Rolls Royce FF Series

Discussion in 'Jet Drives' started by welder13, Dec 1, 2018.

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  1. welder13
    Joined: Nov 2018
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    Location: Boston

    welder13 New Member

    Good morning! I’m hoping someone can help me out on here. Does anyone know if the FF series tunnel is aluminum cast? Severe corrosion issues and someone at work is saying it’s not a sand cast. Thanks in advance for any info!
     
    welder13, Dec 1, 2018
    #1
  2. baeckmo
    Joined: Jun 2009
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    Location: Sweden

    baeckmo Hydrodynamics

    Hi welder and welcome, the FF inlet duct is alu plating, most probably AlMg4.5Mn. The cylindrical impeller housing, stator with vanes and nozzles are AlMg3, as far as I can find from old specifiations on FF 240 and FF310 we installed here in the late 90-ies. There is no problem welding in these parts, as long as correct alu procedure is applied.

    There were some units, where the polyurethane cover in the impeller housing did not stick correctly to the substrate. That would lead to an oxygen free slot between cover and alu, creating serious corrosion. FF-jet were quick to send new housings to the affected customers. Otherwise these units are well designed corrosionwise. If there is problem in the ducting, you should look for galvanic currents, lacking protective anodes or wrong antifouling or painting scheme.
     
    baeckmo, Dec 1, 2018
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  3. welder13
    Joined: Nov 2018
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    Location: Boston

    welder13 New Member



    Wow! You have a lot of great info! I can’t believe it’s not a casting. How could they make that without using a casting if you don’t mind me asking. The corrosion is only on the aft of the duct, but didn’t not affect the ring, the hull or anything else around it. Seems so strange. I appreciate your reply!!
     
    welder13, Dec 1, 2018
    #3

  5. baeckmo
    Joined: Jun 2009
    Posts: 1,663
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    Location: Sweden

    baeckmo Hydrodynamics

    It is a clever use of separately shaped pieces welded together. Which size of FF jet are you talking about, and what are the operating conditions?
     
    baeckmo, Dec 2, 2018
    #4
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