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1 The API 622 standard specifies the requirements for comparative tests of valve stem packing used in the manufacturing process, with volatile leaks being taken into consideration here. The filler should be suitable for temperatures ranging from -29 to 538°C (-20 to 1000°F). The factors considered in this standard that affect volatile leakage include temperature, pressure, thermal cycling, mechanical cycling, and corrosion. Standard API 624 specifies the requirements and acceptance criteria (100 ppmv) for low-leakage testing of stem-and-rotary valves with graphite packing; previously, testing was carried out in accordance with API 622. The filler must be suitable for use at temperatures ranging from -29°C to 538 °C (–20 °F to 1000 °F). The requirements included in this type test are based on the principles of EPA21. Valves with a size larger than NPS24 or a pressure rating higher than class 1500 are not covered by this standard. 3 API 641 Test: This standard specifies the requirements and acceptance criteria for the short-duration discharge mode test of quarter-turn valves. The type test requirements included in this document are based on the elements of EPA Method 21. Valves with an NPS greater than 24 and valves meeting ASME B16.34 Class 1500 are not covered by this standard. Valves at pressure levels where the ambient temperature is below 6.89 barg (100 psig) are not within the scope of this standard. The repackaging or resealing of valves is not within the scope of this standard. 4 ISO15848 International Organization for Standardization – Industrial valves: Procedures for measuring, testing, and certifying low leakage. Low-leakage pressure testing is carried out according to specific application requirements. I’m from Xin Hai Zheng Gong; feel free to discuss with me