Sealing mechanism of flange

Sealing mechanism of flange

When the medium flows through the interface between the internal space and the external space, the leakage is the leakage of the sealing surface. The root cause of leakage is that there is a gap on the touch surface, and the pressure difference and concentration difference on both sides of the touch surface are the driving force of leakage.

In order to reduce the leakage, the contact surface should be installed as much as possible, that is, the cross-sectional area of the leakage channel should be reduced, the leakage resistance should be increased, and it should be greater than the leakage driving force. Applying compression load to the sealing surface to generate compression tension can improve the touch degree of the sealing surface. When the stress increases enough to cause significant plastic deformation of the surface, it can fill the gap of the sealing surface and block the leakage channel.

Metallic gaskets

Metallic gaskets

Initial seal

After the flange is installed, the initial seal can be completed, and the bolts are tightened to compress the flange. The basic condition of the initial seal is to produce satisfactory pressure between the sealing surfaces, that is, the pre tightening stress of the flange makes the flange compressed. Subsequently, the elastic or elastic-plastic tightening deformation occurs, which can fill the roughness sealing surface of the flange and block the interface leakage channel to meet the initial sealing requirements.

The pre tightening stress of flange depends on the tightening function of gasket data. All sealing tightening force comes from the initial tightening force of bolts. Together, the flange shall have satisfactory strength and rigidity to prevent deflection or warping deformation.

Insulating Flanges

Insulating Flanges

Working seal

When the pre tightened flange bolt three component system receives the pressure of working medium, it will force the two sealing surfaces of a pair of flanges to separate relatively. In this case, the flange should have satisfactory springback deformation to compensate the separation.

In addition, the flange also needs to have satisfactory residual flange stress on the sealing interface to ensure the sealing of fluid medium.

The main influencing factors are flange pre tightening force, flange sealing plate, flange sealing surface.

The tightening and resilience of flange is an important condition for flange sealing. The deformation of flange includes two parts: elastic deformation and plastic deformation. The flange with high resilience can well compensate the separation of flange end face and adapt to the fluctuation of working pressure and temperature. Therefore, the sealing function is good.

Haihao Group manufacture flange products more than 30 years,the products sells well all over the world for the high quality. If you have any question,please contact us!


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