Large Opening in Rectangular Vessel
Large Opening in Rectangular Vessel
(OP)
I have a rectangular vessel with stiffeners on 3 sides. There is a large non-circular opening on one side (where a heater is mounted on weld studs). I have analyzed the vessel according to APPENDIX 13, but am not sure how to approach the large opening and reinforcement required.
The Vessel is 1/4" 316L SS Plate (all sides)
Stiffeners are L2x2x1/4 A-36
Heater panel is 3/8" 304SS Plate
The Vessel is 1/4" 316L SS Plate (all sides)
Stiffeners are L2x2x1/4 A-36
Heater panel is 3/8" 304SS Plate





RE: Large Opening in Rectangular Vessel
Seeing the geometrical complexity of the attached JPEG file, I feel that you need to view this problem as that prescribed in U-2(g). Design appears to be propriatry in nature. Obviously if so, ensure vendor takes full guarantee of the mechanical design. Btw, is this a u-stamped/ ASME vessel?
FEM would be the most definitive method to analytically design this "box" based on the complex geometry.
Also, what is the internal/ external design pressures and temperatures and MOC of this "box"?
My reply is not too helpful. Sorry about that
-jehan
RE: Large Opening in Rectangular Vessel
I am fairly new to the whole B&PVC scene as I just graduated a year ago. Its a complex project that i have been assigned to analyze. This is just a tiny piece of the puzzle. It is not U-stamped but customer has asked we build it with all of the criteria as if we were to get it stamped. I keep getting stumped with the U-2(g)reference. Is it safe to assume I can run an FEA on said section and compare to the 1.5SE or 2/3SY allowables??
internal pressure is 5.2 psi
Thanks
RE: Large Opening in Rectangular Vessel
RE: Large Opening in Rectangular Vessel
I can see that that image is more likely a duct and may not be cavered by the vessel design codes.
If my guess is correct the opening requires a structural calculation in addition to flange calculation and sealing check.
You either use stiffeners on the opening cover or on the duct or on both. In case stiffeners used you need to think about the load path, how to take the pressure and gravity loads from the cover onto the duct structure.
Hope it helps.
Ibrahim Demir
RE: Large Opening in Rectangular Vessel
OPTION 1: Page 53(A):Please look at Page 53(A) detail example
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OPTION 2:
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Regard
Leonard Thill
RE: Large Opening in Rectangular Vessel
I agrre with TGS4 views on using ASME Section 8 div 2 to find out the allowable stresses if you are doing FEA.
Saplanti has also correctly pointed out that it looks like some sort of a ducting element and thus ASME S8 might not be the appropriate code and you positively require the help of some seniors to advise you on this problem. What is the service of this "box"
AS I had asked in my first reply, what is the internal/ external design pressures and temperatures and MOC of this "box"?
-jehan
RE: Large Opening in Rectangular Vessel
I missed the mounted heater at the opening in my first reply. It is definetely a duct and the heater is the duct heater. Depending on the type of the heater and air velocity the heater flange may be heavy rigid element, therefore you do not need any stiffener on the heater side. If it is a large cover plate and Kanthal type tube heaters are in a vertical line you may need to stiffen the cover plate as well. Vibration of the tubes under the air velocity might be another problem to check.
I think you are using the large displacement theory to reduce the duct plate thickness down and therefore you need stiffeners on the duct at top and bottom edges to take the created tension load at the edge and the gravity forces of the heater by the bending stiffness of the edge stiffeners.
I suggest you to think how to transfer the heater gravity load and the internal/internal pressure. In case it is different than the Kanthal type tube heaters, due to the overhang (inside/outside) of the heater the top and bottom flanges of the opening may need good attention. Additionally the sealing will play big role in the flange connection. If you can use the prying action of the flanges of the opening you may be able to keep the selected flange thicknesses, but you still need a calculation to verify.
Hope it helps.
Ibrahim Demir
RE: Large Opening in Rectangular Vessel
If duct Please look at Page 53(A) detail example
RE: Large Opening in Rectangular Vessel
Vertical Exhust Connectin for turbines
What is this duck being used for if Vertical Exhust Connectin for turbines installation and unrestrained expansoiion joint at the exhaust, an additional amount of force caused by pressure loading. ( The additional force referred ot is perpendicular to the force of the exhaust flange and central.) For this type of applicatin, calculate the verticdal force component on the exhaust connectin, excluding pressure loading, and compare with value of 1/6 the pressure loading on hte exahust. Use the larger of these two numbers for vertical force ocmponent on exhaust connectin in making calculation.
From Korea
Leonard Thill
RE: Large Opening in Rectangular Vessel
I keep getting stumped with the U-2(g)reference. Is it safe to assume I can run an FEA on said section and compare to the 1.5SE or 2/3SY allowables??
Not in Section VIII Div. 1 unless no Code rules exist.You can only use U-2(g) if no Code rules are given, then the obligation is to make is as safe. If Code rules exist (as they do of course for openings) then you must satisfy them as a minimum. The Section VIII Div. 2 advice is excellent as there is much more flexibility for design by analysis there.