Patent ID: 8256115

Claim:
A method of making a fluid coupling comprising a first and a second coupling member having respective fluid channels communicating with each other, a metal gasket interposed between abutting end faces of the two coupling members and screw means for fastening the two coupling members together, each of the first and second coupling members being provided in the end face thereof with an annular recessed portion having a flat bottom face, the gasket being annular and disposed within a space defined by the recessed portions of the two coupling members, the gasket having an annular ridge formed on each of opposite side surfaces thereof, and the ridge of the gasket has a trapezoidal cross sectional shape defined by an outer tapered face providing an outer peripheral surface, an inner tapered face providing an inner peripheral surface and a flat face providing a top end surface, a radial outer periphery of the gasket comprising axially opposite beveled surfaces, wherein a cavity having a circular-arc cross section is in an axial midportion of an outer periphery of the gasket, the fluid coupling making method including a step determining a hardness of the gasket, an angle between the tapered faces of the ridge, a height of the ridge and an area of the flat top end face of the ridge, so that a value of thrust for tightening up the coupling is between a predetermined minimum value to obtain required sealing properties and a predetermined maximum value to ensure required strength.