ASME VIII Div.1 Vs. Div.2

[Simdro]

Dear All,
I have to buy eleven air coolers in which the bundle is designed as per follow conditions:
-Design Pressure of 325 bars (g)
- Temperature design of 90°C
The material proposed, during the bid phase, from different Vendors is a Super Duplex Type 2507 in order to be in line with the process fluid chemical composition (recycle water with high chloride content).
Considering the above case, I would like to ask you some questions:
1) Could be better to design the Tube Bundle in accordance with ASME VIII Div.2 instead of Div.1?
In terms of headers thickness surely yes, but which are the negative side using the Div.2?
2) Are there other header types which could be employed for this purpose, considering that the actual offers are based on plug and pipe types headers?
3) Using a pipe type header can be the cleanness of tubes provided only if the bundle is one pass?
Any answer or other information on the matter would be greatly appreciated.
Thank you in advance,
Bye bye

 

[gr2vessels]

Simdro,
The air cooler design code is API 661 / ISO 13706.
The reference pressure vessel code for the headers can be ASME VIII Div 2, but the design pressure / temperature doesn't justify that selection. For Super Duplex material you don't get the benefit of significant material cost saving. However, you are most likely spending a lot more on testing, inspection and certificates that you would spend on a bit of extra thickness. Do you want the U2 stamp also? Big money...I suggest you stick to Div 1 and let the various suppliers to compete against each other for the job, which will include their guarantees, instead of blaming any fault on your specification.
Cheers,
gr2vessels

 

[Simdro]

Thank you for your reply gr2vessels.
I completely agree with you.

So Div.1 will be a "must" to design the bundles considering also that the equipments shall be U-Stamp!!!

Many thanks again...

 

[archimedez]

If I understand what you have written here correctly your design pressure is 325 bar g or approx. 4,713 psig.
If that is the case you need to look at Section VIII Div. 1 paragraph U-1(c)(2)(j). I think your design pressure has exceeded the limitations of division 1.

 

[Simdro]

Hi Archimedex and thank you for reply.

You understood very well the design pressure is 325 bars (g) as I wrote on my thread.

Sincerely I did not look the Section VIII Div.1, anyway I do not agree with you on the limitations matter considering that I have already contacted several Air Cooler Manufacturers and many of them refused to quote the Equipment using Div.2 as a designed code.

Anyway I'm going to investigate about Div.1 hoping that you are in trouble more than me.

Many thanks again.

 

[thermmech]

Yes - the limitation there is 3000 psig = 206.8 barg, however, read the whole paragraph through.

Let the suppliers provide design of the headers, welded header boxes would be fine I believe, but some migh opt for billet-type headers.

 

[Simdro]

Ok Thermmech let me read the whole para of ASME so that I will be able to reply you.

Could you help to find some technical information concerning the billet-type header?

Your feed back would be greatly appreciated.
Thanks in advance...bye