Reliability assessment for subsea HIPPS valves with partial stroke testing
Résumé
High integrity pressure protection systems (HIPPS) have been applied in subsea applications to prevent accidents due to over-pressurization. A subsea HIPPS can be regarded as a complete functional loop consisting of sensors, logic solvers and actuating elements. It is important to test subsea HIPPS components with specified time intervals, so as to ensure their safety instrumented functions (SIFs). International standards IEC61508 and IEC61511, as well as many previous research works have given the reliability analysis methods for both SIS in general and HIPPS in particular, however, few of them focus on the different operational issues of HIPPSs in sub-sea. Partial stroke testing (PST) has been adapted on HIPPSs without stopping the subsea production process. PST could also reduce wear of the valve seat area and the probability of sticking seals compared with proof testing (PT). Reliability improvement by PST comes without additional cos