Inert gas shield for welding

Claim 1

APPARATUS FOR WELDING A SEAM BETWEEN TWO ABUTTING METAL WORKPIECES TO PREVENT ATMOSPHERIC CONTAMINATION OF THE WELD COMPRISING A WELDING TORCH PROVIDED WITH AN ELECTRODE AND A NOZZLE, AN ELONGATED, INVERTED CHANNEL STRADDLING SAID SEAM AND PROVIDED WITH EDGES CONTACTING EACH WORKPIECE, A REAR END WALL AND AN APERTURED, TRANSPARENT FRONT END WALL CLOSING SAID CHANNEL TO FORM AN ENCLOSED CHAMBER ABOVE SAID SEAM, MEANS FOR MOUNTING SAID TORCH IN SAID CHANNEL ADJACENT SAID FRONT WALL AND ABOVE SAID SEAM, A SOURCE OF INERT GAS, A FIRST GAS CONDUIT CONNECTING SAID SOURCE AND SAID NOZZLE TO SUPPLY GAS ABOUT THE WELDING ARC, SECOND AND THIRD GAS CONDUITS HAVING RESPECTIVE OPEN ENDS DISPOSED WITHIN SAID ENCLOSED CHAMBER AND OPPOSITE ENDS CONNECTED TO SAID SOURCE TO SUPPLY GAS TO SHIELD THE SEAM BEHIND SAID ARC, A BACK-UP BAR CONTACTING SAID WORKPIECES ON THE SIDE OPPOSITE SAID CHANNEL AND PROVIDED WITH AN APERTURED GROOVE ALIGNED WITH SAID SEAM, A FOURTH GAS CONDUIT CONNECTING SAID SOURCE WITH SAID BAR TO SUPPLY GAS TO SHIELD SAID SEAM THROUGH SAID APERTURED GROOVE, AND RESPECTIVE MEANS FOR COOLING SAID CHANNEL TO COOL SAID SEAM WHILE IT IS SHIELDED BY SAID GAS.