Pressure vessel with longitudinal flanges. 6

[Weldwonk]

I am looking to design a pressure vessel in two half (180 degree) sections with longitudinal flanges that bolt together. No internal ligaments. Flat or dished heads each end. Specs. as follows:
MOC: CS (probably SA-516 Gr 70)
OD: 26"
Length: 40 ft.
DP: 50 PSIG
DT: 500 F
Does anyone have an analysis for this?

 

[TGS4]

Not really sure what your question is. Are you looking for recommendations for companies that can perform such a design? Or have the capability to fabricate such a vessel? Are you looking for a reference to calculations that would allow you to perform the the design yourself?

Where is the vessel to be located?
What is the design Code?
Are you familiar with said design Code?

 

[Weldwonk]

I am looking for a reference to calculations that would allow me to perform the design myself. Thanks.

 

[Weldwonk]

The design code would be ASME Sec. VIII, Div. 1 under para. U-2(g). Location of installation is not yet known.

 

[rumandcola]

You will have to consult numerous parts of section VIII-I to find the required calculations, design rules, etc. Please consult someone with experience in pressure vessel design to help you with this.

You will have to check with the local jurisdiction before building this to ensure any additional legislation is met.

 

[Weldwonk]

Sec. VIII, Div. 1 does not address a longitudinal flange design like the one I am looking for. I think I can prove portions of it using hoop stress and beam theory, treating the bolts as ligaments, but flange rotation and gasket factors would have to be addressed. I don't have FEA capability, but that might be the best answer.

 

[JohnGP]

Weldwonk,

Interesting problem. I don't have an analysis, sorry (never had to do one), but it seems like this is a rectangular or noncircular flange design issue - certainly rectangular if the ends of your "vessel" are flat. I saw a reference to a paper by A.E. Blach "Bolted Flange Connections for Noncircular Pressure Vessels" which sounds like just the thing. A good place to start anyway.

PD5500 also had an Enquiry Case - 5500/133, that provides guidance on the design of flat unstayed ends of non-circular shape and their associated flanges, which may help.

I'm thinking that you may be able to add gussets to the flange for each half to stiffen the connection without having to have ultra thick flanges or vessel wall.

Good luck,
John

 

[doct9960]

Weldwonk,

See the paper below to get some idea...

http://www.peesi.com/Final-Paper-Large-Rectangular-Flange.pdf

Start looking for FEA experts.

 

[Weldwonk]

Many thanks for the feedback from JohnGP and doc9960. The A.E. Blach approach is limited to a rectangular flange that is nearly square (with an aspect ratio of less than 1.5) and treats the flange as an equivalent circular flange following ASME VIII, Div. 1, App. 2 rules. That would be a neat solution if my aspect ratio was within that range. The

http://www.peesi.com

paper also referenced an equivalent circular flange approach for a preliminary design using COMPRESS, followed by FEA using ANSYS. You had the right answer doct9960: "Start looking for FEA experts."

 

[Moersleutel]

Weldwonk, look out for designers of air cooled heat exchangers, the headers are rectangular.

Try and find a copy of "Design of Process Equipment, 2nd Edition" by Kanti Mahajan for a design method (the third edition is available on Amazon).

Regards
Rudol

 

[Weldwonk]

Rudol,
Thanks for the tip. I have the third edition and never thought to look there for a rectangular flange analysis. Mahajan uses a tongue and groove design and I want to use an o-ring design, but I would assume that his analysis works for both. That should give me a pretty good approximation of what I need (at least for quoting purposes). I still like the idea of FEA to verify the design.
Regards,
Weldwonk

 

[racookpe1978]

At only 50 psig, I think you'll be (pleasantly) surprised at how low the stresses will be.

Not (underline, underline, underline!!) trivial, but relatively low. The stiffness required for lifting and moving (taking apart and setting down) the upper half from the individual lifting lugs will be likely comparable to the internal pressures while static and resisting procvcess pressures.