Some considerations on how often safety critical valves should be tested

The regulation given by the Petroleum Safety Authority Norway (PSAN) requires annual testing of safety critical valves. In the present paper we discuss the rationale for this requirement, as annual testing by the operators is considered as too strict. We also show, using expected utility theory as the basis for the discussion, that, at the same time, it is too simplistic in that it focuses on too few parameters. We show that the requirement of annual testing likely will be too strict also from a societal point of view if the objective of annual testing is only improvements in reliability of the valves. One is then disregarding the fact that testing of safety critical valves also has negative effects on safety for those who perform the tests, as well as negative effects for the environment.