TEMA BET Exchanger 2

[Resegone]

Hi everyone

i got a problem with a Shell & Tube Heat Exchanger.

Shell side i got a design pressure of 14 bar(g) with water, on tube side i've got a design pressure of 210 bar(g)

The Customer ask me to supply a BET as per Tema!

Could it be? TEMA limit is 200 bar(g) but it's not clear if this limit is only on shell or it shall be applicable also on the tube.

Now i have another problem that is the Channel has a design pressure of 210 bar(g)

My question is can i consider separate Channel and Shell as two different pressure parts?

Can i consider two different design code? ASME VIII div.1 for Shell and ASME VIII div.2 for channel? Could it be Possible?

 

[georgeverghese]

It is unusual to ask for TEMA T and S head these days for high pressure application - most users can manage with TEMA U and use hydraulic tube cleaning devices to clean the tubes. Tell this company to switch to TEMA U and explain why. Else ask them for justification for TEMA T, which costs much more than TEMA U.

 

[Christine74]

I concur that a BEU or CEU exchanger would normally be preferred for applications like this with such a high design pressure on the tube side.

TEMA Standards are applicable for heat exchangers with an inside diameter D less than 100 inches, a design pressure P less than 3,000 psi, and PD less than 100,000 psi-inches. But you can still use TEMA if you and your vendor both agree to do so.

ASME Section VIII Division 1 was developed for vessels with a design pressure of less than 3,000 psi, but you may still be able to design per Div. 1 if your AI and your vendor both agree. See the special requirements of paragraph U-1(d).

You can design the shell side and the tube side of an exchanger to different design codes as well, but this is tricky because the tubes and the tubesheets see pressures/temperature from both sides of the exchanger so which code those components get allocated to is somewhat arbitrary. Be sure to consult with your AI on how to properly document this is you decide for this option.


-Christine

 

[Resegone]

Thanks for the reply

The changing from BET to BEU was a deviation that i have already asked and it was approved.

Now the problem is the design code and the material

My question was based also on the material, i have sea water so SSDS, but if i select ASME VIII Div.2 as pe table Annex 3-A i could not use SSDS - SA 240 UNS S32750 are not allowed.

One solution is to calculate as per EN13445, but customer wants U-Stamp.

I am in a difficult situation.

I ask to have instead of SSDS a CS + cladding in SSDS but hte customer refuse it.

 

[georgeverghese]

Can you substitute with UNS 08367 - AL6XN ?

 

[GD2]

Resegone,
Limit of 200 bar to 210 bar is not too far. Christine 74 has given you the ASME VIII Div 1 direction on this. Evaluate how you want to go with it - Div 1 or Div 2 and decide.

GDD
Canada