A socket joint for ductile cast iron pipes is locked by toothed locking ring inserts 15 and a counter-flange 11. At least one elastic lip 19 is inserted between the locking ring and the rear face of a rigid stop ring which encloses the smooth or male end of the pipe 1....http://www.google.es/patents/US5297826?utm_source=gb-gplus-sharePatente US5297826 - Locking joint for pipe systems
