According to the maintenance steps of field instrument control valves and the classification of their maintenance levels, the maintenance is divided into three levels. Each maintenance level determines the amount of field maintenance work. 1、 Maintenance level
1. Minor repair refers to the normal minor repair and maintenance on the site pipeline. Namely: replace the packing, replace the accessory joints, pipelines, add grease to the lubrication parts, and replace the diaphragms, springs, seals, etc. online
2. Medium repair refers to disassembly and assembly of actuator, valve body end cover, replacement of packing, valve body gasket, disassembly and assembly of valve stem, core, seat, cage, etc., and effective grinding and assembly, etc. when the control valve is not offline. Online maintenance relative to angle travel valves is not included here.
3. Overhaul refers to the process of removing flange bolts from the control valve and taking off the whole line for comprehensive disassembly, maintenance, commissioning and pressure test.

5. For manual butterfly valves with many times of opening and closing, open the worm gear case cover in about two months, check whether the grease is normal, and keep a proper amount of grease.