A pressure vessel made of two thin-walled, closed-end tube sections joined at a central hub that encircles the open ends of the two closed-end tube sections, with a plurality of radial bolts attaching the sections together. The central hub has an O-ring groove in which an O-ring rests, providing a seal between the interior of the pressure vessel and the outside. The inner wall of the central hub may have radially thin and radially thick sections to distribute and minimize weight without sacrificing strength. The assembly may be attached to a mounting surface through a dovetail mount on the central hub.

A multilayer structure for storing hydrogen, including, from the inside, at least one sealing layer and at least one composite reinforcement layer, an innermost composite reinforcement layer being welded to an outermost adjacent sealing layer, the sealing layers being a composition predominantly of: at least one semi-crystalline polyamide thermoplastic polymer P1i, i=1 to n, n being the number of sealing layers, excluding an amide polyether block (PEBA), up to 50% by weight of impact modifier relative to the total weight of the composition, up to 1.5% by weight of plasticizer relative to the total weight of the composition, and at least one of the composite reinforcement layers of a fibrous material in the form of continuous fibers, which is impregnated with a composition predominantly of at least one semi-crystalline polyamide polymer P2j, j=1 to m, m being the number of reinforcement layers.

A high-pressure composite container having a gastight nozzle structure includes a metal nozzle formed at a side of an inlet of a plastic liner layer that defines an inner layer of the high-pressure composite container; a nozzle insert which is inserted into and attached to the metal nozzle in a direction from an inner side of the plastic liner layer to an outer side of the plastic liner layer; and a nut member fixed to an upper end portion of the nozzle insert.

A pressure vessel assembly incudes a pressure vessel and a gas density gauge. The pressure vessel includes a vessel wall defining an interior cavity. The gas density gauge includes a parallel plate capacitor having a pair of plates. Opposing surfaces of the plates are separated by a distance across an open gap. A capacitance of the capacitor is related to a density of a gas within the open gap.

A pressure vessel assembly including a pressure vessel including a cylinder part and a first side part and a second side part, the first side part and the second side part each having a dome shape and being provided at two opposite ends of the cylinder part, nozzle members respectively provided on the first side part and the second side part, and a plurality of protectors connected to the nozzle members and configured to surround a respective outer surface of the first side part or the second side part.

A hollow molded article having a joining site where two or more split objects are welded by plastic welding and comes into contact with pressurized hydrogen, wherein an average spherulite size in a portion which is 500 μm deep inside from a surface of the hollow molded article is 20 μm or less, and a tensile strength of a test piece containing the joining site of the hollow molded article is 80% or more based on a tensile strength of a test piece not containing the joining site of the hollow molded article.

Method for preparing a hydrogen tank including at least one sealing layer of a composition including at least one polyamide P1, and at least one base in order to provide the tank with at least one opening, wherein the method includes: providing of at least one base, the at least one base being covered by at least one layer of a composition including at least one adhesion primer; preparing the at least one sealing layer; fastening the at least one base to the at least one sealing layer.

A plastic tank liner for the storage of a pressurized fluid includes: two ends; two elongated cylindrical sections, the two cylindrical sections having different diameters; and one connecting section connecting the two cylindrical sections. The connecting section has a concave portion connected to the cylindrical section of smaller diameter, and a convex portion adjacent to the cylindrical section of larger diameter. The convex portion has an isotensoid shape. Two convex domes are located on both ends of the plastic tank liner so that each of the domes is connected to a different cylindrical section.

A multilayer structure for transporting, distributing and storing hydrogen including, from the inside to the outside, a sealing layer and at least one composite reinforcement layer, the sealing layer including from the inside to the outside: a layer of a composition including: a short-chain polyamide thermoplastic polymer, more than 15% and up to 50% by weight of impact modifier, or including: a semi-crystalline long-chain polyamide thermoplastic polymer, up to 50% by weight of impact modifier, up to 3% by weight of plasticizer; a hydrogen barrier layer; a layer of a composition including: a short-chain polyamide thermoplastic polymer, more than 15% and up to 50% by weight of impact modifier, or including: a semi-crystalline long-chain polyamide thermoplastic polymer, up to 50% by weight of impact modifier, up to 3% of weight of plasticizer, the innermost composite reinforcement layer being wound around the sealing layer.

A high-pressure tank comprising: a resin liner for a high-pressure tank including at least one opening portion; an aluminum mouth portion attached to the opening portion; and a reinforcement layer formed on an outer surface of the liner, wherein an aluminum oxide coating is formed on a surface of the aluminum mouth portion, the aluminum oxide coating includes a porous surface layer in which columns with an average height of 10 to 100 nm are arranged in a dispersed state, an average value of a percentages of the protruding portion area of the columns in randomly sampled 400 nm square visual fields of the porous surface layer is 5.0 to 26.0%, and an average value of the numbers of the columns in randomly sampled 400 nm square visual fields of the porous surface layer is 500 to 2000.