METHOD FOR PRODUCING METALLIC PIPELINE WITH PROTECTION OUTER LAYER AND UNDERGROUND PIPELINE LAID TRENCHLESSLY AND/OR WITHOUT SAND BED

摘要

The invention relates to a method for producing an underground metallic pipeline with a protection outer layer installed trenchlessly and/or without a sand bed, comprising encasing a metal conduit with an extruded layer of a polyamide molding material, the layer of the polyamide moulding material is at least 1.0 mm thick, wherein a viscosity of the extruded polyamide moulding material at 240°C and a shear rate of 0.1 sec^-1 according to ASTM D 4440-3 is at least 2000 Pa.s. The invention also relates to an underground pipeline laid trenchlessly and/or without a sand bed produced by said method. The invention provides the durability of the outer shell required for trenchless and/or without a sand bed laying techniques.