In order to check the quality of construction products, prevent the occurrence of running, dripping, leakage caused by various accidents, before the construction, we will test the valve pressure, especially high-pressure valves, has higher requirements.
In that case, what are the standard principles for testing pressure on valves? The following is a collection of small series of valve pressure test standard principles, as follows: (1) Under normal circumstances, the valve does not do strength test, but after the repair valve body and bonnet or corrosion damage of the body and bonnet should be used as strength test.
For safety valves, the constant pressure and seat pressure and other tests shall conform to their specifications and relevant regulations. (2) Valve installation should be used for strength and tightness test.
Low-pressure valve sampling 20%, such as unqualified should be 100% of the inspection, medium and high pressure valves should be 100% of the inspection.
(3) When the test, the valve installation position should be easy to check the direction.
(4) Welded joint form of the valve, with the blind plate test pressure can be used conical seal or O-ring seal to test pressure.
(5) Hydraulic test when the valve air as far as possible to exclude.
(6) When the test pressure to gradually increase, do not allow a sharp, sudden pressurization. (7) The strength test and the seal type inspection duration generally is 2~3min, the important and the special valve should continue 5min. Small-caliber valve test time can be correspondingly shorter, large-diameter valve test time can be correspondingly longer. In the course of the trial, if there is doubt can prolong the test time. When the strength test, the body and bonnet are not allowed to appear sweating or leakage phenomenon. Sealing test, the general valve of the rotor pump only once, safety valve, high-pressure valve, such as the need for the valve two times.
When the test, the low pressure, large diameter of the valve and the provision of allowable leakage of the valve, allows a trace of leakage phenomenon; As the general valves, power station valves, marine valves and other valves vary, the requirements for leakage should be carried out in accordance with the relevant provisions.
(8) The throttle valve does not make the sealing test of closed parts, but it should be used as strength test and sealing test of filler and gasket.
(9) In the pressure test, the valve closes the force only to allow one person's normal physical strength to close, may not use the lever and so on tool afterburner (except the torque wrench), when the handwheel's diameter is larger than waits for 320mm, allows two people to close together. (10) with the seal of the valve should be taken out of the filler for sealing test, seal the crown, check whether leakage. When using gas as a test, water is checked in the filler letter.
The seal is not allowed to be sealed in the sealing test of the packing. (11) Where the valve has a driving device, test the sealing of the application of the driving device closed valve antagonistic test.
For the manual drive device, the sealing test of the valve should be carried out.
(12) After the strength test and the sealing test, the by-pass valve is installed on the main valve, the strength and tightness test is carried out in the main valve, and the main valve closing part should be opened.
(13) Cast iron valve strength test, the application of copper hammer tap valve body and bonnet, check whether leakage.
(14) When the valve is tested, except the plug valve has the stipulation to allow the sealing surface to apply the oil, other valves do not allow the oil test on the sealing surface.
(15) Valve pressure, the blind plate on the valve pressure should not be too large, so as to avoid the valve deformation, impact test results (cast iron valve if pressed too tight, but also damaged). (16) After the valve test pressure, should promptly eliminate the water and clean the valve, but also should be good test records.