Question for assistance: How should the leakage rate of an emergency shut-off valve be selected?
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Dear experts in the field of petroleum refining and chemical engineering, I have a question regarding the leakage rate of emergency shut-off valves. How should the leakage rate of an emergency shut-off valve be selected? Here is some of what I have learned: 1. The SH/T 3005-2016 Standard for the Selection and Design of Automation Instruments in the Petrochemical Industry stipulates that the allowable leakage rate for switch valves shall comply with the requirements specified in GB/T13927-2008, GB/T26480-2011, or API 598. 2. The allowable leakage rates specified in GB/T26480 and API 598 are not graded. It only depends on the valve size. 3. In GB/T13927, the leakage rates are classified into A, AA, B, C, etc.; I’m not sure how to choose.
Reveal the leakage level; conduct a pressure test to check the amount of leakage
It is determined based on the requirements of the process medium; if a leak poses an extreme danger, the safety level is increased. For media that present a high degree of hazard, the leakage tolerance level for control valves should be at least ANSI Class V. You can take a look at the relevant provisions for HG20507.
Checked; it is specified there that the leakage class for control valves should be ANSI V, and ANSI VI can be used if required by TSO. However, according to SH/T 3005-2016, ANSI/FCI 70-2 is the standard that control valves must comply with, while gate valves are required to meet GB/T13927-2008, GB/T26480-2011, or API 598. The provisions of the two standards are inconsistent.
Simply write about the valve leakage tests per API 598, or refer to the leakage volume requirements specified in the API 598 TSO tests for valves of different diameters