Issuing body
API
Latest edition
7th Edition (2020)
Region
USA, Global
Equipment items
3
Scope
Causes of overpressure, relief load determination, depressuring, flare/disposal system design.
Key requirements (6)
- Sizing and design of pressure relief and depressuring systems.
- Relief scenarios: blocked outlet, fire, control valve failure, tube rupture, power failure, thermal expansion, runaway reaction, abnormal heat input.
- Fire heat input: Q = 21,000·F·A^0.82 BTU/hr (vapor space < 25 ft elevation; F = environment factor 0.3–1.0).
- Depressuring: typically blowdown to 50 % of design pressure or 100 psig (whichever lower) within 15 minutes for vessels exposed to fire.
- Flare radiation: max permissible 1.58 kW/m² (continuous), 4.73 kW/m² (limited exposure), 6.31 kW/m² (emergency).
- Disposal system sizing: must handle simultaneous events — 'global event' analysis.
Related standards (1)
Applied to 3 equipment items
Pressure Vessels & Reactors
Safety & Relief