Abstract: Inorganic fibrous pipe insulation in the shape of a tube comprising outer and inner flexible sheets on the outer and inner cylindrical surfaces of the tube. A majority of the fibers are at right angles to the flexible sheets and therefore extend radially of the pipe to offer good compression resistance to impact. By using substantially non-stretchable material for the inner sheet a fibrous layer whose fibers are generally perpendicular to the layer can be permanently formed into generally cylindrical shape. For insulation designed to cover very small diameter pipes the thickness of the fibrous layer is varied to provide fewer adjacent the inner flexible sheet than are adjacent the outer flexible sheet.