The strength test of the safety valve is the same as that of other valves. It is tested with water. When testing the lower part of the valve body, the pressure is introduced from the inlet end and the sealing surface is closed; when testing the upper part of the valve body and the bonnet, the pressure is introduced from the outlet end and the other ends are closed. The valve body and bonnet are qualified without leakage within the specified time.
For sealing test and constant pressure test, the general media used are: safety valves for steam use saturated steam as the test medium; valves for ammonia or other gases use air as the test medium; valves for water and other non-corrosive liquids use water as the test medium . For safety valves in some important positions, nitrogen is often used as the test medium.
The sealing test shall be conducted with the nominal pressure value as the test pressure, and the number of times shall not be less than twice, and no leakage within the specified time is considered qualified.
There are two leak detection methods: one is to seal each connection of the safety valve, and use butter to seal the thin paper on the outlet flange. If the thin paper bulges, it is leaking, and if it does not bulge, it is qualified; the second is to use butter to seal the thin plastic. The plate or other plate seal is attached to the lower part of the outlet flange, and the valve is sealed by filling with water. It is qualified to check that the water does not bubble. The number of constant pressure and return pressure tests of the safety valve shall not be less than 3 times, and it shall be qualified if it meets the requirements.
