On going work by ISO TC67 SC5 Workgroup 2b to modernize the performance property equations of ISO 10400 / API 5C3 identified the need to begin research in an attempt to validate the Failure Assessment Diagram equations that incorporate variables of environment and retained surface imperfections in tubulars. A detailed research project proposal was drafted and submitted to the American Petroleum Institute (API) for consideration in their 2002 research budget. API approved and launched the research project which assembled the materials and conducted tests for two and a half years. Tubular manufacturers donated tubes, processing, inspection, and premium threaded end-caps, which greatly leveraged the API research funding. A consortium of Oil company operators, a metallurgical laboratory and tubular manufacturers donated post-fracture laboratory analysis of test samples that failed in an H2S environment in order to further enhance the understanding of the failure mechanisms. This paper identifies why the attempt to validate the environmental fracture equations for sour environments failed, one area where the project was successful, and enumerates the reasons why this type of research is recommended.

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