LRO: Galvanizing Bulkheads

From: Todd Ondick (greylildogs@hotmail.com)
Date: Tue Apr 10 2001 - 18:24:30 EDT

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    >
    >I know this question has been flogged to death, but how does one get a
    >bulkhead galvanized without having it distort? I vaguely remeber someone
    >saying to search for an outfit that would pre heat/soak the item before
    >dipping? Or do you just wrench it into place and bolt 'er in.
    >

    Don't do it!

    From the info I've gathered, there is NOTHING that will prevent heat related
    warping at some scale. Regardless of how carefully you heat and cool, all
    lengthy, flat spans of unsupported thin sheet metal will warp a bit (esp.
    the panel above tranny tunnel and rear portions of shelves).

    The critical thing is how it is handled out of the zinc bath until the piece
    cools. The bulkhead is mostly made of spot welded pieces of thin steel
    sheet. If man-handled while still hot, the whole thing can bend. bolting
    channel iron across critical spans will help (you usually pay by the pound)
    but other surfaces can still bend. I saw a galv. SI bulkhead at David
    Gage's shop that looked like it had been set down on the engine side a bit
    too hard. The bottom/front of all the shelves & inst. panel had curled up
    and in... ouch.

    That said, to do it over again, I wouldn't galvanize my bulkhead. Too many
    things can and do go wrong. Mine didn't warp too much, but it had a large
    amount of slag and drizzle to grind off (HUGE PIA and it still ain't
    straight). To get it slag free they have to "bump" the piece, while still
    hot, adding to to the inevitable warpage. It is also hard to get the piece
    totally free of slag because of it's compound angles & difficulty in
    manipulation so every section can drain. The passivating solution after
    the zinc bath also has a large effect on slag and surface appearance and all
    galvinizers do not use the same process (so ask). Maybe, If you had a
    spare bulkhead to fall back on, knew the right questions to ask, and had a
    good working relationship w/ the folks at the galvanizers (or went thru
    someone who did), It might be worth considering. maybe but probably not.

    cheers,
    -todd
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