Disconnectible pipe union

Claim 1

A disconnectible pipe union, comprising a pair of annular collars one on each of the pipe ends to be joined, said collars being flared so as to increase in diameter in a direction towards the medial plane of the joint to form an inwardly facing front face and an outwardly facing back face, each said collar terminating in an outer edge portion having a relatively sharp corner, the sharp corners on said pair of collars substantially confronting one another, a segmented clamping ring having a groove on the radially inner face thereof the sidewalls of which groove converge at an angle corresponding to the angle of convergence of the back faces and engage said back faces, means for tightening said clamping ring, whereby when said clamping ring is tightened, the groove side walls subject the back faces of the collars to a camming action which urges the pipe ends axially towards each other and brings the outer edge portions of the collars near one another, a stiff but resilient primary sealing ring disposed between the front faces of the two collars, said primary sealing ring having a cross sectional shape so as to substantially occupy and fill the axial space defined between said front faces to engAge each front face along a circumferential line contact area thereby to provide a narrow sealing contact zone between each side face of the sealing ring and each of said front faces, the side faces of the primary sealing ring extending at an angle relative to one another whereby the primary sealing ring is subjected to both axial and radial compression when the collars are sealingly clamped thereagainst by the clamping ring, the primary sealing ring being provided with a central peripherally extending outwardly opening groove on the outer peripheral surface thereof, and a secondary sealing ring of elastomeric material seated within said groove and having a part thereof projecting outwardly from said groove such that said part sealingly engages both said outer edge portions of the collars, said clamping ring causing the opposed sharp corners to project into the projecting part of said secondary sealing ring on opposite sides thereof, whereby the projecting part of the secondary sealing ring is deformed so as to extend into the space between and sealingly engage the opposed outer edge portions of the collars.