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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


Precipitation
Precipitation

  • 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



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