Reason:
1. The casting quality of the cast iron parts is not high, and the oil circuit board and the single-flow valve body have shortcomings such as sand holes, loose mechanisms, and welding bumps;
2. It will crack in cold storage;
3. The welding of electric welding is not good, and there are shortcomings such as welding bumps, non-electric welding, and internal stress cracks;
4. The pig iron valve is damaged after being hit by the hanging object.
Maintenance method:
1. Improve the casting quality, and carry out the compressive strength test in strict accordance with the regulations before installation;
2. For valves whose temperature is within 0°C and 0°C, thermal insulation or heat mixing should be carried out, and the valves that are deactivated should be cleared of stored water;
3. The welding of the oil circuit board and the one-flow valve, composed of electric welding, should be carried out according to the relevant electric welding safety operation rules. After welding, the flaw detection and compressive strength test should also be carried out;
4. It is strictly forbidden to push and place hanging objects on the valve, and it is not allowed to use a hammer to collide with the valve of pig iron and non-metallic materials. The installation of large-diameter valves should have a support frame.
