API 641 (Testing of Quarter-Turn Valves)

API 641: Type Testing of Quarter-Turn Valves for Fugitive Emissions

API 641 specifies a type-testing approach for evaluating fugitive-emission performance of quarter-turn valves. The 2023 edition supports comparison of valve designs using defined test conditions and acceptance requirements, helping manufacturers and purchasers assess sealing performance for emission-sensitive service.

Scope

The 2023 edition sets the test framework and the operating limits for valves evaluated under this standard. Its scope includes:

• Fugitive-emission type testing and acceptance criteria for quarter-turn valves
• Test methods based on relevant elements of EPA Method 21
• Valves up to NPS 60, subject to the standard’s other stated limits
• Exclusion of valves rated above ASME B16.34 Class 1500
• Exclusion of valves rated below 6.89 barg (100 psig) at ambient temperature
• An additional high-temperature test may be specified for valves rated at or above 400 °C (750 °F)

File Specifications