The Principles of Pressure Tests of Valves
The principles of pressure tests of valves are as follows：(1) Under normal circumstances, a strength test is not required for a valve, but the valve body and bonnet which are repaired or damaged by corrosion should be subjected to a strength test. For safety valves, the constant and return pressure as well as other tests should comply with their specifications and relevant regulations.
(2) The strength and leakage test of the valve should be done before installation. 20% of low-pressure valves should be checked randomly. If they are unqualified, all of them should be checked; medium and high pressure valves should be 100% checked.
(3) In the testing process, the valve's installation position should be in a direction that is easy to check.
(4) For valves with welded connection, if the pressure test with the blind plate fails, the taper or O-ring seal can be used for the pressure test.
(5) Try to remove the air in the valve as much as possible during the hydraulic test.
(6) The pressure should be gradually increased in the process of testing; rapid and sudden pressure is not allowed.
(7) The duration of the strength test and leakage test is generally between 2 to 3 minutes, and important and special valves should last for 5 minutes. The testing time for valves with small diameters can be correspondingly shorter; the testing time for valves with large diameters can be correspondingly longer. In the process of testing, if there is any doubt, the test time can be extended. During the strength test, no leakage should appear for the valve body and valve bonnet. For the sealing test, the valve of the rotor pump is generally performed only once, and the main valves such as safety valves and high-pressure valves need to be performed twice. During the test, for low-pressure, unimportant valves with large diameters and valves with allowable leakage, a small amount of leakage is allowed; Leakage requirements for general valves, power station valves, marine valves and other valves should be in accordance with relevant regulations due to their different requirements.
(8) The closing part of throttle valves shall not be tested for leakages, but the strength test shall be performed and the leakage test of the packing and gaskets should be carried out.
(9) During the pressure test, one person's normal physical strength is allowed for the valve closing force; no lever or other tools (except torque wrenches) can be used to increase the force. When the diameter of the handwheel is greater than or equal to 320mm, two people are allowed to work together to close the valve.
(10) As for valves with upper seals, their packing should be taken out for a leakage test. After the upper seal is closed, check it for leakage. When gas is used in a test, put water in the stuffing box. When the leakage test of packing is performed, the upper seal is not allowed to be in the tight position.
(11) For valves with a driving device, the driving device should be used to close the valve before a leakage test is performed. For valves with manual actuating devices, close valves by hands before a leakage test.
(12) The main valve should be subjected to the strength test and leakage test. The bypass valve installed on the main valve after the strength test and leakage test shall be opened after the closing part of the main valve is opened.
(13) During the strength test of cast iron valves, tap the valve body and bonnet with a copper hammer to check for leakage.
(14) When the valve is tested, except for the plug valve that allows its sealing surface to be oiled, other valves are not allowed to be oiled on their sealing surface.
(15) During the valve pressure test, the pressing force of the blind plate on the valve should not be too great so as not to make the valve deform, affecting 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 the test record should be kept.
Send your message to this supplier
Related Articles from the Supplier
The Principles of Pressure Tests of Valves
- Mar 17, 2021
The Manufacturing Process of Industrial Valves
- Aug 13, 2017
The Importance of the Control Valve
- Aug 17, 2020
How to Prolong the Life of High Pressure Valves?
- Aug 27, 2020
Development Trend of the Electric Regulating Valve
- Sep 22, 2020
The Structure and Classification of Ball Valves
- Sep 28, 2020
The Advantage of the O Type Ball Valve
- Dec 11, 2020
Related Articles from China Manufacturers
The Principles of Purchasing Your Swimwear
- Aug 20, 2021
The Sealing Principles of the Valve (Part One)
- Jan 13, 2021
The Selection Principles of Check Valves’ Clacks
- Jul 27, 2017
The Sealing Principles of the Valve (Part Two)
- Jan 23, 2021
