Subsea valves and actuators: a review of factory acceptance testing (FAT) and recommended improvements to achieve higher reliability

Abstract

Oil exploration is constantly moving into deeper waters. The costs associated with downtime and the maintenance of facilities and equipment such as valves and actuators, collectively known as Operation Expenditures (OPEX), are very high in the offshore sector of the oil and gas industry, particularly the subsea sector, where water depth may reach 1–3 km. Subsea valve and actuator failures contribute to other negative consequences such as loss of production and Health Safety and Environment (HSE) issues such as environmental pollution as a result of oil spillage. Therefore, more reliable subsea equipment, including valves and actuators, is required in the industry. The reliability of valves and actuators is largely dependent on testing, specifically factory acceptance tests (FAT) and qualification test programs. This paper reviews twelve existing tests based on international standards such as the American Petroleum Standard (API) and the International Standardization for Organization (ISO) for valves, actuators and manual gear overrides. Different types of tests such as pressure tests, function tests and operation characterization tests are included in this review. Parameters such as test pressure and duration, test preparation and methods for test implementation are discussed. Eight additional tests are proposed in this paper on the basis of industrial experience to minimize the failure rate of expensive subsea equipment and to increase its reliability.