Developments in underwater wet welding (UWW) over the past four decades have been reviewed, with particular emphasis in the work conducted in the last 10 years. Shielded metal arc welding with rutile-based coated electrodes was established as the most applied process in the practice of wet welding of structural steels in shallow water. Advances achieved in the previous decades had already led to control of chemical composition and microstructure of the weld metal (WM). Research and development in consumables formulation have led to great control of the amount of weld metal hydrogen content and the level of weld porosity. The main focus of research and development in the last decade was on weldability of naval and offshore structural steels and acceptance of welding procedures for Class A weld classification according to AWS D3.6 code. Applications of strictly-controlled welding techniques, including new post-weld heat treatment procedures, allowed for the welding of steels with carbon equivalent values greater than 0.40. Classification societies are meticulously scrutinizing wet welding procedures and wet weld properties in structural steels at depths smaller than 30 m prior to qualifying them as Class A capable. Alternate wet welding processes that have been tested in previous decades such as friction stir welding, dry local habitat and GMAW have not achieved great successes as originally claimed. Effectively, almost all the development of new UWW processes in the last decade has focused on flux-cored arc welding (FCAW) process. This paper describes the advances accomplished in the last 10 years focusing on wet welding of steels. This process is performed with no mechanical barrier between water and welding arc. The principal advantage of the process is its intrinsic simplicity which allows it to be applied even in the most geometrically complex structures.
The first important comprehensive review on underwater welding was performed in 1976, other important reviews were published between years 1990 and 2000. Rowe and Liu in 2001 performed a complete and extensive review containing experimental UWW research results in detail. Minor reviews without in depth reporting of experimental work data were performed in the decade of 2000s. The Third International Workshop on UWW was held in November 2010 in Houston, Texas, USA, during which some reviews were reported, and future trends discussed.
The last important review of this field was performed in 2012 by Liu et al. in Welding Handbook Volume 3. This review is focused on the current state development of UWW processes. It shows that the progress made in previous decades has allowed researchers in the past 10 years to develop state-of-the-art underwater wet welding processes. This paper focuses on discussion about consumable composition optimization, UWW weldability, consumables and procedure qualification, and alternate wet welding processes.