Patent ID: 7530485

Claim:
A method of explosively welding a smaller metal tube to a larger metal tube of equal length, said smaller tube comprising an outside diameter, opposed internal and external surfaces, opposed first and second ends, and a wall thickness, said larger tube comprising an inside diameter, opposed internal and external surfaces, opposed first and second ends, and a wall thickness, wherein the outside diameter of the smaller tube is less than the inside diameter of the larger tube, the method comprising the steps of: a) positioning the smaller tube coaxially within the larger tube; b) inserting at least one shim between the internal surface of the larger tube and the external surface of the smaller tube forming a uniform annular gap between the smaller and larger tubes, said gap defined by overlapping portions of the coaxially-oriented external surface of the smaller tube and the internal surface of the larger tube, said gap further having a width measured by the distance between the external surface of the smaller tube and the internal surface of the larger tube; c) covering the second end of the smaller tube; d) filling at least a portion of the smaller tube with an explosive material bringing said explosive material in direct contact with the internal surface of the smaller tube, said explosive material, once filled, having a top surface within the smaller tube and beneath the first end of said smaller tube; e) placing the second ends of the larger and smaller tubes on a generally flat and horizontal surface; f) sealing the annular gap; g) creating a vacuum in said annular gap; and h) detonating the explosive material from said top surface; wherein said detonation initiates an explosive front traveling down the internal surface of the smaller tube expanding the internal surface of the smaller tube with sufficient velocity to weld the external surface of the smaller tube to the internal surface of the larger tube.