Homopolar pulse welding is a solid state resistance/forge process which uses the discharge current pulse of a homopolar generator to join two or more work pieces. (1). This process is very similar to flash-butt welding. Unlike flash-butt welds, homopolar welds are completed in seconds. Its capacity for fast one station welding makes homopolar welding an attractive alternative for deep sea pipe construction.
The development of homopolar pulse welding coincides with the industry’s shift from S-laying to J-laying. Traditional laying techniques can no longer be used in deepwater projects. Both structural and mechanical problems limit the applicability of such laying schemes to work done in water depths ranging up to 1500ft. J-laying offers an attractive solution for deepwater pipeline construction. To be incorporated, however, a fully automatic, reliable, and fast welding system must first be developed. Both flash-butt and homopolar pulse welding are strong contenders for such a task.
This project presents the initial work done at the Ferguson Structural Engineering Laboratory and at the Center for Electromechanics on homopolar welding for pipeline construction. Eighteen 3.5” x 0.42” homopolar welds were fabricated and tested. From these welds, tensile, hardness, toughness, thermal, and metallurgical homopolar characterizations were developed.