In this technical article we will introduce the reasons, preventive measures and solutions for handweel inflexibility of gate valves from several aspects.
The Main Reasons:
1. Bent stem.
2. Lack of surface accuracy.
3. Thread damage because of hard operation.
4. Lack or the failure of lubricant.
5. Oblique stem nut.
6. Inaccurate tolerance and tight bite.
7. Lack of protection for open gate valve. And the stem thread is covered in dust and sand or corroded by rain, dew, frost or snow.
8. The thread is eroded by medium.
9. Improper selection of materials. For example, it will be easier to bite if you choose the same material for stem and stem nut.
Preventive Measures and Solutions：
1. Control the power strictly, and hard reverse is not allowed.
2. Improve the quality of processing so as to meet the standard requirements.
3. Elaborate manufacture and close it gently.
4. Check the lubrication frequently and maintain its normal state.
5. Straighten or correct the stem nut.
6. Update the stem nut so as to meet the standard.
7. Always clean up dust and sand covered in stem nut to avoid the rusting.
8. Put stem cases on open gate valves.
9. Copper material is a better choice for stem nut, and the same material with stem nut is not recommended.
