After the valve is used for a long period of time, the sealing surfaces of the valve disc and the valve seat will wear out and the tightness will be reduced. Repair sealing surface is a large and important work. The main method of repair is grinding. On the serious sealing surface,it is bead welded first, then regrinding after turning .

 Valve grinding includes cleaning and inspection process, grinding process and inspection process.

1. cleaning and inspection process

 Clean the sealing surface in the oil pan, the use of professional cleaning agents, while washing the surface,  the sealing surface damage should be checked. Fine cracks which are difficult to determine by naked eyes can be examined by coloring inspection.After cleaning,  the valve flap or valve seat sealing surface of the close contact should be checked, with red and pencil. Reddish red test, check the sealing surface printing shadow, to determine the sealing surface close situation;or to draw  a few concentric circles  on valve seat seal surface with pencil,then the valve and valve seat sealing circle rotation, check pencil erase, to determine the seal sealing surface.If the fit is not good, the standard plate can be used to test valve flap or gate sealing surface and valve sealing surface, to determine the grinding site.

2. Grinding process

The grinding process is essentially a process without cutting lathe, pitting or hole depth on the valve seat or valve head are generally within 0.5mm. The method can be used for grinding repair. The grinding process can be divided into coarse grinding, medium grinding and fine grinding.

3. Inspection process

 The grinding process is throughout the test phase, the purpose is to grasp the grind, be aware of the grinding quality meeting the technical requirements. It should be noted that different valve grinding should be used to adapt to various forms of sealing surface grinding tools, in order to improve the efficiency of grinding, to ensure the quality of grinding.