Abstract: Apparatus for electrostatically coating an elongated object of indefinite length which is aligned with the straight line path of the elongated object in a continuous manufacturing and finishing process. Electrostatic applicators are mounted to direct the coating into a substantially closed chamber at a portion of the elongated object passing therethrough. To substantially eliminate the explosive hazard occasioned by the use of an organic solvent-based coating material in the presence of electrical equipment, a combustibly inert atmosphere is maintained in the chamber and in an exhaust system leading therefrom. To maintain the electrostatic field, the coating chamber and associated coating equipment must be electrically isolated from ground.

Abstract: Lengths of polymer-coated tubing are continuously produced from steel strip by roll-forming and welding at a fast rate of speed. The welded tubing is sized, cleaned and heated to raise its temperature to that desired for applying a polymeric coating. After coating, the tubing is heated to a desired baking temperature and then cooled. The tubing is unsupported from a location upstream of the coating station until cooled. Elongated endless belts grip the tubing over a longitudinal distance of at least about 2 feet and pull the tubing in a controlled manner to maintain the tubing in precise spatial location throughout its heating, coating and baking.