However, until recently these advancements have been minimal. Underwater welding has historically been restricted in its use by the very factor that makes it so unique - the water.
Water can cause underwater repairs to become brittle.
Hydrogen, a component within water, can chemically react with newly welded material to create a brittle weld, or can cause delayed cracking in the welded area hours or days after repair. This limits the longevity of the repair. Water also induces rapid cooling of the area, causing detrimental microstructures to form and brittleness to occur if the weld is not properly treated after welding. Similar to the traditional land-based welding practices, underwater welding attaches pieces of metal by the use of intense heat from an electric arc. The flux, consisting of minerals, metals, and organic materials, coats the bare steel core of the rod.