A HIPPS is a SIF that protects equipment or a pipeline against overpressure by closing the source fast enough that the pressure never exceeds the design limit, often instead of a full-capacity relief system or a fully rated downstream system.
Typical design
2oo3 pressure transmitters, a SIL 3 capable logic solver, two fast-acting shutdown valves in series, solenoids in a 1oo2 arrangement, and frequent testing, often with partial stroke testing between full tests.
Why it is demanding
- The consequence of failure is usually high because no other protection exists for the full case.
- The closure time must be short enough for the pressure transient (settle-out pressure, line packing): the response budget is critical.
- Downstream relief may still be needed for small cases (leaking valve, thermal expansion).
- Testing must cover closure time and leakage of both valves.
Before choosing HIPPS
Check whether a fully rated design or relief to a safe place is possible. HIPPS is justified when those options are impractical, and then with full lifecycle discipline.
Written for First Out AI as engineering guidance. It supports engineering work and does not replace it; check every value against your standards, certificates and company rules with a competent functional safety engineer.