METHOD AND APPARATUS FOR METALIZING INTERNAL SURFACES OF METAL BODIES SUCH AS TUBES AND PIPES

摘要

A method for metal coating the inside surface of an elongated metal tubular body which includes placing a plurality of elongated pieces of coating metal into the bore of the tubular body in parallel alignment with the axis of the tubular body and in position within the bore to provide a substantially constant amount of coating metal along the axial length of the bore. The coating metal has a melting point which is below the melting point of the tubular body. The bore of the tubular body is rendered substantially free of oxygen by evacuation or by purging with an inert gas. The tubular body and the elongated pieces of coating metal contained within the bore are rotated at a high rotational speed sufficient to distribute the elongated pieces against the bore surface while maintaining the substantially constant amount of coating metal along the axial length of the bore. The rotating tubular body is then heated sufficiently to melt the coating metal pieces and insufficiently to melt the tubular body. The melted coating metal is spread about the bore surface by means of the centrifugal force imposed upon the melted coating metal by the continued rotation of the tubular body. The rotating tubular body is then passed from the heating zone into a cooling zone, and the tubular body is then withdrawn from the cooling zone with a uniform layer of solid metal coating upon the bore surface.