Sometimes referred to as “the gold standard” for nitric acid heat exchangers, zirconium offers excellent corrosion resistance to nitric acid in all concentrations up to 90% and higher temperatures.

The most important problem is, that retrofitting a shell-and-tube heat exchanger or other process equipment with 100-percent zirconium tube is a very costly undertaking.

With the development of a bimetallic tube with an inner tube made of zirconium (R60702) and an outer tube in UNS S31002, it was possible to manage the challenge to provide zirconium-level performance at an affordable price.

The inner liner prevents corrosion while the outer tube ensures structural integrity and positive welding properties. The bimetallic tube also allows the use of stainless steel tube plate or even re-tubing of an entire stainless steel heat exchanger. And since welding is purely stainless-to-stainless, no post-weld heat treatment is necessary.

Subject
Transpassivation, Materials, Tubes, Zirconium, Welding, Corrosion testing, Condensates, Nitric acid, Heat exchangers, Interfaces, Heat, Corrosion resistance, Stainless steel
Keywords:
Nitric Acid, Bimetallic tube, Zirconium, UNS R60702, UNS S31002
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2018
Association for Materials Protection and Performance (AMPP)
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