EMT Pipes for RTT

So I know a guy that can bend and weld EMT (electrical metal tubing) for me to make bed bars for my RTT. The standard size is 1.5 inch pipes with an outer dimension of 1.74, and the wall thickness is .065. That seems kind of flimsy for supporting the weight of an RTT.
The other option is the heavy pipe which is still 1.5 inches, but has an outer dimension of 1.66, and a wall thickness of 1.33.
My question is should I go with 3 bars of the thin pipe, 2 bars of the thick, or just go nuts and use 3 bars of the heavy? Anyone else out there try this?

 

What's the purpose of the bed bars? Larger EMT (1"+) is actually quite strong and stiff with proper supports, but due to the thin wall can dent pretty easily if abused, and if spanning large distances without supports can't hold a lot of weight. GRC is extremely strong and you could actually use a much smaller diameter than EMT and it would work great for just about anything. It's just super heavy in comparison.

 

I built a 12'x20' greenhouse out of EMT. It's pretty strong, but I'd honestly over build your bed rack. It will be taking some seriousness abuse while you drive on and off road due to that weight.

My greenhouse flexes like a MFer in the wind.

 

Intermediate Metal Conduit (IMC)

Stronger than EMT, weighs less than Rigid.

 

This may actually be what I used for my greenhouse

 

EMT is flimsy. It's certainly not meant to be load bearing. You can see it bow between supports when installing it. You could probably get away with it, but I wouldn't use it for that purpose. I would go with a heavy wall pipe.

 

The problem with it is, once it is dented or crushed, ie. by securing the rtt, the damaged areas will create weak points that will cause a failure. I would not use it, imho. Get some good tubing, rtts are heavy to begin with, then you have to account for the wieght of who ever is climbing in and out of it. Spend the money on good metal

 

No, not strong enough.

GRC or IMC would work(if you were stuck on this direction) EMT is too thin. It's made to be bent, but not to support any type of weight.

 

I am an electrician who works with this type of tubing often, and honestly I would not recommend building anything out of EMT. If it doesn't collapse, fold, or fracture at the welds when you start driving around with it, it will likely rust into nothing from the inside in the locations it's been welded or cut. EMT is made from a very low grade of steel, as it is not required to have any serious structural strength. It has a relatively soft temper, to allow it to be bent easily using a hand-bender in the field.

On a side note, if you you are selling an old car that needs new exhaust, you can easily bend up a new exhaust out of EMT, that will look sharp, and last just long enough to get the insurance transferred before it rots from the inside out.

 

I built an EMT roof rack for the shell on my Mazda pickup. I didn't weld, I used short pieces of pvc pressure fitted into the joints with epoxy. This made the whole inside water tight.

 

It turns out he's not planning on using EMT, but the thicker heavier tubing which is 1.5 inch, but has an outer dimension of 1.66, and a wall thickness of .133. I thought the original dimensions of the EMT were a little flimsy.