flash butt welding

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.

The noun has one meaning:

Meaning #1: butt welding by creating an electric arc between the two pieces which melts and joins them; used for joining segments of metal pipe
  Synonym: flash welding