Production of socket ends in thermoplastic pipes

Claim 1

In combination, a thermoplastic pipe having a socket end including an internal annular groove; and a combined mould and sealing element suitable for sealing off a joint between said socket end and an insert end of a cooperating pipe for being used as a portion of a body of a mould for both fabricating said socket end of said pipe and simultaneously inserting said element in said internal groove, said element consisting of a main body disposed in annular form composed of an elastically yielding material housing a reinforcing core of relatively non-elastic material capable or retaining its shape relative to said main body, said main body having a radial outer portion adapted to its active condition to abut the bottom of said internal groove and in an inactive condition to project freely outwards as a flap to define with an inner and opposing portion of said body an opening dimensioned to facilitate ready introduction and housing of said reinforcing core in said main body, said flap having a wall thickness which is locally reduced relative to said flap and said body at a position remote from the free end of said flap to define a recess to permit ready bending and clamping of said flap against said inner and opposing portion to close off said opening and thereby simultaneously preclude access to said reinforcing core on completing the transition from said inactive to said active condition during relative movement of said socket end of said pipe over the insert end of a cooperatng pipe.