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1. Leakage of valve body and bonnet
reason:
1. The casting quality of iron castings is not high, and the valve body and valve cover body have defects such as blisters, loose structures, and slag inclusions.
2, day freeze cracking.
3. Poor welding, there are defects such as slag inclusion, unwelding, stress cracks, etc.
4. The cast iron valve is damaged after being hit by heavy objects.
solution:
1. Improve casting quality, and conduct strength test in strict accordance with regulations before installation.
2. For valves with air temperature below 0° and 0°, heat preservation or mixing should be carried out, and the valves that are out of use should be drained of accumulated water.
3. The welding seam of the valve body and bonnet composed of welding shall be carried out according to the relevant welding operation regulations, and the flaw detection and strength test shall be carried out after welding.
4. It is forbidden to push and place heavy objects on the valve, and it is not allowed to hit cast iron and non-metallic valves with a hand hammer. The installation of large-diameter valves should have brackets.
Specific treatment methods for valve body leakage:
1. Adhesion method: Using the characteristics of fast curing speed of the adhesive, the area around the pin is filled with adhesive in time to establish a new solid sealing structure to achieve the purpose of preventing leakage. It is a method of plugging leakage under pressure by using the special function of the adhesive. For the pressure medium and the blisters with small leakage, first grind the metal luster near the leakage point, and then use a taper pin to align the leakage point with appropriate force. During operation, fix the top pressure mechanism on one side of the regulating valve, press the screw at high speed, so that the axial direction of the top pressure screw is facing the leakage point, rotate the top pressure screw, and use the rivet at the end of the top pressure screw to firmly press the leakage point. site, forcing the leak to stop.
2. Welding method: when the pressure of the leaking medium of the valve body is low and the leakage is small, a nut with an inner diameter more than double the leakage point can be used to let the leaking medium flow out of the nut, and the nut is welded to the valve. On the body, add a bolt of the same specification as the nut, place a rubber pad or asbestos pad at the bottom of the nut, wrap the top of the bolt with raw tape and screw it into the nut to prevent leakage.
