How to choose between PN16 and PN25 stop valves for steam pipelines with a working pressure of 1.25MPa
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Logically speaking, PN16 is sufficient, but the company uses PN25 in other designs. Is this safer? But haven’t the costs also increased? How to choose a valve?
The pressures designed by design institutes are all high. In fact, most of the pressures are 16 kilograms.
There needs to be a margin in the design, and the working temperature of steam is high, generally above 200 degrees. Under this temperature condition, the PN16 valve exceeds the applicable range, so PN25 is used.
Valve selection is based on actual working conditions such as medium, pressure, temperature, etc., and is not determined by a single parameter. The rated pressure-temperature of the valve can refer to GB/T12224；
The 1.25 you mentioned is normal working pressure. If abnormal conditions occur, PN16 will not meet the requirements.
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The working pressure is 1.25MPa, the design pressure may be 1.5MPa, and the pipeline strength test pressure is 1.5 times the design pressure! Therefore, either isolate the valve during the strength test, or simply choose a 2.5MPa valve. Personal understanding, please correct me.