Internal weld protection of sheet metal pipes

Abstract

The invention relates to a continuous protective film, consisting of a thermoplastic synthetic material, which is applied to the inner side of the longitudinal weld of sheet metal pipes which are supplied end to end across the welding arm of a welding machine and an adjacent applicator arm. The thermoplastic synthetic material is continuously melted and applied using an applicator nozzle across at least the entire width of the weld. The thermoplastic synthetic material fed continuously is preheated, melted and conveyed to the applicator nozzle in a homogeneous liquid state. The discharge opening of the nozzle is subsequently guided at an adjustable constant distance from the inner side of the longitudinal weld of the sheet metal pipes, and the liquid synthetic material is applied in metered quantities. The melting apparatus for carrying out the process comprises means for guiding the discharge opening of the applicator nozzle. The means are, for example, a follow up roller, a sliding block, or a probe.

Dependencies are inferred from the claim text.