Flexible pipe coupling

A coupling for the establishment of a fluidtight connection between the neighboring end portions of two pipes, comprising a deformable elastic sleeve having two open ends, an external surface, an internal surface, a substantially centrally located partition extending from said internal surface and disposed between the end portions of pipes which are inserted into the sleeve through the respective open ends, two inner circumferential grooves provided in said internal surface at opposite sides of said partition, and annular sealing means extending from said internal surface intermediate each open end and the respective inner groove;

• and a clamping unit including a split ring surrounding said external surface and including an arcuate main portion having two axially spaced apart first corrugations extending toward said external surface and two outwardly extending projections which are bonded to said main portion and are relatively movable circumferentially of the sleeve between first positions at a longer distance from one another in which the projections define a gap and second positions at a shorter distance from one another in the circumferential direction of said sleeve, each of said projections comprising a substantially strip-shaped element which is substantially parallel to the axis of said ring and each of said elements having a first side facing the other element and a second side, said clamping unit further including tightening means for drawing said projections from said first to said second positions to thereby tighten the ring around the external surface and deform said sleeve, said tightening means including a fastener having a head adjacent one of said second sides and an externally threaded shank extending through openings provided therefor in said elements, said tightening means further comprising a nut mating with said shank and adjacent the other of said second sides and means for holding said nut against rotation relative to said ring, said holding means comprising at least one socket disposed circumferentially of and provided in said ring, and a projection provided on said nut and extending into said socket, said at least one socket being defined by one of said first corrugations and said clamping unit further including an insert which bridges at least the major part of said gap and is at least partially disposed between said ring and said external surface, said insert having two second corrugations each of which receives one of said first corrugations, said second currugations being substantially mirror symmetrical to one another with reference to a plane which is normal to to the axis of and halves said ring.