Pressure between two SS pipes

[pWr93]

I believe this question is simple but let me know if you need more info.

I have two stainless steel 304 pipes, both pipes are concentric so the smaller one is within the larger one. Both are .125" thick. The first cylinder has OD = 4" and the second cylinder has OD = 6". Now, I need to provide air @3000 psi in between the two pipes which I calculated to be .875" (from OD of small pipe to ID of larger pipe) all the way around. Would this rupture the pipes or will the pipes be able to withstand the pressure? If it does rupture the pipe, what material substitute or dimension changes can I make to adhere to the 3000 psi?

I tried looking into it and I believe it will withstand the pressure based on pressure ratings I found in this link:

http://www.my-ssp-usa.com/resources/pressure-ratings

 

[metengr]

If I understand your question, there are two concerns - the first being internal pressure (hoop stress) on the bore of the larger pipe to prevent rupture and external pressure on the OD of the inner pipe to prevent collapse under external pressure. This assumes two concentric pipes with pressure in the annulus. What is the pressure on the smaller pipe ID surface?

Your current thickness you stated for both pipes will not be safe. ASME B&PV Code, Section VIII, Div 1 provides guidance for this type of scenario.

 

[SnTMan]

And note the external pressure capability of the internal pipe is a function of length as well.

Regards,

Mike

The problem with sloppy work is that the supply FAR EXCEEDS the demand

 

[racookpe1978]

Your "failure points" must also be analyzed:
Internal pipe pressurized, void vented, external pipe vented.
Internal pipe vented, void pressurized, external pipe vented.
etc.

Can there ever be pressure around the external pipe?
Ever a vacuum in the void?

 

[EdStainless]

Is there a design code that you are following?
Are these actually 4" and 6" tubes, or are they 4 and 6 pipe? Very different sizes.
You are looking at roughly 0.300" wall (off the cuff) on the 6".
The 4" needs to be for internal pressure and collapse by external pressure, 0.125" isn't enough.
There are tables in the B&PVC to use for external pressure applications.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, Plymouth Tube

 

[A clark]

You should review UG-28 of Section VIII Div 1. It has a step by step guide to determine MAWP.

 

[cbPVme]

You're creating a very dangerous situation with 3000 psi compressed air if things aren't designed properly. Please hire someone with experience in this field.

 

[LittleInch]

pWr93,

You need to have / supply

Design code
Design temperature
Design pressure (3000 psig?)
Material to be used (304Stl Stl?)

I don't know how from your link you think it will survive when a 2" tube at .125" is only good for about 2,500 psig. A 6" tube will be a lot worse than a 2" tube.

I suspect the bigger issue is collapse of the inner 4" pipe at that sort of pressure if at any time the inner pressure is less than the annulus pressure.

This isn't a straightforward application so some background would be good.

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