Thanks to its outstanding resistance to general and localized corrosion attack properties, Titanium has
been successfully established as the commonly used material for seawater-cooled heat exchanger
tubing, be it for power plants’ surface condensers, thermal desalination plants’ heat exchangers or heat
exchangers used in the chemical and petrochemical processing industry. In the current material market
context in which Titanium price has increased significantly, engineering companies and end-users have
shown an increasing interest for more cost-effective alternative solutions using what are called super
alloys which are highly alloyed stainless steels showing a far better corrosion resistance than
conventional stainless steels.
In addition to Titanium, this paper will focus on six different super stainless steel alloys which may be
considered alternative solutions to Titanium for seawater-cooled applications: UNS S31254, N08367
and S34565 super austenitic alloys, UNS S44735 and UNS S44660 super-ferritic alloys, and S32750
super-duplex alloy.
Taking power plants’ condensers as an example, the paper reviews both mechanical and corrosion
properties for ranking the seven different materials. Both standardized ASTM and electrochemical tests
in artificial seawater have been carried out on welded tubes in order to rank the different grade
materials according to their pitting and crevice corrosion resistance.
Keywords: titanium, super stainless steel, super austenitic stainless steel, super ferritic stainless steel,
super duplex stainless steel, R50400, S44735, S44660, S32750, S31254, N08367, S34565, heat
exchanger tubing, welded tubing, condenser tubing, tubing corrosion resistance