ISA-TR96.05.01-2017

ISA-TR96.05.01-2017, Partial Stroke Testing of Automated Valves, focused on partial stroke testing (PST) of automated valves primarily used in safety and critical process applications, this report provides guidance on the concept, methods, benefits, risks and diagnostic approaches for PST as an alternative or supplement to full stroke valve testing, especially when frequent full stroke tests are impractical. It covers four main PST methods: mechanical limiting, travel limiting, position control and solenoid-operated valves.This technical report discusses their operational characteristics, risks, potential for spurious trips and maintenance considerations. It introduces margin analysis to evaluate valve performance degradation and failure modes, supported by expert-ranked failure mode and effects analyses (FMEA). Diagnostic coverage levels, ranging from basic visual checks to advanced external condition monitoring, are described, with higher levels offering improved detection of valve degradations. Additionally, this report highlights concerns such as over-torquing risks during PST and emphasizes that PST should complement, not replace, periodic full stroke testing.