New generation of super duplex steels for equipment gas and oil production

Abstract

Oil&gas producing industry today is increased production volumes from old deposits on land, offshore and deep-water. The materials used to create modern equipment that meets these trends should be distinguished by increased productivity in conditions of corrosion and high pressure, to ensure trouble-free operation. In such conditions, taking into account the necessary provision of acceptable cost indicators, there is no alternative to duplex steels. Their crystal structure simultaneously allows using the advantages of ferritic and austenitic phases. The report presents the results of using a compositional and technological methods for structure management, the rationale alloying with copper (3.0-3.3%). Application of ESR in the manufacture of steel billets of super duplex steel has demonstrated the ability to simultaneously achieve physical, chemical and structural homogeneity, ensuring high corrosion&mechanical characteristics. The thermodynamic and kinetic conditions for the formation of optimal phase steel composition are determined. Grounded heat treatment regimes, prevent the formation of sigma and psi-phase and contribute to the formation of stable intermetallides (30-300 nm). Based on the test results of “Gazprom-VNIIGAZ” LLC the new steel is recommended for the manufacture of valve bodies and in-vessel internals used in the fields, that containing H2S and CO2 up to 25% in the fluid.