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  • Spin forming of XXL bulkheads for large cryo tanks

    Paper number



    Mr. Alfred Trenkler, MAN Technologie AG, Germany


    Dr. Michael Dogigli, MT Aerospace AG, Germany


    Mr. Ulrich Glaser, MAN Technologie AG, Germany




    XXL (very large) cryo tanks required for today’s launchers like the Ariane 5 (main stage or Etage Principal Cryotechnique EPC respectively) are designed to store 130 t liquid oxygen and 25 t liquid hydrogen. Because of cryo conditions the tanks preferably are made of aluminium alloy (e.g. AA2219). Simplifying, the tank is designed as a cylinder (length 24m, diameter 5,4m) with spherical bulkheads (diameter 5,4m) at each end and a further common bulkhead in the interior of the tank to separate liquid oxygen from liquid hydrogen. Up to now MAN Technologie has manufactured XXL bulkheads of eight individual segments which are spherically formed before being welded to a spherical dome - a successful but relatively costly process.

    An assessment of the bulkhead manufacturing route shows that XXL bulkheads can be manufactured cheaper, faster, more flexible with respect to shape (e.g. spherical, elliptical) and - at the same time - better in quality if the conventional manufacturing process (welding of segments) is replaced by a spin forming process. The paper in hand reports on the development, manufacturing and test of a 5,4m-tank bulkhead for Ariane 5 (EPC) which actually is the biggest spherical dome in the world manufactured by a spin forming process.

    Manufacturing of non-segmented spherical bulkheads by spin forming in our days has become possible since large aluminium plates of sizes >5m are available. Manufacture of a 5,4m non-segmented bulkhead by spin forming demonstrated, that

    beginitemize item no weld seams in the spherical bulkhead area are required. Consequently original material properties are maintained, production is simplified, and production steps as well as manufacturing risks and costs are significantly reduced; enditemize

    beginitemize item spin forming a priori does not require costly and non-flexible moulds because spin forming is a free forming process. Free forming processes can easily and quickly be adapted to shape modifications of bulkheads; enditemize

    beginitemize item spin forming allows various shapes (e.g. elliptical or spherical shapes); enditemize

    beginitemize item mass can be optimised if spin forming is combined with special machining (for example demonstrated by manufacturing the bulkheads for the Japanese launcher H-IIA) and with a pre-machining of the basic raw material plate. enditemize

    Advanced welding methods (e.g. electron beam welding, laser welding) with subsequent forming and heat treatment today allow to join materials almost without deteriorated material properties. Such methods permit to manufacture bulkheads with diameters >5m by welding for example two plates together which are standard material and thus cheaper than big plates, which are world wide made available by only one supplier.

    Up to now MAN Technologie and Zeppelin Technologie GmbH (belonging to MAN Technologie now) have successfully manufactured spin formed tank bulkhead end caps for the Space Shuttle´s main tanks, bulkheads for the second stage (EPS) tanks of Ariane 5 and for the main tanks of the first stage of the Japanese Launcher H-IIA. In the frame of the PI-A5 program (Performance Improvement Ariane 5) an EPC tank bulkhead with a diameter of 5,4m was manufactured by spin forming at MAN Augsburg.

    Making use of the advantages of the spin forming process, a broad variety of geometrical shapes can be realised not only for launchers as demonstrated in the frame of the PI-A5-Program but also for XXL pressure bulkheads e.g. of aeroplanes. Further, spin forming for terrestrial applications is in progress.

    Abstract document


    Manuscript document

    IAC-05-C2.1.A.03.pdf (🔒 authorized access only).

    To get the manuscript, please contact IAF Secretariat.