Elliott Bay Design Group (EBDG) says that its recent weld procedure in a complex engineering and inspection project for the U.S. Defense Department saved construction time and cost, reducing downtime for a critical national defense asset.
EBDG developed an optimized weld procedure for an uncommon grade of steel for TOTE Services, LLC, in support of work on the USNS SBX-1 X-band radar vessel, part of the Department of Defense Missile Defense Agency, which provides key tracking and identification of potential ballistic missile threats. The regulatory agencies in control of the approval and oversight of the procedure include the American Bureau of Shipping (ABS) and U.S. Coast Guard, in support of the Department of Defense Military Sealift Command.
The challenge, said EBDG officials, was to develop a regulatory-approved weld procedure appropriate to the exotic grade of steel used for the hull of the SBX-1. The steel is an American Bureau of Shipping grade FH-36 low temperature steel, which is suitable for service in arctic conditions because it retains higher impact toughness in very cold ambient temperatures compared to more common ABS grade-A steel.
EBDG partnered with Industrial Resources Inc (IRI) at its Sedro-Woolley, Washington location for fabrication and welding of the test assemblies for the range of weld procedure configurations. They worked with IRI to identify weld parameters that would satisfy the material property requirement and also be useable for the real-world fabrication on the vessel. EBDG also employed the Mistras Group in Burlington and Ferndale, Washington to provide nondestructive and destructive testing of the completed test assembly.
As final proof of the success of the procedure development, it was successfully implemented by the shipyard with the final welded joints passing all quality assurance and performance requirements, they said.