Abstract Before 1970 underwater "wet" welding techniques were virtually unchanged after 20 years. All position multiphase welds were not being made and high strength steels could not be welded without cracking. Wet wilding?s role as an underwater tool was, except for minor or isolated cases, relegated to salvage and emergency repairs. Now, after several years of research, development and practical application in underwater welded repairs of offshore structures and harbor facilities it has been demonstrated that sound all position multiphase welds can be made using conventional stick electrodes (shielded metal arc process) in a water environment. Restrained underwater welding tests have shown that steels with a carbon equivalent under .40 can be welded with mild steel electrodes without cracking. Steels with a carbon equivalent over .40 and up to .597 have been wet welded without cracking using austenitic electrodes. This paper is presented as a report on the state of the art of wet welding as represented by CBI research, development and repair work done through February, 1972. Introduction In conjunction with the design, construction, and installation of large underwater storage tanks - Chicago Bridge & Iron Co. established an objective of developing in-house capability of making underwater welded repairs to such structures. The high cost of creating a dry hyperbaric environment for underwater welders directed efforts toward developing the capability of making sound all position multiphase welds in a water environment. A study of the then current state of the art of wet welding offered little encouragement for success of the project. Various reports described the "self-consuming" or drag technique used to make single pass fillet welds but multiphase welds were not recommended because of lack of welder visibility. Some authors said it was impossible to make multiphase overhead welds and others spoke of cracking and stress corrosion. At best, it appeared that, with minor exceptions, wet welding was to be used as a last resort for salvage and emergency repairs. In determining the state of the art of wet welding, it was found that - except for the development of underwater electrode holders and improved waterproof coatings - techniques were basically unchanged over 20 years. CBI felt that improvements could be made through the concentrated and coordinated efforts of a team made up of highly skilled welders and welding engineers. The objective was to determine from first hand experience the value of wet welding before branding it unacceptable for permanent underwater repairs. Personnel were selected and welders given formal diving training, practical offshore experience and many hours of wet welding practice. They were soon comfortable and proficient in their dive gear and in a water environment. Phase I Wet Welding Research Phase I of CBI's underwater welding R&D program was started at the company's Research Center in Plainfield, Illinois. By plan it was to be of short duration - about three weeks - and the objective was to establish whether or not it was feasible to make sound all position multipass welds in a water environment. Welds were made in 33' deep fresh water using the shielded metal arc (stick electrode) process. Welding machines were conventional constant current DC machines set for straight polarity