Abstract: A method of socketing a pipe of oriented plastic having an annular groove inside the socket. An end portion (15) of the pipe is pushed onto a cylindrical mandrel element (11) and the region (l.sub.1) of the end portion at the opening thereof where the groove is to be located is heated to a temperature above the glass transition temperature of amorphous plastic and the crystalline melting point of crystalline plastic, respectively. The rest of the end portion is maintained at a temperature below the glass transition temperature or the crystalline melting point, respectively. The end portion (15) when said region is at a temperature above the glass transition temperature or the crystalline melting point, respectively, is pushed onto a second mandrel element (13) axially aligned with the first mandrel element the bottom portion of the socket being formed by said second mandrel element (13). The rest of the end portion is expanded to form the bottom portion of the socket.