Abstract: A gas cylinder (100) in the neck (20) of which is installed a balanced valve (26). The valve is fitted in the outlet of the cylinder and its output emerges into a recess (22) which opens to the top surface (23) of the cylinder. Thus the valve is protected from physical damage. A thread (27) in the bore enables the attachment of fittings such as a regulator or a filling device (not shown) which cooperate with the valve (26) to control passage of gas from or into the cylinder.

Abstract: A method of treating the internal surface of a container for the storage of gas, such as a gas cylinder, that is made from or lined with aluminum or aluminum alloy. The method is characterized in that it comprises creating a freshly exposed aluminum surface, for example by the use of a wet grinding, in the presence of a surfactant. The surfactant is preferably derived from C6-C18 carboxylic acids. The container for the storage of gas provides long-term gas stability. The internal surface of the container has a substantially continuous disturbed layer and is hydrophobic. It may also incorporate groups or species derived from the surfactant and/or comprise oxides or oxyhydroxides of aluminum.

Abstract: A method of treating the internal surface of a container for the storage of gas, such as a gas cylinder, that is made from or lined with aluminium or aluminium alloy. The method is characterised in that it comprises creating a freshly exposed aluminium surface, for example by the use of a wet grinding, in the presence of a surfactant. The surfactant is preferably derived from C6-C18 carboxylic acids. The container for the storage of gas provides long-term gas stability. The internal surface of the container has a substantially continuous disturbed layer and is hydrophobic. It may also incorporate groups or species derived from the surfactant and/or comprise oxides or oxyhydroxides of aluminium.

Abstract: A gas cylinder (100) in the neck (20) of which is installed a balanced valve (26). The valve is fitted in the outlet of the cylinder and its output emerges into a recess (22) which opens to the top surface (23) of the cylinder. Thus the valve is protected from physical damage. A thread (27) in the bore enables the attachment of fittings such as a regulator or a filling device (not shown) which cooperate with the valve (26) to control passage of gas from or into the cylinder.

Abstract: A pressure vessel has a cylindrical side wall and a closed end joined to the side wall at a knuckle. The fatigue resistance of the pressure vessel is improved by autofrettage which moves a region of peak stress from the internal surface of the vessel to a region within the knuckle. Preferred are pressurized gas vessels of 6000 or 7000 series aluminum alloys.

Abstract: A method of forming a closed-end vessel by backward extrusion comprises providing an extrusion billet having a front surface with an axial recess and a body of an extrudable material positioned in the recess. Backward extrusion results in the formation of a closed-ended vessel, for example a pressurized gas cylinder, composed of the material of the extrusion billet with a weld bonded inner surface lining of the extrudable material.

Abstract: A method of making a pressurized gas cylinder comprises providing an ingot of composition (in wt %); Zn 5.0-7.0; Mg 1.5-3.0; Cu 1.0-2.7; recrystallization inhibitor 0.05-0.40; Fe up to 0.30; Si up to 0.15; other impurities up to 0.05 each and 0.15 in total, balance Al of at least commercial purity, if necessary homogenizing the ingot at a temperature of at least 470.degree. C. and for a time sufficient to reduce the volume fraction of S phase to a value below 1.0%, extruding the ingot preferably by cold backward extrusion, and forming and over-aging the resulting pressurized gas cylinder.