Is the black pipe, the stuff used for natural gas lines, any good for fabbing a strut tower brace? I made a wonderbar out of 1 1/4" pipe and it seems pretty beefy, but I don't know how stiff it really is. The STB will be a little more complex to make, and I just want to be sure it'll be stiff.

 

i would say that it would be stiff enough to use as a STB.if your going to use anything hollow i would cap the ends so you don't have any water sitting in there.

 

If I remember correctly, the gas pipe (black) is iron. Either way that stuff is HEAVY! I was thinking the same thing a while back when I went to Home Depot but after picking it up I figured I would try something else.

 

It's too heavy and brittle.....I would use DOM tubing and do it right the first time.

 

What is DOM tubing?

Regular 3/4" steel pipe would be fine for a STB. Just stay away from galvanized. It's not real heavy and definately isn't brittle.
I built my torque arm out of 3/4" steel pipe and plan to use the same if I build a STB.

 

considering the cost of steel tube over black iron pipe as well as the weight differance why would you want to use it? i'd buy some steel tube in whatever diameter you want to work with and use it. i'd also not seal the ends unless i added a weep hole or two.

 

Drawn Over Mandrel

You obviously haven't worked with pipe much or you would know better. It's just a poor choice for what he wants to do.

 

My bad.

 

black pipe is not brittle, it is steel. i work with it all the time. it should be ok, but it is rather heavy.

 

I measured up my Camaro and determained that you need a piece about 40" long for a STB.

Just for fun I dug around the steel pile until I found a piece of 3/4 ID "pipe" that I used to build my torque arm. A 40" long piece weighs right at 3 1/2 lbs. Add the mounts to the end and your STB should be under 5lbs. I could live with that.

 

Correct. And it is actually quite soft. It bends very easily - even the SCH80 variety. Round or square tubing of a decent alloy will be a lot stiffer on a weight basis. Ideally, an aluminum STB would be the nuts, since it is the rear of the car that could stand a little more mass, not the front.

 

Maybe it's the pipe we use...but I have seen black pipe crack completely in two before on numberous occasions.

 

Maybe, just maybe, there is more than one kind of

PIPE


fuggin-know-it-alls

 

I'll bite, what the hell is wrong with DOM?

 

Go back and re-read the post before that....I said I would use DOM tubing, not black pipe.....you mistunderstood my post. Some guy wanted to know what DOM stands for.

 

please use quality steel TUBING, not PIPE.
not only is it lighter, but its much stronger.
at a steel yard, DOM may be even cheaper than black iron pipe.

 

i bought all the metal to make on a few days ago and spent 20$ aslong as i dont mess up thats all its gunna cost me! i may have to use scrap laying around though but steel is pretty cheap.

 

Black pipe is pretty crappy stuff to use in any structural application, especially in any environment that includes either vibration or fatigue issues. It's not intended to carry loads other than whatever happens from a few feet of its own weight and/or maybe a few degrees worth of thermal expansion over a short distance.

Not that all pipe is bad for structural purposes, but to get the good stuff (like the A106 Gr B spec that's commonly used in nuclear power plants) you have to pay for it.

The term "stiffness" involves several things - including material properties (Young's modulus), cross-section properties (inertia, area, shear area), element length, and attachment conditions.

Norm
(civil-structural engineer/stress analyst)