Generally, the strength test is not required for industrial valves in use, but the valve body and bonnet or the valve body and bonnet damaged by corrosion after repair shall be tested. For the safety valve, its set pressure, return pressure and other tests shall comply with the specifications and relevant regulations. Strength and sealing test shall be carried out for valve installation. 20% of the low-pressure valves shall be sampled, and 100% inspection shall be conducted if the valves are unqualified; 100% inspection shall be conducted for medium and high-pressure valves. The commonly used media for valve pressure test include water, oil, air, steam, nitrogen, etc.
In this paper, combined with the famous import valve brand Germany Locke de lock valve pressure test standard requirements and procedures to analyze the valve pressure test related issues.
1、 Pressure test requirements of inlet valve:
1. Each valve shall be pressure tested before delivery. The famous import valve brand Germany rock de lock strictly implements this standard.
2. Before the completion of shell test, it is not allowed to paint the valve or use other anti leakage coating, but chemical anti rust treatment without sealing effect and lining of lined valve are allowed. For the painted valve in stock, the coating need not be removed if the user's representative requests to repeat the pressure test.
3. Before the sealing test, the oil stains on the sealing surface should be removed, but a thin layer of protective agent whose viscosity is not greater than kerosene is allowed to be coated on the valve sealed by grease according to the design requirements.
4. During the test, the valve shall not be subject to external forces that may affect the test results.
5. Unless otherwise specified, the temperature of the test medium should be between 5 ℃ and 40 ℃. However, in some valves which are required to meet the high temperature medium condition, the medium can also be used for test sealing.
6. The following test medium shall be selected by the manufacturer, but shall comply with the provisions in Table 1 and table 2; a liquid: water (antirust agent can be added), kerosene or other suitable liquid with viscosity not greater than; B gas: air or other suitable gas.
7. When testing with liquid, the gas in the valve chamber should be excluded. When using gas for test, safety protection measures should be adopted.
8. The sealing and upper sealing tests shall be closed in the way given by the design.
9. The test pressure shall meet the requirements.
2、 Pressure test method and procedure of inlet valve
The upper seal test and shell test shall be carried out first, and then the sealing test shall be carried out
1. Upper seal test
Seal the inlet and outlet of the valve, loosen the packing gland (if the valve is equipped with the upper seal inspection device, and the performance of the upper seal can be checked reliably without loosening the packing gland), the valve is in the fully open state, the upper seal is closed, the body cavity is filled with test medium, and the pressure is gradually increased to the test pressure, and then the upper sealing performance is checked
2. Shell test
Seal the inlet and outlet of the valve, compress the packing gland to maintain the test pressure, and the opening and closing parts are partially open. Fill the chamber with test medium and gradually pressurize it to the test pressure (the check valve shall be pressurized from the inlet end), and then inspect the shell (including the stuffing box and the joint between the valve body and the valve cover).
1、殼體試驗壓力為 38℃ 時公稱壓力的 1.5 倍。比如德國洛克DE LOCKE的公稱壓力1.6Mpa的進口球閥，它的殼體試驗壓力為2.4Mpa，2.5Mpa的進口截止閥，它的殼體試驗壓力為3.75Mpa
2、高壓密封試驗和高壓上密封試驗壓力為 38℃ 時公稱壓力的 1.1 倍。 比如德國洛克DE LOCKE的公稱壓力1.6Mpa的進口閘閥，進口電磁閥，他的高壓密封試驗和高壓上密封試驗壓力為1.76Mpa
4、蝶閥的密封試驗壓力為 1.1 倍的額定壓差。
5、止回閥的密封試驗壓力為 38℃ 時的公稱的壓力。
3、 Understanding of relevant terms of pressure test pressure
The test pressure is divided into shell test pressure and seal test pressure. The specified pressure for Shell Test of valve is called excess distribution test pressure. The specified pressure for valve sealing test is called sealing test pressure.
The standard of "valve test and inspection" stipulates that:
1. The shell test pressure is 1.5 times of the nominal pressure at 38 ℃. For example, for the imported ball valve with nominal pressure of 1.6Mpa in Germany, its shell test pressure is 2.4Mpa, and the shell test pressure of 2.5MPa inlet stop valve is 3.75mpa
2. The pressure of high pressure sealing test and high pressure upper sealing test is 1.1 times of the nominal pressure at 38 ℃. For example, Germany's Locke de Locke has a nominal pressure of 1.6Mpa for the inlet gate valve and the imported solenoid valve, and the pressure of its high-pressure sealing test and high-pressure upper sealing test is 1.76Mpa
3. The pressure of low pressure sealing test and low pressure upper sealing test is 0.5 ~ 0.7MPa.
4. The sealing test pressure of butterfly valve is 1.1 times of rated differential pressure.
5. The sealing test pressure of check valve is the nominal pressure at 38 ℃.
Specific different types of valve pressure test method back analysis.