What is HIPPS and how does it differ from conventional relief systems?

HIPPS (High Integrity Pressure Protection System) is a safety instrumented system that isolates the pressure source before overpressure occurs, as an alternative or supplement to pressure relief devices. Typically SIL 2-3. Components: pressure transmitters (usually 2oo3 voting), logic solver (safety PLC), and fast-acting isolation valves. Benefits over relief: prevents release to atmosphere, faster response, handles larger volume excursions. Design considerations: response time analysis, valve closure time, upstream pressure source, downstream volume, and process-specific failure modes. Requires rigorous SIL verification and proof testing per API 14C and IEC 61511.