Arc welding apparatus and method of arc welding

Claim 1

APPARATUS FOR PRODUCING A WELD INTERNALLY AT A CIRCULAR JOINT BETWEEN ABUTTING PARTS, COMPRISING A SPINDLE HOUSING SUPPORTED ON A MANDREL ENGAGING AT LEAST ONE OF SAID PARTS, MEANS ROTATING SAID HOUSING RELATIVE TO SAID MANDREL ABOUT AN AXIS SUBSTANTIALLY COINCIDENT WITH THE AXIS OF SAID TUBES, A SPINDLE SUPPORTED BY SAID HOUSING ROTATABLY IN A CIRCULAR PATH WITH SAID HOUSING AND EXTENDING INTO SAID ONE PART GENERALLY PARALLEL TO THE AXIS OF SAID JOINT, AN ELECTRODE MOUNTED ON SAID SPINDLE, SAID SPINDLE BEING SET WITH SAID ELECTRODE OPPOSITE SAID JOINT, AND MEANS CONNECTED TO SAID SPINDLE AND HOUSING FOR MOVING SAID SPINDLE RELATIVE TO SAID HOUSING GENERALLY PERPENDICULARLY TO SAID AXIS TO SET SAID ELECTRODE A PREDETERMINED DISTANCE FROM SAID JOINT TO SET THE ARC LENGTH OF AN ARC TO BE PRODUCED IN THE WELDING OF SAID JOINT.