flash butt welding

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. A technique for joining segments of metal rail or pipe in which segments aligned end to end are electronically charged, producing an electric arc that melts and welds the ends of the segments, yielding an exceptionally strong and smooth joint. Also called flash welding.

WordNet 3.0

1. n. butt welding by creating an electric arc between the two pieces which melts and joins them; used for joining segments of metal pipe