Valve pressure test standard principle:
(1) Generally, the valve is not subjected to a strength test, but the valve body and bonnet or the valve body and bonnet damaged by corrosion should be subjected to a strength test after repair. For safety valves, the constant pressure and return pressure and other tests shall comply with the specifications and relevant regulations.
(2) The strength and tightness test of the valve installation should be done. Low-pressure valves should be spot-checked 20%, if they are unqualified, 100% should be checked; medium and high-pressure valves should be 100% checked.
(3) During the test, the valve installation position should be in a direction that is easy for inspection.
(4) For valves in the form of welded connection, if the pressure test with the pallet fails, the taper seal or O-ring seal can be used for the pressure test.
(5) During the hydraulic test, try to remove the valve air as much as possible.
(6) During the test, the pressure should be gradually increased, and sudden and sudden increase in pressure is not allowed.
(7) The duration of strength test and sealing test is generally 2~3min, and important and special valves should last for 5min. The test time for small-bore valves can be correspondingly shorter, and the test time for large-bore valves can be correspondingly longer. During the test, if in doubt, the test time can be extended. During the strength test, no sweating or leakage of the valve body and valve cover is allowed. For the sealing test, the valve of the rotor pump is generally performed only once, and the main valves such as safety valve and high-pressure valve need to be performed twice. During the test, for low-pressure, large-caliber unimportant valves and valves with regulations that allow leakage, a small amount of leakage is allowed; due to the different requirements for general valves, power station valves, marine valves and other valves, there is a requirement for leakage It should be implemented in accordance with relevant regulations.
(8) The throttle valve shall not be tested for the sealing performance of the closing parts, but shall be tested for the strength and the sealing performance of the packing and gasket.
(9) During the pressure test, the valve closing force is only allowed to close by one person's normal physical strength; no levers or other tools (except torque wrenches) can be used to add force. When the diameter of the handwheel is greater than or equal to 320mm, two people are allowed to work together. Closed.
(10) For valves with upper seals, the packing should be taken out for a tightness test. After the upper seal is closed, check for leakage. When using gas as a test, put water in the stuffing box to check. When making the packing tightness test, the upper seal is not allowed to be in a tight position.
(11) For valves with a driving device, the driving device should be used to close the valve when testing its tightness to conduct a tightness test. For manual actuating devices, a sealing test of the dynamic closing valve shall also be carried out.
(12) The bypass valve installed on the main valve after the strength test and tightness test undergoes strength and tightness tests on the main valve; when the main valve closing element is opened, it should also be opened.
(13) During the strength test of cast iron valves, tap the valve body and bonnet with a copper hammer to check for leaks.
(14) When valves are tested, except for plug valves that allow the sealing surface to be coated with oil, other valves are not allowed to be tested with oil on the sealing surface.
(15) When the valve is pressure tested, the pressing force of the blind plate on the valve should not be too large, so as to avoid deformation of the valve and affect the test effect (if the cast iron valve is pressed too tightly, it will be damaged).
(16) After the valve pressure test is completed, the water in the valve should be removed and wiped clean in time, and test records should be made.
Why do we need to perform a valve pressure test?
The main purpose is to inspect the quality of construction (products) and prevent various accidents caused by running, emitting, dripping, and leaking. Especially for high-pressure valves, the requirements are more stringent. For details, please refer to "GBT 13927-2008 Industrial Valve Pressure Test". Clear requirements and specifications.