CORROSION-RESISTANCE OF CAST STEEL IN HYDROXYLAMINE SULFATE-SOLUTION

In hydroxylamine sulphate production processes fittings made from cast steel 18Cr-10Ni failed after short working periods due to inadequate corrosion resistance. By means of weight loss measurements different a ustenitic and austenitic-ferritic grades of cast steel with higher amo unt of alloying elements were tested in cold hydroxylamine sulphate so lution before hydrolysis and in hot solution after second reactor. Cas t steel types 20Cr-25Ni and 25Cr-6Ni have shown the highest corrosion resistance. The laboratory results were verified by industrial tests w here gate valves made from cast steel type 20Cr-25Ni after 4 years of working period are still in a good state.