Materials Selection – Service Environment

Materials are selected to limit corrosion to acceptable, economic rates in the service environment. “Service environment” as used here means what the vessel will contain, its temperature and pressure, any contaminants, physical state, and sometimes flow rate. For a given service environment, materials selection should be made with consideration for both corrosion rates and other potential deterioration mechanisms, such as stress corrosion cracking and hydrogen damage.

Information about corrosion rates can be obtained from several sources. Past experience is the best source if there is a vessel in similar service. A review of the inspection records for vessels in similar services can indicate whether the materials selection was correct and what corrosion rates may be expected. The comparison should also include a review of the similarity of the new and old service environments.

Other sources of corrosion data include the Corrosion Prevention and Metallurgy Manual, laboratory tests, and published data. The Corrosion Prevention and Metallurgy Manual gives general material selection guidelines for several specific plants.

Contact a materials specialist for additional information and specific recommendations. Certain environmental conditions may cause other deterioration mechanisms such as stress corrosion cracking, sulfide stress cracking, and hydrogen attack. The Corrosion Prevention Manual describes these mechanisms and, in the chapters dealing with specific plants, highlights potential deterioration mechanisms to consider.

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