State College, PA-At a recent meeting of the National Shipbuilding Research Program’s (NSRP) SP-7 Welding Technology Panel the Applied Research Laboratory (ARL) at Penn State presented a paper about a project that the SP-7 panel funded to investigate the potential for using laser-GMA hybrid welding for joining pipe. This project is intended to determine the weld quality and return on investment that a shipyard can expect by applying recent advances in laser welding technology to pipe welding during ship fabrication.
Conventional pipe welding often requires multi-pass welding of beveled joints. Significant cost savings with the hybrid approach are anticipated due to the elimination of multi-pass requirements while taking advantage of the deep penetration offered by keyhole laser welding, which will enable direct, single-pass butt-welding of pipes with little or no bevel required. Specific laser welding technologies addressed in this paper included high-power Nd:YAG (up to 6 kW) with more than twice the power available for previous NSRP laser pipe welding studies, fiber laser technology, and laser-assisted GMA (hybrid) welding.
During a tour of ARL Penn State’s Laser Processing Laboratory, demonstrations were made of combined laser/GMA hybrid welding to join 1/2-inch thick steel in a single pass (see photo). Laser free forming (or cladding) of metal matrix composite materials was also demonstrated.
The Laser Processing Division of the ARL Penn State has several ongoing programs to develop and implement laser beam welding technology for shipbuilding. These include the development and commercialization of laser fabricated corrugated structures (LASCOR), development and application of laser-arc hybrid welding for marine piping systems, and the development of joining techniques, such as laser beam welding, laser-arc hybrid welding, and laser stir welding, for various shipbuilding applications such as structural stiffeners and lightweight hatch doors. According to Ted Reutzel at the ARL, laser stir welding, involving the manipulation of the keyhole during welding (which has been developed and patented by ARL Penn State and Alcoa Laboratories) offers the potential for thick section welding, similar to hybrid techniques.
Additionally, laser cutting is finding increasing acceptance in shipyards in the U.S., and installations can be found at Bender Shipbuilding Company (Mobile, AL), the General Dynamics Electric Boat Division (Quonset Point, RI), Northrop Grumman Ship Systems’ Ingalls Operations, and Northrop Grumman Ship Systems’ Avondale Operations. Reutzel also points out that many systems are installed in European and Asian shipyards.
The NSRP Welding Technology Panel normally meets twice per year. The Laser Processing Division of the ARL at Penn State was chosen to host this meeting, which was held on September 16 and 17, as it was demonstrating the capability to laser weld pipe.
The NSRP is a government/industry research program, with the goal to develop more economical construction approaches to shipbuilding. The SP-7 provides a public forum for discussing methods and processes to improve the technology of welding, cutting, forming, and burning as it pertains to and is applied to the shipbuilding/repair industry and its customers. This panel attracts the leaders of the shipbuilding welding community-from the welding equipment suppliers to the shipyard customers.
The meeting attracted more than 35 attendees from across the country, with representatives from the U.S. Navy and commercial shipyards, government, and regulatory agencies, and from a host of welding equipment suppliers, including Applied Thermal Sciences, Edison Welding Institute, ESAB, Schuler, and Lasson Technologies.
This meeting and others like it support a key element of Navy ManTech’s role by developing and disseminating the latest research in various aspects of shipbuilding and repair to a broad and interested audience. It supports the goal of reducing overall ship acquisition and life-cycle costs by helping to transition technology developed in Navy ManTech-supported laboratories to shipbuilders and suppliers who can ultimately provide commercialized product and necessary follow-on support.