Corrosion

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1 INTRODUCTION Corrosion is a natural process, from which a modified material will either break down into a more basic state or be broken down (Gundiler et al, 2000). The process causes undesirable traits in the product which may range from a change in appearance to failure of structures. The effect of corrosion as addressed by Ahmad (2006) costs many billions to governments, as an outcomeindustry has developed many ways to combat corrosion. Combating corrosion can be done though two methods, by design and by inhibition. This report examines in sections 2 and 3 examples of corrosion control mechanisms from the standpoint of active and then passive responses. The issues of economic alloy, environment and corrosion control combinations are addressed in section 4. 2 EXAMPLES OF CORROSION CONTROL MECHANISMS In preparation for deployment to an environment, materials have to go through many stages of refinement. The considerations for corrosion protection and design can be illustrated inmany ways. Roberge (2005) emphasised that it must be understood by the designer that materials have a certain life expectancy, in particular he emphasised points on proactive design (see appendix 2). There exist many types of active corrosion management. Most applications for active corrosion management can be separated into two groups by their makeup, inorganic or organic. Organic inhibitors have a hydrocarbon base and are good for generating film coatings as opposed inorganic inhibitors are made from a large variety of chemicals. (NPL, 2003) Active corrosion prevention is considered a permanent protection. Applied before installation active corrosion management requires ongoing operation to protect the material and is specified to last the lifetime gau...

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... about 1 mm to 2mm per year which can be achieved though using multiple methods of corrosion protection. 5 CONCLUSION Overall the costs to a project by using of a combination of corrosion management techniques are much less than having an inadequate corrosion management plan. Corrosion control has in the past been relegated to a last step during design as discussed by Ahmad (2006). Having a wider appreciation of corrosion we can see that many fundamental steps should be taken in design and that there are a number of economical choices that can be made. Appendix 1 and 3 show a corrosion control checklist and passive design considerations. Both types of corrosion control incorporate practices that will increase the serviceable life of a product. Both passive and active corrosion management should be used in a design, building more efficient and more durable structures.

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