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Workshop on Low Corrosion Rates. ASTM Committee G-1 May 18, 2005, Reno, NV. Workshop Chairs. Sheldon W. Dean Neal S. Berke Sean Brossia. Traditional Concepts. Negligible corrosion rate: <1 mpy Primary concern: loss of strength Service Life: <10 to 50 years

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workshop on low corrosion rates

Workshop on Low Corrosion Rates

ASTM Committee G-1

May 18, 2005, Reno, NV

workshop chairs
Workshop Chairs
  • Sheldon W. Dean
  • Neal S. Berke
  • Sean Brossia
traditional concepts
Traditional Concepts
  • Negligible corrosion rate: <1 mpy
  • Primary concern: loss of strength
  • Service Life: <10 to 50 years
  • Low corrosion rate problems occur when these concepts do not apply
low corrosion rate cases
Low Corrosion Rate Cases
  • Nuclear waste storage: 100K years
  • Medical implants: reaction to c.p.’s
  • Semiconductor manufacturing: c.p.’s
  • Sterile water: rouging
workshop objectives
Workshop Objectives
  • Examine actual examples of LCR’s
  • Learn state of art
  • Can standards development assist in coping with LCR problems?
standards development astm g 1 scope
Standards Development: ASTM G-1 Scope
  • Promotion of knowledge
  • Stimulation of research
  • Collection of engineering data
  • Development of standards:
    • Corrosion
    • Methods for corrosion protection
types of g 1 stds
Types of G-1 Stds.
  • Test methods
  • Practices
  • Guides
  • Classifications
  • Specifications
  • Terminology
workshop program
Workshop Program
  • Introduction: S.W.Dean
  • Lab Corrosion Testing of Medical Implants- R. Corbett
  • Rouging- a Discoloration of Stainless Steel- R. Corbett
  • Rouging: Issues Facing the Pharmaceutical & Biotech Industries- P. Banes
rouging terminology
Rouging -Terminology
  • Terminology – G01.02 Meeting
  • Development of colored, usually red or brown, layer on stainless steel in pure or sterile water
  • Not usually associated with localized corrosion
  • Not well understood
rouging conditions
Rouging - Conditions
  • Major concern for water for injection, WFI
  • Also seen in other sterile water systems
  • Water usually >60°C
  • Water is air saturated
  • Low impurity levels, 10 –100 ppm Cl
  • Long residence times, days or weeks
rouging concerns
Rouging Concerns
  • Cosmetic – Systems look dirty, unacceptable for medical purposes
  • Contamination of product with corrosion products
  • Future regulation from FDA?
rouging mechanisms
Rouging Mechanisms
  • Deposition of film from colloidal solution
  • Precipitation of film from supersaturated solution
  • Growth of passive film
colloidal deposition
Colloidal Deposition
  • Passive film dissolves in water releasing ferric ions
  • Ferric ions precipitate in solution to form colloidal particles
  • Particles adhere to stainless steel surface
  • Mechanism requires particles to be less soluble than passive film
  • Passive film dissolves releasing ferric ions
  • Ferric ions precipitate on stainless surface
  • Film forms and grows
  • Problem: How can passive film dissolve and precipitate at the same time?
passive film dissolution
Passive Film Dissolution
  • Passive film is amorphous, contains OH –
  • Fe(OH)3 is much more soluble than ferric oxides
  • Fe+3 from Fe(OH)3 can precipitate FeOOH or Fe2O3
growth of passive film
Growth of Passive film
  • Normal passive film very thin: 10 – 100nm
  • Oxidizing conditions cause passive film to thicken at a decreasing rate
  • When film exceeds 200 nm it becomes visible
important questions
Important Questions
  • Potential of stainless steel during rouging?
  • Nature of rouge, crystalline or amorphous? Type of crystal?
  • Particle size and degree of organization of rouge?
  • Chemical composition of rouge?
mti program
MTI Program
  • Purpose: to gain fundamental understanding of mechanism
  • Project development team formed
  • Champion: M. Renner, Bayer
  • Staff: F. G. Hodge
  • Pourbaix (Potential- pH) diagrams calculated