The factors that affect the sealing effect of pressure vessel flange

In the last article,we introduced the working principle of the pressure vessel flange.Next step,we will introduce the factors that affect the sealing effect of the pressure vessel flange.

1.Bolt tension

A proper preload can ensure that the sealing gasket can retain a certain sealing specific pressure when it works. If the preload is too large, the gasket will be crushed or extruded, which is not conducive to sealing. Under the condition of meeting the space required for fastening and dismantling bolts, the number of bolts shall be increased appropriately to ensure the uniform distribution of pre tightening force.

Inconel 825 RF weld neck flanges

Inconel 825 RF weld neck flanges

2.Performance of gasket

Sealing gasket is an important component of flange sealing. The proper gasket material will not only produce the necessary elastic deformation, but also be crushed or extruded out of the sealing surface under the proper preload. At the same time, the sealing gasket is required to have enough resilience. When the pressure between the sealing surfaces of the flange of the high pressure vessel increases, the sealing surface can be properly deformed and filled, and the good sealing performance of the connecting surface can be maintained.

3.Sealing surface characteristics of high pressure flange

The type of flange sealing surface which is required to be strict under working conditions shall be concave convex surface and tenon groove surface. The water line and roughness of the flange sealing surface shall meet the specification and match with the sealing gasket.

4.Strength of high pressure vessel flange

If the strength of flange is not enough, the flange will bend and deform, and the final seal will fail. Many factors will affect the flange strength, among which strict control of flange material, increase of flange thickness, increase of flange outer diameter and other methods can improve the flange stiffness, the flange deformation is small, the bolt force will be evenly transmitted to the sealing gasket, in order to obtain uniform and sufficient sealing pressure, which is the key to improve the sealing performance. The moment of flange can be reduced and the sealing failure can be reduced by reducing the force arm of bolt properly.

American standard slip on flanges finished in Haihao Group

American standard slip on flanges finished in Haihao Group

5.Working condition

The higher the temperature is, the smaller the viscosity of the medium and the greater the possibility of leakage; the higher the temperature is, the greater the chemical and physical activity of the medium, the greater the corrosion and dissolution of the gasket and flange; the higher the temperature is, the creep and stress relaxation of the bolt, flange and sealing gasket will occur. Understand the specific conditions of the working condition to ensure the sealing effect of the flange to the maximum extent.