Protective polymer layer

• Main Authors: Purmonen Jouni, Leiden Leif
• Format: Patent
• Language: English
• Published: 11.04.2017
• Subjects: APPLYING LIQUIDS OR OTHER FLUENT MATERIALS TO SURFACES, IN GENERAL; BLASTING; CHEMICAL SURFACE TREATMENT; CHEMISTRY; CLADDING OR PLATING BY SOLDERING OR WELDING; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATIONOR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY IONIMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; COATING MATERIAL WITH METALLIC MATERIAL; COATING METALLIC MATERIAL; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; DIFFUSION TREATMENT OF METALLIC MATERIAL; ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVEFUNCTIONING OF MACHINES OR INSTALLATIONS; HEATING; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION INGENERAL; JOINTS OR FITTINGS FOR PIPES; LIGHTING; MACHINE TOOLS; MEANS FOR THERMAL INSULATION IN GENERAL; MECHANICAL ENGINEERING; METAL-WORKING NOT OTHERWISE PROVIDED FOR; METALLURGY; PERFORMING OPERATIONS; PIPES; PROCESSES FOR APPLYING LIQUIDS OR OTHER FLUENT MATERIALS TOSURFACES, IN GENERAL; SOLDERING OR UNSOLDERING; SPRAYING OR ATOMISING IN GENERAL; SUPPORTS FOR PIPES, CABLES OR PROTECTIVE TUBING; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THESURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; THERMAL INSULATION IN GENERAL; TRANSPORTING; WEAPONS; WELDING; WORKING BY LASER BEAM

The present invention relates to a method of joining polymer coated steel pipes comprising the steps of-providing polymer coated pipe segments with an uncoated length on both ends of the segments; -welding the polymer coated pipe segments together; -applying a curable polymer (A) onto the uncoated length of the welded pipe segments to form an first coating layer; and-applying a polymer composition (B) onto the first coating layer to form a topcoat layer with a thickness of 0.5 to 10 mm, wherein the polymer composition (B) has a melt flow rate MFR2 of 1.0 to 6.0 g/10 min, determined according to ISO 1133 at a temperature of 190° C. under a load of 2.16 kg, and includes a base resin comprising (B-1) a non-elastomeric polyethylene in an amount of 60 to 85 wt % of the total polymer composition being produced in a process using a single-site catalyst, and (B-2) an elastomer comprising a copolymer of ethylene and at least one polar comonomer, wherein component (B-1) or components (B-1) and (B-2) have been grafted with an acid grafting agent and the use of polymer composition (B) as topcoat layer with a thickness of 0.5 to 10 mm in a coating of coated steel pipe field-joints, a method of coating a steel pipe and the use of polymer composition (B) for the coating of steel pipe joints or steel pipes.