APPLYING SIMULTANEOUSLY EXTRUDED THERMOPLASTICS COVERING AND ADHESIVE LAYERS TO A STEEL TUBE

摘要

A method for making a polyethylene jacket on steel pipes including applying an inner foil upon the preheated steel pipe for purposes of providing adhesion thereto and of an outer, jacketing foil, also to be applied through a duel extrusion head which is to be heated to an operating temperature of approximately 170 DEG C. During extrusion, a gaseous mixture is fed to the space between the surface of the tube to be jacketed and the inner foil, which gaseous mixture consists of air to which a reactive gaseous component, such as ozone, has been added; the inner foils is made from a material so that the gaseous mixture reacts under the formation of groups which provide adhesion, such as carboxylic groups.