High-pressure valve designs use bonnet seals in a triangular shape instead of a sheet gasket because of the extreme pressure put on the bonnet bolts. This design uses the actual line pressure to assist in creating the bonnet seal. One major flaw in this approach is that the metal bonnet seals tend to stick to the valve body and require excessive force to remove, often causing damage to the valve and seal.
Chesterton’s 5900 Graphite Bonnet Seal addresses these issues. It conforms to worn surfaces and can solve safety and maintenance issues.