Therefore, the stress concentration, residual stress and poor quality of the root gap of the welded joint of the valve body have become the weak link in the valve body structure, which has attracted the attention of the valve industry at home and abroad, but there is no relevant report to solve this problem, which has become a hidden danger of the integrity of the product structure boundary.

Use and maintenance
1. The purpose of use and maintenance is to extend the service life of the valve and ensure reliable opening and closing.
2. The valve rod thread often rubs with the valve rod nut, and a little yellow dry oil, molybdenum disulfide or graphite powder should be coated for lubrication.
3. For valves that are not opened and closed frequently, the handwheel should also be turned regularly to add lubricant to the stem threads to prevent seizure.
4. For outdoor valves, the valve rod shall be protected from rain, snow, dust and rust.
5. If the valve is mechanically waiting, add lubricating oil to the gearbox on time.
6. Always keep the valve clean.
7. Frequently check and maintain the integrity of valve parts. If the fixed nut of the hand wheel falls off, it should be complete and can not be used properly, otherwise it will grind the upper four sides of the valve stem, gradually losing the reliability of cooperation, and even can not be started.
8. Do not rely on the valve to support other heavy objects, and do not stand on the valve.
9. The valve rod, especially the thread part, should be wiped frequently, and the lubricant that has been soiled by dust should be replaced with a new one, because the dust contains hard debris, which is easy to wear the thread and valve rod surface, affecting the service life.