in connecting a pipe with another pipe or another connector element , a cylindrical member is provided which is inserted into the end of the pipe . the cylindrical member has ring means thereon which are radially expanded in situ by an expanding tool which is inserted into the cylindrical member . as the ring means expands , the adjacent walls of the pipe are plastically deformed to form circumscribing grooves whereby the ring means are accommodated in the circumscribing grooves to thereby sealingly secure said cylindrical member to said pipe . the aforementioned securement may be effected while maintaining the integrity of any covering layer such as insulation or the like on the outside of the pipe .