Abstract: A mobile automated pipeline welding and quality control system comprising a gas metal arc welding carriage and a weld data monitor and acquisition unit. The welding carriage carries a welding torch, wire feed device for feeding consumable wire to the torch, an oscillator for oscillating the torch and a motorized drive mechanism for moving the carriage about a weldment. A controller for the carriage includes digital control circuitry for dosed loop control of the drive, oscillator and wire feed devices. By default, the controller operates each device at one of a plurality of pre-programmed nominal speeds selected from a mode table. The controller is responsive to drive, oscillation and wire feed speed variation signals under the control of an operator, and varies the speed of each device within speed ranges which are selected to ensure compliance with welding specifications. The monitor has voltage and current transducers for measuring current and voltage at the welding torch.