Jointing system for pipes

The invention relates to a jointing system for joining pipes, especially copper plumbing pipes. A copper pipe has a circumferential groove formed in an outer wall to receiver an O-ring seal. The groove is formed a pre-set distance from a free end of the pipe. Two pipe lengths are jointed together by a coupling having a housing with pipe seal-receiving seats at each end for receiving the O-ring seal fitted to the pipe. Caps screw threadingly engage the housing to clamp the pipe lengths in the housing. The fitting can be pre-assembled and used as a push-in fitting with a subsequent tightening by hand.