Half-pipe Jackets as in ASME Scope?

Found this....

"Question: Are there established criteria and details for the design of half-pipe coil jacketed vessels in Section VIII, Division 1?

Reply: There are no specific geometric requirements in Section VIII, Division 1 However, it is our opinion that this type of construction is not prohibited, and that the rules and guidelines in U-2(g) and UG-101 can be applied for the design, construction, and testing of this type of vessel."

Thank you,

In case we design the jacket acc. to nonmandatory App. EE, Shall we indicate the MAWP / MDMT values in same nameplate ? (for vessel, for jacket) ?

Regards

Ömer

Not every reader here is male, Mildred. You don't mind if I call you Mildred, do you?

This kind of hybrid vessel structure might or might not have an applicable code, and even if it does, the half-pipe coil might fall under a pressure piping code rather than a pressure vessel code. There is no such thing as 2" OD pipe, so this whole situation is unclear, anyway. What are the fluids and temperatures involved? High temperatures such as steam, versus low temperatures such as refrigerants, may dictate different material choices and testing requirements.

Vessel

MAWP: 10bar (145 psi) Design Temp.: 250C (482F) MDMT:-29C (-20F)

Fluid:Grease soap . Shell OD:1400mm (55in)

Jacket

MAWP:25bar (362psi) Design Temp: 250C (482F) MDMT:-29C (-20F)

Fluid:Air . Half pipes are spirally coiled around the vessel to heat the vessel. 2" SCH40 pipes are used.

Why is the air at such a high pressure, and how is it getting that hot? Btw, 2" pipe is 2.375" OD, no matter what schedule it is. In ASME, the MDMT of -20dF is no problem.

It is a process requirement, from the client, to heat the grease inside the vessel. correction; Pipe nominal size is 2", not OD.

So Jacket data needs to be in nameplate ?

See figure #1 of this document:

http://www.che.utah.edu/department_equipment/Projects_Lab/R_Glass_Lined_Reactor/MANUAL_Maintenance.pdf

I agree with the question of the person above...

Why is the pressure in your half-pipe jacket so high ?. This will probably make your vessel very expensive and the welding of your thick half-pipe jacket very difficult and time consuming.

Your selection of a vertical pressure vessel with a half-pipe jacket is not the best. For obvious thermal reasons, you may be better served with a "pipe-in-pipe" heat exchanger configuration....

http://www.brighthubengineering.com/hvac/64548-double-pipe-heat-exchanger-design/

Thank you for specs.

This was actually "Design by client" when reading the spec that you sent i realised it too that this design is not the best, but no chance to change it now.

It's too bad the design can no longer be altered. I agree that a half-pipe jacket is not the best solution for this application.

In my experience, a jacketed vessel is normally considered as a single vessel in terms of AMSE VIII compliance. The higher of the two pressures (vessel vs jacket) would be used to determine design and MAWP but in your case the very large pressure difference is highly unusual.

Without any specific and definite guidance from the code, I would think you will need to err on the side of caution and treat the vessel and jacket as separate entities. Since you are applying a half jacket directly to the inner vessel, you would have to assume the inner vessel must sustain an external pressure of 15 bar (the difference of the vessel internal pressure of 10 bar and the jacket pressure of 25 bar acting externally on the inner vessel). You now have a vessel with an external pressure of 15 bar and pressure piping with an internal pressure of 25 bar. That may necessitate separate testing and nameplates for both components.