Production and manufacturing of good valves must go through a variety of performance testing, one of the most important test is the test pressure. Test pressure is to test the pressure value of the valve can withstand whether the production requirements, the general valve pressure test must comply with the following principles and precautions:
(1) In general, the valve does not make strength test, but after repairing the valve body and valve cover or corrosion damage to the valve body and valve cover should be made strength test. For safety valves, its fixed pressure and seat back pressure and other tests should be in accordance with the provisions of its instructions and relevant regulations.
(2) Valve installation should be made in recognition of the strength and sealing test. Low-pressure valves sampling 20%, such as unqualified should be 100% of the inspection; medium and high-pressure valves should be 100% of the inspection.
(3) Test, the valve installation position should be easy to check the direction.
(4) Welded connection form of valve, with a vertically plate test pressure can not be used when the conical seal or O-ring seal test pressure. (5) Hydraulic test on the valve air as far as possible to exclude.
(6) Test pressure to gradually increase, do not allow sharp, sudden pressure.
(7) Strength test and sealing test duration is generally 2-3min, important and special valves should last 5min. small diameter valve test time can be correspondingly shorter, larger diameter valve test time can be correspondingly longer. In the test process, if in doubt can extend the test time.
Strength test, do not allow the valve body and bonnet sweating or leaking phenomenon.
Sealing test, general valves only once, safety valves, high-pressure valves and other vital valves need to be carried out twice.
Test, low-pressure, large-diameter unimportant valves, as well as the provisions of the allowable leakage of the valve, allowing a small amount of leakage phenomenon.
Due to the general valve, power station valves, marine valves and other valve requirements vary, the leakage requirements should be implemented in accordance with relevant regulations.
(8) Throttle valve does not close the sealing test, but should be made strength test and packing and gasket at the sealing test.
(9) Test pressure, the valve closing force only allows a person's normal physical strength to close, not with the help of levers and other tools to add force (in addition to the torque wrench), when the diameter of the handwheel is greater than or equal to 320mm, allowing two people to close together.
(10) With the upper seal of the valve should be taken out of the packing for the sealing test, the upper seal after the official close, check whether the leakage. With gas for the test, in the packing box in the water check. For packing sealing test, do not allow the upper seal is in a closed position.
(11) Where the valve has a driving device, test its sealing should be driven to close the valve antagonist sealing test. Hand-driven device, should also be used to close the valve sealing test.
(12) Strength test and sealing test installed in the main valve on the bypass valve, the main valve for strength and sealing test; the main valve closure parts open, it should also be opened.
(13) Cast iron valve strength test, should be a copper clock tapping the valve body and valve cover, check for leakage.
(14) Valve test, in addition to plug valves have provisions to allow the sealing surface of oil, other valves are not allowed to apply oil on the sealing surface of the test.
(15) Valve test pressure, the blind pressure on the valve should not be too large, so as not to produce deformation of the valve, affecting the test results (cast iron valves, if pressed too tightly, but also broken).
(16) Valve pressure test is completed, the valve should be removed in a timely manner and wipe the water inside the valve, should also make a good record of the test.