Pipe coupling having a deformed inner lock

Claim 1

A JOINT BETWEEN A FIRST PIPE AND A SECOND PIPE, BOTH SAID PIPES BEING MADE OF A RIGID MATERIAL HAVING MALLEABLE CHARACTERISTICS, SAID FIRST PIPE UNASSEMBLED POSITION HAVING AN END PORTION FORMED WITH AN INTERNAL SHOULDER, SAID SECOND PIPE IN UNASSEMBLED POSITION HAVING AN END PORTION SLIDABLE WITHIN SAID FIRST PIPE END PORTION, SAID SECOND PIPE END PORTION IN UNASSEMBLED POSITION HAVING A SUBSTANTIALLY UNIFORM THICKNESS AND HAVING AN ANNULAR GROOVE THE WALL OF WHICH AT LEAST PARTIALLY EXTENDS INWARDLY OF THE INSIDE SURFACE OF THE REMAINDER OF SAID SECOND PIPE END PORTION ACJACENT SAID GROVE WHEREBY SAID GROOVE IS ADAPTED TO BE BUCKLED UPON ABUTMENT OF THE END OF SAID SECOND PIPE END PORTION AGAINST SAID SHOULDER BY INSERTION OF THE SECOND PIPE END PORTION WITHIN SAID FIRST PIPE END PORTION AND AXIAL FORCING OF SAID PIPES TOWARDS EACH OTHER TO EXPAND THE ANNULAR OUTER ENDS OF SAID GROOVE WALL BEYOND THE OUTER SURFACE OF THE REMAINDER OF SAID SECOND PIPE END PORTION ADJACENT SAID GOROOVE TO DEFORM THE INNER WALL OF SAID FIRST PIPE END PORTION TO FORM AT LEAST ONE INTERNAL ANNULAR DEPRESSION, SAID SECOND PIPE END PORTION IN ASSEMBLED POSITION HAVING SAID ANNULAR GROOVE IN BUCKLED CONDITION WITH THE ANNULAR OUTER ENDS OF SAID GROOVE EXTENDING OUTWARDLY BDYOND THE OUTER SURFACE OF THE REMAINDER OF SAID SECOND PIPE END PORTION ADJACENT SAID GROOVE AND EACH OF SAID ANNULAR ENDS BEING DISPOSED IN SAID ANNULAR DEPRESSION.