Abstract

Oil and gas production applications demand high reliability, which implies low failure probability over the lifetime of the components. The service environments encompass high pressure high temperature (HPHT) conditions inside and seawater with cathodic protection (CP) systems on the outside. New material combinations are being employed, including thermo-mechanically processed low alloy steels and corrosion resistant alloys (CRA). Additively manufactured (AM) alloys are also entering the market, creating further variability and directionality in properties. Material qualification involves two types of accelerated, laboratory tests – standard and fit-for-purpose. However, the acceleration vectors used in these types of tests are usually not clearly identified. Relating the materials qualification tests to service performance requires a systematic approach that considers the uncertainties in the acceleration vectors such as, loading conditions, environmental compositions, operating parameters, and material microstructures. In this paper, we describe the acceleration vectors typically used in qualification tests and a risk framework that may be used to relate the test results to long term service performance. The benefit of a risk informed approach is not only avoidance of unnecessary testing, but also investing the testing resources to attain highest reliability.

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