How do carbon steel flange manufacturers do a good job of sealing?

Sealing principle of carbon steel flange:

The two sealing faces of the bolt press against each other and form a seal, but this also causes damage to the seal. In order to adhere to the seal, it is necessary to maintain a large bolt force. To this end, the bolts have to be made large. Large bolts are matched to large nuts, which means that bolts that require large diameters create conditions for tightening the nuts. However, the larger the diameter of the bolt, the more suitable the flange becomes, which is to increase the wall thickness of the flange portion. Moreover, fundamentally, the flat weld flange is an ineffective seal that requires 50% of the bolt load to be used to squeeze the gasket, while the load used to hold the pressure is only 50%.