As the match of the two carbon steel flanges can not be absolutely concentric, leading to carbon steel flange sealing surface is not parallel. So tighten the bolt when the carbon steel flange bending moment, so that the force carbon steel flange is not uniform. As a result, on the sealing surface, while reducing the sealing pressure, on the other side to strengthen the sealing pressure, in order to achieve the purpose of sealing, had to tighten the bolts tighten, this will lead to carbon steel flange deformation under the action of the load , It is prone to leakage.
Another is the rigidity of the carbon steel flange requirements, the original design of the carbon steel flange, the only strength calculation, but little rigidity calculation, but more and more production practice has proved that carbon steel flange stiffness will also affect the carbon steel flange seal , Rigidity of the carbon steel flange will produce insufficient warping deformation, the gasket force is not uniform, and lead to leakage.
Source: China Flange Manufacturer – Yaang Pipe Industry Co., Limited (www.yaang.com)