Abstract

Wellhead connectors form a critical part of subsea tree production systems. Their location in the riser load path means that they are subjected to high levels of bending and tension loading in addition to the internal pressure and cyclic loading. As such, they are essential equipment and various industry standards influence their design and qualification requirements. This is particularly true of High Pressure High Temperature (HPHT) equipment where heavier blowout preventers and larger rigs are required to deal with this challenging environment.

Industry standards that cover wellhead connectors include a range of verification techniques based on different base analysis codes each of which uses different factors to determine a design margin. Some of the different methods may therefore lead to different actual design margins on the connector from failure to a safe working load. In order to meet the requirements of the industry and to ensure product integrity a HPHT verification and validation methodology based on API 17TR8 [1] and ASME VIII Div. 3 [2] is presented here for subsea wellhead connector designs. The results from a series of verification and full scale validation tests for a subsea wellhead connector family are presented and discussed. The results prove the design margins of the connectors using this methodology and allow for a full understanding of the limits and true performance of the design.

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