Welding

Initially applied for the temporary repair for damaged steel hulled vessels underwater welding has evolved into an accepted method of construction and repair of engineered structures. Recent applications include engineered repair and alterations of off-shore structures, submerged marine pipelines, underwater port facilities and nuclear power plant components.

With the AWS D3.6:2010 Underwater Welding Code, the American Welding Society defines important variables associated with underwater welding (e.g. metal transfer characteristics, solidification behavior, weld appearance, mechanical properties, ...) and to describe welding and inspection procedures so that work of a known quality level can be conveniently be specified.

Three weld classes (A, B and O) are specified in the current document. Each weld class defines a set of criteria for weldment properties that must be established during qualification. Welds in each class must meet all criteria specified for that class.

The PQR’s and WPS’s at Subsea Global Solutions are all based on class A weld requirements in accordance with AWS D3.6:1999. Class A welds are of the same quality as their surface counterpart. SGS qualified underwater wet welding fillet weld procedures to AWS D3.6 Class A requirements in 1999, witnessed by all major classification societies. Certificates were issued by ABS, DNV, GL, LR and BV.

The welder qualification requirements at SGS are based on class A welds.

In 2013, SGS qualified underwater wet welding procedures for groove welds to AWS D3.6 Class A requirements together with LR.

In May 2014, SGS qualified underwater wet welding procedures for groove and build up welds. The welding and the NDE and mechanical testing of the plates was witnessed by DNV GL, ABS and Lloyd’s Register.

In September 2014, Subsea Global Solutions LLC (SGS) was granted permission by DNV-GL as the first company world-wide to carry out permanent repairs by underwater wet welding on certain areas of vessels. Subsea Global Solutions’ global network of coded welder divers are available to perform these permanent repairs on a case by case basis utilizing the approved underwater wet welding procedures in suitable locations throughout the world in accordance with the approvals given by DNV-GL.

Subsea Global Solutions successfully performed underwater weld repairs on numerous projects on vessels classed by all major classification societies.