stand aquare tube size for 2tons

[Warren]

Yikes!!

If in the Christchurch earthquake this tank had stayed together and not ruptured down the seams or the tank had not slid off the base due to no restraints or not tipped over due to not being bolted down then the stand would have collapsed. The small diagonals are almost useless and add only minor strengh. To do it properly the diagonals need to go from top corner to opposite bottom corner. The 50mm x 50mm x 3mm steel is ok for this tank as the acrylic can flex more than glass can without rupture so a small amount of give in the stand is ok. It will load up the acrylic glue joints a bit so there's high-stress points...

Yes, you do need stupidly sized structual members to support big tanks. The stand must have no flex in it under all conditions or stress gets transferred into the tank from the frame. The tank will already be under enough stress from the water force on the silicone. If you add more force you risk rupturing the joins or breaking the glass.

This tank would fail in a decent earthquake - if the tank manages to hold together or not slide off the the stand then the stand will break followed by the tank as it comes crashing down. If you'r not interested in building a seizmic-proof stand then you get 'get away' with something fairly flimsy like this stand although for a glass tank it should have more legs down the front and back + another row of legs down the middle. I wish these guys luck with this stand - they're going to need it.

[Warren]

So if 3.8 is the "industry standard" safety factor for tanks in the US/Europe, why do none of the commercial stands I've ever seen come anything close to what is suggested above (including California, which is about as earthquake prone as NZ)?

I think the reason why is the regulators get complacent. They haven't had an earthquake for so long they relax the codes. In South Korea it's more mountainous than NZ and the mountains were formed by significant seizmic acivity. But, because they haven't had a big event in over 1000 years they make their buildings just strong enough to stand up by themselves - NZ buildings are way stronger. If there was a big earthquake there would be a disaster.

It also costs a lot more to build a good stand vs one that will stay up by itself. Everyone wants to focus their spending on the tank and spend as little as possible to hold it up. This is why we have most stands sub-standard. I'd like to see the statistics on the Christchurch earthquke for how many tanks survived vs how many broke due to stand failure...

[David R]

Yikes!!

This one will make you have a heart attack then!!

Yes, you do need stupidly sized structual members to support big tanks. The stand must have no flex in it under all conditions or stress gets transferred into the tank from the frame. The tank will already be under enough stress from the water force on the silicone. If you add more force you risk rupturing the joins or breaking the glass.

This is the part that concerns me about the stand for my tank (2400x1200x700), I don't want to spend my life savings going total overkill and build a stand from 100x100 box that could support my entire house, but I also want to build something that is going to do the job and safely support my tank for years to come (and thru the very occasional small earthquakes we get up here). I guess I need to find out how flexible certain sized steel is to see what size span it is capable of supporting, going by what the engineer/fabricator who is making the stand for me six legs of 50x50x3 will be fine for supporting the weight, but the real question is what will it take to support the pressure on the base of the tank evenly.

Going for 65x65x3 over 50x50x3 will be about another $150 in materials [roughly], which is probably cheap insurance. I haven't asked about 75x50x3, but I guess using that on edge for the top frame would be better again and provide a more rigid base for the tank, then use 50x50 for the legs, base and diagonal bracing. Or would it be better to stick with the 50x50x3 and build in more support (perhaps a row of legs down the centre) to provide support over the 1200 width.

It's actually looking like timber may be the way to go, making two frames of 200x50 H3 timber then stacking them one on top of the other (and glued together for when the big shake comes) will be every bit as rigid as a steel frame and a whole lot cheaper.

[Warren]

I went timber on my last stand because overall it was cheaper but still gave the strenght required. What you suggest will work but you should also have a full-length member going down the middle as well as lots of front to back supports.

Then I started integrating the stand into the tank with all-steel frames...

If using steel, 63mm x 50mm would be ok if the spacing was reduced a fraction. Support from a flat bar-type member reduces at a rate of the square of the distance change. Say you need 400mm spacing of the legs for 75mm material, as an approximation you would need to go to 63² / 75² = .7056 so 400 x 0.7056 = 282mm spacing for the thinner profile steel.

Another option would be to make the corner legs out of 50mm x 50mm and every second leg out of 38mm x 38mm (or even 25mm x 25mm x 3mm RHS). As long as it can support the weight the main legs and diagonal braces will stop the frame from pancaking. All the diagonal members can also be thinner material. Ideally the structure under the tank made from the 63mm x 50mm or 75mm x 50mm should be replicated at the floor as well to ensure equal loading of all the legs to the floor although this could be made from 50mm x 50mm. Once the diagonal braces are welded in place it then also means the whole frame start to behave more like a single beam rather than a thin floppy base with legs on it.

[David R]

I went timber on my last stand because overall it was cheaper but still gave the strenght required. What you suggest will work but you should also have a full-length member going down the middle as well as lots of front to back supports.

Why? Here's the base I made for my 1400L tank, only reason it ended up not being use is I foolishly under-estimated the unevenness of rough sawn timber. :facepalm:

Those two frames sat on top of each other, the front-to-back supports had ~237mm between them, what would an additional full-length member down the middle achieve other than nearly double the amount of cutting and screwing?

If using steel, 63mm x 50mm would be ok if the spacing was reduced a fraction. Support from a flat bar-type member reduces at a rate of the square of the distance change. Say you need 400mm spacing of the legs for 75mm material, as an approximation you would need to go to 63² / 75² = .7056 so 400 x 0.7056 = 282mm spacing for the thinner profile steel.

Do you have figures for the amount of flex of steel that size or are you just estimating? I'm certainly not saying you're wrong, but suggesting 75x50x3mm is only good for supporting a 400mm span seems somewhat overkill, and makes me wonder how the 400L tank on a 40x40 stand with only six legs (let alone my old 1400L on a similar configuration!) is still standing.

All the diagonal members can also be thinner material. Ideally the structure under the tank made from the 63mm x 50mm or 75mm x 50mm should be replicated at the floor as well to ensure equal loading of all the legs to the floor although this could be made from 50mm x 50mm. Once the diagonal braces are welded in place it then also means the whole frame start to behave more like a single beam rather than a thin floppy base with legs on it.

So you would obviously suggest diagonal bracing more like Option B than A?

Or would a single diagonal running from top-left to bottom-right of the front (and back) inside the legs be better again? I'm not worried about access under the stand as the sump will be in the garage rather than under the tank, and the stand will only be 400mm high anyway. I'm not too worried about the floor, it will be sitting directly on the concrete slab and I would expect that the 50x50 be enough to distribute the weight enough to avoid putting too much pressure on any one point of the slab.

Then I started integrating the stand into the tank with all-steel frames...

I'd love to hear more about that, and see some pics. I'm following a guy on MFK building a 14x8x4' steel framed tank (out of 50x50x3 I might add), though it will be sitting on the floor so no stand needed. I have thought about doing a steel framed, ply and fibreglass lined tank with a glass window in the front, but for simplicities sake I think I'd pour a 200mm high concrete plinth for it to sit on directly onto the floor then bolt the steel frame onto that. Sadly the wife isn't too happy about me doing something that will probably require a jackhammer to remove (she was fine with a big timber/fibreglass build tho!) so that isn't an option.

[Warren]

Yeah, like option B but with diagonals between every vertical support.

The diagonal bracing round the sides and back can be welded and bolted along the front. You could also make one or two front legs bolted so the sump could be accessed (the tank would need to be empty or close to empty to remove the legs though).

The wooden stand looks good. You might have been able to use it if you'd put a filler-glue between the layers and a couple of layers of ply on top with the same filler-glue to take up the uneven spots - depend just how uneven it was. By sitting the tank on top of the wood while the glue was curing it would have forced the ply to conform to the bottom of the tank pretty evenly. The downside with wood vs steel is there is usually no space for a sump under the tank...

[David R]

The downside with wood vs steel is there is usually no space for a sump under the tank...

Not a problem for me, I don't like tall stands that make tanks too high for maintenance and too high for viewing while seated, and I don't like having to get on all fours to clean my sump!

Any chance of pics or a write up on the steel framed tank with integrated stand? I think I've pestered you about it before, sounds interesting. Surely you're getting bored not having any fish, must be about time for another project...

[Warren]

Here's the original photo's taken just after the 19mm thick glass panel was siliconed in place. I used this tank for about a year then had to move. It was a wee bit too big so I sold it to the National Aquarium where it still lives today as the NZ Native Fish display tank. It's made from 200mm x 100mm x 6mm RHS for the base. The corner uprights are 75mm x 75mm x 6mm RHS. The top is 100mm x 50mm RHS. The rim around the inside of the frame is 30mm x 10mm solid bar - this retains the glass and plywood. The bottom has 7 front to back supports evenly spaced of 75mm x 75mm x 6mm RHS to support the bottom plywood. All the plywood is construction grade, 2 layers of 19mm laminated to 38mm thickness glued and screwed into the frame. There are no diagonal braces as the plywood provides the bracing. This was coated with 2 layers of boatcloth and epoxy resin prior to installation. The whole interior is then covered with 3 layers of chopstrand and epoxy with 2 coats of matt-black gelcoat to finish. Overall finish size is 3000mm x 1200mm x 1000mm (W x H x D)with the front viewing window 900mm x 2790mm.

The bottom of the tank was 100mm below the bottom edge of the glass so the gravel sat at the bottom of the viewing area - why waste window space??

The side could also have been glass with no loss in strength but 19mm glass is pretty expensive so ply was my cost saving compromise. All up painted this tank cost just over $2k.

[Warren]

What isn't shown or mentioned above is there are also 2 bolt-on top braces that go front to back at 1/3 and 2/3 along the length. This was required because even 100mm x 50mm x 6mm RHS bends quite a bit with the force from the water. These braces meant there was only 0.25mm bend in the steel between the braces ensuring the top edge of the glass was properly supported to preserve the design safety factor.

[Warren]

Here's what I'm considering for the new tank. Now I'm not travelling at all I can think about getting into it again.

It's an AutoCAD design so possibly not so clear as a jpg...

The dimensions are: 1550mm wide x 1568mm tall x 850mm depth.

The internal tank dimesions are: 1546mm x 810mm x 800mm = 807 Litres

The front viewing window is: 1490mm x 710mm x 15mm low iron toughened (safety factor 31.25) - only going this crazy because I can

It also has a lowered bottom area for the gravel - why use up expensive window space!!??

Design safety factor for the tank as a whole is around 8 which means the house will fall down first. It's only this high because the materials are strong for the size of the tank so little to no compromise is required.

The design will use tig welded stainless steel angle for the bulk of the frame and earolam back and bottom panels with a fibreglass sealing coat. Earolam is 12mm thich honeycomb with kevlar on both sides. It's one of the composite products used on America's Cup boats. It's incredible strong for its thickness.

[henward]

wow

I think when i build my dream tank.

it will be like that picture above... steel. ply with a monster glass panel in the front.

the company im getting to make a stand will build that for me!

just add glass lol

nice tank, i dream of a tank that requires me to go into it to clean it:D

[alanmin4304]

The next trick would be strengthening the floor of the house to take the weight would it not?

[henward]

concrete slab for me.

the weights on each point is actually quite low

[alanmin4304]

If you have point loads the force on each would be considerable. The aim would be to spread the load over the whole footprint would it not?

[henward]

If you have point loads the force on each would be considerable. The aim would be to spread the load over the whole footprint would it not?

yes, like a horizontal bar going across at the legs so it spreads.

but say the tank water and stand is 2.5 tons.

312kgs on each point

a car can be 2 tons with 4 points, 500kgs each.

but yes, i know what you mean.

[alanmin4304]

You don't park the car in your lounge---I hope

[henward]

You don't park the car in your lounge---I hope

haha, my car is on the drive, garage is for tanks and stuff only:D

http://media.smh.com.au/property/domain ... 86376.html

wouldnt mind though

[scottscape]

I don't know what you are going to get charged for a custom build job, but depending on the cost going for pallet racking could be a cost effective option, and very strong.

2 frames at about $150, whatever width you want, two high strength beams rated to 2400kg at 2.4metres long (or 3 tonne if you want to be safe and avoid any flex) at between $80-150 depending on strength, two lighter beams low down to give structure, then $50 pallet supports at whatever frequency you judge with a $50 - $100 tri board cover spanning the whole lot could suit you.

For a more accurate quote with exactly what specs you want I can get you an exact amount.

As far as flex goes the stronger you go the less flex you will get in Seismic events, though this stuff is built with it in mind.

From there you would just need to paint it, or you could get a melteca Bar Back panel to face off the front and sides for a good looking finish.

Anyways if this helps or you want to know more let me know.

[Warren]

Have you ever seen the bend in this type of racking system with 3000kg evenly distributed across 2 x 2400kg bearers? It's around 7-8mm sag in the middle - way too much for an aquarium. You want less than 0.1mm or the load will start to appear on the glass and silicone. At 0.25mm bend almost 100% of the force is on the glass and silicone and 0% on the bearer.

[scottscape]

Have you ever seen the bend in this type of racking system with 3000kg evenly distributed across 2 x 2400kg bearers? It's around 7-8mm sag in the middle - way too much for an aquarium. You want less than 0.1mm or the load will start to appear on the glass and silicone. At 0.25mm bend almost 100% of the force is on the glass and silicone and 0% on the bearer.

Well yeah 3 tonnes on beams rated for 2400kg is certainly not going to work, but 2 tonne on 3.6 tonne beams or a similar load rating wouldn't have much flex depending on the span - I would have to go to the solidwork programme to be sure. If it did there is potential to put another frame in the middle, or to use a different type of beam.

Weight distribution is a biggie as you say and getting the edges across the frames would certainly be ideal.

My point was that getting this kind of thing custom made to the millimetre like a tank requires will not be cheap, and in some cases racking could suffice. Its really dependent on a few variables - the tank specifications and what you lay on top of the frame are just a couple.

In any case you know more about Aquariums than myself Warren, obviously timber on timber as you have shown in your picture is the ideal, however it doesn't leave much room to play with beneath it, and getting that dead level is a mission in its own right.

[Warren]

Yeah, dead straight with big loads is very difficult to do cheaply and requires big steel with lots of legs and bracing.

I thought the beams you were talking about were rated at 2400kg each so 4800kg total. Is the rating on them actually for the pair? If so then I've seen many of these racking systems seriously overloaded!! At my old job the stores would put 2 pallets of batteries on each shelf totaling about 3000kg. Sounds like they were pushing it a bit!!

[scottscape]

Yeah, dead straight with big loads is very difficult to do cheaply and requires big steel with lots of legs and bracing.

I thought the beams you were talking about were rated at 2400kg each so 4800kg total. Is the rating on them actually for the pair? If so then I've seen many of these racking systems seriously overloaded!! At my old job the stores would put 2 pallets of batteries on each shelf totaling about 3000kg. Sounds like they were pushing it a bit!!

Yeah haha like a 2.4metre span fits two pallets which are meant to be about a tonne - giving you a leeway of 200kg extra per pallet for mis-loading. The guy selling the racking to the manager should have asked what the application was!

I've seen tests done where racks were grossly overloaded, and real world scenarios where I wouldn't walk in the storeroom! 300kg overload per beam is not a good long term solution but not the worst I have seen.

Pallet storage is a serious issue and I wouldn't personally work around overloaded or improperly loaded racks. They are fantastically strong but when they go its real bad. Significant bowing or not bending back straight when unloaded is a bad sign.

Companies are supposed to get yearly checks done(but they dont), they only cost $120 and might save pallets of stock - not to mention lives.

Its just another example of how slack kiwi companies are that you were working around and I presume loading racking with no idea of its weight capacity. Things are changing though.