Abstract: An automatic welder is used in an internal welder unit which travels along the interior of a pipeline and provides the interior weld passes at the junction of abutting pipe joints. The internal welder unit has an electronic control system which includes a plurality of microprocessor control units, each of which performs specific functional operations for the internal welder unit. The microprocessor control units are interconnected by a serial communication link which permits the transmission of commands and data between all of the microprocessor control units. The control system includes a back end control unit positioned in the internal welder unit, a front end control unit with a panel in the weld unit, a reach rod control unit at the end of a reach rod and a power supply control unit adjacent the arc power supply. The control system directs the operation of orbiting internal welders to have a zero or slow travel speed at a start point to ensure a high reliability of arc initiation.

Abstract: A flux for the submerged arc welding of aluminum-bronze comprises a granular mixture of cryolite and a binder. The flux preferably also contains alumina. A method for the submerged arc welding of aluminum-bronze employing the flux is disclosed.

Abstract: Signals which contain components that vary with the lateral position of an electric welding instrument as it travels along a weld path between opposite work pieces are obtained from the arc or other heat source and are first processed to remove confusing or nonsignificant components. The processed signals are then compared or combined with each other, or with other signals of predetermined value, to obtain outputs which can be used to determine or control the lateral position or movement of the welding instrument along the weld path. Specifically, in electric arc welding of metals, signals from an electrical characteristic at the arc, such as arc current, which include a component indicative of lateral position of the welding instrument with respect to one or more sidewalls, are first filtered and processed to remove undesirable components.