Stand Stabilty Issues Or How to Avoid 240g On the Floor...

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T

T.J

Feeder Fish
MFK Member
Jun 16, 2010
35
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U.K
Hi all,

After much drama with trying to DIY a stand for our 8x2x2ft tank we decided to get one fabricated from steel, when delivered it looked ok for the job but now the tank is on it i'm not so sure :-(

The stand is made from a mix of 25mm box section and 40mmx40mm angle iron for the top rails and outside corners. Whilst I'm pretty confident this will support the weight the whole thing feels rather unstable, pushing against the stand will cause movement / wobble - its mainly from front to back but can also be noticed from side to side. I think some of this is being caused by the thick carpet / underlay not yet being fully compressed but to be honest I'm wondering about the bracing or rather lack of on the stand itself.

I'm thinking of adding some diagonal timber bracing to the two end and centre rear sections and possibly placing a board between the carpet and stand.

Attached are a couple of pictures showing the stand, any and all suggestions are more than welcome, really not keen on filling the tank and taking a chance atm :(

Cheers
T.J

IMG_1936.jpg

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I would not trust that stand either it should have been made using 2inch square tubing that is over 2400 pounds it will be holding up. If you went with the 2 inch tubing I think you could get away with one support in the middle of the stand front and back which should leave room to put in your sump. See if they will take that stand back and do it using 2 inch tubing just my thoughts.
 
Hi,

Thanks for the replies :-) I'm going to contact the tank builder Monday and get his thoughts on it, judging from his initial reaction when delivering the tank I doubt they'll be positive though....

As much as i'd like moving the tank off the stand and sorting a replacement is going to be a right mare, whilst not ideal about the only option I can see is to strengthen the stand with the tank on it :screwy:

To be honest this whole project is starting to get me down now - tried two different DIY routes for the stand and through no fault of my own it wasn't viable and now despite giving someone all the measurements / weights and trusting them to deliver something suitable I'm still left with problems.

Anyone want an 8x2x2 tank and wonky stand? :ROFL:

Cheers
T.J
 
I am with most of the others.... that stand should be 2" tube.
The stand I have that will hold my two 180's is 2" tube with 1/4" sheet corner bracing.
The stands for my stacked 75's are made from 1.5" tube and do not wiggle at all (they are on carpet too).
I question why they used angle iron and not tube all the way around. I think angle iron is not as rigid as tube.

Burt :)
 
Hi again,

Been trying to crunch the numbers regarding the weight of the tank and the "amount" of steel in the stand to see if the problem is lack of overall strength or just rigidity due to the angle iron flexing.

My maths could be way off but here they are anyway...

Worst case weight of tank: 3300lbs (about 1500kg)
Tensile (yield) strength of mild steel: 36,000 PSI
Area of one corner leg: 0.155"^2
Total area of corner legs: 0.62"^2

Pressure on just the corners: 5322 PSI less whatever the 25mm uprights are carrying, of course this assumes the wall strength of the box section is sufficient that the legs simply don't buckle along their length :eek:

I'm crossing fingers here and hoping that the math is correct and the problem can be cured by reducing the flex? If so would some 2x4" timber bolted to the inside of the angle iron legs with another piece connecting them at diagonals do the job?

Thanks again
T.J
 
Tensile strength is when you are pulling it apart. Compression strength is when you try to squeeze it together (the legs are in compression). The yield strength is where elastic deformation ends and plastic deformation begins.

Have a mechanical engineer evaluate it. Steel stands never look sufficient, but they will hold more than anyone will admit. The latteral support is lacking, which is why it feels wobbly. Add some end panels and backing to the stand to stiffen it up (plywood will do fine).
 
CHOMPERS;4360146; said:
Tensile strength is when you are pulling it apart. Compression strength is when you try to squeeze it together (the legs are in compression). The yield strength is where elastic deformation ends and plastic deformation begins.

Have a mechanical engineer evaluate it. Steel stands never look sufficient, but they will hold more than anyone will admit. The latteral support is lacking, which is why it feels wobbly. Add some end panels and backing to the stand to stiffen it up (plywood will do fine).
Click to expand...

Hi,

Thanks for that - pretty hopeless when it comes to number crunching and couldn't find much info on the compressive strength of steel, just a little bit about it being more or less the same as tensile.

In all honestly I'm starting to wonder if adding lateral support will be enough - not sure on the wall thickness of the box section but would guess it to be about 1.5 or 2mm at best and the corners seem to be welded up in a less than ideal fashion as shown in the pic. The image is a little funny looking as the tank itself has a plywood trim on the edge and I've used an 18mm sheet of ply with a 15mm "furniture" board on top of that, if nothing else the top should be pretty resilient to flexing :cry:

Cheers
T.J

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