AWS D3.6M:2017

This code covers the requirements for welding structures or components under the surface of water. It includes welding in both dry and wet environments. Clauses 1 through 8 constitute the general requirements for underwater welding, while clauses 9 through 11 contain the special requirements applicable to three individual classes of weld as follows: Class Aâ??Comparable to above-water welding Class Bâ??For less critical applications Class Oâ??To meet the requirements of another designated code or specification
Scope : This code covers underwater welding in both dry and wet environments. Five basic methods for underwater welding are covered in this specification as follows: (1) Welding in a pressure vessel in which the pressure is reduced to approximately one atmosphere, independent of depth (dry welding at one atmosphere). (2) Welding at ambient pressure in a large chamber from which water has been displaced in an atmosphere such that the welder/diver does not work in diving equipment (dry welding in a habitat). (3) Welding at ambient pressure in a simple open-bottomed dry chamber that accommodates, as a minimum, the head and shoulders of the welder/diver in full diving equipment (dry chamber welding). (4) Welding at ambient pressure in a small, transparent, gas-filled enclosure with the welder/diver outside in the water (dry-spot welding). (5) Welding at ambient pressure with the welder/diver in the water without any mechanical barrier between the water and the welding arc (wet welding). This document is intended to define the important variables associated with underwater welding and to describe welding and inspection procedures so that work of a known quality level can be conveniently specified. Three weld classes (A, B, and O) are specified herein. They encompass the range of quality and properties currently produced by application of the various methods. Each weld class defines a set of criteria for weldment properties that must be estab¬lished during qualification, and a set of weld soundness requirements that are to be verified during construction. Welds in each class must meet all the criteria specified for that class. This code does not address the selection of the class that meets the service requirements of a particular application. The selection of the class of weld to be provided is to be prescribed by the Customer. All provisions of this document apply equally to new construction and to modification and repair of existing structures underwater. This document may be used in conjunction with other applicable codes or specifications for design, construc¬tion, or repair. 1.2 Units of Measurement. This standard makes sole use of International System of Units (SI). Approximate mathematical equivalents in U.S. Customary Units are provided for comparison in parentheses or in appropriate columns in tables and figures. 1.3 Safety. Safety and health issues and concerns are beyond the scope of this standard; some safety and health information is provided, but such issues are not fully addressed herein. Recommended Guidelines for Safety in Underwater Welding are found in Annex B (Informative). Safety and health information is available from the following sources: American Welding Society: (1) ANSI Z49.1, Safety in Welding, Cutting, and Allied Processes.(2) AWS Safety and Health Fact Sheets (3) Other safety and health information on the AWS website Material or Equipment Manufacturers: (1) Safety Data Sheets supplied by materials manufacturers (2) Operating Manuals supplied by equipment manufacturers Association of Diving Contractors International: (1) International Consensus Standards for Commercial Diving and Underwater Operations International Marine Contractors Association: (1) IMCA D 014, International Code of Practice for Offshore Diving (2) IMCA D 045/IMCA R 015, Code of Practice for the Safe Use of Electricity Underwater Applicable Regulatory Agencies Work performed in accordance with this standard may involve the use of materials that have been deemed hazardous, and may involve operations or equipment that may cause injury or death. This standard does not purport to address all safety and health risks that may be encountered. The user of this standard should establish an appropriate safety program to address such risks as well as to meet applicable regulatory requirements. ANSI Z49.1 should be considered when devel¬oping the safety program. 1.4 Application 1.4.1 All references to the need for approval shall be interpreted to mean approval by a duly designated person acting for and on behalf of the Customer on all matters within the scope of this code. The Customer may designate an engineer, inspector, or other(s) to act in the Customerâ??s behalf to ensure that the requirements of this code are fulfilled. The Customer should specify the authority of the authorized representatives. Hereinafter, the term Customer shall be used to mean the party contracting for the work or the authorized representative. 1.4.2 In this code, the term â??shallâ? indicates a mandatory requirement and has the significance of excluding the idea of discretion. The word â??shouldâ? indicates a nonmandatory recommended practice. The word â??mayâ? implies no obligation and expresses liberty or permission. 1.4.3 Where alternative requirements are permitted by the specification, all requirements that modify this code shall be incorporated into contract documents. 1.4.4 For Class O welds (see 4.1.6 and 7.5), conflicts between referenced documents and this document shall be brought to the attention of the Customer for disposition. In general, the referenced documents may take precedence in matters not affected by the underwater environment. However, this document shall take precedence in matters related to the underwater welding environment and working conditions. 1.5 Base Metals 1.5.1 This standard covers the welding of low alloy, carbon steels, and austenitic stainless steels. The weldability of the steel and the procedures for welding it shall be established by qualification. The carbon content, carbon equivalent, and tensile strength of low alloy and carbon steels are critical variables for underwater welding. Production welding on low alloy and carbon steels with a carbon content, carbon equivalent, or tensile strength above that qualified shall require requalification of the procedure. 1.5.2 This code may be used for welding of other base metals. In such cases, applicability of specific requirements shall be determined by the Customer. 1.6 Welding Process 1.6.1 Gas metal arc welding (GMAW), gas tungsten arc welding (GTAW), flux cored arc welding (FCAW), plasma arc welding (PAW), and shielded metal arc welding (SMAW) are the principal joining processes addressed by this code. These processes may be used, provided the welding procedure is qualified in accordance with all applicable requirements of this document. 1.6.2 Other welding processes may be used at the discretion of the Customer, provided the applicable qualification requirements of this code are met. 1.7 Welding and NDE Symbols. Welding and examination symbols shall be those shown in AWS A2.4, Standard Symbols for Welding, Brazing, and Nondestructive Examination. Special conditions shall be fully explained by added notes or details.