Simulation of underwater conditions for subsea Valves—A review of hyperbaric tests and validation

Highlights: • Importance of hyperbaric test on subsea valves to improve safety and reliability. • Application of finite element analysis (FEA) to validate subsea valves under hyperbaric condition. • Importance of input data accuracy to FEA model. Subsea valves face the unique challenge of requiring zero maintenance for a relatively long period of time (e.g., a lifetime of between 20 and 30 years). Many new subsea projects are located at water depths between 1,000 and 3,000 m. Hyperbaric testing is the only method of testing that can ensure the reliability of valves working in subsea conditions. Finite element analysis (FEA) should be performed prior to hyperbaric qualification testing to demonstrate that the valve has the capability to withstand the proposed external pressure without failure. Hyperbaric chamber testing may not be feasible for larger and/or complex-shaped valves. The solution, based on API 17TR12 for large pieces of equipment, including valves, that cannot fit in a hyperbaric chamber, is to validate their design using FEA. The literature review includes in this article provides a critical review of FEA analysis performed on subsea valves. The first reviewed paper is done on another FEA analysis of a subsea ball valve. The gaps or data missing from these two FEAs are identified and discussed in this paper. Since the wall thickness of the valve is not specified in the first paper reviewed here, two approaches based on ASME B16.34 and ASME Sec. VIII Div. 02 are introduced and used for wall thickness calculations. The second article describes the performance of FEA on the pressure-containing parts, i.e. the valve body and bolting, of a subsea gate valve proved that the deformation values in the FEA model are very similar to the actual test deformation values. In addition, the paper reviews international standards related to hyperbaric testing. The main aim of the literature review is to call attention to the benefits of hyperbaric testing and provide a critical review of existing FEA analyses of subsea valves to improve the validity of the analysis and finally improve the safety and reliability of subsea valves. An analysis and design review of the non-pressure containing valve parts (bearings, sealing, etc.) to improve the reliability of subsea valves in deep water is proposed for future research.