Liu Y., 2013, Testing Strategies of Redundant Safety Instrumented Systems with Dangerous Detected Failures, Chemical Engineering Transactions, 33, 373-378.
Proof testings are regularly conducted on safety instrumented systems (SISs) to reveal dangerous undetected (DU) failures so as to reduce process risks. Sometimes, self-diagnostic tests of SISs can find dangerous detected (DD) failures which will be fixed as soon as possible. If such detections of failures also activate further tests for all components in the SIS in order to discover hidden failures, the original functional test strategy will be adjusted. Three following test strategies for redundant SISs including parallel structures are discussed in this paper given that a DD failure has been found, and then models for these strategies are proposed based on Petri nets.
