Sealing gasket installation requirements2019-02-15
1. The sealing gasket and flange sealing surface should be cleaned, and there should be no defects such as scratches and spots that affect the connection sealing performance.
2. The outer diameter of the sealing gasket should be smaller than the outer surface of the flange sealing surface. The inner diameter of the sealing gasket should be slightly larger than the inner diameter of the pipeline. The difference between the two inner diameters is generally 2 times the thickness of the sealing gasket to ensure the sealing gasket after compaction. The inner edge does not protrude into the container or conduit to prevent interference with the flow of fluid in the container or conduit.
3. The pre-tightening force of the gasket should not exceed the design regulations, so as to avoid the excessive compression of the gasket and the rebound ability.
4. When the gasket is pressed, use a torque wrench. For large bolts and high-strength bolts, use a hydraulic tensioner. The tightening torque should be calculated according to the compression of a given gasket. The hydraulic pressure of the hydraulic tensioner should also be determined by calculation.
5. When installing the gasket, tighten the nuts in order. However, the design value should not be reached once. Generally, it should be circulated for at least 2 to 3 times so that the stress distribution of the gasket is uniform.
6. For pressure vessels and pipelines with flammable and explosive media, safety tools should be used when replacing gaskets to avoid sparks caused by the collision of tools with flanges or bolts, resulting in fire or explosion accidents.
7. If the pipeline leaks, it must be replaced after the pressure reduction treatment or adjust the installation of the gasket. It is strictly forbidden to operate with pressure.
Second, special installation requirements for gaskets
1. When installing the sealing and winding gasket matched with the protruding plane flange, care should be taken to ensure that the sealing member is concentric with the pipe. Generally, the outer reinforcing ring is placed in contact with the inner circumferential surface of the bolt to be positioned, and eccentric mounting is not allowed. When installing the basic type of wound gasket in the flange of the groove surface sealing surface, be careful to keep the gap with the groove wall surface.
2. When installing a metal-coated gasket with a narrow width, a steel plate with a certain thickness should be placed on the outside of the gasket, and then the flange should be pressed to prevent the coating of the metal gasket from being pressed after the metal gasket is pressed. (or lap) expand and 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 sealing gasket to prevent the sealing gasket from sealing with the flange sealing surface at high temperature, and to increase the inspection and replacement of the sealing gasket. trouble.
4. When the sealing surface is not flat, sealant can be applied on the sealing surface before installing the sealing gasket. The sealant is generally composed of manganese dioxide, lead dan, graphite powder and linseed oil (dry oil). The corresponding type and grade of liquid sealant can be selected according to the conditions of sealing medium, working temperature and medium pressure.
5. For the installation of octagonal metal ring gaskets, when the metal ring gasket and the flange sealing groove are not ideally processed, it can be closely fitted by matching research. For large-diameter metal ring gaskets, it is difficult to match the research. In order to fill the small unevenness of the metal surface, a sealant can be used.