[LWC Ltd]

We have a 400L flat tank and have made a cage for it out of angle iron.

Is it a bad idea to weld the cage to the van floor?

Bolting it would be a right pain cos of the position of the fuel tank etc underneath. (Citroen Berlingo)

Anyone have experience with this? Looking at old pics on here starting to think maybe should have got upright tank.

[[GQC] Tim]

I've got an upright one in a Citroen Berlingo, what you have to do is remove the fuel tank, then bolt it. Had somebody else install it for me, because I'm not too good with that sort of stuff so unfortunately I don't have any pictures.

Welds won't ever take that sort of force in an accident.

[NWH]

Vans and cars are welded everywhere to a standard to stand up to impacts,if ti`s welded in a proper way what`s the difference.

[L.J.Thorpe]

can you bolt outriggers to cage and then bolt thru floor
personlly like NWH i think welding would be fine if done with correct gear by a competent welder
but get ready for loads of experts to tell you otherwise

[[GQC] Tim]

Vans and cars are welded everywhere to a standard to stand up to impacts,if ti`s welded in a proper way what`s the difference.

They don't have 450kg of weight attached to those welds which in an accident could be 30ton in a split second. Cars and vans are made to crumble up, absorbing much of the energy, the welds are not in place to hold everything perfectly together, but welds must do that for the tank in question. Even if the welds would hold, the van floor wouldn't. It's just thin metal, nothing more.

[LWC Ltd]

The welder I have in mind is competent.

I would have thought that a weld is stronger than a bolt.

Just wondering if anyone else welded to van floor. Most I hear about are bolts.

 

[[GQC] Tim]

Just wondering if anyone else welded to van floor. Most I hear about are bolts.

There is a particular reason for that.

[LWC Ltd]

I hear what you are saying about the van floor being thin. Guess plates underneath would spread the load but its only the strength of the bolt at the end of the day.

I appreciate everyone answering and don't want to throw answers back in anyones face.

I know most people will say bolts but I need convincing why shouldn't weld it! I can't get my head round why the chance of bolts shearing is less than chance of a length of angle iron welded to floor of van ripping it open.

[L.J.Thorpe]

ask marcus
he should know
he is (was :) a coded welder

[[GQC] Tim]

I hear what you are saying about the van floor being thin. Guess plates underneath would spread the load but its only the strength of the bolt at the end of the day.

I appreciate everyone answering and don't want to throw answers back in anyones face.

I know most people will say bolts but I need convincing why shouldn't weld it! I can't get my head round why the chance of bolts shearing is less than chance of a length of angle iron welded to floor of van ripping it open.

Bolts don't just shear, they are called high tensile steel bolts, an 8.8 bolt can withstand 15 Kilo newton of force. It's definitely where the bolts go as well as spreader plates, but a weld on a length of angle iron? No way....never.

[Wayne Thomas]

Welds are much stronger than the parent metals being joined together. The weakness is around the edge of the welded area where heat has affected the parent metal. In a collison the weakest part isn't the weld as that would remain intact if welded correctly. The weakest point would be around the edge of the weld where it meets the parent metal which would normally result in a crack running alongside the weld which would be prone to shearing the thin sheeting used on vehicles.
High tensile bolts is a much stronger method of securing the tank frame to the vehicle. Even Using solid rivets spread at a minimum interval to prevent shearing or spliting of the parent metal would be a better idea than welding as used on the old steam boiler tanks.
Also, using mild steel is a bad idea because from day one it will start rusting unless treated with red lead paint which I believe is now banned so it would have to be galvanised with a suitable coating. Angle iron really isn't strong enough as it will twist and distort the frame completely out of shape in a collison.

I would rather dangle 8stories off a building welding an external staircase or whatever onto a building like I have in the past than weld a frame into a van.

[MNWC]

Welds are much stronger than the parent metals being joined together. The weakness is around the edge of the welded area where heat has affected the parent metal. In a collison the weakest part isn't the weld as that would remain intact if welded correctly. The weakest point would be around the edge of the weld where it meets the parent metal which would normally result in a crack running alongside the weld which would be prone to shearing the thin sheeting used on vehicles.
High tensile bolts is a much stronger method of securing the tank frame to the vehicle. Even Using solid rivets spread at a minimum interval to prevent shearing or spliting of the parent metal would be a better idea than welding as used on the old steam boiler tanks.
Also, using mild steel is a bad idea because from day one it will start rusting unless treated with red lead paint which I believe is now banned so it would have to be galvanised with a suitable coating. Angle iron really isn't strong enough as it will twist and distort the frame completely out of shape in a collison.

Spot on its called Lamellar Tearing 

[matt]

why not find points you can get to , then fit some tie-down points ( with the spreader plates on the rear ) and ratchet strap the tank down ( with BIG straps )

i await the "crach tested " & " bodgit " posts  :

[Captain Scarlet]

welding to the floor pan is a very very bad idea. You will come across alot of problems if you do so and I doubt very much it would be very strong. It would probably end up looking a bit of a mess too and because the floor pan is so thin, resulting in a weld that isnt very deep and very weak. Infact I would imagine it would come loose just under normal driving, with the weight of water putting pressure on the weak welds when you break and go around corners. Bolting is a far far far better idea, Luke

[LWC Ltd]

OK. Thanks for the replies everyone. Might have to take some stuff off underneath the van to do it properly.

[Ian Lancaster]

I got two lengths of 1/4" thick angle iron long enough to reach across the floor of the van.  I then chose a convenient chassis member and bolted the angle iron down through the chassis (Not just the floor pan).

I then drilled the upright bit of the angle iron to accept the claws of two 10 ton ratchet straps which pass over the tank holding it down.

In the event of a crash the most likely thing to happen is that the chassis members will fail and pull up through the floor, but as they are the strongest part of the vehicle, there's no stronger way of securing the tank.

[ftp]

That's pretty much how mine is done too.

[Allways Cleaning]

mmm im just doing the same thing....

4mm thick angle 50mmx50mm, 900 mm either side of tank , width of van.
4 x100mm spreader plates underneath, ht threaded bar attached to lifting eyes that are threaded too plus nuts and washers. plus a couple of fine wide straps.

its what you need, i have no bulkhead in my van so it aint gonna move at least i hope it wont