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How To Choose A Gasket

Sep. 16, 2020
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Selection requirements for gasket plate supplier


1. Gasket Sheet Supplier for pressure vessels and pressure pipelines must obtain special equipment manufacturing licenses issued by the State Bureau of Technical Supervision, have complete manufacturing and inspection methods, pass quality system certification, and have good performance in the petroleum and petrochemical industry.


2. The material purchasing department organizes the quality inspection of the gaskets after they are put into the warehouse, including the certificate, material certificate, specifications and models, etc. For the sealing gaskets of key equipment and sealing materials with special material requirements, the manufacturer shall propose necessary re-inspection requirements. The re-inspection shall be carried out in accordance with the corresponding manufacturing standards. The number of sampling inspection and acceptance shall not be less than one piece per batch.


Gasket selection


1. The type and scope of the gasket should comply with the design documents and the current effective standards of the country and related industries. The change of gasket material and usage standards must be approved.


2. There are many factors influencing the selection of gaskets. Generally, on the premise of ensuring safe operation, try to choose gaskets that are cheap, easy to manufacture, and easy to install and replace.


3. The thickness of the gasket depends on the specific situation. Generally speaking, if the sealing surface is processed well and the pressure is not too high, thin gaskets should be used. However, when the internal pressure is high, the gasket is too thin, which corresponds to the extension of the bolt, and the rebound of the gasket is too small to achieve the necessary recovery amount, which may cause leakage. Therefore, when the pressure is high, a thicker one should be selected. Gasket.


4. In order to ensure the interchangeability of gaskets, the specifications and materials should be unified as much as possible when selecting the type. While considering meeting the use requirements, the specifications and materials should be merged as much as possible, and unnecessary diversification should be avoided.


5. In the case of gas medium and high pressure, it is not allowed to use high-strength graphite gaskets without edging, and corrugated gaskets are not allowed for tongue and groove flanges.


6. Special requirements should be taken care of. If a certain medium does not allow microfibers to be mixed, Asbestos Rubber Sheet and other fibrous gaskets should not be used. Some parts vibrate greatly, so it is necessary to choose a gasket with strong vibration resistance and high resilience and durability.


7. Asbestos rubber gaskets are not allowed to be used for highly toxic, explosive, highly corrosive, highly polluting media and harmful gases.


8. Spiral wound gaskets with metal protection rings should be used for the valve and flange gaskets of the bottom of the liquefied balloon tank;


9. When metal gaskets are used, they should be used in a fully annealed state, and softer metal materials should be used as much as possible. The hardness of the gasket should be lower than that of the flange sealing surface, HB30-40.


10. The replacement principle of gaskets on imported equipment is to replace the type and material as they are. When the gasket form or material needs to be replaced due to special reasons, approval is required.


11. The type and material of the gasket should be selected according to the fluid, operating conditions (pressure, temperature) and the sealing requirements of the flange joint. The flange sealing surface type and surface roughness should be compatible with the gasket type and material.


12. When Asbestos Gasket or flexible graphite gaskets are used for stainless steel or nickel-based alloy flanges, the chloride ion content in the gasket material shall not exceed 50PPm.


13. When flexible graphite materials are used in oxidizing media, the maximum operating temperature should not exceed 450 ℃


14. For flanges with a nominal pressure less than or equal to 1.6MPa, when semi-metal gaskets or metal ring gaskets such as spiral wound gaskets and metal-clad gaskets are used, rigid flange structures such as necked butt-welded flanges should be used. Type (very important).


15. When selecting the gasket size, pay attention to ensure that the inner diameter of the non-metallic flat gasket or the inner diameter of the spiral wound gasket shall not be lower than the inner diameter of the flange. If the inner diameter of the gasket (or inner ring) is required to be flush with the inner diameter of the flange , The flange inner diameter corresponding to the method shall be provided to the gasket plate supplier as the gasket inner diameter, but sufficient pressure-bearing width of the gasket shall be ensured.


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