After briefly describing the physical aspects of explo sive welding ingefieral terms, this paper outlines how the underlying principles are applied to the making of pipeline connections under water. Using the same basic weld geometry, two general connection types are available -a pipe flange and a sleeve weld. '-The associated systems of pipe preparation, flushing and drying, dewatering, welding, and subsequent inspection receive attention, and in all cases the minimal requirement for operator skill is emphasized. Results of mechanical property tests are presented for particular pipe sizes. Finally, practicaIapplications are proposed with emphasis on the suitability of the technique for all water depths.

Both explosive welding and bottomtowed pipelines have considerable merit in their own right in the field of offshore pipeline engineering. The present paper describes how these two techniques complement each other to provide a pipeline construction method which is both technically attractive and cost effective. In addition to being applicable to the normal range of pipeline construction projects it may be sufficiently attractive to irtfluence a move to a pipeline in marginal cases where the cost or difficulty of laying a pipeline would not normally be justified. The bottom-tow and explosive welding techniques have certain common features and advantages which permit them to be mobilized qUickly for short periods of commitment. Both can utilize a range of simple, cheap and readily available surface vessels and are not particularly sensitive to surface weather conditions. Both techniques are carefully controlled and monitored from the surface and provide a flexibility of application in meeting different types of project. Details are presented of work which demonstrates the feasibility of a new method of accurately stabbing a pipeline with an appropriate end fitting onto a previously positioned pipeline.

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