Page 83 - Pipeline Risk Management Manual Ideas, Techniques, and Resources

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Corrosion Index

1. Overview C3. Coating 0-25 pts
Fitness 0-10 pts
CorrosionThreat = (Atmospheric Corrosion) 10% Condition 0-15 pts
+(Internal Corrosion) 20% Overall Threat of Corrosion 0-100 pts
+ (Buried Metal Corrosion) 70%
100%
II. Background
Corrosion Threat
The potential for pipeline failure caused by corrosion is per-
A. Atmospheric Corrosion 0-10 pts haps the most familiar hazard associated with steel pipelines.
A1 . Atmospheric Exposures 0-5 pts This chapter discusses how common industry practices of cor-
A2. Atmospheric Type 0-2 pts rosion analysis and mitigation can be incorporated into the risk
A3. Atmospheric Coating 0-3 pts assessment model (see Figure 4.1). A detailed discussion of the
B. Internal Corrosion 0-20 pts complex mechanisms involved in corrosion is beyond the
B1. Product Corrosivity 0-10 pts scope of this text.
B2. Preventions 0-10 pts Corrosion comes from the Latin word corrodere, meaning
C. Subsurface Corrosion 0-70 pts “gnaw to pieces.” Corrosion, as it is used in this text, focuses
C 1. Subsurface Environment 0-20 pts mainly on a loss of metal from pipe, although the concepts
Soil Corrosivity 0-15 pts apply to many corrosionlike degradation mechanisms. From
Mechanical Corrosion 0-5 pts previous discussions of entropy and energy flow, we can look at
C2. Cathodic Protection 0-25 pts corrosion from a somewhat esoteric viewpoint. Simply stated,
Effectiveness 0-15 pts manufactured metals have a natural tendency to revert to their
Interference Potential 0-10 pts original mineral form. While this is usually a very slow process,