Plastic pipe coupling with frangible lugs

Claim 1

A PIPE JOINT COMPRISING: A PIPE MADE OF PLASTIC CHARACTERIZED BY A TENDENCY TO SHRINK WITH AGE; A HOLLOW FITTING HAVING A RECESS THEREIN TEREMINATING AT ITS INNER END IN AN OUTWARDLY-FACED SHOULDER; MEANS DEFINING A CIRCUMFERENTIAL ENLARGEMENT WELDED TO ONE END OF SAID PIPE AND DISPOSED FOR AXIAL AND ROTATIONAL MOVEMENT IN SAID RECESS; MEANS PROVIDING A CIRCUMFERENTIAL FLUID SEAL BETWEEN SAID ENLARGEMENT AND SAID RECESS WHILE ALLOWING SAID MOVEMENT; A COUPLING MEMBER DETACHABLY CONNECTED TO SAID FITTING; AND YIELDABLE MEANS OPERATIVELY ASSOCIATED WITH SAID MEMBER AND SAID ENLARGEMENT ADJACENT THE REAR END OF THE LATTER FOR NORMALLY RETAINING SAID ONE END OF SAID PIPE SUBSTANTIALLY IN ENGAGEMENT WITH SAID SHOULDER BY PERMITTING CONTRACTION OF SAID PIPE TO A PREDETERMINED DEGREE IN A DIRECTION AWAY FROM SAID SHOULDER WITHOUT IMPAIRING SAID SEAL.