Battery · Surface Facilities
Pressure Safety Valve
A spring loaded relief valve on a pressure vessel, the device that relieves pressure before the vessel exceeds its rating.
What it does
Opens at its set pressure, normally the vessel MAWP, and sends the relief to a flare or vent system. Process components are protected by a primary and a secondary level of protection.
Basics
| Set at | Normally the vessel MAWP |
| Discharges to | Flare or vent system |
| Sizing and installation | API RP 520 |
| Disposal systems | API RP 521 |
| Also called | PSV, relief valve |
Common failures
- Block valve under the relief valve left closed; these valves must be car sealed or locked open
Troubleshooting
- Symptom
- Relief valve leaks at normal pressure
- Likely cause
- Operating too close to the set pressure
- What to check
- Increase the margin between operating and set pressure