The University of Texas at Austin Center for Electromechanics is conducting a research program to study homopolar welding of line pipe for J-Lay applications. In 1995, the third year of the five year research program, process improvements increased Charpy V-Notch impact toughness properties to near parent metal values, while maintaining acceptable strength.After demonstrating repeatable performance, research focused on real world effects including evaluating the effect of poor fit up resulting from misalignment and rough and wavy interfaces. During the final year of the research program, the pipe welding program has scaled up to 12-inch nominal line pipe, a sevenfold increase in cross-sectional area. The paper will cover basics of homopolar welding, mechanical properties, weld upset profile, HPW metallurgy, and the studies of real world effects. Results from homopolar welding of 12-inch pipe will also be presented.
HOMOPOLAR OFFSHORE PIPELINE WELDING RESEARCH PROGRAMA consortium of six oil companies (Amoco, BP, Exxon, Mobil, Shell, and Texaco), a welding contractor (CRC-Evans), an equipment contractor (Parker Kinetic Design) and two federal agencies (the Office of Pipeline Safety of the DOT and the Mineral Management Services of the DOI) funded this joint industry program (JIP) to develop homopolar welding for J-lay applications. The research, which started in February 1993, is being conducted at UT-CEM, and has achieved the following major objectives:• optimize weld parameters for homopolar welding 3-inch HSLA API 5L line pipe