Abstract: A plurality of electric blasting caps are fired through the ignition system which includes a transformer having a primary winding and a secondary winding. The secondary winding of the transformer is connected to the resistive elements of the blasting caps through a blasting circuit which is electromagnetically coupled to the resistive elements of the blasting caps via a small toroid transformer. A D.C. voltage is stored on a storage capacitor which has one end connected to the center point of the primary winding. The other ends of each half of the primary winding are connected through a driver circuit to ground. Each driver circuit is enabled by a flip-flop at predetermined intervals, whereby the storage capacitor will discharge through the appropriate half of the primary, to thereby produce a pulse train at the output of the secondary. The pulse train provides the ignition power for igniting the electric blasting caps.

Abstract: An explosive package is provided which is particularly adapted to be placed against and around the inside and outside curvature of a metal pipe for explosive welding purposes. The package is a substantially flat trapezoidal-shaped container, the shorter, non-parallel ends of which can be adjustably abutted against the non-parallel ends of a similar package in order to provide a continuous ring or band of explosives inside or outside the circumference of a pipe.