How to improve seat tightness of valves?

After the valve is used for a long time, the sealing surfaces of the valve disc and the valve seat will be worn and the tightness will be reduced. Repairing sealing surfaces is a large and very important task. The main method of repair is grinding. Let's look at the grinding process of the valve together.

Valve grinding process

1. Cleaning and inspection process

Clean the sealing surface of the valve, use professional cleaning agent, and inspect the sealing surface for damage while washing. Fine cracks that are difficult to determine with the naked eye can be performed by color inspection.

After cleaning, the tightness of the disc or gate valve and the sealing surface of the valve seat should be checked. Use red and pencil for inspection. Check the seal on the sealing surface to determine the tightness of the sealing surface; if the sealing is not good, you can use a standard flat plate to inspect the valve disc or gate sealing surface and the valve body sealing surface to determine the grinding part.

2. grinding process

The grinding process is essentially a cutting process that does not require a lathe. The depth of pits or small holes on the valve head or valve seat is generally within 0.5 mm, which can be repaired by grinding. The grinding process is divided into coarse grinding, medium grinding and fine grinding.

Coarse grinding is to eliminate defects such as abrasion, indentation, and pitting on the sealing surface, so that the sealing surface can obtain a higher flatness and a certain degree of smoothness, and lay the foundation for the intermediate grinding of the sealing surface. Medium grinding is to eliminate the rough lines on the sealing surface and further improve the flatness and smoothness of the sealing surface. Fine grinding is the last process of valve grinding, mainly to improve the smoothness of the sealing surface.

3. inspection stage

The inspection stage runs through the grinding process, the purpose is to grasp the grinding situation at any time, so that the grinding quality meets the technical requirements. It should be noted that when different valves are being ground, grinding tools adapted to various sealing surface forms should be used to improve the grinding efficiency and ensure the quality of the grinding.

Valve grinding is a very meticulous work, which requires constant experience, exploration and improvement in practice. Sometimes grinding is very good, but it still leaks steam and water after installation. This is because of the imagination of grinding during the grinding process. The grinding rod is not vertical, skewed, or caused by deviation in the size and angle of the grinding tool.

One of the most important in valve grinding is the abrasive. Because the abrasive is a mixture of abrasive and abrasive fluid, the abrasive fluid is only general kerosene and motor oil. Therefore, the most important part in the correct selection of abrasives is the correct selection of abrasives. Do you know how to choose? The next article tells you the answer.