Pressure Test Method for Industrial Valves

Industrial valves are not the same as ordinary ones. They have higher quality and strength than our daily use. After installation, we need to do pressure testing to check whether the products are reliable. Here are some methods of equipment pressure testing.

I. Pressure Test Method of Check Valve

1. Check valve test status: lift check valve disc axis is perpendicular to the horizontal position; swing check valve channel axis and disc axis are approximately parallel to the horizontal position.

2. In the strength test, the test medium is introduced from the inlet end to the specified value, and the other end is closed to see that the valve body and cover are qualified without leakage.

3. Sealability test introduces test medium from the outlet, and inspects the sealing surface at the import end. No leakage at the filler and gasket is qualified.

2. The pressure test method of gate valve: There are two methods for sealing test.

1. Open the gate to raise the pressure in the valve to the specified value:

(1) Close the gate and take out the gate valve immediately. Check whether there is leakage in the seal on both sides or inject test medium directly into the plug on the valve cover to the specified value. Check the seal on both sides.

(2) Intermediate pressure test, which is not suitable for sealing test of gate valves with nominal diameter less than DN32mm.

2. Open the gate to raise the test pressure of the valve to the prescribed value, then close the gate to open one end of the blind plate, check whether the sealing surface is leaking, and then reverse, repeat the above test until qualified.

3. Pressure Test Method of Diaphragm Valve

1. Strength test introduces medium from either end and opens the valve disc. When the pressure of the other end is increased to the specified value, it is considered that the valve body and cover are qualified without leakage.

2. Reduce the pressure to the sealing test pressure, close the valve disc, open the other end for inspection, no leakage is qualified.

4. Pressure Test Method of Globe Valve and Throttle Valve

1. Strength test usually places the assembled valve in the pressure test stand, opens the disc, injects the medium to the prescribed value, and checks whether the valve body and cover are sweating and leaking. Strength test can also be carried out on a single piece, and sealing test can only be done on the globe valve.

2. During the test, the stem of the globe valve is in a vertical state. The valve disc opens. The medium is introduced from the bottom of the valve disc to the prescribed value. The filler and gasket are checked. The valve disc is closed when qualified, and the other end is opened to check whether there is leakage.

3. If the strength and sealing test are to be done, the strength test can be done first, then the pressure can be lowered to the specified value of the sealing test to check the filler and gasket, then the valve disc can be closed, and the outlet end can be opened to check whether the sealing surface is leaking.

V. Pressure Test Method of Butterfly Valve

1. The strength test of pneumatic butterfly valve is the same as that of globe valve.

2. Sealing performance test should introduce test medium from the end of medium flow, butterfly plate should be opened, the other end should be closed, injection pressure to the prescribed value; check filler and other seals without leakage.

3. Close the butterfly plate and open the other end. Check that there is no leakage in the seal of the butterfly plate to be qualified. Butterfly valves used to regulate flow can not be tested for sealing performance.

6. Pressure Test Method of Cock Valve

1. When the strength test of the cock valve is carried out, the medium is introduced from one end, the other paths are closed, and the plugs are rotated to all the working positions in turn. No leakage is found in the valve body to be qualified.

2. Sealing test

(1) The straight-through cock should keep the pressure of the cavity equal to that of the passage, rotate the plug to the closed position, check it from the other end, and then rotate the plug 180 degrees to repeat the above test.

(1) Three-way or four-way cock valves should keep the pressure in the cavity equal to that at one end of the channel, rotate the plug to the closing position in turn, and introduce the pressure from the right-angle end, and inspect the other end at the same time.

3. A non-acid thin lubricant is allowed on the sealing surface in front of the test bench. No leakage or enlarged water droplets are found within the prescribed time. The test time of the cock valve can be shorter. Generally, the nominal diameter is 1-3 minutes.

4. The cock valve for gas shall be tested for air tightness at a working pressure of 1.25 times.

Generally, industrial valves are not tested for strength when they are in use, but after repairing the body and cover or corrosive damage, the body and cover should be tested for strength, and the pressure test will only be good for the product but not bad for it. We should learn the method.