Double Wall Pipe- Pressure Vessel?

[nbog]

6" pipe, 2 feet long, built as a pyrolysis chamber for R&D, welded cooling jacket.
Gas side: T~ 600 C, P = 10-15 inWg vacuum,
Jacket: water, 40 psig, 20C in, 35 C out

R&D is over, we ran the system for a year, pyrolyzing salts and collecting the powders, all worked good... time to build a demo plant. The "chamber" is followed by 2" tube-in-tube, custom built conveying pipe, water cooled.

Is the chamber considered a pressure vessel, i.e. do I have to have it stamped? The same question is for the conveying pipe which also sees about 30 psig water pressure.

Thanks.

 

[Fzob]

One of the first things to consider is the size of the vessel. Below a specific volume and or dimensions the "vessel" is treated like a pipe.

 

[nbog]

Fzob, the "vessel" is made of a 6" pipe, jacket welded onto it.

 

[Latexman]

Sounds more pipe-ular than vessel-ular to me.

Good luck,
Latexman

 

[Fzob]

The ASME BPVC code section VIII U-1 scope will provide the answer to your question.

For such a high temperature application an option is to build to the code but not have it stamped. (assuming it does not need to be stamped)

 

[moltenmetal]

Operating pressure or design pressure doesn't matter. RELIEF pressure does. So: what is the maximum pressure you're setting the relief devices to?

On the water side, one could argue that it's water in a jacket- not generally a code item, if properly relieved. The tubeside is running under vacuum, but unless it is relieved below 15 psig it will either be a vessel or B31.3 pipe. If it is indeed relieved below 15 psig, I'd argue that it's nothing- neither B31.3 pipe nor a vessel- but since B31.3 even regulates piping running below 15 psig if the temperature is high enough, others would argue that this thing is a B31.3 pipe regardless.

I'd design and build it to a code regardless. Whether or not you obtain the stamp is a matter between you (as owner) and your regulator- or your insurance company.

 

[nbog]

40 psig is the backpressure in the cooling jacket.