Patent ID: 8192798

Claim:
A process for coating the exterior surfaces of pipelines with a polymer that is cross-linkable under exposure to water, comprising the steps: a) coating the exterior surface of the pipeline with at least one polymer that is cross-linkable under exposure to water, wherein the employed cross-linkable polymer comprises alkoxy silane grafted HDPE; b) cross-linking of the cross-linkable polymer by exposure to water at elevated temperatures, thereby forming a cross-linked polymer layer, until a degree of cross-linking of ≧30% to ≦80% is reached, wherein the layer of cross-linked polymer is the most exterior top pipeline coating, and wherein the process comprises the following steps: heating the pipeline to ≧170° C. to ≦230° C.; application of an epoxy resin by an electrostatic powder spray process with a layer thickness of ≧0.08 mm to ≦0.16 mm; application of an adhesive agent by a wrapper extrusion process with a layer thickness of ≧0.15 mm to ≦0.30 mm; application of an HDPE layer by extrusion with a layer thickness of ≧2.8 mm to ≦3.2 mm; application of silane cross-linkable HDPE layer by extrusion with a layer of thickness of ≧0.8 mm to ≦1.2 mm; treating of the pipeline with water.