Sheldon W. Dean, Jr.Dean Corrosion Technology, Inc

www.deancorrtech.comCorrosion 2010, San Antonio, TX

NACE International

Plenary Lecture:Corrosion Standards- Who Needs

Them?

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 Method1969

• 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

• 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

52C125F

24C75F

Issues with C Steel Tanks

• Corrosion allowance

• Nozzle problems

• Inlet/outlet design

• Hydrogen grooving

• Inspection frequency

NACE SP 0294

• 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?

• 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

• Intergranular cracks found

• Multiple branched cracks

• Strain hardened alloy structure

• External corrosion products– Bluish color noted– Mottled appearance

Probable Cause

• 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

• 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

Qualification of Specimens

Control Test

• 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