Pressure Safety and Relief Valves (PSV) are totally directed by codes and regulations. The four most important codes and standards for PSVs (safety valve standards) are ASME (USA), API (USA), ISO (international) and PED (Europe).
ASME and API Safety Valve Standards for PRV.
We will try simplifies the main objective of the API and ASME play on pressure relief valves, and how the code and standards are envisioned to be used:
- API 526 provides basic design requirement for spring loaded and piloted operated PSVs:
- Orifice designation and area.
- Valve size and pressure rating, inlet and outlet.
- Materials.
- Pressure-temperature limits.
- Centre-to-face dimensions, inlet and outlet.
- API 520 provides detailed sizing procedure and methods based on steady state flow:
- Determine the required relief loads.
- Select preliminary valve sizes.
- ASME BPVC manages testing, reparation and certification of safety relief valves.
Most manufacturers have approvals from ASME and PED (as they considered as laws). When installing, select settings or sizing a safety valve, you need to be in accordance with these codes.
The leading standards and acclaimed practises are API 520 (USA) part 1 and part 2, EN4126 (Europe) and ISO 4126 and its 10 parts.
API 520 part 1 & part 2 incorporates details on Sizing, Selection, and Installation of Pressure-relieving Devices. API 520 includes information on correction factors (more conservative) for back pressure and viscosity, therefore is the standards (code) mostly used for pressure relief valve sizing or installation.
USA Standards
for Pressure Relief Valve.
ASME (AMERICAN SOCIETY OF MECHANICAL ENGINEERS) / ANSI (American National Standards Institute).
| CODES AND STANDARDS | Title |
| ASME I | Direct fired pressure vessels. |
| ASME III | Nuclear power plants. |
| ASME IV | Heating Boilers. |
| ASME VIII | Unfired pressure vessels. |
| ANSI/ASME PTC 25.3 | Performance test codes. |
| ASME B31.1 | Power Piping. |
| ANSI B31.8 | Gas Transmission and Distribution Systems. |
API (American Petroleum Institute ).
| CODES AND STANDARDS. | Title . |
| API RP 510. | Pressure Vessel Inspection Code. |
| API 520 Part 1. | Part 1 : Sizing selection and installation of pressure relieving . |
| API 520 Part 2. | Part 2 Installation. |
| API 521. | Guide for pressure relieving and de-pressurising systems. |
| API 526 | Flanged steel pressure relief valves. |
| API 527. | Seat tightness of pressure relief valves. |
| API IRE C16. | Guide for Inspection of Refinery Equipment Chapter XVI-Pressure-Relieving devices. |
| API Standard 2000. | Venting Atmospheric and Low Pressure Storage Tanks. |
| API RP 576. | Inspection of Pressure Relief Devices. |
Europe.
| CODES AND STANDARDS: | Title: |
| PED 97/23/EC. | Pressure Equipment Directive – Classifies pressure equipment into four categories (I, II, III, IV). |
| EN4126. | Safety devices for protection against excessive pressure. |
International ISO (International Organization for Standardization).
| CODES AND STANDARDS: | Title: |
| ISO 4126-2. | Safety devices for protection against excessive pressure — Part 2: Bursting disc safety devices. |
| ISO 4126-3. | Safety devices for protection against excessive pressure — Part 3: Safety valves and bursting disc safety devices in combination. |
| ISO 4126-4. | Safety devices for protection against excessive pressure — Part 4: Pilot operated safety valves. |
| ISO 4126-5. | Safety devices for protection against excessive pressure — Part 5: Controlled safety pressure relief systems (CSPRS). |
| ISO 4126-6. | Safety devices for protection against excessive pressure — Part 6: Application, selection and installation of bursting disc safety devices. |
| ISO 4126-7. | Safety devices for protection against excessive pressure — Part 7: Common data. |
| ISO 4126-9. | Safety devices for protection against excessive pressure — Part 9: Application and installation of safety devices excluding stand-alone bursting disc safety devices. |
| ISO 4126-10. | Safety devices for protection against excessive pressure — Part 10: Sizing of safety valves for gas/liquid two-phase flow. |
Other Countries.
| Country: | CODES AND STANDARDS: | Title: |
| South Korea. | KS B 6216. | Spring loaded safety valves for steam boilers and pressure vessels. |
| Japan. | JIS B 8210. | Steam boilers and pressure vessels – spring loaded safety valves. |
| Austria. | SAA AS 1271. | Safety valves, other valves, liquid level gauges and other fittings for boilers and unfired pressure vessels. |
ASME Code Stamps For PSV.
The new certification mark accompanied by an appropriate designator replaced all of the existing ASME code stamps including those of boilers, pressure vessels and the PRDs (Pressure Relief Valves).
