Longitudinal finned resistance weld pin

A metallic welding pin for the attachment of insulated batts to a metallic duct substrate by resistance welding comprising, in combination, an axially elongate shank portion having a head at one end and a sharpened tip at the other end, said head having a planar uppermost contact surface, said tip being conical in configuration, a washer member of greater diameter than said head mounted over said shank and disposed at the junction of said head and shank, said shank including a plurality of generally axially directed ribs extending from a point adjacent said head to the junction of the major diameter of said tip with said shank, the minor diameter of said shank in the areas between said ribs corresponding substantially to the major diameter of said tip, the lowermost ends of said ribs, at their radial innermost ends merging with said minor diameter of said shank at a heightwise position substantially coincident with the junction of said tip and shank, the included angle between said lowermost ends and said tip being less than 180.degree..