A method for forming a hybrid metal-polymer joint, the method comprising: forming a first structured surface on a first connection area of a first metallic object wherein the first metallic object is a first metallic end piece of a cryogenic storage tank and the first connection area is a first annular flange arranged in the outer surface of the first metallic end piece; forming a second structured surface (20; 27) on a second connection area of a second metallic object (17; 24) wherein the second metallic object (17; 24) comprises a clamp; applying one or more fibre-reinforced polymer-based composite plies to the first structured surface; welding the one or more composite plies to the first structured surface of the first connection area; applying the second structured surface (20; 27) of the second connection area of the second metallic object (17; 24) onto the one or more composite plies that are welded to the first structured surface of the first connection area of the first metallic object; welding the second structured surface (20; 27) of the second connection area of the second metallic object (17; 24) to the one or more composite plies; wherein the clamp comprises a separate annular ring or a separate plate and the clamp is welded to the first metallic end piece and to the one or more composite plies arranged on the first annular flange, or wherein the clamp comprises a flap that is integral with the first metallic end piece, wherein the second structured surface of the second connection area is applied to the one or more composite plies by folding the flap onto the composite plies and the flap is welded to the one or more composite plies arranged on the first annular flange. forming a first structured surface on a first connection area of a first metallic object wherein the first metallic object is a first metallic end piece of a cryogenic storage tank and the first connection area is a first annular flange arranged in the outer surface of the first metallic end piece; forming a second structured surface (20; 27) on a second connection area of a second metallic object (17; 24) wherein the second metallic object (17; 24) comprises a clamp; applying one or more fibre-reinforced polymer-based composite plies to the first structured surface; welding the one or more composite plies to the first structured surface of the first connection area; applying the second structured surface (20; 27) of the second connection area of the second metallic object (17; 24) onto the one or more composite plies that are welded to the first structured surface of the first connection area of the first metallic object; welding the second structured surface (20; 27) of the second connection area of the second metallic object (17; 24) to the one or more composite plies; wherein the clamp comprises a separate annular ring or a separate plate and the clamp is welded to the first metallic end piece and to the one or more composite plies arranged on the first annular flange, or wherein the clamp comprises a flap that is integral with the first metallic end piece, wherein the second structured surface of the second connection area is applied to the one or more composite plies by folding the flap onto the composite plies and the flap is welded to the one or more composite plies arranged on the first annular flange.