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Re: Breech opening in steel stack

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Try the ASME standard - I'm not sure if it the current edition addresses breech calculations - we used to use different resources.  The manual was pretty awful about 15 years ago, but has steadily improved.  You should probably be referring to it anyway if you are sealing the stacks - there's some tricky issues to address (vortex shedding + localized forces), and they can't just be analyzed as a simple section.

Rich K.

On Tue, Sep 14, 2010 at 5:51 PM, Joseph R. Grill <vveng(--nospam--at)> wrote:

From my previous post I will say that all the licensing issues appear to have been worked out.


The steel stack that I am working on is not tall being less than 50 ft.  There are some breech openings in the stack near the base.  The openings are round and will be “stiffened” due to horizontal pipes the same diameter of the opening that will be welded to that location.  I have to go to my “archives” located in my not so clean garage to locate a reference that I only think is there.  I had to reduce the archived library some time back.  Anyway, it has been quite some time since I have done a stack design and I am looking for a reference/example of reinforcing breech openings.  I have some pages from ASME with some stack design requirements, but it doesn’t (at least the portion that I have) say a lot about the breech reinforcement.


I will say that in doing some very quick ballpark calcs, I’m not sure the reinforcement is all that critical in my case.  If I take the portion of the stack between the breech openings (without stiffeners) and check compression stresses from gravity and wind. The stresses appear to be o.k.  that would even be with assuming the width of the compression element does not increase due to the circular nature of the opening and being unstiffened.  Anyway, if anyone has some a reference, example or help in general, I would certainly appreciate it.



Joseph R. Grill, PE

Verde Valley Engineering, PLLC

email: VVEng(--nospam--at)