Pressure testing of low-temperature valve housings
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Regarding the pressure testing of low-temperature valve housings, when testing the housing at room temperature, the standard requires a water pressure of 1.5 times the nominal value. Can air pressure at 1.1 times this value be used as a substitute? Are there any standards that allow for substitution? The experienced worker said that if hydraulic pressure is used to shape the housing, and then the valve body needs to be dried at low temperatures, it takes a very long time.
Typically, such valves do not require pressure testing on-site, and many of them are valves connected by welding. If pressure testing is required, it is carried out on the equipment and pipelines together, and gas is generally used for this purpose. If pressure testing with water is required due to special circumstances, drying is essential; typically, dry gases such as air or nitrogen are used. For reference.
For pressure testing, the pressure must first meet the requirements of the specified test pressure; thereafter, it is necessary to decide whether to use water pressure or air pressure. There are no strict restrictions regarding the method to be used, but air pressure is generally not chosen as it poses a higher risk. If the pressure level is not high, air pressure can be used as an alternative to water pressure, but the pressure must still correspond to the test pressure specified in the design drawings.