Donut Shaped Pressure Vessel
Donut Shaped Pressure Vessel
(OP)
Hi,
I am currently designing a pressure vessel system for hot water with a max temp of 99C and operating pressure of 160psi. The part is shaped like a donut with wholes through one face to allow for hot water piping to be welded as this unit will be part of an outlet manifold. I am double checking the strength calculations as this is a part I have inherited and is not my own design. I am wondering the best way of checking this part as it does not fit in well with the standard ASME pressure vessel calcs.
My approach thus far has been break the part into two components, the outer and inner tube. I have treated the outer tube as if it is a standard pipe with internal pressure and used standard ASME calcs to ensure strength. I have then treated the inner diameter as if it is a standard pipe with external pressure acting on it. I feel like this should satisfy the criteria but I would like to see if anyone else has some advice as I wouldn't consider myself an expert on all things ASME.
I have attached a drawing below to give an understanding of the geometry.
Thanks
I am currently designing a pressure vessel system for hot water with a max temp of 99C and operating pressure of 160psi. The part is shaped like a donut with wholes through one face to allow for hot water piping to be welded as this unit will be part of an outlet manifold. I am double checking the strength calculations as this is a part I have inherited and is not my own design. I am wondering the best way of checking this part as it does not fit in well with the standard ASME pressure vessel calcs.
My approach thus far has been break the part into two components, the outer and inner tube. I have treated the outer tube as if it is a standard pipe with internal pressure and used standard ASME calcs to ensure strength. I have then treated the inner diameter as if it is a standard pipe with external pressure acting on it. I feel like this should satisfy the criteria but I would like to see if anyone else has some advice as I wouldn't consider myself an expert on all things ASME.
I have attached a drawing below to give an understanding of the geometry.
Thanks





RE: Donut Shaped Pressure Vessel
Regards,
Mike
The problem with sloppy work is that the supply FAR EXCEEDS the demand
RE: Donut Shaped Pressure Vessel
prex
http://www.xcalcs.com : Online engineering calculations
http://www.megamag.it : Magnetic brakes and launchers for fun rides
http://www.levitans.com : Air bearing pads
RE: Donut Shaped Pressure Vessel
RE: Donut Shaped Pressure Vessel
Sorry for the typo on 'wholes' that chicopee so readily pointed out. The 'holes' are to accommodate piping that will be welded in place. They go through one side as they function as an inlet whilst there is a single outlet on the top of the component. This will have 4" piping welded in place. The unit is manufactured by welding sheet metal along the seams of the faces.
My understanding, which may well me wrong, is that if there was no inner hole then this part could be regarded as a simple cylinder. I could treat the part as a standard cylindrical pressure vessel but also accommodate for the welded connections. The inner hole that makes this a donut shape is the main thing I am unsure of but please feel free to correct my interpretation!
I have attached another sketch with more details.
Thanks
RE: Donut Shaped Pressure Vessel
RE: Donut Shaped Pressure Vessel
The outer cylinder was designed for the chamber's internal pressure. The chamber's internal pressure produced an interesting effect on the inner cylinder: the inner cylinder was subject to "external pressure" from the chamber's internal pressure for purposes of circumferential compressive stress; but the chamber's internal pressure produced longitudinal tension in the inner cylinder, quite the opposite of a typical vacuum vessel. If anything, the combination of longitudinal tension and circumferential compression produced a condition more susceptible to buckling (I think of those woven tubular "handcuffs" given away at fairs when I was a kid, you'd stick a finger in each end and as you tried to pull your fingers out the woven tube would constrict and get tighter). Just eyeballing it, your donut wouldn't seem to be prone to buckling of the inner cylinder, but that all depends on the pressure, temperature, material, thickness, etc.
RE: Donut Shaped Pressure Vessel
yes the two parts are welded together in compliance with Div IV of ASME, Heating Boilers. Can you specify why you cannot calc as inner and outer? My approach is to consider the end with the opening for the piping as a tube sheet with stays, then the external wall as standard pressure vessel. I have treated the inner as a cylindrical part under external pressure and from theses calcs it seems like 1/2" 316L sheet metal is strong enough.
@TomBarsh
I can see how that would be a possibility, would not have expected that myself, but I think that I my part is at such a low temp and small height that this would not be an issue.