Procedures for valve maintenance
General procedures for valve maintenance
1. When removing the valve, use the steel word on the valve, and the flange connected with the valve, make a good repair number, and record the working medium, working pressure and working temperature of the valve, so as to select the corresponding materials when repairing.
2. When repairing the valve, it is required to be carried out in a clean environment. First clean the outside surface of the valve, either by blowing compressed air or cleaning with kerosene.  But remember the nameplate and other marks.Check appearance for damage and record. Then REMOVE ALL OTHER PARTS OF THE VALVE, CLEAN WITH KEROSENE (DO NOT USE GASOLINE TO AVOID FIRE), INSPECT THE OTHER PARTS FOR DAMAGE, AND MAKE A RECORD.
3, the body of the valve cover strength test. High-Pressure Valves, Non-Destructive Testing, such as Ultrasonic Testing, X-Ray Testing.

4. The seal ring can be inspected by red powder, the consistency of the seat and the gate (valve disc).Check stem for bending, corrosion and thread wear.Check the wear of the stem nut.
5. Deal with the problems detected.Body repair welding defects. Surfacing or updating seal ring.Straighten or replace stem.Repair any other parts that should be repaired;If it cannot be repaired, replace it.
6. Reassemble the valve. When assembling, gaskets and fillers should be replaced completely.