Valve pressure testing principle and pay attention to the following matters:
(1) generally, the valve should not be strength test, but after the repair body and cover or corrosion damage of the body and cover should be strength test. For the relief valve, the constant pressure and back seat pressure and other test shall conform to the specifications and the relevant provisions of regulations.
(2) the valve installation shall be all strength and leakage test. Low pressure valve check 20%, such as not qualified shall be 100% of the inspection; Medium and high pressure valves shall be 100% of the check.
(3) test, valve installation position should be easier for the direction of the inspection.
(4) welding connection form of valve, with huang plate test no can use conical seal or o-ring seal test.
(5) hydraulic tests will try to eliminate air valve.
(6) test pressure to rise, don't allow sharp, suddenly booster.
(7) strength test and sealing type test duration is generally 2 ~ 3 min, important and special valve should be continued for 5 min. Small valve test time can be short some corresponding, large diameter valve test time long some corresponding. In the test process, if in doubt can prolong test time. Strength test, are not allowed to body and bonnet appear sweat or leakage phenomenon. Leakage test, general valve only once, relief valve, high pressure valve and valve should be born to two times. Test for low pressure, large diameter is not important valve and the rules to allow the valve leakage, to allow a trace of leakage; Due to the common valve, power stations with valve, Marine valves and other valves different requirements, the leakage requirements shall be in accordance with relevant provisions.
(8) throttle valve should not be shut down a leakage test, but should be strength test and packing and gasket in leakage test.
(9) test, the valve closing force only allow a person's normal physical strength to close. Do not use leverage and so on tool strength (except torque wrench outside), when the hand wheel diameter greater than wait until in 320 mm, allow two people close together.
(10) with the seal of the valve should be take out packing for leakage test, and after the official seal, check leakage. With gas for test, the gland in water inspection. For packing sealing test, not allowed to go to seal in the close position.
(11) who has the drive valve, to test its sealing used to close the valve drive of leakage test. Opponents dynamic drive, but also should undertake with moving close the valve seal test.
(12) strength test and leakage test after the main valve installed in the bypass valve, in the main valve for strength and leakage test; The main valve closed a open, also should then open.
(13) cast iron valve strength test, the application of copper hammer tapping body and bonnet, check for leakage.
(14) valve test, in addition to cock valve has a regulation allows sealing surface oil outside, other valves are not allowed in the seal surface oil test.
(15) valve test, blind for suppressing the valve pressure force shoulds not be too big, lest the valve deformation, the impact test effect (cast iron valve if pressure too tight, will damage).
(16) valve pressure test after completion, should be ruled out in the valve and clean water, still should make test record.
 

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