Abstract: A method of manufacturing a liner for use in a pressure vessel includes a cold drawing process that shapes a transition zone (20b) part of an aluminum alloy liner shell (10). The transition zone (20b) links a thinner walled drum part (18) and a thicker walled end region (20a), which is at an open top of the shell. The transition zone (20b) may be shaped by the cold drawing process such that it reduces susceptibility of the shell to fracture during removal from a cold drawing press and also redistributes shell material in preparation for a subsequent process in which a threaded neck is formed from the end region (20a). This process is particularly suited to processing harder aluminum alloy materials such as AA7060 or AA7032.

Abstract: A method of manufacturing a liner for use in a pressure vessel includes a cold drawing process that shapes a transition zone (20b) part of an aluminium alloy liner shell (10). The transition zone (20b) links a thinner walled drum part (18) and a thicker walled end region (20a), which is at an open top of the shell. The transition zone (20b) may be shaped by the cold drawing process such that it reduces susceptibility of the shell to fracture during removal from a cold drawing press and also redistributes shell material in preparation for a subsequent process in which a threaded neck is formed from the end region (20a). This process is particularly suited to processing harder aluminium alloy materials such as AA7060 or AA7032.

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 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.

Abstract: Problems are caused by stress corrosion cracking and exfoliation cracking in the heat-affected zones adjacent welds in structure of welded components formed of Al alloys, particularly of the 7000 series but also of the 5000 series. The invention seeks to overcome these by the use of Al-Mg welding wire containing 0.01-0.5% Ga and/or In and/or Sn, the composition being chosen such that the weld bead has a potential at least as electronegative as the components and preferably in the range -1200 to -1300 mV with reference to a standard calomel electrode. To prevent diffusion of Ga/In/Sn, the components may be pre-coated e.g. by using a double-pass welding technique.