The strength test of the pneumatic brass ball valve should be carried out in the half-open state of the ball.

1.1 Floating brass ball valve sealing test: put the valve in a half-open state, introduce the test medium at one end, and close the other end; rotate the ball several times, open the closed end when the brass valve is closed, and check the packing and gasket at the same time There must be no leakage. The test medium is then introduced from the other end and the above test is repeated.

1.2 Sealing test of the fixed brass ball valve: before the test, rotate the ball several times without load, the fixed brass ball valve is in the closed state, and introduce the test medium from one end to the specified value; check the sealing performance of the leading end with a pressure gauge, use The accuracy of the pressure gauge is 0.5 to 1, and the range is 1.5 times the test pressure. Within the specified time, if there is no depressurization phenomenon, it is qualified; then introduce the test medium from the other end, and repeat the above test. Then, put the brass valve in a half-open state, with both ends closed, the inner cavity is filled with medium, and check the packing and gasket under the test pressure, and there must be no leakage.

1.3 The three-way brass ball valve should be tested for tightness at each position.

Brass check valve test state: the axis of the lift-type brass check valve disc is in a position perpendicular to the horizontal; the axis of the swing-type brass check valve channel and the disc axis are in a position approximately parallel to the horizontal line.

During the strength test, the test medium is introduced from the inlet end to the specified value, and the other end is closed, and it is qualified to see that the valve body and valve cover have no leakage.

In the sealing test, the test medium is introduced from the outlet end, and the sealing surface is checked at the inlet end. If there is no leakage at the packing and gasket, it is qualified.

3.1 The strength test of the brass pressure reducing valve is generally assembled after the single-piece test, and can also be tested after assembly. Duration of strength test: 1min for DN150mm.

After the bellows and the components are welded, apply 1.5 times the maximum pressure of the brass pressure reducing valve, and conduct the strength test with air.

3.2 The airtightness test shall be carried out according to the actual working medium. When testing with air or water, test at 1.1 times the nominal pressure; when testing with steam, use the maximum working pressure allowed under the working temperature. The difference between the inlet pressure and the outlet pressure is required to be not less than 0.2MPa. The test method is: after the inlet pressure is adjusted, gradually adjust the adjusting screw of the valve, so that the outlet pressure can change sensitively and continuously within the range of the maximum and minimum values, without stagnation or jamming. For the steam brass pressure reducing valve, when the inlet pressure is adjusted away, close the valve and then shut off the valve. The outlet pressure is the highest and lowest value. Within 2 minutes, the increase in the outlet pressure should meet the requirements in Table 4.176-22. At the same time, the valve should be The volume of the rear pipeline meets the requirements in Table 4.18 to be qualified; for the water and air brass pressure reducing valves, when the inlet pressure is adjusted and the outlet pressure is zero, close the brass pressure reducing valve to conduct a tightness test, and there is no leakage within 2 minutes. is qualified.

The strength test of the pneumatic brass heater valve is the same as that of the brass globe valve. For the sealing performance test of the brass heating valve, the test medium should be introduced from the flow end of the medium, the disc should be opened, the other end should be closed, and the injection pressure should reach the specified value; after checking that there is no leakage at the packing and other seals, close the disc and open the other end. , check that there is no leakage at the seal of the butterfly plate as qualified. The brass heater valve used for regulating flow may not be tested for sealing performance.

5.1 When the brass plug valve is tested for strength, the medium is introduced from one end, the remaining passages are closed, and the plug is rotated to the fully open working positions for the test. The valve body is qualified if no leakage is found.

5.2 During the sealing test, the straight-through cock should keep the pressure in the cavity and the passage equal, rotate the plug to the closed position, check from the other end, and then repeat the above test by rotating the plug 180°; three-way or four-way brass The plug valve should keep the pressure in the cavity equal to one end of the passage, rotate the plug to the closed position in turn, introduce the pressure from the right-angle end, and check from the other end at the same time.

Before the brass plug valve test, a layer of non-acid dilute lubricating oil is allowed to be applied on the sealing surface, and it is qualified if no leakage and enlarged water droplets are found within the specified time. Brass plug valve test time can be shorter, generally according to the nominal diameter of 1 ~ 3Min.

Brass plug valves for gas should be tested for air tightness at 1.25 times the working pressure.

In the strength test of brass diaphragm valve, the medium is introduced from either end, the valve flap is opened, and the other end is closed. After the test pressure rises to the specified value, it is qualified to see that the valve body and valve cover have no leakage. Then reduce the pressure to the tightness test pressure, close the valve disc, and open the other end for inspection, if there is no leakage, it is qualified.

For the strength test of brass globe valve and throttle valve, usually put the assembled brass valve in the pressure test frame, open the valve disc, inject the medium to the specified value, and check whether the valve body and valve cover sweat and leak. The strength test can also be carried out on a single piece. The tightness test is only done for brass globe valves. During the test, the valve stem of the brass globe valve is in a vertical state, the valve disc is opened, the medium is introduced from the bottom end of the valve disc to the specified value, and the packing and gasket are checked; after passing the test, close the valve disc and open the other end to check whether there is leakage . If both the strength and tightness test of the brass valve are to be done, the strength test can be done first, then the pressure is reduced to the specified value of the tightness test, and the packing and gasket are checked; then the valve disc is closed, and the outlet end is opened to check whether the sealing surface is leaking. leak.

The strength test of the brass gate valve is the same as that of the brass globe valve. There are two methods for the tightness test of brass gate valves.

8.1 Open the gate to make the pressure in the valve rise to the specified value; then close the gate, take out the brass gate valve immediately, check whether there is leakage at the seals on both sides of the gate, or directly inject the test medium into the plug on the valve cover to The specified value, check the seals on both sides of the gate. The above method is called intermediate pressure test. This method is not suitable for the sealing test of brass gate valves with a nominal diameter below DN32mm. 

8.2 Another method is to open the gate to make the test pressure of the brass valve rise to the specified value; then close the gate, open one end of the blind plate, and check whether the sealing surface is leaking. Then turn back and repeat the above test until it is qualified.

The tightness test of the packing and gasket of the pneumatic brass gate valve shall be carried out before the tightness test of the gate.

9.1 The strength test of the water heater safety valve is the same as other brass valves, which is tested with water. When testing the lower part of the valve body, the pressure is introduced from the inlet I=I end, and the sealing surface is closed; when testing the upper part of the valve body and the bonnet, the pressure is introduced from the outlet El end, and the other ends are closed. If the valve body and bonnet have no leakage within the specified time, it is qualified.

9.2 For the sealing test and constant pressure test, the commonly used medium is: the safety valve of the water heater for steam uses saturated steam as the test medium; the valve for ammonia or other gases uses air as the test medium; the valve for water and other non-corrosive liquids uses water as the test medium test medium. Nitrogen is often used as the test medium for water heater safety valves in some important positions.