The MSS standard MSS-SP-61 Pressure testing of valves

Manufacturer's Standardisation Society (MSS)

The MSS standard MSS-SP-61: Pressure Testing of Valves was originally adopted in 1961. It was developed for the purpose of providing a uniform means of testing valves commonly used in the "full open" and "full closed" type of service. It is not intended for use with control valves. Refer to standard ANSI/FCI 70-2 for Control Valves.

Section 5 of their Pressure Testing of Steel Valves, relates to seat closure tests, and defines the following leakage rates:

Gate, Globe, Ball valves:

10 cc/hr per inch of nominal pipe diameter. (Example: A 6" globe valve is allowed to leak 60 cc/hr in a test)

Check valves:

40 cc/hr per inch of nominal pipe diameter

All shutoff or isolation valves specified to MSS-SP-61 must pass the above standards. The seat closure test must be performed at a fluid (liquid or gas) pressure no less than 1.1 times the 1000°F (380°C) rating rounded to the next 5 psi (0.5 bar).