Abstract: A tube union for forming a joint between adjacent lengths of malleable tubing formed by a pair of push-rings, each push-ring of the pair being the mirror image of the other and disposed in an opposed abutting engagement in a common plane of abutment normal to the axes of the push-ring collectively defining a sleeve-expansion chamber characterized by annular cross sections and tapering in opposite directions from a major diameter in the plane of abutment to a minor diameter in planes uniformly spaced from the sides of a plane of abutment, a malleable sleeve having its mid-portion radially expanded into engaged relationship with the adjacent surfaces of the chamber and further characterized by an internal, tube-coupling cavity substantially conforming to the shape of the sleeve-expansion member, a pair of end portions of lengths of malleable tubing oppositely inserted into the sleeve, each of the end portions being radially expanded into engaged relation with the adjacent surface of the tube-coupling cavity and