Tube couplings for co-axial tubing

A tube coupling for co-axial tubing comprising a body having a throughway open at one end for receiving an end portion of a length of co-axial tubing, the throughway having an internal annular seat spaced from said open end to receive the outer tube of the co-axial tubing, a tube locking means disposed between the seat and said open end to receive and lock the tubing in the throughway, an annular seal disposed between the seat and locking means to seal with the outer surface of said tubing and said body, a conduit extending along the throughway and a single radial web formed integrally with and extending between the conduit and body to mount the conduit concentrically in the throughway and to define inner and outer concentric passageways extending through the body for communication with the inner and outer tubes respectively, one end of the conduit having an encircling recess to receive an inner tube of said co-axial tubing and an annular encircling seal located in the recess to seal with said tube.