Patent GB-1468370-A (GB)
Title: Joining together of cylindrical members
IPC: F16B1/00
Filed: 1974-02-27
Abstract: 1468370 Pipe joints SENTRALINSTITUTT FOR INDUSTRIELL FORSKNING 27 Feb 1974 [27 Feb 1973] 8902/74 Heading F2G [Also in Divisions B3 and H2] A cylindrical inner member is joined to a surrounding member by a locking element deformed into engagement with one or both of the members by an explosive element positioned between the members to form a series of axially spaced annular zones of interlocking connection. Piles, rods, wires and electric cables may be joined; pipes may be closed off or joined on the sea bed. Pipes 20a, 20b, Fig. 1, are joined to a sleeve 21 by locking rings 22 of soft metal expanded by explosive elements 23 into recesses 24. Holes 25 are provided for indicating that the rings have been deformed, e.g. by means of pins or electrical contacts. Strain gauges or pressure sensors may be incorporated in order to record the course of the explosion in the passages. The rings may be expanded successively in the axial direction of the members from one end to the other, from both ends towards the centre or from the centre towards the ends. Corrosion is prevented anodically by inserts 26 of zinc, cadmium or aluminium; chromium plating may also be used. A welded joint, Fig. 2 (not shown), is provided in each ring 22 and a firing device may be provided diametrically opposite the weld or to one side of the weld. Alternatively the rings may be unjoined at their ends for ease of insertion. A flange may be provided at each end of the sleeve 21, one of the flanges preferably being fixed after insertion of the rings 22 which have passages of elongated or circular cross-section for the explosive. In another form, Fig. 4, a helical coil explosive fuse cord 223 is embedded in a cylindrical or helical locking sleeve 222 for securing a soil pipe 220a in a socket 221. In a further form, Fig. 3 (not shown), a welded socket is used and the locking rings deform the inner pipe. A locking sleeve 322, Fig. 5, may be welded to the socket 321 which has grooves 327 for the explosive. Grooves 427, Fig. 6, for the explosive 423 and closed by protective rings 429 and welding 430 provide integral locking elements 422. Several other constructions are described, Figs. 7-10 (not shown), in one of which (Fig. 8) rebound is reduced by a ring (632) of aluminium or copper which then functions as a seal. Rebound may also be reduced by isolating the joint by rubber seals and replacing water with air, hydrogen or a vacuum. The locking elements may consist of frustoconical wedges 922, Fig. 11, which are deformed against the members 920a, 921 by an explosive element 923. The explosive element 23, Fig. 12, may have flat strips of explosive or round tubes containing the explosive. A plastics transmission material 41 surrounds the explosive or is on one side, the other being covered with a shock-absorbing textile. A heat-shield such as asbestos protects the explosive against welding temperatures, the element being encased in a plastics, aluminium or copper alloy sheath 43. A stronger metal case 31 may be provided. An interior secondary detonator (44), Fig. 13 (not shown), may be used with a primary detonator (52).