GB1430141A - Explosive welding of hollow metal cylinders such as pipes - Google Patents

Abstract

1430141 Welding by pressure EXXON RESEARCH & ENG CO 20 March 1973 [12 May 1972] 13233/73 Heading B3R An apparatus for use in the explosive welding of the ends of hollow metal cylinders comprises an annular metal collar to be welded about the abutting ends of the hollow cylinders which collar has a maximum radial cross-sectional thickness at least at its central diametral plane and a minimum radial cross-sectional thickness in the diametral planes at its ends and its inner surface is divergent towards each end of the collar so that when arranged on the cylinders annular spaces increasing in width towards the ends of the collar are provided, explosive material is located on the outer surface of the collar and means are provided for simultaneously detonating the explosive material at two or more equiangularly spaced initiation points in the central diametral plane of the collar. In an embodiment a mandrel 11 is arranged within two abutted pipes 40, 40a, Fig. 9, and the mandrel is expanded into tight contact with the abutting pipe ends. The mandrel comprises four interengaging wedge segments 12, 13, 14, 15, Figs. 1, 3, arranged about two telescoping members 41, 42 extending respectively from plates 22, 25. A rotatable threaded rod 26 engages in a nut 27 secured to plate 22 and is connected to plate 25 by lock nuts 28, 29 to allow rotation relative thereto and resilient pads 30, 31 are provided between the segments 12, 14 and plate 22 and pads 32 between segments 13, 15 and plate 25. Rods 16, 16<SP>1</SP>, 17, 17<SP>1</SP>, 18, 18<SP>1</SP>, 19, 191 extend from each end of each segment. The expansion of the mandrel is effected by rotating the rod 26 to draw the plates 22, 25 together, involving compression of the pads. A collar 46 with cylindrical outer surface and tapered inner surfaces and carrying layers of explosive 46 is arranged about the abutting ends and then the rod 26 is rotated in the opposite direction to release the plates 22, 25, the segments remaining wedged in contact. A number of strips of explosive are arranged on an annular body 47 in contact with the explosive 46 at spaced points and are simultaneously initiated. During detonation of the explosive the collar is formed into welding contact with the pipe ends and the mandrel segments are released by the explosive forces. The collar may, in a modification, have an inward curvature in its outer surface, a portion of the inner surface being cylindrical which may be long enough to cover a V recess formed between the pipe ends. A metal or other ring may be placed in the recess. The explosive may be moulded or cast.