Cargo tank (4, 40) comprising a support system for vertical arrangement of said cargo tank in a vessel, wherein the cargo tank (4, 40) comprises a cylindrical shell having a flat and flexible base; the cargo tank (4, 40) further comprising support point pairs with tank pressure faces fastened to the tank shell and corresponding hull pressure faces fixable to the vessel with insulation material arranged between the tank pressure faces and hull pressure faces, and wherein two support point pairs are arranged at the upper end of the tank (4, 40) and two support point pairs are arranged at the lower end of the tank (4, 40); wherein: - the cargo tank (4, 40) comprises support elements evenly distributed underneath the base of the tank, each comprising an insulation layer, wherein vertical forces from the tank are transferable as pressure evenly distributed from the contents of the tank to the bottom structure of the vessel; - one support point pair at the upper end and one support point pair at the lower end have tank pressure faces arrangeable transversely in the vessel, - and the other upper and lower support point pairs have tank pressure faces arrangeable longitudinally in the vessel, - a corresponding hull pressure face arranged close next to each of the tank pressure faces and fastenable to an inner ship side or to a bulkhead; and wherein - the tank pressure face and the corresponding hull pressure face are made so long and aligned such that a centre line orthogonal to the tank pressure face and orthogonal to the hull pressure face extends along a line tangential to a circle concentric to the tank shell and going through the middle of the wall of the tank (4, 40), and wherein the insulation layers are configured to transfer the load between the tank pressure face and the hull pressure face as pressure orthogonally related to the faces of the insulation layer and, at the same time, thermally insulate between the cargo tank (4, 40) and the vessel. - the cargo tank (4, 40) comprises support elements evenly distributed underneath the base of the tank, each comprising an insulation layer, wherein vertical forces from the tank are transferable as pressure evenly distributed from the contents of the tank to the bottom structure of the vessel; - one support point pair at the upper end and one support point pair at the lower end have tank pressure faces arrangeable transversely in the vessel, - and the other upper and lower support point pairs have tank pressure faces arrangeable longitudinally in the vessel, - a corresponding hull pressure face arranged close next to each of the tank pressure faces and fastenable to an inner ship side or to a bulkhead; and wherein - the tank pressure face and the corresponding hull pressure face are made so long and aligned such that a centre line orthogonal to the tank pressure face and orthogonal to the hull pressure face extends along a line tangential to a circle concentric to the tank shell and going through the middle of the wall of the tank (4, 40), and wherein the insulation layers are configured to transfer the load between the tank pressure face and the hull pressure face as pressure orthogonally related to the faces of the insulation layer and, at the same time, thermally insulate between the cargo tank (4, 40) and the vessel.