A pressure clamp for connecting pressure vessel segments can include a pair of semi-circular sections, which can be placed around the ends of the segments, so that there is a slight gap between the semi-circular sections. The inner surfaces of the semi-circular sections can be formed with two notches with beveled surfaces. The beveled surfaces can engage corresponding slanted surfaces on the segment ends, to urge the segments towards each other as the clamp is tightened. A pair of jack screws can be threaded through the semi-circular sections so that the jack screws extend slightly outwardly from one of the sections and contact the other section at the beginning of the tightening process, to establish an initial assembly gap. As fasteners tighten the clamp around the segment, the jack screws can be backed out to maintain a uniformly decreasing assembly gap between the semi-circular sections.

A pressure clamp for connecting pressure vessel segments can include a pair of semi-circular sections, which can be placed around the ends of the segments, so that there is a slight gap between the semi-circular sections. The inner surfaces of the semi-circular sections can be formed with two notches with beveled surfaces. The beveled surfaces can engage corresponding slanted surfaces on the segment ends, to urge the segments towards each other as the clamp is tightened. A pair of jack screws can be threaded through the semi-circular sections so that the jack screws extend slightly outwardly from one of the sections and contact the other section at the beginning of the tightening process, to establish an initial assembly gap. As fasteners tighten the clamp around the segment, the jack screws can be backed out to maintain a uniformly decreasing assembly gap between the semi-circular sections.

A portable gas cylinder assembly is disclosed which includes a gas cylinder having a central axis and a protective shroud configured to encase the gas cylinder and including opposed half-sections mechanically connected to one other along a vertical plane intersecting the central axis of the gas cylinder.

The high pressure tank includes a liner, a hoop layer, and a helical layer. The liner includes a cylindrically-shaped trunk portion and dome portions disposed on both ends in an axial direction of the trunk portion. In the hoop layer, a fiber impregnated with a resin is wound in hoop winding and laminated to cover the trunk portion. In the helical layer, a fiber impregnated with a resin is wound in helical winding and laminated to cover at least the dome portions. An interface strength between the fiber and the resin on the hoop layer covering the trunk portion has a low fatigue strength and a high tensile strength compared with an interface strength between the fiber and the resin on the helical layer covering the dome portions.

The high pressure tank includes a liner, a hoop layer, and a helical layer. The liner includes a cylindrically-shaped trunk portion and dome portions disposed on both ends in an axial direction of the trunk portion. In the hoop layer, a fiber impregnated with a resin is wound in hoop winding and laminated to cover the trunk portion. In the helical layer, a fiber impregnated with a resin is wound in helical winding and laminated to cover at least the dome portions. An interface strength between the fiber and the resin on the hoop layer covering the trunk portion has a low fatigue strength and a high tensile strength compared with an interface strength between the fiber and the resin on the helical layer covering the dome portions.

A method of producing a barrier layer of a pressure vessel includes applying the barrier layer to a liner and/or to a fiber-reinforced layer of the pressure vessel while a pressure difference between the internal volume and the surroundings of the pressure vessel is being maintained.

A method of producing a barrier layer of a pressure vessel includes applying the barrier layer to a liner and/or to a fiber-reinforced layer of the pressure vessel while a pressure difference between the internal volume and the surroundings of the pressure vessel is being maintained.

A composite pressure vessel liner suitable for use in a composite pressure vessel for storing high-pressure hydrogen is provided. The composite pressure vessel liner is made of a steel material including: a predetermined chemical composition; and a metallic microstructure in which an area fraction of martensite at a position of ¼ of a wall thickness on an inner side is 30% or more, a total area fraction of martensite and bainite at the position of ¼ of the wall thickness on the inner side is 95% or more, and a total area fraction of martensite and bainite in a wall thickness center part is 95% or more, wherein the composite pressure vessel liner has a wall thickness of 20 mm or more in a longitudinal center part, and a tensile strength of 850 MPa or more in the wall thickness center part.

A composite pressure vessel liner suitable for use in a composite pressure vessel for storing high-pressure hydrogen is provided. The composite pressure vessel liner is made of a steel material including: a predetermined chemical composition; and a metallic microstructure in which an area fraction of martensite at a position of ¼ of a wall thickness on an inner side is 30% or more, a total area fraction of martensite and bainite at the position of ¼ of the wall thickness on the inner side is 95% or more, and a total area fraction of martensite and bainite in a wall thickness center part is 95% or more, wherein the composite pressure vessel liner has a wall thickness of 20 mm or more in a longitudinal center part, and a tensile strength of 850 MPa or more in the wall thickness center part.

An embodiment pressure vessel includes a liner including a cylinder part and dome-shaped side parts at both ends of the cylinder part, and a carbon fiber layer including a first hoop layer surrounding a part of an outer circumferential surface of the cylinder part, and second hoop layers surrounding remaining parts of the outer circumferential surface of the cylinder part, each of the second hoop layers having a thickness that gradually decreases in a direction from the cylinder part to a respective one of the side parts.