AWS D3.6M:2010

This Code covers the requirements for welding structures or components under the surface of water. It includes weldingin both dry and wet environments. Clauses 1 through 6 constitute the general requirements for underwater welding whileclauses 7 through 9 contain the special requirements applicable to three individual classes of weld:

• Class A-Comparable to above-water welding
• Class B-For less critical applications
• Class O-To meet the requirements of another designated code or specification