Does a rubber expansion joint need a flange gasket
Aug 20,2025
Whether rubber expansion joints need to be equipped with flange gaskets depends on a comprehensive judgment based on the type of joint and working conditions. The following is a specific analysis:
I. Situations where gaskets are not required
Rubber joint with self-sealing design
Most standard rubber expansion joints (such as flexible rubber joints) come with a vulcanized rubber sealing layer and can be directly attached to the flange during installation without the need for additional gaskets .
EPDM/NBR joint
Corrosion-resistant rubber (such as EPDM) has good sealing performance under normal temperature and pressure. Adding gaskets may instead affect the elastic compensation function .
Ii. Situations where gaskets are required
High pressure or high temperature conditions
When the system pressure is greater than 1.6MPa or the temperature is greater than 80℃, it is recommended to add metal wound gaskets or graphite gaskets to enhance the seal .
The flange surface is uneven or corroded
If there are scratches or rust on the flange sealing surface, the defect should be filled with a non-asbestos gasket (such as PTFE) .
Special medium transportation
For easily permeable media such as strong acids and organic solvents, it is recommended to use fluororubber gaskets to prevent chemical corrosion .
Iii. Installation Precautions
Bolt tightening : Use a diagonal tightening method to avoid leakage caused by unilateral force .
Displacement control : During installation, it is strictly prohibited to forcibly stretch or compress beyond the allowable displacement (usually ±10% of the length) .
Note: There may be differences between the new and old national standard products. It is recommended to first check whether the joint body has an internal sealing structure .
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