Causes of damage to the sealing surface of the exhaust valve
It is caused by improper material selection, improper installation, poor use and maintenance. The so-called natural damage refers to the damage caused by the wear and tear of the valve under normal working conditions, and the inevitable corrosion and erosion of the sealing surface of the exhaust valve caused by the medium. The damage to the blanks that cannot be resolutely prevented is called natural damage. The reasons for the damage can be attributed to the following: 1. The processing quality of the sealing surface of the exhaust valve is not good: the main surface has cracks, pores and air holes on the sealing surface of the exhaust valve. Defects such as ballast are caused by improper selection of surfacing and heat treatment standards, as well as poor operation during surfacing and heat treatment. The hard transition of the valve sealing surface is too high or too low, caused by incorrect material selection or improper heat treatment. The sealing surface of the exhaust valve has uneven hardness and is not resistant to corrosion, mainly because the underlying metal is blown onto it during the surfacing process, which dilutes the alloy composition of the valve sealing surface. There are also design problems. 2 . Damage caused by improper selection and poor operation: the main appearance is that the valve is not selected according to the working conditions, and the shut-off valve is used as a throttle valve. The sealing surface is eroded and worn. 3. Improper installation and poor maintenance lead to abnormal operation of the sealing surface of the exhaust valve, the valve runs in a diseased manner, and prematurely damages the sealing surface of the exhaust valve. 4. Chemical corrosion of the medium: exhaust The medium around the sealing surface of the valve, in the condition that no current is generated, the medium directly acts chemically with the sealing surface of the exhaust valve, and the rot is the sealing surface of the exhaust valve. 5. Electrochemical corrosion: the sealing surfaces of the exhaust valve are in contact with each other, The contact between the sealing surface of the exhaust valve and the closing part and the valve body, as well as the concentration difference of the medium, the oxygen concentration difference, etc., will generate a potential difference, and electrochemical corrosion will occur, and the valve sealing surface on the anode side will be corroded.