The valve stem of forged steel globe valve is its core moving component, and the role of the valve stem directly determines the opening and closing control and adjustment accuracy of the valve. Therefore, when the valve stem experiences a switch malfunction, it is necessary to promptly identify the cause and take corresponding measures!
The common causes of valve stem failure in forged steel globe valves include insufficient lubrication or tight packing, valve stem deformation or corrosion, foreign object jamming, or seal damage.
Insufficient lubrication or overly tight packing is manifested in the lack of lubricating grease on the valve stem threads, leading to increased friction, especially under high temperature conditions where lubricants are prone to failure; The pre tightening force of the stuffing box cover is too high, which compresses the valve stem and causes movement resistance. It is necessary to remove the packing gland, clean the valve stem, and apply high-temperature lubricating grease.
Valve stem deformation refers to the bending of the valve stem due to external impact or long-term biased load, which hinders the normal engagement of threads. It is necessary to place the valve stem on a flat plate and gently tap the bent part with a copper rod to gradually correct it; Corrosion may be caused by the adhesion of rust on the contact surface between the valve stem and packing in a humid environment. In severe cases, the valve stem assembly with thrust bearings should be replaced, and 316L stainless steel material should be preferred to improve corrosion resistance.
Foreign object blockage refers to the blockage caused by impurities entering the valve stem guide groove or thread gap in the pipeline. After disassembling the valve cover, flush the valve chamber and use a copper wire brush to remove impurities from the valve stem thread and guide groove; The accumulation of worn debris on the sealing surface at the bottom of the valve stem can also limit its lifting movement, requiring grinding or replacement of the hard alloy sealing surface.