Experience with shipyard installation of a hybrid pipe welding system
Laser-Gas Metal Arc (GMA) hybrid welding is fast making the transition from laboratory to production, in industries as diverse as shipbuilding to automobile manufacture. For the past 3 years, our team has striven to both develop a hybrid welding process for steel pipe, and to specify, build, and install a hybrid pipe welding system in a General Dynamics NASSCO shipyard. In March 2007, the system was successfully installed into the shipyard. This work presents a summary of our continued experimental explorations into various practical aspects of hybrid welding, discusses the system design, and provides an overview of the installation of the system into the shipyard. Test results are presented, as well as lessons learned throughout the project.
Low heat input welding for thin steel fabrication
As thinner members are used in marine construction, the use of conventional joining techniques results in significant angular and buckling distortion due to the inherent high heat input with these processes. Several low heat input alternatives, including laser beam, gas metal arc, and hybrid laser arc welding, are explored. The paper focuses on process development, real time distortion measurements, and implementation of these processes.
LETTERS TO THE EDITOR: Observation of a transition into a stable mode for an arc burning on a rotating anode
High current arcs in air at atmospheric pressure, initiated between a rotating anode and a stationary cathode, have been observed to change to a stable stationary mode. The transition, which occurs over a narrow range of currents, is characterized by a drop in arc voltage and cessation of ablation of the anode surface.