Rationalization of Toughness Requirements for Subsea Forgings Available to Purchase

The oil and gas industry has historically relied on experience-based, toughness target values when qualifying various components, including subsea forgings. However, this experience has been mainly with lower strength grades of steel and modest thicknesses. The increasing demand for higher yield strength steels or thicker cross sections to meet design needs necessitates the development of adequate toughness requirements to ensure safe operation of these components. The approach presented here involves utilization of fracture mechanics assessment methods to develop a more rationalized basis for toughness requirements. The guidance developed in the paper is related to critical components, both static and those that are fatigue-sensitive. And the fatigue-sensitive requirements can be applied to weld procedure qualification.