Welding 9% nickel steel for liquefied natural gas (LNG) applications

摘要

For more than five decades, storage facilities for liquefied natural gas (LNG) are being built with 9% nickel steel in order to obtain sufficient ductility and structural integrity at -163℃ and below. Although research has been carried out with matching welding consumables for the welding of these applications, at present still only nickel base consumables have proved to meet the requirements such as mechanical properties. This paper will briefly describe the history of 9% nickel steel [1]. A more detailed description will be given of the metallurgy of 9% nickel steel, the nickel base welding consumables and the welded joints in relation to the chemical composition, heat treatments, mechanical properties, physical properties, international specifications and project requirements for LNG tanks. For the welding of 9% nickel steel with SMAW and SAW, some practical guidelines will be presented and exemplified with recent reference projects. Lincoln Smitweld has been involved with the development of welding consumables for 9% nickel steel, as for example the Nyloid 2 covered electrode, for over 30 years.