Coupling assembly for replacement of return bend

Claim 1

A coupling assembly for attaching a return bend to a heat exchanger tube, said tube being formed with an expanded cylindrical end portion spaced outwardly from a tube support sheet, said expanded end portion terminating in an outwardly flaring bell which extends a relatively short distance from the tube sheet, said tube having a substantially constant wall thickness; said assembly including a coupling nut formed at the inner end thereof with a cylindrical bore terminating at an annular shoulder surface extending radially outward from said cylindrical bore, and merging with an enlarged bore extending to the outer end of said nut, said cylindrical bore being dimensioned to permit said nut to be passed over said flaring bell end of said tube, a two-part split sleeve formed at the inner end portion thereof with a cylindrical bore merging with an outwardly extending conical surface formed comparable to said flaring bell end of said tube, said conical surface being spaced from said inner end of said sleeve a distance not greater than the spacing of said expanded portion of said tube from said tube sheet; said sleeve being formed intermediate its ends with an external shoulder spaced axially for engagement by said shoulder in said nut, when said nut and sleeve are positioned on said tube sheet, said enlarged bore in said nut being dimensioned to permit the segments of said sleeve to be inserted successively between said tube and said nut when said nut is positioned on said tube sheet, said assembly further including a coupling member fixed to a return bend and being formed for threaded engagement by said nut, said nut being cooperable upon being threaded to said coupling member to draw said split sleeve against said flaring bell end of said tube and the latter in leak-tight engagement with said coupling member.