Which safety valve standards are commonly used for international projects?

Common safety valve standards for international projects include ASME BPVC, API 520, API 521, API 526, API 527, ISO 4126, DIN / EN standards, GB standards and project-specific owner specifications. The applicable standard depends on the protected equipment, country, industry, medium, pressure class and inspection requirements.

What is the difference between API 520 and API 521?

API 520 is mainly used for sizing and selection of pressure-relieving devices, while API 521 focuses on pressure-relief and depressuring systems, including relief scenarios, fire case, flare systems and system-level relief analysis.

Which standard is used for ASME pressure vessel safety valves?

ASME BPVC Section VIII is commonly referenced for pressure vessels and related pressure relief requirements. Safety valve sizing, selection and documentation may also reference API 520, API 521 and project specifications.

Which standard is used for boiler safety valves?

ASME BPVC Section I is commonly referenced for power boilers and boiler safety valves. Boiler projects may also require ASME B31.1 for power piping and additional owner or local regulatory requirements.

What documents are usually needed when ordering safety valves by standard?

Typical documents include valve datasheet, sizing calculation, general arrangement drawing, material certificates, set pressure calibration report, pressure test report, seat tightness test report, nameplate information, applicable standard statement and inspection records required by the project.

Safety Valve Standards, Codes & Engineering References

Review common safety valve and pressure relief standards used in product selection, sizing, installation, testing, flange connection and pressure-temperature evaluation. This page helps buyers understand which standards may apply before requesting a quotation.

Popular Standards Resources

API 520 Safety Valve Sizing › API 521 Pressure Relief Systems › ASME Safety Valve Standards › ISO 4126 Safety Valve Standards › ASME B16.5 Flange Dimensions › Pressure-Temperature Ratings ›

Standards overview

Use standards pages to prepare better safety valve inquiries

Safety valve procurement is not only a product model decision. Buyers may need to confirm applicable code family, flange rating, pressure-temperature limits, testing requirements, material requirements, documentation and project-specific acceptance criteria.

ZOBAI organizes these pages as practical engineering references for international buyers, EPC teams, pressure equipment manufacturers and maintenance engineers. The pages are written to support quotation communication and datasheet preparation, not to replace official standard documents.

Important notice

Official standards are copyrighted documents. This standards center provides practical orientation only. Final valve selection, sizing, testing and certification must follow the applicable project specification, official standard and authorized engineering review.

Standards Library

Safety valve standards and reference pages

Use these pages to understand the role of each standard before sending a safety valve datasheet, project specification or quotation request.

ASME

ASME Safety Valve Standards

Pressure equipment, boiler, pressure vessel and piping overpressure protection references for international projects.

API 520

API 520 Safety Valve Sizing

Sizing, selection and installation communication for pressure-relieving devices in process industry projects.

API 521

API 521 Pressure Relief Systems

System-level relief scenarios, fire case, flare, depressuring and safe discharge philosophy.

API 526

API 526 Flanged Safety Valves

Flanged steel pressure relief valve references for size, orifice, pressure class and model communication.

API 527

API 527 Seat Tightness Test

Seat tightness and leakage testing communication for pressure relief valve inspection and acceptance.

ISO 4126

ISO 4126 Safety Valve Standards

International safety device requirements for protection against excessive pressure.

DIN/EN

DIN / EN Safety Valve Standards

European-style project specifications, valve terminology, connection expectations and documentation review.

GB Safety Valve Standards

Chinese pressure equipment and safety valve references for domestic and export project communication.

B16.5

ASME B16.5 Flange Dimensions

Flange dimensions, pressure class, facing type and connection details for safety valve inlet and outlet.

P/T

Pressure-Temperature Ratings

Material, flange class and temperature limits that must be checked before final valve selection.

API 576

API 576 PRV Inspection

Inspection, testing, maintenance and repair communication for pressure relief valves in service.

NACE

NACE MR0175 / ISO 15156 Sour Service

Material and documentation review for H2S-containing sour gas or corrosive service.

API Standards

API references commonly used for pressure relief projects

API standards are frequently used in oil, gas, petrochemical, refinery, LNG and process industry projects. Buyers often mention API 520, API 521, API 526, API 527 and API 576 when discussing sizing, relief scenarios, flanged valve dimensions, seat tightness or inspection.

How the API pages should be used

API 520 supports sizing and selection communication.
API 521 supports system-level relief scenario and depressuring review.
API 526 helps with API-style flanged steel PRV dimensions and orifice references.
API 527 helps clarify seat tightness test expectations.
API 576 supports inspection, testing and maintenance communication.

Regional & International Standards

ASME, ISO, DIN / EN and GB references for safety valve projects

Different projects specify different standards depending on country, equipment code, end-user requirement and industry practice. Confirm the correct reference before quotation and production.

ASME

Often used for international pressure equipment projects involving boilers, pressure vessels, piping and overpressure protection requirements.

ISO 4126

Useful for international terminology and safety devices for protection against excessive pressure.

DIN / EN

Commonly referenced in European-style specifications, connection details and customer project documents.

GB

Used in Chinese safety valve and pressure equipment projects and export-related compliance communication.

Connection & Rating

Flange size and pressure-temperature ratings must match the real service condition

A safety valve cannot be selected by nominal size alone. The inlet and outlet connection, flange class, material group, pressure-temperature rating, gasket and bolting requirements should match the actual pressure and temperature.

Medium-Specific Standards

Add medium-specific references where the service requires special safety review

These pages are not always needed in the top navigation, but they should be linked from LNG, LPG, Hydrogen, Oxygen, Ammonia and corrosive service pages to improve topical authority and buyer confidence.

NFPA

NFPA 58 LPG Safety Requirements

For LPG storage, transfer, handling and pressure relief discussions.

NFPA

NFPA 59A LNG Safety Requirements

For LNG production, storage, handling, regasification and cryogenic relief review.

NFPA

NFPA 2 Hydrogen Safety Code

For hydrogen generation, storage, piping, use and handling safety communication.

NFPA

NFPA 55 Compressed Gas Safety

For compressed gases and cryogenic fluids used in industrial gas projects.

IIAR

IIAR Ammonia Refrigeration Standards

For ammonia refrigeration, R717 receivers, compressors and relief discharge review.

ASTM

ASTM G93 Oxygen Cleaning Standard

For oxygen-clean requirements, cleanliness level, packaging and inspection discussion.

CGA

CGA G-4.4 Oxygen Piping Systems

For oxygen pipeline, velocity, cleanliness and compatibility review.

ASME

ASME B31.12 Hydrogen Piping

For gaseous hydrogen, hydrogen blends and liquid hydrogen piping systems.

Before Quotation

Information needed when a project specifies API, ASME, ISO, DIN / EN or GB

Send the specification together with the real working conditions. This helps ZOBAI review whether the product series, materials, connection, testing and documentation can match the project requirement.

FAQ

Common questions about safety valve standards

Does ZOBAI publish the full text of API, ASME, ISO, DIN / EN or GB standards?

No. Official standards are copyrighted documents. ZOBAI provides practical overview pages that help buyers understand standard-related project communication and prepare better RFQ data.

Which standard should I use for my safety valve project?

It depends on the project country, equipment code, end-user specification, industry, pressure system and procurement requirement. Send the datasheet and project specification for review.

Should API 520 and API 521 be separate pages?

Yes. API 520 is more closely related to sizing, selection and installation communication. API 521 is more system-level and should cover relief scenarios, fire case, flare and depressuring review.

Are flange standards important for safety valve selection?

Yes. Inlet and outlet connection, flange class, facing type, gasket, bolting and pressure-temperature rating should be checked before quotation and production.

Should medium-specific standards be linked from the Standards page?

Yes. Hydrogen, oxygen, LNG, LPG and ammonia pages should link to relevant NFPA, IIAR, ASTM, CGA, NACE or ASME B31 pages where applicable. This improves internal linking and engineering credibility.

Need help matching a safety valve to your project standard?

Send your working conditions, datasheet, required standard and project specification. ZOBAI will review the request and respond with the appropriate recommendation or quotation.