Copper washers are generally sealed with threads. Its sealing principle is that the two joint surfaces squeeze the copper ring to make the two surfaces of the copper washers fit tightly with the two joint surfaces without the slightest gap, thereby obtaining a sealing effect. In order to achieve the sealing effect, annealing treatment is generally carried out before use. The purpose is to soften the copper sealing ring to achieve a better sealing effect, and it can also effectively prevent the gasket from falling apart and the corrosion of the medium. Therefore, it is generally used in joints with installation grooves, such as: male and female matching flanges, bonnets, pressure gauge unions, etc. The standard is thickness and diameter. The thickness is determined by the gap between the sealing joints. It is processed according to the size of the sealing groove.