INCONEL® alloy 690 is a high chromium content version of INCONEL® alloy 600 with
excellent resistance to many oxidising acids and salts and some
resistance to sulphidation at elevated temperatures. The resistance
in Nitric acid plus hydrofluoric acid mixtures lends itself to
pickle shop duties. However the superior stress cracking resistance
of the alloy caused it to supercede INCONEL® alloy 600 in steam
generation nuclear reactors for piping, separators and weldments.
More recently the alloy has superceded INCONEL® alloy 601 as the
material of choice for metal dusting environments, which in
conjunction with INCONEL® alloy 693 have created an excellent
engineering material for the latest designs of compact reformers
and Fischer -Tropsch syngas generation units.