Compressible coupling

A coupling for attaching to an end of a tube, pipe, conduit or other round solid or hollow section, the coupling comprising:

• a monolithic inner body section having an outer frustoconical surface and an interior bore having an inner surface, the bore passing through at least a portion of the inner body and configured to receive a tube;
• a collar arranged to be axially received about the inner body, the inner body and the collar being configured such that when the collar is forced onto the inner body it applies a circumferential compressive force to deform the body inwardly;
• and
• at least one interior annular protuberance extending into the bore and defining in an axial direction one or more annular teeth arranged such that, in use, when a tube is received in the bore and the inner body is inwardly deformed by the collar, the one or more annular teeth engage the tube to form a seal with it;
• wherein the inner surface of the bore further comprises a plurality of circumferentially arranged projections defining in a circumferential direction a series of axially aligned, circumferentially spaced teeth forming longitudinal rows axially spaced from the at least one annular protuberance, at least one of the circumferentially spaced teeth extending into the bore from the inner surface the same distance as the at least one annular protuberance and configured to, in use, engage with and penetrate the surface of the tube following compression of the inner body by the collar to create a circumferentially interlocking arrangement between the tube and the inner body to prevent relative rotation between the tube and the inner body, wherein the inner surface of the bore further comprises a plurality of circumferentially spaced smooth portions extending circumferentially and longitudinally between the rows of circumferentially spaced teeth, and the outer frustoconical surface surrounds the at least one annular protuberance and circumferentially spaced teeth prior to the collar being arranged around the inner body.