Gaskets

The smoothest metal mating surfaces still have imperfections which can allow leakage. To try to prevent leakage at critical joints, gaskets of soft, form-fitting material are used to fill in the imperfections.

To be most effective at their task, gaskets are designed to "crush", to become thinner as they are pressed together between mating parts. Once a gasket has been used and crushed, it is no longer capable of making as good a seal as when new, and is much more likely to leak. For this reason, gaskets should not be reused. Always plan to use new gaskets for any reassembly.