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NIRE Annual Report
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1998

Steel Pipe Repair Technique using the Explosives Welding

Fracture Mechanics and Explosive Division
Safety Engineering Department
Objectives
It is necessary to repair the gas and water pipe line network urgently in case of the disasters like an earthquake. However it is impossible to move the large-scale restoration machine and a lot of number of men in the struck area which the connecting road was cut in pieces. Therefore, the development of the new method to repair the energy life-line is hoped for in the struck area. The explosive weldings was applied to repair the energy life-line.
Results
Fig.1 shows the outline to apply the explosive weldings to the urgent restoration method of the destroyed pipe-line. The experiments of explosive weldings were carried out to know the deformation of steel pipe and joint between the flyer plate and steel pipe. The dimension of flyer plate is 25×100mm and the thickness of the plate is 1.5mm and it was made of SS400 steel. The emulsion explosives is changed from 20g to 50g and initiated using electric detonator.
Fig.2 shows the relation between the Maximum deformation of the steel pipe and distance of stand-off. The experiments with 0mm stand-off distance and 20g with 2mm stand-off distance were failed to joint. However other experiments except above results can be jointed between the flyer plate and steel pipe. So the enough explosive over 25g can be jointed with 2mm distance of stand-off. In case of 20g explosives charge it is possible to joint over the 5mm distance of stand-off. The deformation distance of the steel pipe after experiments is increasing in proportion to the amount of explosives. In case of same amount of explosives, the Maximum deformation distance of steel pipe is shown in 0mm stand-off and the deformation of the steel pipe is decrease as the distance of stand-off is increasing, But the stand-off over 5mm is shown the same deformation. As the results of these experiments the condition to suppress the deformation distance of the steel pipe to the minimum is 20g explosives and the distance of stand-off is over 5mm on this experiment condition.


Selected Publications
1) Analysis of the Movement of Flyer Plate in Explosive Weldings,2nd Asia-Pacific Conference on Shock & Impact Loads on Structure, 1997
2) Study on the behavior of the flyer plate for explosive welding using high-speed camera, Symposium on High Speed Photography and Photonics, 1997

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