This specification covers the requirements for welding structures or components under the surface of water. It includes welding in both dry and wet environments. Sections 1 through 6 constitute the general requirements for underwater welding while sections 7 through 10 contain the special requirements applicable to four individual classes of weld: Class A - Comparable to above-water welding Class B - For less critical applications Class C - Where load bearing is not a primary consideration Class O - To meet the requirements of another designated code or specification. Operations required at the surface related to and in support of underwater welding are within the scope of this document, but welding above the surface is not.