Coupling fitting for pipes

A coupling fitting comprising:

• a pipeline having an inner diameter and defining an end and an outwardly directed radial annular bead disposed at a predetermined distance from said end;
• a connecting sleeve pushed onto said pipeline;
• said connecting sleeve having a first end disposed in the region of said annular bead and an inner wall surface defining a first inner diameter dimensioned to cause said annular bead and said inner wall surface to conjointly define a gap therebetween;
• said connecting sleeve further having a second end defining a second inner diameter which corresponds to said inner diameter of said pipeline;
• a transition zone of said connecting sleeve is defined between said annular bead of the pipeline and said end of the pipeline;
• wherein said first inner diameter of said connecting sleeve transitions from said first inner diameter at said second end to said second inner diameter of said first end of said connecting sleeve to permit said connecting sleeve to be pushed onto said pipeline only so far until said end of said pipeline does not fit any farther into said second diameter of said connecting sleeve;
• an annular cavity between a said inner wall surface of said connecting sleeve and an outer surface of said pipeline;
• an elastic annular seal disposed in said annular cavity;
• an injection molded connecting ring made of plastics material disposed in a region of said coupling fitting which is axially dimensioned so as to permit said injection molded connecting ring to cover over said first end of said connecting sleeve both in a first direction toward said second end of said connecting sleeve as well as in a second direction opposite said first direction to a predetermined dimension;
• and,
• the plastics material, because of injection pressure, extending through said gap into said annular cavity up to said elastic annular seal and extending from behind said annular bead in a direction away from said end of said pipeline so as to form a shoulder extending inwardly to said pipeline.