ASME Code on Pressurized Vessel inside a Pressure Vessel

[biofuelblondie]

I'm dealing with an unfired pressure vessel. One vessel is pressurized (internal) and nested inside of the other vessel (external).

The internal vessel will contain a pressurized chemical. The external vessel contains the internal vessel as well as piping and other components such as a pump. The interstitial space within the external vessel will also be pressurized. The pressure in both vessels is greater than 15 psig and less than 500 psig.

I am of the opinion that both vessels will require ASME stamps. I cannot find the chapter verse code section that provides guidance on this issue.

I appreciate the help.

 

[btrueblood]

Can rupture of the internal vessel cause harm to persons (even if the outer vessel is only occupied rarely, such as in maintenance intervals); or would rupture of internal vessel cause rest of system to perform in unexpected or dangerous manner? Then treat it as a code vessel.

 

[metengr]

Size, application and operation above 15 psig govern code stamping requirements. Look at the introduction of ASME B&PV Code, Section VIII, Div 1. Second, I would check with the local Jurisdiction where the vessel will be installed for guidance. If none is given because pressure vessels are exempt from regulation, I would design and stamp both vessels, period.

 

[davefitz]

I am not sure of the applicalbility in the general case described in the posted question, but in the case of shell and tube feedwater heaters of the same generic description, the outer shell vessel must have its safety relief valve sized to inlcude the case of one internal pipe failing and discharging thru two open ends of the pipe.

 

[GenB]

in one vessel you are dealing with interal and external pressure, in outer vessel internal only... a lot of calculations.
one design one certification as a unit
ASME STAMPING AND CERTIFICATION as one unit design.
if one can be disassembled from the other then you can separately stamp each vessel.
safety is another issue: safety relief on the internal and external vessels are to be considered per Code.

genblr