Originally designed to replace the copper type washers in higher pressure systems.
The gasket comprises of a metal disc, usually in Steel, square or rectangular in section and a trapezoidal section of elastomer bonded to the metal disc. The metal disc resists the bursting forces that limits the deformation of the elastomeric element.
The self-centring version is designed to stop leakage due to seal offset, with the additional benefit of pre-assembling on to the threads with the consequent production line savings. The thin flange seal offers little resistance during assembly.
Bonded washers are typically used in Hydraulic Hose assemblies as they are ideal to prevent fluid leakage under the application of pressure, but they are not limited to this use.