Patent ID: 7040628

Claim:
A method of making a large diameter seal having a PTFE or lip and a two-piece metal casing, said method comprising forming the lip portion of said seal from of an extended strip of a PTFE material, forming at least a partial flange in one margin of said strip of material, forming a large circumferentially spaced apart areas of weakness in the opposite margin of said strip, forming said strip having said areas of weakness into a continuous loop of PTFE material by abutting the end portions of said strip together, placing a thin strip of compatible material over said abutted ends and raising said end portions to an elevated temperature, said areas of weakness of said strip lying toward the outer margin of said strip, placing at least said areas of weakness overlying the radial flange portion of an outer casing and placing a rubber-like gasket material adjacent said areas of weakness, covering said outer margin of said strip with an inner casing that nests with said outer casing, crimping said outer casing over said inner casing, thereby tightly confining said strip of PTFE material in place, and thereby creating a seal having a flanged, work-engaging lip of PTFE material.