Introduction to the maintenance, grinding and cleaning of the valve during use
A valve is a device used to control the direction, pressure, and flow rate of a fluid in a fluid system. It is a device that allows the medium (liquid, gas, powder) in the piping and equipment to flow or stop and can control its flow. During the use of the valve, the performance of the valve needs to be tested regularly. The maintenance of the valve includes some testing and observation of the valve cleaning and sealing performance. Zhongzhi Valve will introduce you to the maintenance, grinding and cleaning of the valve during use.
1. Cleaning and inspection process:
Clean the sealing surface in the oil pan, use a professional cleaning agent, and check the damage of the sealing surface while washing. Fine cracks that are difficult to identify with the naked eye can be performed by staining flaw detection.
After cleaning, check the tightness of the disc or gate valve and the sealing surface of the valve seat. Use red and pencil when checking. Use red lead to test the red, check the seal surface impression to determine the tightness of the sealing surface; or use a pencil to draw a few concentric circles on the sealing surface of the valve disc and the valve seat, and then rotate the valve disc and the valve seat tightly, and check the pencil circle Wipe off the situation to confirm the tightness of the sealing surface. If the tightness is not good, a standard flat plate can be used to inspect the sealing surface of the disc or gate and the sealing surface of the valve body respectively to determine the grinding position.
2. Grinding process:
The grinding process is essentially a cutting process without a lathe. The depth of the pits or small holes on the valve head or valve seat is generally within 0.5mm, and the grinding method can be used for maintenance. The grinding process is divided into coarse grinding, middle grinding and fine grinding.
Rough grinding is to eliminate defects such as scratches, indentations, and corrosion points on the sealing surface, so that the sealing surface can obtain a higher level of flatness and a certain degree of smoothness, and lay the foundation for the middle grinding of the sealing surface. Rough grinding uses a grinding head or a grinding seat tool, using coarse-grained sandpaper or coarse-grained grinding paste, with a particle size of 80#-280#, coarse particle size, large cutting volume and high efficiency, but the cutting lines are deeper and the sealing surface surface is rough. Therefore, rough grinding only needs to smoothly remove the pitting of the valve head or valve seat.
Middle grinding is to eliminate rough lines on the sealing surface and further improve the flatness and smoothness of the sealing surface. Use fine-grained sandpaper or fine-grained abrasive paste, the particle size is 280#-W5, the particle size is fine, the cutting amount is small, which is beneficial to reduce the roughness; at the same time, the corresponding grinding tool should be replaced, and the grinding tool should be clean. After the middle grinding, the contact surface of the valve should be bright. If you draw a few strokes on the valve head or valve seat with a pencil, turn the valve head or valve seat lightly around, and erase the pencil line.
Fine grinding is the last process of valve grinding, mainly to improve the smoothness of the sealing surface. For fine grinding, it can be diluted with engine oil, kerosene, etc. with W5 or finer fractions, and then use the valve head to grind the valve seat instead of drama, which is more conducive to the tightness of the sealing surface. When grinding, generally turn it clockwise about 60-100°, and then turn it about 40-90° in the opposite direction. Gently grind for a while. It must be checked once until it is polished and can be seen on the valve head and valve seat. When there is a very thin line and the color is black and bright, lightly rub it with engine oil several times, and wipe it with clean gauze. After grinding, eliminate other defects, that is, assembling as soon as possible, so as not to damage a ground valve head.
Manual grinding, regardless of rough grinding or fine grinding, always runs through the grinding process of lifting, lowering, rotating, reciprocating, tapping, and reversing operations. The purpose is to avoid the repetition of the abrasive grain track, so that the grinding tool and the sealing surface can be uniformly ground, and the flatness and smoothness of the sealing surface can be improved.
3. Inspection stage:
In the grinding process, the inspection stage is always running through, and its purpose is to grasp the grinding situation at any time, so that the grinding quality can meet the technical requirements. It should be noted that when grinding different valves, grinding tools suitable for various sealing surface forms should be used to improve grinding efficiency and ensure grinding quality. Valve grinding is a very meticulous work, which requires constant experience, exploration, and improvement in practice. Sometimes the grinding is very good, but after installing it, it still leaks steam and water. This is because there is an imagination of grinding deviation during the grinding process. The grinding rod is not vertical, skewed, or the angle of the grinding tool is wrong.
