Abstract: A weldless one-piece flow device body such as a valve body has one or more tubes or stubs having distal ends of a greater diameter than the stubs, the stubs extending integrally from the valve body. All machining, plating, and valve assembly operations are performed before end fittings such as compression nuts are affixed to the stubs. The compression nuts with internal threads are slid over the stubs' distal ends, and the reverse side of a vacuum face seal on each distal end has a controlled radius R.sub.0. The nut includes an internal cylindrical semi-circular groove inboard of the end of the nut opposite the nut threads. An aperture having a diameter equal to or somewhat greater than 2R.sub.0 extends at an angle through a nut wall and provides a tangential route to force a slide wire into and around the groove and partially into an annulus formed around the stub between the controlled radius R.sub.0 and a wall of the valve body.