Corrosion Audit Essay Research Paper TERM PAPERTOPIC

Corrosion Audit Essay, Research Paper

TERM PAPER

TOPIC: CORROSION AUDIT

AT IIT CAMPUS

Index

1.Introduction

2.Main materials used in IITK

3.Inspection

4.Causes

5.Life of a material and remedies provided

6.Cost

7.Conclusion

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. Thus CI is majority used for pipelines for water supply, and GI is also used where small length pipes are needed.

3.Inspection:

In most of the cases corrosion is recognized by visual inspection.

· Steel:

Corrosion of steel is easily recognized because the corrosion product is red rust.

· RCC:

RCC(Reinforced Concrete Council) is used in all the building constructions. There are always voids present in the structure. In these voids moisture will collect and will lead to corrosion. But this corrosion is usually not spotted out till 10-15 years. It is noticed when after 10-15 years cracks appear on the surface.

· Electric power supply pillars:

The power pillars get corroded very soon in top region, where two different metals are joined.

In some cases inspection can not be done on regular intervals, e.g. underground pipelines.

4.Causes:

There can be many reasons of corrosion. In different systems there can be different mechanism of corrosion.

· Iron based alloys:

When iron base alloys corrode, dark corrosion products usually form first on the surface of the metal. These products are protective. However, if moisture is present, this ferrous oxide coating is converted to hydrated ferric oxide, which is red rust. This material will promote further attack by absorbing moisture from the air.

Except this the presence of some chemicals (acids) in laboratory make the metal corrode very fast.

· In water supply pipelines corrosion is not observed very soon. In fact, corrosion does not occur till there is water filled in pipes, because metal is not in contact with atmosphere (oxygen). So whenever the water supply is stopped, due to reasons like maintenance etc, metal start corroding.

Note: It can be observed that as supply is again started, first few amount of water is red colored.

Thus metal in pipeline corrode only when pipeline is empty. So pipelines in IIT does not corrode very soon. But the pipelines in Kanpur City corrode very fast. The reason is quite obvious. They remain empty for longer periods.

· Corrosion in RCC structures can occur, because of voids remained in the structure. Moisture will collect in these voids, air is also there, and the combination of two will lead to corrosion.

· In some cases like the pipes used in the shower pool in front of the PK Kelkar library, the me

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