standard and Installation Requirements of Sealing Gasket

July 22, 2022

Occupation standard:

1、GB4622.2-93 winding gasket tube flange size series;

2、GB9126.1-88 Asbestos rubber sheet for flat-type steel pipe flange;

3、GB9126.2-88Asbestos rubber sheet for convex surface steel tube flange;

4、GB9126.3-88 Asbestos rubber sheet for concave and convex surface steel tube flange;

5、GB9129-88 Technical conditions of asbestos Rubber Gasket for steel pipe flange;

6、GB9130-88Technical conditions of metal ring cushion for steel pipe flange connection;

7、HGJ70-91 Flexible graphite composite gasket for steel pipe flange;

Installation requirements of sealing gasket:

1. The sealing pad and flange sealing surface shall be cleaned without any scratches, spots and other defects affecting the connection and sealing performance.

2. The outer diameter of the sealing gasket should be smaller than the flange sealing surface, the inner diameter of the Flange Gasket should be slightly larger than the inner diameter of the pipeline, the difference between the two inner diameter is generally twice the thickness of the sealing gasket, to ensure that the inner edge of the sealing gasket does not extend into the container or pipeline, so as not to hinder the flow of fluid in the container or pipeline.

3. The pre-tightening force of the Valve Gasket shall not exceed the design regulations to avoid the excessive compression of the sealing gasket and losing the rebound capacity.

4. When the sealing gasket is pressed, it is best to use a torque wrench. For large bolts and high strength bolts, a hydraulic compsier is preferred. The tightening torque shall be calculated according to the given tightness of the sealing gasket, and the oil pressure of the hydraulic compsier shall also be determined by the calculation.

5. When installing the sealing gasket, the nuts should be tightened in sequence. But should not twist once to reach the design value. Generally should cycle at least 2~3 times, so that the sealing gasket stress is distributed evenly.

6. For pressure vessels and pipes of flammable and explosive media, safety tools should be used when replacing sealing gaskets, so as to avoid sparks when the tools touch with flanges or bolts and cause fire or explosion accidents.

7. If there is leakage in the pipeline, the sealing gasket must be replaced or adjusted after the pressure reduction treatment. Operation with pressure is strictly prohibited.

Special installation requirements of Sealing Gasket:

1. When installing the sealing and winding gasket matched with the protrusion plane flange, attention should be paid to ensure that the sealing parts are concentric with the pipe. Generally, the external reinforcing ring contacts the inner circumference of the bolt to locate, and eccentric installation is not allowed. When installing the basic winding spacer in the flange of the groove surface, it should be paid to keep the gap consistent with the groove wall.

2. When installing the metal coated gasket with a narrow width, the steel plate of a certain thickness should be placed on the outside of the Viton Gasket, and then press the flange, so as to avoid expanding the interface (or lap mouth) of the metal shell in the metal gasket and damaging the metal coated FPM Gasket.

3. When the working temperature of the flange is higher than 200℃, the sealant should be applied between the flange sealing surface and the FKM Gasket to prevent the sintering of the seal between the sealing gasket and the Flange Gasket surface at high temperature, and increase the trouble for the maintenance and replacement of the sealing gasket.

4. The sealing surface is not normal, so the sealing pad can be installed after applying the sealant on the sealing surface. Sealant is generally composed of manganese dioxide, lead Dan, graphite powder and boiled linseed oil (dry oil). The liquid sealant of the corresponding type and brand number can be selected according to the sealing medium, working temperature and medium pressure.

5. For the installation of octagonal metal ring gasket, when the metal ring pad and flange sealing groove processing is not ideal, it can be matched to achieve tight fitting. For the large diameter metal ring gasket, it is more difficult to study, in order to fill the small bumps of the metal surface, the sealant can be used.

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Author:

Mr. Zheng

이메일:

zheng@rmiplast.com

Phone/WhatsApp:

+86 15888074637