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UG-39 4
- Thread starter heaterguy
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We hired an expert to do FEA on our flanges and FEA shows that our flanges do NOT need to be as thick as UG-39 dictates. I was just wondering if the holes are filled then are the filled holes still considered an opening. Is there ANY way to use the FEA instead of UG-39?
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In your FEA you should not only discard any collaboration from the heater rods (material and weld presumably not per code), but also apply pressure over the hole (or on the hole border). Having done that, you shouldn't find a big difference with UG-39, except for the fact that your holes are not centered, so that they require less reinforcement, but the code doesn't allow to profit of that.
Concerning your first question, well of course it is an opening, as some material is cut from pressure boundary and is not replaced with something of equivalent strength (heater rods do not normally count as structural material).
And sorry, you have no (practical) alternative.
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Concerning your first question, well of course it is an opening, as some material is cut from pressure boundary and is not replaced with something of equivalent strength (heater rods do not normally count as structural material).
And sorry, you have no (practical) alternative.
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Online tools for structural design
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Well perhaps we are doing our reinforcement calculation incorrectly since the FEA says our flanges are too thick.
How do you calculate the following UG-39(b)(2):
"...the required reinforcement for each opening in the pair...shall be summed together and then distributed such that 50% of the sum is located between the two openings."
How do you calculate the following UG-39(b)(2):
"...the required reinforcement for each opening in the pair...shall be summed together and then distributed such that 50% of the sum is located between the two openings."
I am familiar with some heater designs as we mfr electric steamers (sec I and IV)
Have you consider UHx-12 design?
if you heaters have u bends, may qualify for UHX design,
there is where the FEA takes consideration as the TEMA style tubesheets.
'hope this helps, let us know please.
GenB
Have you consider UHx-12 design?
if you heaters have u bends, may qualify for UHX design,
there is where the FEA takes consideration as the TEMA style tubesheets.
'hope this helps, let us know please.
GenB
Heaterguy, what you are describing in your opening question about welding heater rods to the flat head appears to be a similar situation with firetubes being seal welded to tube sheets of a firetube boiler, therefore, ligament calculations stated by GenB apply.
My question to you is, are you intending to detail out a manufacturer's data for the pressure vessel that you are fabricating?
My question to you is, are you intending to detail out a manufacturer's data for the pressure vessel that you are fabricating?
chicopee sec I fire tube boilers are way different to any sec VIII-1 pc. larger inmersion heaters require partial
data report to be intended for unfired steam or HWB boilers or process heaters
therefore require calculations to comply with the Code.
genb
1 find the required and use the reminder t on the flange for your reinforcing, if more reinforcing is required,
use add-on metal, weld metal,
perhaps a stiffening ring will suffice.(do not ask me I do not know how to calc the stiffener)
genb
data report to be intended for unfired steam or HWB boilers or process heaters
therefore require calculations to comply with the Code.
genb
1 find the required and use the reminder t on the flange for your reinforcing, if more reinforcing is required,
use add-on metal, weld metal,
perhaps a stiffening ring will suffice.(do not ask me I do not know how to calc the stiffener)
genb
heaterguy,
to me that sentence sounds simply as:
- take d=half the centerline distance of the two openings (but of course not more than UG-37 limitations).
Another way to interpret that sentence, telling exactly the same, is that reinforcement material can never be used twice an that 50% of it must be located on each side of the penetration.
prex
Online tools for structural design
to me that sentence sounds simply as:
- take d=half the centerline distance of the two openings (but of course not more than UG-37 limitations).
Another way to interpret that sentence, telling exactly the same, is that reinforcement material can never be used twice an that 50% of it must be located on each side of the penetration.
prex
Online tools for structural design
d in my previous post is to be understood as the limit of reinforcement along vessel wall, that, sorry, is not called d in UG-37 (unfortunately there's no symbol for the limits of reinforcement)
prex
Online tools for structural design
prex
Online tools for structural design
Read U-1(a)(3)... again. I call this the Sound Engineering Practice Disclaimer.
If your FEA dude has done everything right, and I have found that it takes several iterations for them to get everything right, then you should be able to go with the FEA results. However, be aware that if there is a problem and your FEA results turn out to be incorrect, whereas The Code would have given you the correct results, you will be hosed.
My personal experience is to go with The Code if it has the application. Why would you want to take the risk associated with deviating from The Code? Steel is a lot cheaper than litigation.
Last but not least, if you have one, talk this over with your A.I. Most of those guys know their stuff and are happy to help.
chili
If your FEA dude has done everything right, and I have found that it takes several iterations for them to get everything right, then you should be able to go with the FEA results. However, be aware that if there is a problem and your FEA results turn out to be incorrect, whereas The Code would have given you the correct results, you will be hosed.
My personal experience is to go with The Code if it has the application. Why would you want to take the risk associated with deviating from The Code? Steel is a lot cheaper than litigation.
Last but not least, if you have one, talk this over with your A.I. Most of those guys know their stuff and are happy to help.
chili
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chili,
I have to disagree with your assessment that FEA can trump Code rules. Referring to U-2(g), you can apply alternate rules IF there are no rules provided in the Code. Unfortunately for heaterguy, the consensus seems to be that there are rules that apply in his instance.
I have to disagree with your assessment that FEA can trump Code rules. Referring to U-2(g), you can apply alternate rules IF there are no rules provided in the Code. Unfortunately for heaterguy, the consensus seems to be that there are rules that apply in his instance.
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TGS4,
Perhaps I did not state my opinion correctly. I have used FEA many times, but never if there was a clear example in The Code. Unfortunately, in custom equipment design, there has been many applications where I could not find a relative application in The Code. The bottom line is Sound Engineering Practice. Using Code rules that are applicable would be considered as Sound Engineering Practice.
As noted..."My personal experience is to go with The Code if it has the application. Why would you want to take the risk associated with deviating from The Code? Steel is a lot cheaper than litigation."
chili
Perhaps I did not state my opinion correctly. I have used FEA many times, but never if there was a clear example in The Code. Unfortunately, in custom equipment design, there has been many applications where I could not find a relative application in The Code. The bottom line is Sound Engineering Practice. Using Code rules that are applicable would be considered as Sound Engineering Practice.
As noted..."My personal experience is to go with The Code if it has the application. Why would you want to take the risk associated with deviating from The Code? Steel is a lot cheaper than litigation."
chili
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