The cost and schedule drawback of the conventional forged titanium metal tank and liner manufacturing method is outlined. From this point of departure progress has been made based on a standard mill products approach with application of plate, sheet and bar. New shell forming methods and an increased welding share had to be developed. Depending on diameter, thickness and shape of the required domes, different forming methods have been identified: For large thin-walled domes the room temperature netshape counter-roller spin-forming and for smaller domes an elevated temperature near-net shape press- or spin-forming method has been selected, respectively. Cylinders are rounded and welded from sheet metal. Freedom from ITAR restrictions is emphasized. TIG as well as EB welding procedures are applied as appropriate to the requirements. Special parameters had to be elaborated for mixture welds between different titanium alloys. Lightweight propellant tank design options based on carbon fibre over-wrapped liners are emerging by virtue of advances in manufacturing and testing. A full over-wrap is selected together with an integrally wound skirt, which exhibits some advantage over the skirt piece part approach. The interface to the central satellite tube is maintained by special titanium inserts. Both NDI and damage tolerance aspects are mandatory to be followed comprehensively during development, inspection and testing of tank hardware. The appropriate NDI methods are available for the inspection of liners, over-wrap, CFRP skirt and the bond between liner and over-wrap. Special consideration is devoted to the advantage of over-wrapped propellant tanks over all-metal tanks in terms of design flexibility and safety. The highly damage-tolerant over-wrap allows to control the amount of bending in "flat" domes, to fine-tune the eigenfrequency of the tank shell and to impart strain-control on the liner. Three different, completely over-wrapped, typical hardware demonstrator tanks have been manufactured to an advanced degree and partly tested at MAN Technologie. The first is a polar mounted small diameter high pressure vessel following a near-netshape boss forming approach. It is intended to store hydraulic liquid, helium and xenon. The second is a large diameter high pressure vessel following a netshape dome forming approach. It is intended to store helium and is either polar or skirt mounted. The last tank is a very large, skirt mounted propellant tank, again following the net-shape dome forming approach.
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