Corrosion Audit

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Corrosion Audit

1.Introduction:

Corrosion is the electrochemical deterioration of a metal because of its chemical reaction with the surrounding environment. While new and better materials are continuously being developed, this progress is offset, in part, by a more aggressive operational environment. This problem is compounded by the fact that corrosion is a complex phenomenon. It can take many different forms and the resistance of materials to corrosion can drastically change with only a small environmental change.

Corrosion is most often thought of as a slow process of material deterioration, taking place over a significant period of time (examples being general corrosion, pitting, exfoliation, etc.). Other forms of corrosion degradation can occur very quickly, in days or even hours, with catastrophic results. These forms (such as stress corrosion cracking, environmental embrittlement, and corrosion fatigue) depend on both the chemical and mechanical aspects of the environment and can cause catastrophic structural failure without warning.

Some of the data of losses due to corrosion follows. In the United Kingdom the Paint Research Association has estimated that metallic corrosion costs developed countries some up to four per cent of gross national product (GNP) annually. In the UK this would equal about £30 billion. In the United States, various reports put the cost of corrosion slightly higher at four to five per cent, equating in that country to about US $300 billion, of which it is claimed that around one-third could be prevented. In India approximately 5% of the GDP is lost due to corrosion, of which again it is claimed that around one-third could be prevented.

CORROSION AUDIT: There is no clear definition of corrosion audit. It mainly contains inspecting the corrosion sites, analyzing the reasons of corrosion, suggesting methods of prevention, doing the cost analysis of prevention and losses due to corrosion.

2.Main Materials Used in IITK:

 Centrifugally cast iron (CI)

 Galvanized iron (GI)

 Steel

 Stainless steel

 Cast iron

 PVC (Poly venyl chloride)

 RCC (Reinforced concrete council)

Centrifugally cast iron vs. Galvanized iron: CI is more resistant to corrosion in soil and water environment as compared to GI. But CI cannot be threaded much frequently, as it will corrode very fast near the threads and thus will lead to breakage and leakage. So CI is used only, where long pipes are needed. For small length pipes, like those in houses, GI is the better option.

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