a method for assembling components that are sealed hydraulically or pneumatically includes forming an outer component having an inner surface , a groove for holding a seal , the groove having an opening at the inner surface . a seal is fabricated in the form of a substantially circular ring having a scarf cut extending through the width and the thickness of the seal , and a second inner surface having an inside diameter . the seal is then placing over a mandrel having a diameter that is larger than the inside diameter of the second inner surface so that the seal is expanded by plastic deformation such that a gap is formed at the scarf cut . then the seal is inserted in the groove while the seal is expanded .