Tank Stand Design

Discussion in 'General Discussions and Advice' started by christiaan, 15 Jan 2009.

  1. christiaan

    christiaan

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    Hi Hennie

    Seeing as you've had lots of experience with stands and tanks and breaking glass - I'd love to pick your brain for a moment.

    I'm planning a new reef - I've been collecting everything I need to start over the last couple of months and all I need to do now is the stand - the second hand tank I bought has a stand that is too low and I have to weld a new one.

    Heres a bit more about the system Im planning - tank dims are 2m x 50 wide x 70 high - sump is 1.5 x 40 x 40. Everything else is standard - the space where I want the tank is the challenge.

    Here is a pic of the location in my hallway.

    [​IMG]

    The space is 2m(well 197cm - will have to grind 3cm off the wall) x 70 deep.

    So originally I planned something like this

    [​IMG]

    This is what I want it to look like in the end.

    [​IMG]

    This is the stand that I have in mind now

    [​IMG]

    Its built out of 50mm squaretubing(3mm thick on main beams and 2mm thick on supports. The main goal here is working room under the tank - I hate not having room - becuase the tank is in the hallway it will be 1meter high. Becuase the hole in the wall is 70cm deep and the tank only 50 I want the sump to not be right under the tank becuase I would be wasting the space behind the sump - SO - I want the sump against the back wall - hence no supports in the middle back and front - only the one in the middle.

    Will this stand hold - is it overkill? Obviously the less metal etc etc the better so if its to much where whould you scale down or would you do the whole thing differently - One guy here in Pretoria told me that simply a squaretubing plain boxframe would work - I think the 1 ton tank would be too heavy - am i right

    Thanks for the help Hennie!
     
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  3. Mike

    Mike Retired Moderator

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    Won't the centre support be in the way of the sump? - even out of 50mm box steel, you will still need the supports front and back in the middle or you'd be in danger of the tank cracking.
     
    Last edited: 15 Jan 2009
  4. christiaan

    christiaan Thread Starter

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    The sump will fit between the middle support and the back wall - what do you meen - even out the 500 box steel?
     
  5. Mike

    Mike Retired Moderator

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    Sorry, i meant 50mm box steel, i just edited my post to remove the error, why not have a front and rear support and have more room for the sump and other kit, also giving more strength to the frame.
     
  6. christiaan

    christiaan Thread Starter

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    Did I not explain this right? - the back cannot be supported becuase the sump will be there - I need lotsa room under there.
     
  7. Mike

    Mike Retired Moderator

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    I don't think that a single upright will be enough for the 2m span, by moving the sump forward 50mm you will be able to have support front and back in the middle, that way you will prevent sag.
     
  8. christiaan

    christiaan Thread Starter

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    But I'll loose the space Im trying to save - So you think that the 2 supports will be that much better than the one in the middle?

    \The two "train rails" will help with the sag IMO - am I wrong?
     
  9. christiaan

    christiaan Thread Starter

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    [​IMG]

    This was another design I had in mind before - this one fills the whole space in the wall
     
  10. christiaan

    christiaan Thread Starter

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    The problem here is that the back beam will again not be supported(to make room for the sump again)
     
  11. RiaanP

    RiaanP Moderator

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    Your design will go crash...
    The middle upright ends up on a horizontal that is connected at its ends to the bottom of the top rails. That horizontal part will bend, as it has to take all the weight in the middle. It need a V supports from bottom outwards to the top of the rails.

    And then why not include the other two "middle" supports. Remember, that the sump will then never come out. If something goes wrong, have to fix it in there.

    Also on what will the tank stand? you got the back bar running in the middle of the sump, as I see it the sump will be 20cm into the stand and "overhang" to the back by 20cm. So on what metal support will it sump stand.
     
  12. Reef Maniac

    Reef Maniac MASA Contributor

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    Christiaan, I will have a look at this tomorrow (Saturday). I do agree with RiaanP and Mike, though - we will probably need to make a few structural changes...

    Hennie
     
  13. RiaanP

    RiaanP Moderator

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    How High is your sump stand?
    1m
    And then the rail removes another 200mm at the top.

    One day - make that every time - you have to stick your hand into the sump, Yes you will, you will bump your head against the rail.
    Every time, you will hear me - "I Told You So"
     
  14. christiaan

    christiaan Thread Starter

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    Haha - thanks for the help guys - have to work now but we'll talk later.
     
  15. Reef Maniac

    Reef Maniac MASA Contributor

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    Just remember that anyone who've experienced a sudden, total tank failure such as mine is bound to be over-cautious :whistling:

    Also please keep in mind that I'm not a structural engineer, so don't take everything a say as gospel :whistling:

    Looking at the diagram, I agree with RiaanP that the center support is a bit suspect, and you would either have to install "V" braces between the center leg and the bottom of the frame, or install two legs front and back. Of course, if you build the top structure strong enough that it can span the full two meters without deflecting more than what the glass can handle, you don't need any support in the center... but I'm pretty sure that 50mm x 50mm x 3mm square tubing won't be "stiff" enough, and will have too much deflection in the configuration as you've drawn it.

    I don't really see why this would be a major issue. If you use the 50 x 50 square tubing your sump will only be (say) 60mm away from the wall. That is really not a large waste of space - in fact, if your sump ends up similar to most people's, you might actually need a bit of space behind the sump for wires, pipes, etc.

    I would suggest that you consider one of two options:

    • Build a frame similar to a roof truss - instead of having a "box" with vertical uprights as shown in your sketch, why not make the supports triangular between the top and bottom members of the "beam"? This will give *much* greater stiffness for nearly the same amount of steel used
    • build a reinforced concrete slab capable of spanning the full length of the tank - this is what I've done on my 1.8m tank. I used 75mm x 50mm x 6mm angle iron to build the frame, then shuttered the bottom of the frame and cast a 75mm thick concrete slab inside the frame. I originally built this without center support legs, as a structural engineer colleague of mine designed this slab, and assured me that if would be able to span the 1.8m without undue deflection. After completion I tested the slab, and found that the deflection was still more than what I felt comfortable with, so I retrofitted two 38mm x 38mm square tubing legs in the center of the span. In your case, I would go for a 100mm thick slab (at least...), and measure the deflection after construction (load it with people, such as I did, or with cement pockets equivalent to the expected weight...) - if it works, fine, if not, add the center legs... The advantage of a solid concrete slab is that you can then use much thinner glass for the tank bottom (the same thickness as the tank sides...).

    Either way, if you really want to be sure before you start, it would be highly advisable to have a structural engineer do the design for you.

    Hennie
     
  16. Reef Maniac

    Reef Maniac MASA Contributor

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    I quickly copied and edited your drawing in MS Paint (yes. I know... not the greatest...). This is what I had in mind (just did one side...):

    [​IMG]

    Hennie
     
  17. christiaan

    christiaan Thread Starter

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    Thanks so much Hennie - I agree and I'm back on the drawing board! - will let you guys see the new design as soon as I have a new idea!
     
  18. christiaan

    christiaan Thread Starter

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    How about building in a platform with bricks and lintels guys? - will 3 lintels carry the weight of this tank if only support them on the sides? So it will be like a 190cm span. . .
     
  19. Mike

    Mike Retired Moderator

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    Lintels or I beams - i have seen this work on a 3m tank, you just need to be sure you are level and reinforce the uprights - Sean K is probably the man to sort out sizes etc for you.
     
  20. Reef Maniac

    Reef Maniac MASA Contributor

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    Perhaps I'm misunderstanding you here, but lintels should not be placed on their sides - they have pre-stressed reinforcement, and are designed to support a certain load when placed upright.

    Three lintels should easily carry the weight, but I think that they will still deflect a bit more than the glass would like if only supported on their ends. Personally I would still recommend casting a proper concrete slab if you want to span the full length without any supports in the centre - if this is not an option then some type of welded square tubing "space frame"...

    Yes, I too would like to hear Sean's recommendations - he certainly has more experience and knowledge in building these types of structures than I do :)

    Hennie
     
  21. Mike

    Mike Retired Moderator

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    Hennie, the I beams or RSJ's would be fine if they were sized correctly.
     
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