Shaw Industries, Inc.

Shawcor Ltd.

Dennis Wong

Joseph G Mordarski

Jiri Holub

Marcos Mockel

Roberto Varagnolo

Catherine Lam

A method of providing a foamed insulation coating on at least a portion of a pipe, including extruding a melt stream over the pipe portion. The melt stream includes a matrix polymer and expandable fillers in an unexpanded state, the melt stream being maintained at a sufficiently high temperature to maintain the matrix polymer in extrudable form and at a sufficiently high pressure to maintain the expandable fillers in the unexpanded state. Once extruded, the expandable fillers are permitted to expand into an expanded state at a lower pressure.

Foamed insulation coating on pipes and methods therefor

The invention provides a composite protective coating applied to a steel pipe, the coating comprising an epoxy resin primer bonded to the outer surface of the pipe, a polyolefin outer sheath, and an interlayer consisting of a mixture of epoxy resin and polyolefin. The composition of the mixture forming the interlayer is graded throughout its thickness, being substantially all epoxy resin adjacent to the primer coating and substantially all polyolefin adjacent to the sheath.

High performance composite coating

Two methods are provided for applying and forming a protective composite coating on a metallic substrate. In the first method, the substrate is heated to a temperature between about 175.degree. C. and 275.degree. C. and a powdered coating of epoxy resin between 100 and 400 microns thick is applied to the outer surface of the heated substrate. A premixed powder coating of epoxy resin and polyolefin is applied directly onto the epoxy resin coating, forming an interlayer of interspersed domains of epoxy and polyolefin between about 100 and 400 microns in thickness. On to this, powdered polyolefin is sprayed to produce a polyolefin sheath coating for the metallic substrate between 200 and 1000 microns in thickness. In the second embodiment of the method, the interlayer is formed by spraying pure epoxy resin powder and polyolefin powder from separate sources simultaneously onto the substrate. By these methods, a metallic substrate coated with a composite epoxy/polyolefin protective coating is produced. A particular advantage of the methods results from the fact that the powders are applied in a common spray booth through which the substrate is advanced.

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Toronto, Canada

Dennis Wong