Abstract: A method and apparati are presented for non-chamber root side purging in fusion welding of oxygen reactive metals which require that the molten weld zone and local solid areas of the weld seam remaining at high temperatures be shielded from normal atmosphere to prevent degradation of the welded area. The apparatus provides an inert atmosphere to the root side of a weld joint through a porous medium whereby the jet-like thrust of the plasma arc actually draws the continuously supplied inert atmosphere into the path of the molten or high temperature solid weld zone. The porous medium is configured so it can be placed at the borders of the weld seam and substantially parallel to the seam without restricting the view of the root side of the seam. The inert gas is dispersed evenly through the porous media and across the weld seam, at the point of arc penetration and in front of and behind the arc.

Abstract: A plasma arc welding torch wherein a first plasma gas is directed through the body of the welding torch and out of the body across the tip of a welding electrode disposed at the forward end of the body. A second plasma gas is disposed for flow through a longitudinal bore in the electrode. The second plasm gas enters one end of the electrode and exits the electrode at the tip thereof for coacting with the electric welding arc to produce the desired weld. A shield gas is directed through the torch body for circulating around the head of the torch adjacent the electrode tip.

Abstract: A plasma arc welding torch wherein a plasma gas is directed through the body of the welding torch and out of the body across the tip of the welding electrode disposed at the forward end of the body. The plasma gas is provided with a vortexing motion prior to exiting the body by a vortex motion imparting member which is mounted in an orifice housing member and carried in the forward portion of the torch body. The orifice housing member is provided with an orifice of an predetermined diameter through which the electric arc and the plasma gas exits.

Abstract: A welding torch for plasma arc welding apparatus has a transparent shield cup disposed about the constricting nozzle, the cup including a small outwardly extending polished lip. A guide tube extends externally of the torch and has a free end adjacent the lip. First and second optical fiber bundle assemblies are supported within the guide tube. Light from a strobe light is transmitted along one of the assemblies to the free end and through the lip onto the weld site. A lens is positioned in the guide tube adjacent the second assembly and focuses images of the weld site onto the end of the fiber bundle of the second assembly and these images are transmitted along the second assembly to a video camera so that the weld site may be viewed continuously for monitoring the welding process.

Abstract: A welding torch for plasma arc welding apparatus has an inert gas applied circumferentially about the arc column externally of the constricting nozzle so as to apply a constricting force on the arc after it has exited the nozzle orifice and downstream of the auxiliary shielding gas. The constricting inert gas is supplied to a plenum chamber about the body of the torch and exits through a series of circumferentially disposed orifices in an annular wall forming a closure at the forward end of the constricting gas plenum chamber. The constricting force of the circumferential gas flow about the arc concentrates and focuses the arc column into a more narrow and dense column of energy after exiting the nozzle orifice so that the arc better retains its energy density prior to contacting the workpiece.