Need advice about suitable tubing for high pressure air reservoir 1

[sonargodz]

Sirs,

I am wondering if anyone knows of a source for seamless (not dom welded) tubing similar to Timken T90 or T95. I am designing a pressure vessel for pnuematic application that needs to be 1.5 inches OD with a .12 wall thickness.

I would like the yield strength of the alloy to be at least 60kpsi so that my pressure vessel can operate at 3000 psi with Nitrogen or dry air.

I am a novice mechanical engineer, and any words of advice or suggestions are appreciated in advance.

 

[israelkk]

Pressure vessel is a bomb!!. You should check with your state lows to see who is licensed to design pressure vessels and what are the qualifications. If this is for a lab use or for a commercial use usually you should follow ASME code. If it is for military or aerospace use you should follow MIL-STD-1522A. Added to this the metal that the vessel is made off should be insensitive ro stress corrosion. For quidance see NASA MSFC-SPEC-522 and MSFC-SPEC-522. Pressure vessels for air should be painted inside the vessel unless they are made of stainless steels.

 

[israelkk]

Sorry, NASA MSFC-SPEC-522 and MSFC-STD-3029

 

[metengr]

Obtain a copy of ASME Power Piping Standards B31.1 or B 31.3 and review the formulas and suitable materials for piping. For designing a pressure vessel, refer to ASME Boiler and Pressure Vessel Code, Section VIII.

Contact an experienced engineering firm that deals with pneumatic systems for technical advice. This is not something that a novice engineer should do on their own.

 

[EdStainless]

Why 90 or 95? Do you expect corrosion issues? High temp issues?

Why not welded? There is no difference in properties. In fact in a lot of whys welded and drawn tubing will be better. It will have a more uniform wall thickness and might have a better inside surface finish. (easier to clean and inspect)

You could do this in a duplex stainless. Welded, drawn, annealed. The size and properties are no problem.


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Corrosion never sleeps, but it can be managed.

http://www.trenttube.com/Trent/tech_form.htm

 

[ApC2Kp]

sonargodz,
The use of smaller diameters for a high pressure reservoir will keep the wall thickness to within commonly available pipe dimensions. If "pressure vessel" is fabricated with seamless pipe and fittings, then your application might not be required to comply with ASME Pressure Vessel Code, but be viewed as a wide space in the piping designed to the ASME B31.3 or B31.1 Piping Codes , as suggested by metengr. That would avoid the regulatory hassles and ASME vessel stamp requirements.
The most common seamless carbon steel piping material is ASTM A106 gr B for NPS 1.5", and I would suggest avoiding special grades like your Timken T90 /T95. The A106 gr B pipe with a Schedule 160 wall thickness would be capable of the 3000 psi service. You will need to evaluate the volume requirements to see if the pipe size needs to be 2" for the thicker Schedule 160 wall. Pipe sizes 3" and 4" with the Schedule 160 wall thickness would be capable of 3000 psi, so you could have some tradeoff of diameter versus length. Pipe fittings should be CL3000 forged steel. If your application has a requirement of minimal weight for aerospace purposes, then other materials could be considered.
The fluid being compressed air or nitrogen, have you considered just renting air cylinder or nitrogen cylinder? Are your air consumption volumes too high to afford the cost of 3000 psi bottled air or nitrogen? I guess if there is 3000 psi air available from existing compressor system then cost of air is free.