Author: Site Editor Publish Time: 2019-01-28 Origin: Site
Under normal circumstances, industrial valves are not tested for strength during use, but the valve body and bonnet or corrosion-damped valve body and bonnet should be tested for strength after repair. Trunnion mounted ball valve strength and tightness tests shall be performed prior to valve installation.
Before the test, the ball is idling several times, the trunnion type ball valve is closed, and the test medium is introduced from one end to the specified value; the pressure at the inlet is used to check the sealing performance of the inlet, and the accuracy of the pressure gauge is 0. 5 to 1 level, the range is 1.5 times the test pressure. In the specified time, no depressurization is acceptable; then the test medium is introduced from the other end, and the above test is repeated. Then, the valve is in a half-open state, the ends are closed, the inner cavity is filled with the medium, and the packing and the gasket are inspected under test pressure, and there is no leakage.
1. All valves should be inspected after opening the box, including the complete nameplate on the valve body, the product quality certificate, the valve is closed, no other damage such as blue surface, no stain, and protective cover at both ends.
2. The operator should be familiar with the operation of the test bench.
3. The operator should be familiar with the safety hazards of the valve pressure test, reverse transport and other processes and have corresponding preventive measures.
4, the valve pressure test process: valve shell strength test, upper seal test, seal test.
(1) Valve shell strength test The medium is water, the pressure is 1.5 times the nominal pressure of the valve, the dwell time is 5 min, and no dripping or damp is qualified.
(2) The seal test medium on the valve uses water, the pressure is 1.5 times of the nominal pressure, the dwell time DN≤50 is 15s, the 65≤DN≤300 is 60s, the DN≧350 is 120s, and no leakage is qualified.
(3) Valve sealing test Conduct low pressure sealing test. The test medium adopts air (gate valve), the pressure is 0.6MPa, the dwell time DN≤50 is 15s, 65≤DN≤150 is 60s, DN≧200 is 120s, the penetration is consistent. The requirements are qualified.
(4) After the pressure test is passed, the water in the valve chamber should be blown dry with compressed air.
(5) The valve passed the pressure test is marked on the valve body with√, and the valve that is not qualified is marked with ×.
(6) After the pressure test, the valves should be stacked separately according to the model specifications, and the unqualified products should be stacked separately; each stacking area should be erected with obvious sign plates. After the pressure test, the valve should be covered back to the cover and covered with colored strips in the stacking area.
(7) After the pressure test of the valve, fill in the “Valve/Fitting Test Record” according to the device in time, and fill in the purchase contract number on the valve body in the model column.
(8) The valve issued by the test shall be filled out with the valve “valve release record”, and the signature of both parties shall be issued and received.
(9) Unqualified valves need to establish a separate list of "unqualified valves"