Anybody know how much pressure 3.5" 16g aluminum tubing will hold? I can only find info for smaller diameters.

 

Which grade of aluminum?

 

stress= Pr/t
P = Pressure
t = thickness
r = radius

calculate for P, material's strength would be sub'ed for "stress", adjust for whatever factor of safety you want.

 

6063 aluminum

Not sure what unit goes in for material strength?? I found yield strength for 6063 is 21000psi.

21000= 1.75P/.065

P=780psi

Doesn't sound right to me, am I doing it correctly?

 

It depends on your tube, if you are buying mill grade tube you will never know, but material with ASTM certs will tell you what pressure the tube can hold. I wouldn't build anything intended to hold pressure that didn't come with certs.

 

Yes, your calculation is correct. If you concern about it rupturing, you can use the uts.

In regards to what it can actually hold, test it.
In regards to what it theorhetically can hold, it is based on your application and assumptions (material's props, temp, etc).
In regards to what it is certified, the paper will tell you.
It's what the intentions are.

 

The tubing is ASTM-B221. There will also be mandrel bends and welded seams. It will be tested anyways.

It is for intercooler piping that could possibly see 100psi (including extra safety margin). I have seen pictures of 1/8" aluminum intercoolers blown apart at those pressures. I haven't seen many aluminum intercooler pipes on 30+psi builds and was wondering if there was a reason.

 

It is possible, but much of that is either bad welding or poor design. Nobody builds square pressure vessels, but intercoolers with appreciable flat surfaces are quite common.
This is a no-no. 100psi is pretty high though, must be a diesel application.

 

I ran 49 psi on 3" al i/c piping with no issues. It had a liquid to air i/c.