High Design Pressure 1

[picasa]

Is there an upper limit on the design pressure above which you can not use ASME Section VIII Div 1? If so, please provide reference.

 

[TGS4]

My understanding is that, strictly speaking, there is no "maximum pressure" above which one cannot use Division 1 - see in particular the formulae in 1-2 and 1-3, which discuss appropriate formulae for pressures exceeding 0.375SE (for cylinders) and 0.665SE (for spheres).

As with most things in life, this inevitably comes down to an economic decision. That is, there are break-points where going to the other divisions of Section VIII are cheaper. It should be noted that Division 3 is intended for use "generally above 10,000 psi". See the discussion on

http://www.asme.org/bpvc/bpvc8d3.shtml.

Does this answer your question?

 

[abbver98]

ASME VIII Div.1 U-1(d) states that the rules of this division for vessels with design pressure not exceeding 3000 psi.
See introduction (U paragraph) for other limitation.

 

[TGS4]

abbrev98, I agree that U-1(d) places a 3000psi limit. However, it goes on to state that "deviations from and additional to these rules usually are necessary to meet the requirements of design principles and construction practices for these higher pressures. Only in the event that after having applied these additinal design principles and construction practices the vessel still complies with all the requirements of this Division may it be stamped with the applicable Code symbol." This to me definitely says that, while 3000psi may be a practical limit without doing additional engineering, there is no defined maximum pressure that a vessel may be made to in accordance with Division 1.

One additional caveat that I will add - some jurisdictions may apply a hard and fast maximum pressure over and above these practical/economic limits in the Code. As, always, check with the local jurisdiction.

 

[GenB]

TGS4
Do you mean you design to Div 2 and build to Div 1?
(I know the process but I want your input)
genb

 

[TGS4]

GenB,
From my perspective, you've really highlighted a serious issue with this paragraph of Div. 1. Without rules, how exactly would you design a vessel and then have it stamped to Div. 1? My take on that would be that so long as the design margins in Div. 1 are respected, especially w.r.t. the allowable stresses, then ANY methodology _should_ be acceptable for Div. 1. We do this all the time with U-2(g)-type analyses such as nozzle load evaluations.

That said, even if you _could_ do it, the better/real question is _should_ you do it. Considering that the economical break-point is probably at a lower pressure anyway, why bother? And, considering the current price of steel, I suspect that the break-point that several suthors (I can't remember references off the top of my head, though) calculated, it likely even lower now.

That's a really wishy-washy answer, but it's the best I can do so early in the morning...