A tube nut includes a first member and a second member. The first member is threaded and defines a first hole. The second member is selectively rotatable with respect to the first member and defines a second hole. A tube or pipe extends through the first and second holes. The rotation of the first member in a threaded hole causes an axial load on the second member and the tube to urge the tube against a seat to provide a seal between the tube and a fluid passage. Relative rotation between the first and second members reduces or eliminates torsional strain on the tube.