Coupling with tongue and groove

A method of coupling first and second pipe elements in end-to-end facing relationship comprising:

• obtaining a coupling, the coupling including
• an annular gasket, the annular gasket including at least one sealing surface directed radially inwardly and an outer surface directed radially outwardly;
• at least one segment, each segment being approximately semi-circular and including at least one inner surface, at least one outer surface, and at least two ends, each segment including a fastener pad protruding proximate to each end, each fastener pad defining a fastener hole, each end including at least one of a tongue and a groove, each tongue protruding circumferentially from at least one end, each tongue defining a tongue outer surface facing radially outwardly, each groove defined circumferentially in at least one end, each groove defining a groove shoulder surface facing the tongue outer surface of a one of each tongue, the tongue outer surface angled at a non-zero angle relative to the groove shoulder surface, the tongue outer surface being nonparallel to the groove shoulder surface;
• and
• at least one fastener, wherein at least one portion of a shaft portion of the fastener is sized to engage at least one fastener hole in at least one segment;
• obtaining a first pipe element, the first pipe element defining a pipe element groove proximate to the end of the first pipe element;
• slipping the entire coupling onto the first pipe element beyond the pipe element groove in the first pipe element such that the pipe element groove is positioned between each portion of the coupling and the end of the first pipe element;
• aligning the second pipe element in end-to-end facing relationship with the first pipe element;
• slipping the coupling onto the second pipe element such that the segments of the coupling straddle the ends of the first and second pipe elements;
• and
• engaging each fastener with each segment to bring each segment into contact with an outer surface of each of the first and second pipe elements;
• and
• deforming each segment around the outer surfaces of the first and second pipe elements by tightening each fastener to reduce a radius of each segment, wherein deforming each segment aligns the tongue outer surface of each tongue with the groove shoulder surface of a one of each groove and positions the tongue outer surface of each tongue parallel and flush to the groove shoulder surface of a one of each groove.