuric Acid at
30º C Showing Acceptable Data Range and Crevice Corrosion Affected Data Points from ASTM
G 5
ASTM G 5 Standard Reference
Method
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First reference method
Results demonstrated reproducibility
Method widely used to qualify labs
Basis of many potentiodynamic studies
Method upgraded and improved several
times
Who Needs ASTM G5?
• New researchers learning electrochemical
methods
• Technicians learning electrochemical
techniques
• Lab managers overseeing labs using
electrochemical methods
• Technical reviewers judging laboratory
qualification to run electrochemical methods
Sulfuric Acid Storage Tanks
• Sulfuric acid widely used chemical
• Common grades: 93%, 96%, 98 to 99%
• Carbon steel is tank material of
construction
– Corrosion rate low and manageable
• Catastrophic failures have occurred
• Other problems occur
Storage Tank Design
• API 650 is the basis for flat bottom
tanks
• API 650 is not adequate for sulfuric acid
• Many problems have occurred with this
design
• Modifications are required for success
• A design standard was needed
Problems with Concentrated
Sulfuric Acid
• Velocity accelerated corrosion of steel
• Corrosion rate increases
catastrophically when acid is diluted
• Hydrogen corrosion product caused
problems
• Increased temperature increases
corrosion rate
163C
325F
107C
225F
52C
125F
24C
75F
Issues with C Steel Tanks
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Corrosion allowance
Nozzle problems
Inlet/outlet design
Hydrogen grooving
Inspection frequency
NACE SP 0294
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Original RP in 1994
Revision in 2006
Covered vertical and horizontal designs
RP 0205 covered spent alkalation acid
– Fatal accident occurred earlier
Who Needs SP 0294?
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Sulfuric acid producers
Sulfuric acid users
Tank inspectors
Plant maintenance engineers
Plant engineers
Consultants and contractors
Failures in High Pressure Gas
Systems
• Cylinder valve/pressure regulator
connections
• Cracking failures
• Brass components, CDA 360
• Older systems
Failure Analyses
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Intergranular cracks found
Multiple branched cracks
Strain hardened alloy structure
External corrosion products
– Bluish color noted
– Mottled appearance
Probable Cause
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Stress corrosion cracking
Ammonia or amines likely
Source- leak detection fluid (LDF)
Ammonia used to adjust pH of LDF
Brass strained through repeated
tightening of components
Need: To Qualify LDFs
• Old MIL Spec not relevant
– Non corrosive = <100mpy
• Test to detect ammonia difficult
– How much NH3 is needed to reject?
• Method should simulate service
– Performance test
Path Forward
• Find an SCC test for LDFs
• Find a susceptible brass specimen
– Test to verify susceptibility
• Design atmospheric exposure program
• Need to qualify atmosphere
– Ammonia fumes are common in labs
– May cause unrelated failures
Result: ASTM G 186
• C-ring specimen of UNS C27200
– Hard drawn temper, H80
– 0.65% strain
– 5 replicates required
• LDF with copper powder added
• Wick of fiber glass, apply and air dry
• 15 cycles to pass
– Pass = no cracks
Qualification of
Specimens
• Run preliminary test with Mattsson’s
solution
– ASTM G 37
• 1 cycle to fail specimen
• Must complete test before running LDF
samples
– Ammonia from Mattsson’s solution will
contaminate atmosphere
Control Test
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Solution: DI water plus copper powder
Run simultaneously with LDF samples
Same specimens as LDF
15 cycles required
No cracks means LDF test valid
LDF Specification: ASTM
G188
• Requirement for LDF to pass ASTM
G186
• Responsibility of LDF manufacturer
• Sampling plan required
• Label to show that LDF meets ASTM
188 required
Who Needs ASTM G 186/188?
• LDF manufacturers and suppliers
• Users of compressed gas systems
– Labs
– Hospitals
– Users of welding equipment
• Industrial gas companies
• Independent labs desiring to do
qualifications of LDFs
Types of Standards
• Test methods (TM)
– ASTM G186
– ASTM G 5-Reference Method
• Standard Practice (SP) aka RP
– NACE SP 0294
– NACE RP 0205
• Specification
– ASTM G188
Summary: Who Needs
Corrosion Standards?
• Industries dealing with corrosive
situations
• Engineers and designers
• Governments specifying materials for
projects
• Academics teaching how to use
materials in the real world
Why Use Corrosion
Standards?
• Improve safety of equipment and
systems
• Improve reliability
– Minimize unplanned shutdowns
• Reduce cost of operation
– Improve efficiency
• Avoid duplication of effort
Thank You!
Wayne France
Len Rowe
Bob Baboian
Harvey Hack
Sally Ketcham
Alan Fabiszewski
Florian Mansfeld
Sankara Papavinasam
Ed Hibner
Scott Whitlow
Steve Brubaker
Bob Smallwood
Kang Xu
Bill Watkins
John Scully