Welded sleeve fitting

Claim 1

A tube coupling structure comprising: a body having a port and a threaded portion coaxially of said port; a tubular sleeve having an inner end adapted to sealingly engage the body, an annular radially outer, axially outwardly facing shoulder, and a tubular outer end extending axially outwardly of said shoulder and terminating in a distal end; an annular nut having a threaded portion threadedly connected to the body threaded portion, said nut coaxially encircling said sleeve and having an inturned flange disposed axially outwardly of said sleeve shoulder for engaging said shoulder to urge said sleeve into sealing engagement with said body as an incident of threaded advance of said nut toward said body; a tube end extending coaxially inwardly into said sleeve; and an annular weld between said sleeve distal end and said tube sealingly connecting the sleeve to the tube end, said weld and said shoulder having a radial outer dimension greater than the corresponding radial inner dimension of said nut flange whereby said nut flange is captured axially movably between said sleeve shoulder and said weld in the made-up arrangement of the tube coupling, the length of said sleeve outer end outwardly of said shoulder being preselected to permit withdrawal of the nut axially outwardly of the axially inner end of the sleeve thereby to permit separation of said sleeve and nut from said body with said nut flange maintained radially outwardly of said sleeve outer end.