Corrosion issue in LiBr boiler for absorption chiller

[Alfredo C]

hey guys
in our company we build boilers for LiBr type absorption chillers , after recently we have corrosion like issue with tubes , do you have any idea that what is wrong, we expand tubes and then weld them to tubesheet , and whole boiler is in vacuum condition but after 1 year of working corrosion happens , is there anyone who has some experience with building boilers to help me fix this problem
best regards

 

[EdStainless]

What are the materials?
Is this failure at the weld end?

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, Plymouth Tube

 

[Alfredo C]

yes the failure is at the weld end, its DIN ST35.8 heat resistant seamless pipe , and all pipes are hand welded ,

 

[metengr]

Send the tube in for proper metallurgical failure analysis. The OD surface looks like metal dusting,

 

[EdStainless]

and since the attack looks exclusive to the HAZ you really need to look at some tubes with less corrosion, so that you can figure out what is wrong with the welding process.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, Plymouth Tube