The valve stem threads in the valve fittings mainly include two forms, trapezoidal thread and ordinary thread. In use, the threaded fasteners on the valve directly withstand the pressure of the medium and play an important role in preventing the leakage of the medium. Therefore, the materials selected must ensure sufficient strength and impact toughness at the operating temperature and pressure of the valve. The damage forms of these two kinds of threads mainly include corrosion, breakage, and tightening of the thread pair.
In order to ensure the normal use of the valve stem, the above-mentioned damage problems need to be repaired in time. The surface of the trapezoidal thread can be repaired with a trowel and sanding cloth; the thread pair can be over-tightened to apply abrasive paste on the thread; the ring can be trimmed with a small file.
For the damage of the common thread of the valve stem in the valve fitting, three different repair methods can be used: respectively: 1. Insertion method, the thread of the damaged part is cut off, and then the hole is drilled in the square seam Tapping, then combining the prepared screw plug with the valve stem and sticking it with glue; 2. Threading, cutting off the damaged part of the thread, drilling and tapping on the square end face, and then between the screw and the hand wheel Into the spring forging ring; 3, shorten the valve stem, if the thread is seriously damaged or the square is seriously damaged, can not be repaired, the thread and the square part can be cut off, and then processed according to 2. It is also possible to cut off the unrepairable thread and replace it with a new one.http://www.pump-casting.com/