A METHOD OF PRODUCING STEEL PIPES HAVING AT LEAST TWO OUTER LAYERS

摘要

A method of producing steel pipes having at least two outer layers. The method comprises two steps (a) and (b). In step (a) the outside of the steel pipe (3) is coated with a first anti-corrosive layer (4) of a material chosen from among the following materials: bitumen, SBS-modified bitumen, APP-modified bitumen, polyalpha-olefin-modified bitumen, bitumen enamel and tar enamel, at least one fibre-reinforcement felt (2), eg of fibre glass, being applied at the same time. In step (b) a layer of polypropylene is applied directly onto the fibre-reinforcement felt (2) by extrusion to form a shield around the pipe. As a result the pipe becomes more impact-resistant and better protected against most chemicals than hitherto known.