Stainless strap strong enough for this?

[Dylan T]

Hi all -

Got a left field project I was hoping someone could help with. Fixing a water tank under a camper conversion I'm working on. The tank had an optional steel strapping that it normally comes with that had sold out but I've got some stainless steel strapping here that i was hoping could work. But now I'm having 2nd thoughts that's strong enough. Due to limitations of space and places to fix, I'm hanging J bolts from under the chassis and was going to bolt these onto the strapping. The tank is 57l so really it needs to hold around 60kg. Does anyone know of the tensile strength of 1mm stainless steel strap like this? It's this exact one here. Will be used towards both ends of the tank and I have enough to double it up. Thanks!

 

[Deleted member 174758]

That is builders band, rather than solid strapping. You normally just use to hold up pipes, cabling etc. In use I you'd probably be able to load 60kg onto two of them

You could always get some and do a test with a static load of, say 120 to 180kg (I figure you'd need to be able to accommodate a dynamic load as vehicles do bump up and down) - there is quite a bit on a roll so you should have plenty to spare. You might also want to take a look at the way they strap fuel tanks onto trucks - they often use rubber banding between the steel straps and the tank to prevent the steel cutting-into the tank

I think the biggest problem might be how to fix the strapping to the vehicle so the screws won't either pull through the holes (so penny washers needed) or pull out of what they are screwed into

 

[jj4091]

Any good https://autocraftmotorcaravans.co.uk/product/universal-water-tank-steel-strap-mounting-kit/

 

[Mr Chibs]

Doubled up that strapping will support 60kg. Find some rubber strips to go between the tank and the straps. Could cut up a car floor mat.

 

[bernardgreen]

60kg static load becomes a dynamic load much greater than 60kg when the vehicle goes over a speed bump or pothole.

 

[jj4091]

60kg static load becomes a dynamic load much greater than 60kg when the vehicle goes over a speed bump or pothole.

No expert in that field but surely if the tank is firmly fixed to the bottom of the vehicle then the speed it moves up/down over speed bump will always remain the same as the rest of the vehicle & therefore the load will not vary as any shocks will be taken up by the vehicles suspension.

 

[Deleted member 174758]

Isn't there also some additional dynamic loading caused by water within the tank moving as well? More especially when the tank is part full? The tank may be static, but the contents aren't and that puts additional loading on the strap and it's fixings (which I think is a more likely failure point). If you've ever towed a part empty water trailer or driven a tanker lorry you'd know what I'm talking about (water can move around a lot)

 

[Dylan T]

Haha thanks all - I'm glad I'm not the only one that found this tricky to work out. As luck would have it I managed to snoop under a professionally converted van and they had used the same strapping so I'm just going to double it up and assume it will be fine. I spoke to a retired engineer this morning who said stainless steel is a good bet as aluminium can become brittle under repeated stresses. I'll keep an eye and if I ever see signs of strain then I'll opt for thicker steel.

 

[Deleted member 174758]

Good call! Belt and braces is always better

 

[Keithmac]

No expert in that field but surely if the tank is firmly fixed to the bottom of the vehicle then the speed it moves up/down over speed bump will always remain the same as the rest of the vehicle & therefore the load will not vary as any shocks will be taken up by the vehicles suspension.

If the floor of the vehicle moves up, the stapping is then under more load as it has to pull the 60kg tank up rather than just supporting it.