FIELD: tube insulating techniques. SUBSTANCE: method comprises steps of applying onto steel tube insulation layer containing at least one layer of rigid foamed polyurethane and in addition at least one layer of polyisocyanurate plastics placed between steel tube and layer of rigid polyurethan; applying protective coating onto insulation layer. Tubes coated by such process are suitable for continuous operation at temperature up to 200 C. EFFECT: enhanced strength of tubes. 11 cl, 1 tbl
