Pipe joint

Claim 1

A PIPE JOINT BETWEEN ADJACENT PIPE SECTIONS, EACH OF THE PIPE SECTIONS COMPRISING AN OUTER RIGID BODY AND A LINING OF A SYNTHETIC RESINOUS MATERIAL SUBJECT TO COLD FLOW, EACH OF THE PIPE SECTIONS HAVING A TERMINAL END TO BE JOINED, A FLANGE AFFIXED TO THE RIGID OUTER LAYER OF EACH PIPE SECTION AND DEFINING A GENERALLY OUTWARDLY EXTENDING RADIAL SURFACE, MEANS TO SECURE ADJACENT FLANGES TO EACH OTHER, A TERMINAL FLANGE OF SYNTHETIC THERMOPLASTIC RESINOUS MATERIAL INTEGRAL WITH THE LINING IN EACH PIPE SECTION AND EXTENDING ALONG THE RADIALLY OUTWARDLY EXTENDING FACE OF THE AFFIXED FLANGE, EACH TERMINAL FLANGE HAVING AN ANNULAR GROOVE OF SUBSTANTIALLY THE SAME RADIUS WITHIN THE OUTWARDLY EXTENDING SURFACE, AN O-RING OF A RESILIENT SEALING MATERIAL DISPOSED IN SAID GROOVES, THE AXIAL DEPTH OF EACH OF THE GROOVES BEING LESS THAN THE RADIUS OF THE ORING CROSS-SECTION, THE GROOVES BEING DISPOSED ADJACENT THE OUTER TERMINAL PORTION OF THE SYNTHETIC RESINOUS FLANGES SAID SECURING MEANS DRAWING SAID FLANGES TOGETHER TO COMPRESS SAID O-RING AND THE TERMINAL FLANGES TO THEREBY EFFECT A DOUBLE SEAL AT SAID JOINT INTERFACE.