Abstract: A fitting includes a stepped passage having a pair of axially spaced apart shoulders, one of which acts as a stop shoulder preventing a bell shaped end of a tube support from being inserted past the stop shoulder, and the other of which has a trepan formed therein which is deformed radially inwardly to wrap around the bell shaped end portion. The trepan has a generally triangular shape cross section including an axial inner wall in alignment with the outer diameter of the stop shoulder and a tapered outer wall intersecting the inner wall at an acute angle. In one form of the invention, the entire outer edge of the trepan is deformed radially inwardly to form an inturned lip that wraps around the bell shaped end portion of the tube support. In another form of the invention, a plurality of circumferentially spaced segments of the outer edge of the trepan are deformed radially inwardly to form individual fingers that wrap around the bell shaped end portion of the tube support.