Valve Fugitive Emission Testing: API 624 and API 641

The Regulatory Context

Fugitive emissions from valve stems are a significant source of volatile organic compound (VOC) and methane releases at refineries and gas plants. Regulations in the US, EU, and globally mandate low-emission (LE) valve technology and monitoring programs (LDAR).

API 624: Rising-Stem Valves

API 624 specifies type testing of rising-stem valves (gate, globe, check) for fugitive emissions. The test uses methane as the test fluid and requires the valve stem to perform 310 mechanical and thermal cycles while maintaining leakage below 100 ppmv at the gland.

API 641: Quarter-Turn Valves

API 641 applies the same low-emission philosophy to quarter-turn valves (ball, butterfly, plug). Valves must demonstrate less than 100 ppmv methane leakage over 610 thermal and mechanical cycles in the type test.

ISO 15848 European Standard

• ISO 15848-1: classification and qualification tests for fugitive emissions

• Defines Class A (best), B, and C emission levels

• Covers rising-stem and quarter-turn valve types

• Used by European projects and increasingly adopted globally

Specifying Low-Emission Valves

• Request API 624 or API 641 type test certificates from manufacturer

• Specify low-emission packing (graphite or PTFE formulations)

• Include live-loading (spring-loaded) gland specification to maintain packing load

• Require installation torque values and re-torque intervals in the valve datasheet