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Quotes - Engineering - SalesU-Tube Heat Exchangers For
Duplex and High Alloy Construction
U-Tube Duty
Duplex 2205 and super duplex. A mixed austenitic-ferritic structure giving roughly twice the strength of 316L and far better chloride stress-corrosion cracking resistance. The higher strength allows thinner walls. The caution is that duplex work-hardens noticeably during bending, so minimum bend radius is more generous and forming is less forgiving.
Alloy 20. Developed for sulfuric acid service and still the default there, with good resistance to a range of mixed acids.
AL-6XN and Monel. AL-6XN is a super-austenitic alloy sitting between duplex and the nickel alloys, strong in high-chloride and seawater duty. Monel suits hydrofluoric acid and certain reducing conditions where stainless fails quickly.
Request a QuoteDuplex and High Alloy Construction Applications
Duplex and the U-Bend
Duplex is the alloy where bending most affects the design. It work-hardens significantly, which raises forming loads and springback, and the ferrite-austenite balance in the cold-worked region needs attention.
In practice this means a more generous minimum bend radius, a fabricator experienced with the material, and in some services a post-bend solution anneal. None of it is exotic, and all of it needs to be decided before the tubes are ordered.
Selection Data We Need
Flow rate and identity of both fluids, inlet and required outlet temperatures, operating and design pressures, allowable pressure drop on each side, and any code, alloy or hygienic requirement. Fouling history, turndown range and cleaning method matter as much as the design point.
