Patent ID: 6149969
Filing Date: 2000-11-21
Classification: B05D,F16L

Abstract:
A method for repair of a defective section of a protective coating on the exterior of a metal pipeline in the field, comprising:(a) stripping a portion of said protective coating from said pipeline, said portion including the defective section of the protective coating;(b) forming a clean metal surface on said portion of the pipeline;(c) applying an undercoat of at least 5 mil of liquid polyepoxide or polyurethane composition to said clean metal surface, said composition having a curing agent for said polyepoxide or polyurethane;(d) optionally applying a non-melted, powder layer of a thermoplastic polyolefin selected from ethylene/(meth)acrylic acid copolymers and polyolefins modified with functional ethylenically unsaturated carboxylic acid groups or derivatives by means of forced air onto the entire surface of the undercoat and onto the protective coating adjacent thereto;(e) allowing the undercoat to cure until the coating exhibits no flow when a stream of heated air is applied; and(f) applying a topcoat of at least 5 mil of a thermoplastic polyolefin selected from ethylene/(meth)acrylic acid copolymers and polyolefins modified with functional ethylenically unsaturated carboxylic acid groups, or derivative thereof, onto said undercoat, by contacting the undercoat and protective coating adjacent thereto with said thermoplastic polyolefin in a non-melted state, the pipeline being at a temperature such that the polyolefin melts and undergoes melt flow on contacting the undercoat and protective coating adjacent thereto.