Coated grooves for pipe coupling

Claim 1

IN A PIPE JOINT FORMED BY SEATING AN ANNULAR GASKET IN AT LEAST ONE ANNULAR GROOVE IN AN INTERNAL PERIPHERAL SURFACE OF A COUPLING THEREFOR AND BY EXERTING SUFFICIENT FORCES ON SAID GASKET BY RELATIVE AXIAL MOVEMENT BETWEEN AT LEAST ONE PIPE END AND SAID COUPLING TO DEFORM SAID GASKET BETWEEN SAID PIPE END AND SAID COUPLING TO FORM A FLUID TIGHT SEAL, AND WHEREIN, DURING SAID RELATIVE MOVEMENT BETWEEN SAID PIPE END AND SAID COUPLING, SAID GASKET BEING LOCATED ADJACENT ONE AXIAL END PORTION OF SAID GROOVE, SAID PIPE END HAS A TENDENCY TO EXERT ON SAID GASKET A FORCE SUFFICIENT TO DISPLACE AT LEAST A PORTION OF SAID GASKET FROM SAID GROOVE, THE COMBINATION COMPRISING: (A) A COUPLING HAVING AN INTERNAL DIAMETER GREATER THAN THE OUTSIDE DIAMETER OF SAID PIPE END AND AT LEAST ONE ANNULAR GROOVE FORMED IN THE INTERNAL PERIPHERAL SURFACE THEREOF; (B) AN ANNULAR RESILIENT DEFORMABLE GASKET HAVING IN A RELAXED STATE A GENERALLY CIRCULAR CROSS-SECTIONAL CONFIGURATION; (C) SAID GASKET BEING SEATED IN SAID GROOVE WITH THE INNER PERIPHERY OF SAID GASKET EXTENDING IN A GENERALLY RADIALLY INWARD DIRECTION A SUBSTANTIAL DISTANCE OUT OF SAID GROOVE;