Abstract: A method is provided for the explosive welding together of sections of large diameter metal pipe of the kind used in the construction of high volume oil and gas pipelines. In the method, internal and external band charges of welding explosive are simultaneously detonated adjacent to overlapped telescoped pipe ends. The welding charges are detonated simultaneously by means of very high detonation velocity initiation explosive charges placed along a leading edge of each welding explosive charge. The initiating explosive charges are each set off by a single detonator means. The velocity of detonation of the initiating explosive is selected so that welding charges are simultaneously detonated around the pipes while maintaining the detonation fronts at superimposed locations and at a large angle to the pipe axis. This avoids unbalancing forces on the pipes and minimizes the collision of circumferential shock waves thus preventing pipe damage and imperfect welds.

Abstract: A method and apparatus for attaching strain gages to substrates is described, which is especially useful for field installation, and especially for materials which experience a drastic reduction in fatigue strength when heated as in spot welding. A strain gage having a backing plate is attached to a substrate by using a foil of brazing material between the backing plate and substrate. A pair of electrodes that are connected to a current source, are applied to opposite sides of the backing plate, so that heating of the structure occurs primarily along the relatively highly conductive foil of brazing material. Field installations are facilitated by utilizing a backing plate with "wings" extending at an upward incline from either side of the backing plate, by attaching the electrodes to the wings to perform the brazing operation, and by breaking off the wings after the brazing is completed.