Unique variable polarity plasma arc welding for space shuttle

Since the introduction of the Plasma Arc Torch in 1955 and subsequent to the work at Boeing in the 1960's, significant improvements crucial to success have been made in the Variable Polarity Plasma Arc (VPPA) Process at the Marshall Space Flight Center. Several very important advantages to this process are given, and the genesis of PA welding, the genesis of VPPA welding, special equiment requirements, weld property development, results with other aluminum alloys, and the eventual successful VPPA transition to production operations are discussed.