Tube to tubesheet joint of feedwater heater

[Andr89]

Dear mechanical engeneers and welding experts,
I am looking for help for Feedwater high pressure heat exchanger. The most critical part of this unit is tube to tubesheet joint. Does someone has experince of this type welding. In the past it was manual TIG root + top rod layer. Now welding technology have been developed and a lot of tube to tube sheet joints are done by orbital welding. Does someone have experience of orbital welding for high pressure unit (more 20 MPa). How it was after operation conditions? Any failures?

Thank you in advance for your answers!

 

[MJCronin]

There has been decades of research done on HP feedwater heaters funded by the US Government. This has been done by the scientists and engineers of EPRI. The proper design of this complex type of high-temperature, high-pressure HX far outranks the complexity of a process chemical shell and tube heat exchanger.

The welded joint you are taking about is an important failure point that affects reliability of the entire power plant.

The selection of the best weld procedure and inspection methodology (as well as the best design details for the entire HP feedwter heater) is not something I would trust to anonymous voices of the internet ....

MJCronin
Sr. Process Engineer

 

Ditto.
Automatic orbital welding, or any welding for that matter, is not something you can just pick up and perform on pressure equipment.


"Everyone is entitled to their own opinions, but they are not entitled to their own facts."

 

[Andr89]

Thank you for your answers. I am not looking any welding proceedures here. We already done a lot of test and welding proceedures corespond to all relevant standards. I ask just experience during explotation of both methods.
Could someone share link to research in that field?

 

[EdStainless]

Shops that do a lot of them now will use semi-automatic orbital welding, TIG with wire feed.
They clean the reamed holes and tube ends, install the tubes, lightly roll then just to contact, purge for weld, weld (single pass), NDT (often PT and air test), then hard roll (either just front and back of full length in steps), then final test.
There are shops still manual welding. Some one pass and some two.
There are some out there that explosively weld the tubes into the tubesheets.
If done correctly they can all work.

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P.E. Metallurgy, Plymouth Tube