1. The sealing gasket and flange sealing surface should be cleaned without scratches, spots and other defects that affect the sealing performance of the connection.
2. The outer diameter of the gasket should be smaller than the outer diameter of the flange sealing surface, and the inner diameter of the gasket should be larger than the inner diameter of the pipe. The difference between the two inner diameters is usually twice the thickness of the gasket to ensure that the inner edge of the gasket does not protrude into the vessel or pipe and impede the flow of fluid in the vessel or pipe.
3. The pre-tightening force of the sealing gasket shall not exceed the design specification, so as to avoid excessive compression and loss of resilience.
4. Use a torque wrench when compressing the gasket. For large bolts and high-strength bolts, use hydraulic tighteners. The tightening torque should be calculated according to the given gasket pressure, and the oil pressure of the hydraulic tightener should also be determined through calculation.
5. When installing the sealing gasket, the nuts should be tightened in sequence. But the design value should not be tightened at one time. Generally, it should be cycled at least 2~3 times to make the stress distribution of the sealing gasket even.
6. When replacing pressure vessels and pipes with flammable and explosive media, safety tools should be used to avoid sparks caused by the contact between tools and flanges or bolts, causing fire or explosion accidents.
7. When the pipeline leaks, the sealing gasket must be replaced or adjusted after the pressure is reduced, and operation under pressure is strictly prohibited.
Special installation requirements.
1. When installing the sealing wound gasket that matches the protruding flat flange, care should be taken to ensure that the seal is concentric with the pipe. Generally, the outer reinforcing ring is used for positioning in contact with the inner circumferential surface of the bolt, and eccentric installation is not allowed. When installing the basic wound gasket in the tongue and groove sealing surface flange, care should be taken to keep the gap consistent with the groove wall.
2. When installing a metal-coated gasket with a narrow width, a steel plate of a certain thickness should be placed on the outside of the gasket, and then the flange should be pressed tightly to avoid expansion of the metal shell interface (or interface) after the coating filler in the metal gasket is compressed. ), damage the metal-coated gasket.
3. When the working temperature of the flange is higher than 200°C, a sealant should be applied between the flange sealing surface and the gasket to prevent the gasket and the flange sealing surface from sintering at high temperature, which will increase the maintenance and replacement of the gasket. trouble.
4. If the sealing surface is uneven, you can apply sealant on the sealing surface, and then install the sealing gasket. The sealant is generally composed of manganese dioxide, lead red, graphite powder and linseed oil (dry oil). The corresponding type and brand of liquid sealant can be selected according to the sealing medium, working temperature and medium pressure.
5. For the installation of the octagonal metal ring gasket, when the processing of the metal ring gasket and the flange sealing groove is not ideal, a tight fit can be achieved through research. For large-diameter metal ring gaskets, the research is more difficult. To fill small bumps and bumps in the metal surface, a sealant can be used.
