This paper presents the development of the first Enhanced Vertical Deepwater Tree (EVDT) system rated for 20 ksi pressure and 35° F to 350° F temperature applications. This project was a joint venture with five major operators. This system was designed and qualified to API 17TR8 and internal requirements.
The 20 ksi system design was a progression of 15 ksi and 400° F development, therefore many components are common between the 15 ksi and 400° F system and the 20 ksi and 350° F system. The 20 ksi design reduces cost as compared to a traditional EVDT by utilizing methods of simplification, elimination, and integration without compromising functionality. The scope of this development included materials testing and qualification, elastomeric seals, metallic seals, gaskets, bolted flanges, a new family of gate valves and actuators, tubing hanger, tree components, and a series of connectors.
This was a four-year development project which included component design, Failure Mode Effect and Criticality Assessment (FMECA), prototype testing, validation testing, meetings with BSEE, and independent third party reviews of technical documentation.