Abstract: This invention pertains to the use of a plasma arc welding technique when welding a nozzle to the interior of a vessel. More specifically, it pertains to a method and apparatus for making an inside weld when access to the interior of the vessel is restricted.

Abstract: A robot drive for cutting fins having pipes extending on opposite sides therefrom, with the pipes laying in parallel spaced apart rows, comprises a carriage which can move in the longitudinal direction between rows of the pipes. A pair of driven guide rollers is mounted to the carriage for rolling against the pipe of one of the rows. The carriage also carries four spring loaded pressure wheels which bear against the fins of the pipe in an adjacent row so as to press the carriage and guide rollers against the pipe on which the guide rollers roll. A pair of cutting torches or mechanical cutters are connected to the carriage on opposite sides of the guide rollers so that they can cut the fins of the pipes on which the guide rollers roll.