S.C.C. STUDIES ON DUPLEX STEEL IN CHLORIDE ENVIRONMENT

Abstract

The offshore drilling has been undertaken in a very extensive manner to obtain oil from the sea bed. Duplex steel tubes are used to carry the gas and oil from the seabed. The outside of the duplex steel is surrounded by the ballast which consist of Brine solution. An attempt is being made to replace the borine solution by Sodium Bromide and so this necessitated the study of reaction between sodium Bromide and duplex steel at 120°C under higher pressure. This problem was referred to Metallurgical Engg. Department of this university. The main aim of the present investigation was to find out whether Duplex steel is prone to SCC in NaCl/NaBr environment at 120°C under high pressure. The duplex steel sample were obtained from the tube provided by ONGC U-shaped samples were subjected to NaBr and NaC1 in an auto-clave at 120°C for 300 hours. The samples after the autoclave test were examined by metallography and Scanning Electron Microscopy to examine whether the cracks got initiated or not. It was found that under the given conditions i.e. NaC1 260 g/1 and NaBr 375 g/1 and for a temperature of 120°C and 300 hours duration respectively. The given duplex steel does not undergo S.C.C. -