Thanks to its chromium and molybdenum contents, UR™ 31 presents an excellent resistance to localized corrosion, much better than conventional 6% Mo grades and relatively close to 625 alloy when tested according to the most common standards.
The high nickel content contributes to an enhanced resistance to stress corrosion cracking. It can be used for a variety of very demanding applications.
In environments representative of phosphoric acid production*, UR™ 31 is resistant up to 110°C (230°F) even if fluorhydric acid is present.
UR™ 31 has excellent resistance in pure and contaminated sulfuric acid over a broad range of concentrations up to 80 °C (176° F). In fresh water, UR™ 31 is almost not susceptible to corrosion.
Long-term immersions of UR™ 31 coupons have demonstrated that it is very resistant to pitting and crevice corrosion in renewed seawater up to 50°C (122°F), even if 0.5 ppm of free chlorine are added.
UR™ 31 has proven to be a good candidate for open loop marine scrubbers, above the wet/dry interface.
Sour environments
UR™ 31 has proven to be resistant in a solution containing 150 000 ppm of chlorides at pH 4.5 and 150°C under a H2S partial pressure of 14 bar.
This environment is representative of very aggressive conditions encountered in Oil & Gas production units, and is much more aggressive than the current NACE MR0175 / ISO15156 limits. In these conditions, standard 6%Mo grades suffer from stress corrosion cracking.


• Flue gas cleaning systems: inland and marine scrubbers
• Pulp and paper industry: bleaching equipment
• Oil and Gas applications
• Chemical industries


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