The use of bushings can reduce equipment wear, vibration and noise, and have an anti-corrosion effect. The use of the bushing can also facilitate the maintenance of mechanical equipment, simplify the structure and manufacturing process of the equipment. The role of the bushing in actual work has a lot to do with its application environment and purpose. In the field of valve application, the bushing is installed in the valve cover to cover the valve stem, so as to reduce the leakage of the valve and achieve the sealing effect.