Ambient Temperature Temperbead Welding Using the Underwater Laser Beam Welding Process

Ambient temperature temperbead welding using the Machine Gas Tungsten Arc Welding (GTAW) process is widely accepted in the nuclear industry. GTAW machine ambient temperature temperbead welding, addressed in ASME Code Case N-638, has been used to repair ASME Class 1 components in numerous safety related applications. Underwater laser beam welding (ULBW) is gaining increasing industry recognition as a method for producing high quality welds in high radiation environments. Since ULBW enables high quality weld deposition in underwater environments, the process enables water to serve as a radiation moderator, reducing personnel exposure levels. ULBW’s advantages go beyond radiation exposure reductions, and this paper will provide the reader a better understanding of the ULBW process’s capabilities and properties. A recently formed ASME Task Group is preparing a new Code Case that will delineate specific requirements and essential variables governing use of ULBW to repair ASME Class 1 components. In addition, this Code Case will provide specific rules for use of the ULBW process for ambient temperature temperbead welding. Extensive testing has been performed to demonstrate ULBW’s capabilities with regard to ambient temperature temperbead welding in an underwater environment, and this paper summarizes testing and test results. It also provides a technical summary of the new Code Case, it’s requirements, and summarizes several of the bases for these requirements.