What Is a Flange Seal?

The sealing principle of the ANSI flange is extremely simple: the two sealing surfaces of the bolt squeeze the flange gasket against each other and form a seal. However, this also results in the destruction of the seal. In order to maintain the seal, a large bolt force must be maintained. For this, the bolts need to be made larger. Larger bolts need to match larger nuts, which means that larger diameter bolts are needed to create conditions for tightening the nut. As everyone knows, the larger the diameter of the bolt, the more suitable the flange becomes. The only way is to increase the wall thickness of the flange. The entire device will require significant size and weight, which becomes a particular problem in offshore environments, where weight is always the main issue that must be a concern. And, fundamentally, the ANSI flange is an ineffective seal, which requires 50% of the bolt load to be used to squeeze the gasket, and only 50% of the load to maintain pressure is left.