Abstract: A length of flexible metal piping includes an interlockably shaped metal band spirally formed into a plurality of winding groups wherein each group includes a plurality of interlocked windings. Each of the winding groups are connected to each other by at least one free winding wherein the leading portion of a first winding is separated from the leading portion of a corresponding subsequent winding and interlocking is prevented for at least one revolution. Each free winding, which constitutes one circumference of the piping, is formed by the insertion of a shaping tool into contact with the leading portion of the free winding prior to the point where this leading portion would normally interlock with the leading portion of a corresponding subsequent winding one revolution later. The shaping tool alters the cross-sectional arrangement of the metal band such that interlocking of that portion of this spiralling band which is contacted by the shaping tool is prevented.

Abstract: An apparatus for axially joining two tubular members of differing diameters in which a band of metal is passed around the adjacent ends of the members and circumferentially stressed by means of reinforcing, notched bars secured to the band, to conform with the outer surfaces of the members. The clamping device may be used to make a strong gas or sound leak-proof joint between two substantially incompressible tubular members in which event the band of metal is substantially stretched plastically so that it conforms intimately with the outer surfaces of the tubular members. The clamping device may also be used to make a joint which is not necessarily gas-leak-proof and is more easily disconnected by not stressing the band of metal to the point where it goes through a substantial amount of plastic yielding.