All Springer/NP/PCP Air Gun Discussion General > Engineering- Research & Development

Seamless tubing for air reservoir ?

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Some time ago I came across a couple meters of seamless tubing.  The idea of using some of the tube for an AG project intrigues me.  It is 1.361" outside diameter with a bore of 0.835 inside diameter.  Along the side I can make out the following lettering, (* is used to designate illegible letters.)

*MLES  CS  8CH160  1"5**  81564  ASTM  A106  /  A53 GR  B  /AP/  5L  GR  B 

It is carbon steel with the above mentioned dimensions, but other than that I'm not exactly sure what I've got.  I was told it was rated at over 5,000  lb psi for use in pneumatic applications, hence my interest in using it in an AG application.  It's heavy material, for sure.    I'm looking at building an air reservoir for a PCP out of it,or perhaps a SSP. 

Any information as to the actual type of seamless tubing I've got and its suitability for the pressures involved in building a PCP air reservoir would be greatly appreciated.

I haven't a clue what the markings mean, but with over a 1/4" wall, if it's seamless DOM steel tubing you should be OK at 5000 psi.... My spreadsheet, using 44K Yield for mild steel gives a yield strength of 27,700 psi for a safety margin of 5.5:1....


Thank you, sir!  That info is quite gratifying.  I'm still not sure how to approach the project, but that kind of safety margin should cover for many beginner mistakes as far as the air reservoir / pump tube goes.  It will make for one heavy piece, but somehow anything I make tends to end up that way.  There was the time that I made up a homebrew muzzle loader, years ago, and used a piece of extremely dense brazilian hardwood for the stock.  It took two men and a boy to carry it but recoil was practically non-existent!

Some info on the markings means that this pipe conforms to:

ASTM A106 Grade B = carbon steel with 0.3% carbon, max

A53 = ASTM A53 Grade B (electric resistance welded seamless)

AP (API) 5L, Grade B

(all are seamless high temp rated)

I would guess that MLES has something to do with the manufacturer and the 8CH160, a part number?  I pulled the ASTM A106 standard and it mostly relates to metallurgy specs, tensile strengths, and dimensional requirements.  No pressure specs that I could see.  Then I pulled the A53 standard and I'm not enough of an engineer to properly interpret their pressure testing standards and meanings, so I won't.  Anyway, the grade conformity above might help Bob with his lookup tables for carbon/mild steel to hone in on a pressure yield value, if you want.  Keep in mind your threaded couplings/endcaps will likely be the weak points...


--- Quote from: sperho on March 08, 2013, 01:56:42 PM ---Keep in mind your threaded couplings/endcaps will likely be the weak points...

--- End quote ---

That's what I'm thinking. There should be enough "beef" around these points to ensure safe use to 3,000 psi or so. 


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