NEU Exchanger Manufacturing Sequence and Heat Treatment

[Faraz12]

We have an NEU Exchanger with heat treatment required on tube side as channel thickness 52 mm.
Tubesheet has integral lip on both channel & Shell sides.
The manufacturing sequence of this exchanger is as follow.

Step-1:Manufacturing of Tube Bundle including tube-to-tubesheet weld.
Step-2arallel manufacturing of channel including welding of girth flange and nozzles.
Step-3WHT of Channel (without channel being welded with tubesheet)
Step-4:Welding of channel with tubesheet and local PWHT of channel to tubesheet weld.
Step-5:Welding of shell with tubesheet from other side.

This local PWHT is carried to avoid letting tube bundle go inside furnace.

My question is:
Is the above sequence correct for manufacturing NEU Exchanger with PWHT required on tube side?
IS this right to avoid PHWT of tubes?

Regards,
Sarfaraz
farazhunzai@hotmail.com

 

[SnTMan]

Faraz12, your sequence sounds about right to me. Some of the steps could be swapped depending on shop preferences, etc, but you've got it about right.

Regards,

Mike

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

 

[Faraz12]

@SnTMan

what could be consequences of Heat treatment of complete tube-side along with tube bundle?

Regards
Sarfaraz

 

[SnTMan]

Faraz12, materials are unstated but a couple of possibilities are: Altering material properties detrimentally and / or dimensional distortion. A local PWHT at the round seam would be preferable, and is commonly done.

Regards,

Mike

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

 

[EdStainless]

I see high pressure feedwater heaters being fully PWHT with the tubes in place.
I don't like it but they come out fine.

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P.E. Metallurgy, Plymouth Tube