ASME VIII Div. 1 Ed. 2017, Part UHX-13.10 - Application Fields

[Silvio Cresto]

Good Morning,

I'm designing a Shell & Tube heat exchanger according to ASME VIII Div. 1 Ed. 2017. The condenser is like a NEN Tema Heat Exchanger (so not K shell type) with the tubesheet welded with shell and with water boxes but with a shell side configuration made with cylinder-cone-larger cylinder-cone-cylinder just like figure UHX-13.10.3-1

As you may notice ASME VIII Div. 1 Ed. 2017 has updated Part UHX with chapter UHX-13.10 "Calculation Procedure for Kettle Shell Exchanger With Fixed Tubesheet".
My doubt is when the restrictions of this chapter are applicable:
[li]The title of the chapter UHX-13.10 state "Calculation Procedure for Kettle Shell Exchanger..." and my HE is for sure not a kettle or a reboiler[/li]
[li]While paragraph UHX-13.10.1 Scope state "This procedure describes how to use rules of UHX-13.5 when an eccentric cone & small cilynder exist between the large shell and the tubesheet on both sides"[/li]
[li]Paragraph UHX-13.10.1 (d) state "this procedure applies only when 0.5 <= L_ecc/D_ecc,S <= 1.5"[/li]

So established that my condenser is not a Kettle but meet the requirements of UHX-13.10.1 what if I do not meet the requirements of UHX-13.10.2 (d)?
With a shell side configuration with cylinder-cone-larger cylinder-cone-cylinder (see figure UHX-13.10.3-1) Am I forced to meet requirement of UHX-13.10.2 (d) and use UHX-13.10 in any case or once I do not met the requirements of UHX-13.10.2 (d) I am automatically exempeted from UHX-13.10??

 

[SnTMan]

Silvio Cresto, I have not had occasion to attempt to perform the UHX-13.10 calculations as yet, but will take a pass at your questions.

First, I'd say that no matter what terminology you are using, if your design meet the configuration of Fig. UHX-13.10.3-1, i.e., TS, small cyl, ecc cone, large cyl, ecc cone, small cyl, TS, then, under Part UHX it is a kettle. I'd further note that a reboiler is a type of service, not an arrangement of geometries.

Then, given that it is a Part UHX kettle, I'd say you are bound by all the Conditions of Applicability of UHX-13.10.2, otherwise you cannot be reasonably certain that any calculations that are performed under Part UHX are of useful accuracy. You cannot also assume that third parties, such as your AI, any clients or owners will accept such calculations without further justification on your part.

If it were my problem I'd try to adjust geometry such that all conditions of UHX-13.10.2 are met. I usually find it preferable to bend my designs to meet the Code, rather the opposite.

Regards,

Mike

The problem with sloppy work is that the supply FAR EXCEEDS the demand

 

[Silvio Cresto]

Dear Mike,

Thank you very much for your reply, your way to see the problem cleaning out my mind.

Despite the use of the word "Kettle" that in my opinion could lead misundestanding (at least in my mind ) I still don't understand why the code formulates Conditions Of Applicability saying "The procedure apply only when...." and not saying "The shell shall comply the requirements..." as for example in UHX-10.
For instance UHX-12.6.2 Conditions of Applicability states "This calculation procedure applies only when the tubesheet is integral with the shell or channel (configurations a, b, c, e, and f)" that do not means that tubesheet shall be anycase integral integral with channel or with shell. It simply means that if tubesheet is not integral with channel or with shell another procedure shall be used.

I think this formulation lead to a procedure that "wear" some particular vessel configuration but do not force the vessel to withstand this condition.
Even if UHX-13.10.1 Scope clearly includes all the configuration of Fig. UHX-13.10.3-1.
Again, the Code in this section it is not so clear to me.

Regards
Silvio

 

[SnTMan]

Silvio Cresto, I'm curious, how would you define a kettle?

I don't know why exact wordings are used, but regarding your example of UHX-12.6, it is an alternate procedure that modifies UHX-12.5, when the proper conditions apply. Similarly, UHX-13.10 is alternate to UHX-13.5, if applicable.

Honestly, there is much about Part UHX that I do not well understand.

Regards,

Mike

The problem with sloppy work is that the supply FAR EXCEEDS the demand