burst pressure of 1" black iron

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Mon Apr 19, 2010 4:09 pm

I was wondering if someone could calculate the burst pressure of a piece of 1" black iron pipe for me, as I do not know how to. The wall thickness is approximately 3.1mm (incase this pipe deviates from standards). Thanks.
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Mon Apr 19, 2010 4:26 pm

the unit wrote:I was wondering if someone could calculate the burst pressure of a piece of 1" black iron pipe for me, as I do not know how to. The wall thickness is approximately 3.1mm (incase this pipe deviates from standards). Thanks.
Likely more than you can feed it, I would definitely be happy taking it to 500 psi.
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maverik94
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Mon Apr 19, 2010 5:43 pm

Likely more than you can feed it, I would definitely be happy taking it to 500 psi.
I'm pretty sure this kind of pipe or very similar pipe has been used for high-powered hybrids, so the pipe should be just fine, unless maybe you plan on making a larda-style super armor-piercing monster.. :D I would feel comfortable taking it to 800 psi at least.
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Mon Apr 19, 2010 5:47 pm

I plan on using it for a 10x hybrid, but possibly more if I can still maintain around a 5:1 safety factor.
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Mon Apr 19, 2010 5:57 pm

I haven't used black iron in a 10x hybrid but I have used 1 1/4" galvanised iron. I imagine the only difference is one fitting is painted black and the other is galvanised (if not both).

Though I wouldn't feel safe going any higher, perhaps with remote ignition.
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Mon Apr 19, 2010 6:04 pm

The thin-walled approximation for burst pressure gives a minimum of 8900psi for the pipe itself (I assumed 35k psi tensile yield). This will decrease if your pipe is threaded, and I'd also want to add to the safety factor if it has a welded seam.

10X will generate a maximum of somewhere around 1200psi in perfect conditions.
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Mon Apr 19, 2010 6:31 pm

Thanks DYI, in my application I am going to be welding 3/4" nipples into both ends to provide me with threads, and will then use a bell reducer to go down to 1/2", and use a 1/2" union for my burst disk holder and a 1/2" tee for my ignition and fuel/air adaptor. Do you think this will stand up to a 10x mix? Also the pipe does have a seam.
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Mon Apr 19, 2010 8:42 pm

So long as it's a good quality weld, I don't see any problems developing.

If you're planning on being near it or holding it when it fires though, I'd recommend some hydro-testing first though, or at least remote firing at 20X if possible.
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Mon Apr 19, 2010 10:05 pm

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