Valve Packing Emission Testing: ISO 15848 vs API 622

ted wang
Jun 4
2 min read

Why Emission Testing Standards Matter

Volatile organic compound (VOC) and greenhouse gas (GHG) emissions from valve stem packing contribute significantly to industrial air pollution. Regulatory programs such as EPA Method 21, LDAR (Leak Detection and Repair), and EU Industrial Emissions Directive require verified low-emission packing systems. Two major standards govern valve packing qualification.

ISO 15848 Overview

Part 1: classification system and qualification procedures for industrial valves
Part 2: production acceptance testing
Three tightness classes: AH (tightest), BH, and CH
Test medium: helium (sensitive leak detection)
Test conditions: thermal cycling between low and high temperature limits
Mechanical cycling: 500, 1500, or 2500 cycles depending on class

API 622 Overview

American standard focusing on process industry fugitive emission performance
Test medium: methane or propane representative of refinery process fluids
Required leak rate: less than 100 ppm using EPA Method 21 sniffing probe
Mechanical cycling: 1510 cycles (equivalent to 5 years service life)
Thermal cycling: ambient to 260°C and back to ambient twice
Includes packing removal and repacking after thermal cycles

Comparing the Two Standards

ISO 15848 uses helium as the test fluid and provides three classes of tightness, making it more flexible for specifying different emission levels. API 622 uses hydrocarbon gas and represents a single pass-or-fail threshold of 100 ppm, aligned with EPA regulatory requirements. Both standards require similar test procedures but differ in detection methods and acceptance criteria.

Packing Selection Guidance

Flexible graphite packing rings: best emission performance for high-temperature service
PTFE and expanded PTFE: suitable for chemical service and lower temperatures
Spring-loaded packing: maintains sealing force as packing relaxes over time
Certified packing systems should carry the ISO 15848-1 or API 622 test report
Verify packing is compatible with process fluid, temperature, and pressure range