A revised edition of the American Welding Society’s AWS D3.6M Underwater Welding Code, has been published. The standard known as D3.6M:2010 supersedes the 1999 edition. The 142-page book covers underwater welding in both dry and wet environments. All provisions of the document apply equally to new construction and to modification and repair of existing structures underwater. Initially applied as a means of temporary repair for damaged steel-hulled vessels, underwater welding has evolved into an accepted method of construction and repair of engineered structures. Recent applications included engineered repair and alteration of off-shore structures, submerged marine pipelines, underwater port facilities and nuclear power plant components.