engleski

Underwater welding

Underwater technologies take special role in modern offshore facilities, pipelines, ships and floating objects repair and maintenance. Huge numbers of underwater structures which are used in oil and gas production, as well as increasing intensity of naval transport present the technological cornerstone of the economical development and strategic issues. On the other hand, almost daily we are witnessing various cases of environmental pollution that are caused by means of improper usage of these installations or inadequate maintenance. Maintenance of structures or eventual repairs under the water line demands application of sophisticated technologies such as underwater welding, in wet or dry environment. Underwater welding is unique process which integrates several, on the first sight, contradictory phenomena as water or gas at high hydrostatic pressure, electricity and electric arc as a heat source and metallurgical transformations during solidification of weld metal, everything constricted in a small space and short time. Interactions of mentioned physical phenomena in, what is considered normal conditions, presents not only the huge risk for the weld quality but life threatening safety risk for the welder. So, the question arises, how is it possible to weld underwater and achieve good and solid weld joint, able to perform all the tasks in harsh environment? Due to high safety risks, great importance and responsibility in performing of these activities is on the highly trained and educated human resources, including divers and organization team on the surface. Specially designed equipment is necessary for successful accomplishing of practical tasks. In global aspects investigations for improvement and application of underwater welding and NDT techniques have been highly intense through recent decade. In this chapter main issues about underwater wet and dry welding are described giving basic knowledge and understanding of these, very often misunderstood, sophisticated technologies. Technological variations, consumables and weldability problems are presented through analysis of basic physical and chemical processes. Besides, brief scope of underwater NDT techniques is given in order to help understand how difficult and important quality evaluation of welds on underwater structures is.

underwater dry welding, underwater wet welding, weldability, equipment

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