Flange sealing principle

　　The two sealing faces of the bolt are pressed with each other to form a seal, but at the same time, it also leads to the destruction of the seal. In order to keep the seal, you have to maintain a huge bolt force, to this end, the bolt will do even greater. And greater bolt must match the larger nut. This means that larger diameter bolts need to create conditions for the nut is tightened. However, the greater the diameter of the bolt, the flange will become more curved, the only way is to increase the thickness of the flange part of the flange. The whole device will require a great deal of size and weight, which is a special issue in the offshore environment, because in this case the weight is always the main problem that people have to pay attention to. And from the point of view of the fundamental, flat welding flange is an invalid seal, it needs the extruded shim for 50% of the bolt load and to keep the pressure on the load for only 50%.