Valve production is a complex and simple process, the production of ordinary valves such as the cycle of the production valve, ball valve, globe valve, butterfly valve, check valve in three days, producing a good valve must pass through the performance test, one of the most important is the detection of pressure test. Test pressure is to test whether the pressure valve can meet the production requirements, the general valve pressure test must comply with the following principles and matters needing attention:
- In general, the valve shall not be subject to strength test, but the body and bonnet shall be subjected to strength tests after the repair of the body and bonnet or corrosion damage. For the relief valve, the constant pressure and seat return pressure and other tests shall be in accordance with the specifications and the relevant regulations. Valve installation shall be done for strength and tightness test. Low pressure valve sampling 20%, if not qualified should be 100% of the inspection; medium and high pressure valve should be 100% of the inspection.
- Valve installation shall be done for strength and tightness test. Low pressure valve sampling 20%, if not qualified should be 100% of the inspection; medium and high pressure valve should be 100% of the inspection.
- When testing, valve installation position should be in the direction of easy inspection.
- Welding connection valve, not with blind plate pressure test can be used when the cone seal or O ring seal pressure test.
- Hydraulic test will air out as much as possible.
- Pressure should be increased gradually during testing, and no sudden and sudden pressurization will be allowed.
- Strength test and seal type test duration is generally 2 – 3min, important and special valves should last 5min. Small caliber valve test time can be a little shorter, large caliber valve test time can be longer. During the test, the test time can be extended if in doubt. Strength test, does not allow the body and bonnet sweating or leakage. Sealing test, the general valve only once, safety valve, high pressure valve and other raw valve to be carried out two times. When testing for the low pressure, large diameter valve is not important and there are provisions to allow leakage of the valve, allowing a small amount of leakage; the common valve, power station valves, marine valves and other valve requirements vary on leakage requirements according to relevant regulations.
- The throttling valve does not make the sealing test of the closing parts, but the strength test should be carried out and the tightness test of the stuffing and gasket shall be carried out.
- The pressure test, the valve closing force only allows a person’s normal physical strength to close; not augmented with tools like leverage (except torque wrench), when the hand wheel diameter is greater than the wait at 320mm, allowing two common off.
- With the sealing of the valve should be taken out of packing for sealing test, sealing officer closed, check whether leakage. When gas is used as a test, check the water in the stuffing box. When sealing test is carried out, the upper seal is not allowed to be in the tight position.
- When a valve with a driving device is tested, the sealing test shall be carried out by using a driving device to close the valve. For manual drive units, seal test shall also be done with the actuating closing valve
- After the strength test and sealing test, the bypass valve installed on the main valve shall be tested on the main valve for strength and tightness. The main valve should be opened when the closing member is opened.
- Iron valve strength test, the application of Pratia tapping valve and valve cover, check whether there is any leakage.
- Valve test, in addition to the provisions of the plug valve to allow sealing surface oiling, other valves are not allowed in the sealing surface of the oil test.
- Valve pressure test, the blind plate on the valve pressure should not be too large, so as to avoid deformation of the valve, affecting the test results (cast iron valve if pressed too tight, will be damaged).
- After the valve pressure test, should promptly remove the water inside the valve and wipe clean, should also be prepared to test records.
