Abstract: An orbital type welding apparatus adapted for use in welding tubes into a tubesheet by an inert gas electric arc welding process. The welding apparatus includes a housing, a rotor rotatably mounted within the housing, and a pilot probe unit extending from the housing lower side. The pilot probe unit contains a plurality of resiliently-mounted convex projections such as balls, which are spaced apart both circumferentially and longitudinally with respect to the pilot probe unit. The balls are mounted in transverse openings in the pilot unit. The spring-loaded projections serve to center the pilot unit and welding apparatus more quickly and accurately within a tube being electric arc welded to a tubesheet. Alternatively, a pilot probe unit having a plurality of transverse grooves can be used for welding tubes which are essentially round.

Abstract: Method and front-end fixture adapted for use with manually-operated electric stud welding guns, which permits the successful welding of a plurality of metal studs uniformly onto a workpiece. Various aspects of the invention provide for repeated accurate spacing of the studs as they are successively welded, for accurate alignment of a series of studs, and for each stud to be oriented in a disposition substantially perpendicular to the surface of the work piece. The preferred embodiments include a bracket mounted to a conventional welding gun, an alignment bushing mounted on the bracket forward of the chuck of the gun for contacting a previously-welded stud, and a footpiece mounted on the bracket rearward of the chuck.

Abstract: Welding apparatus includes a welder and an electrically pre-heated wire that is fed into the perimeter of a weld puddle. The apparatus has equipment to produce relative motion between the welder and the workpiece. A stream of gas, such as a mixture of inert gas and oxygen, is applied to the weld puddle at a location between the welder and the pre-heated wire. Pipes may be rapidly welded in an end to end fashion using such apparatus by rotating the pipes past the welder. The welder is mounted at the side of the joint of the pipes and the pipes are rotated so that the portion thereof adjacent to the welder translates upwardly. The electrically pre-heated wire is fed into the melted portion of the joint which trails the welder.