Hello Ricardo
Please excuse my sense of humour, but we only eat bananas in America. Seriously, perhaps you mean something a little more serious. Maybe you are referring to the banana effect a long vessel experiences with all the welding, and the vessel gets bent into a banana shape. This occurs especially if you have a lot of nozzles on one side of the vesel. One way of straightening the vessel is to partially half grind out the circumferential weld seams on the outside bend of the 'banana' and re-weld them. The shrinkage from the welding pulls the vessel straight. Be very careful if it is a stainless steel vessel which is more prone to shrinkage.
You can get a lot of advise from the book: Design of Welded Structures by Omar Blodgett which is a Lincoln Welding Foundation bood. This book is a masterpiece.
If your banana question refers to something else, then please let me know.
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Sincerely,
Ray Delaforce
CADWorx & Analysis Solutions
Hexagon PPM