Preformed foam insulation in longitudinal sections forming segments of an annulus are bonded to outer sheet metal covers. The segments are assembled about a pipeline which is to carry hot gas or oil in a cold climate such as the Arctic. To eliminate shear forces on the insulation because of differential thermal expansion and contraction of the pipe and the cover, the insulation has an inner diameter larger than the outer diameter of the pipe and friction reducing means is provided between the insulation and the pipe.