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Commonly used medium pressure test with water, oil, air, steam, nitrogen, etc., all kinds of valve pressure testing method is as follows.

(1) cut-off valve and throttle valve Globe valve and throttle valve strength test, usually put the assembled valve pressure test, the material, open the valve, injection medium to the specified value, check whether the body and cover is sweating and leakage. Also may carry on the strength test piece. Do stop valve leakage test. Test valve stem into vertical state, when the valve opens, media from one end under the disc e., introduced to check the packing and gasket; After being qualified close the valve, the opening at the other end to check whether there is leakage. If the valve strength and tightness test should be done, can do strength test first, then step-down to leak test specified value, check the packing and gasket; To close the valve disc, open the outlet check leakage sealing surface.

(2) the gate

Gate valve strength test and globe valves.

There are two kinds of valve sealing test method.

1) gate open, makes the pressure inside the valve to specified value; Then close the gate, immediately remove the gate valve, check gate on both sides of the seal leakage or directly into the plug on the valve cover injection test medium to the specified value, check the gate on both sides of the seal. The above method is called the middle pressure testing. Under this kind of method is unfavorable in nominal diameter DN32mm gate seal test.

(2) another way is to open the gate, the test pressure valve to specified value; Then close gate, open the blind flange at one end, check leakage sealing surface. Lie down again, as above repeated trials until qualified.

Gate valve packing and gasket sealing test shall be carried out before the gate leakage test.

(3) the ball valve

Ball valve strength test shall be carried out under the sphere ajar.

1) floating ball valve leakage test: the valve is in a state of half-open, end the introduction of test medium, the other end closed; Rotating the ball a few times, when the valve is closed to open the closed end check, and check the packing and gasket sealing performance, can not have leakage phenomenon. Then the test medium, introduced from the other end, www.sypv.com repeat the test.

(2) fixed ball valve leakage test: sphere no-load rotational several times, before the test valve closed, from one end of an experiment medium to the specified value; Use pressure gauge to check into the sealing performance, the use of 0.5 ~ 1 grade pressure gauge precision, range of test pressure of 1.6 times. Within the prescribed time, no buck phenomenon for qualified; Again from the other end of the introduction of test medium, repeat the test.

Then, the valve is in a state of half-open, both ends closed, inner cavity filled with medium, under the pressure test to check the packing and gasket, can not have leakage.

(3) three-way ball valve leakage test should be in each position.

(4) the cock

(1) strength test cock, medium from one end of the introduction, closed the rest of the channel, will plug the rotation in order to fully open the experiment work position, body found no leakage for qualified.

(2) the leakage test, cut-through cock should be pressure maintain cavity and pathways is equal, rotate the plug to the closed position, on the other side to check, then rotate the plug 180 ° repeat the above test; Three-pass four general formula or plug valves shall be equal pressure maintain cavity and pathways end, will plug, in turn, rotate to the closed position, pressure is introduced from the right end, from the other end at the same time for inspection.

Plug valve test before to allow coating a layer of non acid dilute lubricating oil on the surface of the seal, no leakage found within the given time and expand water droplets as qualified. Cock test time can be short, generally as stipulated in the nominal diameter for l ~ 3 min.

Gas with plug valves should be 1.25 times the working pressure of air leakage test.

(5) butterfly valve

Butterfly valve strength test and globe valves.

Butterfly valve sealing performance test should be the introduction of test medium medium to shed end, butterfly plate should be open, the other end closed, the injection pressure to the specified value; Check the packing and other seal, no leakage, after closing butterfly plate, open the other end, check the disc seal has no leakage for qualified. As a butterfly valve for regulating flow doesn't do sealing performance test.

(6) the diaphragm valve

Diaphragm valve strength test medium, introduced from either end, open the valve, the other end closed, the test pressure to e. after, no leakage of qualified for the body and cover. Then buck to leakage test pressure, close the valve, open the other end of the inspection, no leakage for qualified.

(7) check valve

Check test condition: lift check valve disc axis in and horizontal vertical position; Swing check valve channel axis and axis disc in parallel with approximate horizontal position.

Strength test, the test medium to the specified value, introduced from the inlet side, the other end closed, no leakage of qualified for the body and cover.

Leakage test test medium, introduced from the outlet, in the inlet side check the sealing surface, no leakage for qualified for packing and gasket.

The relief valve (8)

The strength test of safety valve and other valves, water as test. Test the lower part of the body, the pressure from introduced into I = I end, seal face closed; When test upper valve body and bonnet, pressure from the El end, introducing the other end closed. Body and cover within the time required for qualified no leakage phenomenon.

(2) the sealing test and constant pressure test, general use medium is: steam valve with saturated steam as the test medium; Ammonia in the air or other gas valve test for medium; Water and other corrosive liquid with valve with water as the test medium. For some of the important position of the relief valve commonly used medium nitrogen for test.

Sealing test with nominal pressure value for the test pressure test, the number of not less than two times, no leakage for qualified within the given time. Leakage test method has two kinds: one is the relief of each joint sealing, butter stick thin seal on the El flange, tissue paper up to leak, don't take for qualified; 2 it is to use butter stick thin plastic sheet or other plate seal at the bottom of the outlet flange, water seal disc, check the water bubble for qualified.

Relief valve set pressure and back pressure test number not less than 3 times, conform to the regulations for qualified.

Various properties of the relief valve test GB/T 12242-12242 ((relief valve performance test methods.

Pressure reducing valve (9)

(1) the strength of the pressure reducing valve test general with single test after assembly, also can test after assembly. Strength test duration: DN < 50 mm lmin; DN65 ~ 150 mm larger than 2 min. DN > 150 mm is more than 3 min.

Corrugated pipe and components after welding, the application after the valve top pressure of 1.5 times, the strength test in the air.

(2) according to the actual work medium leakage test. With air or water test, the test to 1.1 times the nominal pressure; Steam test, to working temperature to allow maximum working pressure. The difference between the inlet pressure and outlet pressure requirement is not less than 0.2 MPa. After the test method is: the inlet pressure setting, gradually adjust the adjusting screw of the valve, make the outlet pressure sensitive reaction in the maximum and minimum value range, continuously change, can not have stalled, jam phenomenon. With steam pressure reducing valve, when the inlet pressure, close the valve after the block valves, outlet pressure as the highest and lowest, within 2 min, the outlet pressure of appreciation should comply with the specified in table 4.176-22, at the same time, the valve pipe volume after conform to the specified in table 4.18 for qualified; , air to water pressure reducing valve, when the inlet pressure setting, the outlet pressure is equal to zero, close the valve leakage test, no leakage for qualified within 2 min.