(1) In the pressure test of double-flange dismantling joints, the strength test pressure is higher than the working pressure and the time is short; the tightness test pressure is equal to the working pressure, and the time is long and cannot replace each other.
(2) Tap water or pump pressurized water should be used to flush the pipeline during pressure test, otherwise the scum in the pipe cannot be washed away, the water quality will be polluted and the tightness of the valve will also be affected.
(3) There is air in the tube during pressure test, which makes the pressure gauge reading unstable. An air release valve should be installed at the height of the system.
(4) Use zone control valves as an isolation means for zone pressure test, which often results in failure of pressure test due to valve leakage. Use plugging plates or wire plugs as temporary isolation.
(5) Part of the isolation valve was deliberately closed during the overall pressure test of the pipeline, which caused the pressure test pipeline to be shortened and the capacity was qualified, but the authenticity of the overall qualification was lost. Supervisors should carefully check and mark to prevent fraud.
(6) When testing the pressure of the double-flange dismantling joint, check whether the pressure gauge can be reset to zero, and install two qualified pressure gauges for comparison.