HIPPS valves are used as the final part of an instrumented system intended to prevent an unacceptably high pressure occurring in downstream equipment. They are always arranged to fail closed and spring/hydraulic actuators are usually the only practical alternative for operation. HIPPS valves are called High Integrity Pressure Protection System (HIPPS) valves
In general, closure times should be maximized or, if times have to be short, tests should be undertaken Required closure speed depends on the closed-in volume downstream and the working fluid (e.g. if there is a high volume, gas filled system downstream, valve closure speed need not be fast).
HIPPS valve applications have the following characteristics
- High pressure always available at time of emergency closure.
- Low differential pressure during closure
- High differential pressure after closure
- Requirement for periodic closure (or partial closure) and seat leakage testing; (Occasionally) fast closure.
The first two make for particularly benign operating conditions and the temptation to specify an unnecessarily high differential pressure during closure should be resisted.