Abstract: The insulating cover comprises a gas and water impermeable first foil (13) which defines a first circumferential outer rim, a gas and water impermeable second foil (26) substantially coextensive with said first foil (13) and defining a second circumferential outer rim. The first (13) and second foil (26) are joined together at the first and second outer circumferential rims of the first (13) and second outer circumferential rims of the first (13) and second foils (26), to define an enclosure between the first (13) and second (26) foils. A body of insulating material (24) is inserted in the enclosure. A plurality of supporting tubular elements (20) in co-planar relationship with said first (13) and second foil (26) provide a stiffness of the insulating cover (15) in axial direction of the plurality of supporting tubular elements (20) and flexibility of the insulating cover (15) in a direction perpendicular to the axial direction.