(1) Generally, strength test is not require for valves, but strength test shall conduct for valve body and bonnet after repair or valve body and bonnet damaged by corrosion.
(2) The valve shall test for strength and tightness during installation. 20% for low-pressure valves, 100% for unqualified valves and 100% for medium and high-pressure valves.
(3) During the test, the valve shall install in the direction easy for inspection.
(4) For valves with welded connection, if the blind plate pressure test fails, the conical seal or O-ring seal can use for pressure test.
(5) During the hydraulic test, clean the valve air as much as possible.
(6) During the test, the pressure should be increased gradually, and no sharp and sudden pressurization is allowed.
(7) The duration of strength test and sealing type test is generally 2-3min, and 5min for important and special valves.
(8) The throttle valve shall not be subject to the sealing test of the closing part, but shall be subject to the strength test and the sealing test of the packing and gasket.
(9) During the pressure test, the valve closing force only allows one person’s normal physical strength to close; it is not allowed to rely on levers and other tools to add force (except for the torque wrench). When the diameter of the hand wheel is greater than or equal to 320mm, it shall close by two people together.
(10) For valves with upper seal, the packing shall take out for sealing test. After the upper seal is close, check whether there is leakage. When testing with gas, check with water in the stuffing box. When conducting the packing sealing test, the upper seal is not allow to be in the tight position.
(11) For valves with driving equipment, the sealing test shall be carried out by closing the valve with driving equipment. For the manual driven equipment, the sealing test of the valve closed by the action shall also be carried out.
(12) The by-pass valve installed on the main valve after strength test and sealing test shall test for strength and sealing of the main valve; when the closing part of the main valve is open, it shall also open accordingly.
(13) During the strength test of cast iron valve, use a copper hammer to tap the valve body and bonnet to check for leakage.
(14) When the valve is test, except that the sealing surface of the plug valve is allow to oil according to the rules, other valves are not allow to oil on the sealing surface.
(15) During the pressure test of the valve, the pressure of the blind plate on the valve should not be too large, so as to avoid the deformation of the valve and affect the test effect.
(16) After the pressure test of the valve, the accumulated water in the valve shall clean in time, and the test records shall be made.