Authors:	L. Karlsson, Rigdal, Thalberg, Stridh
Title:	Development in Welding of 9 % Nickel Steel for LNG Applications
Abstract:	The market for liquefied natural gas (LNG) increases approximately 4 % per year. Driving forces are the growing energy consumption in combination with unstable oil prices and environmental aspects. Since most reserves are located in remote areas low temperature liquefaction is necessary to make gas handling and storage feasible. This paper will present ways of increasing productivity and weld quality in production of 9 % Ni steel LNG storage tanks. Cylindrical storage tanks are constructed using SAW for horizontal welds and MMA welding for vertical welds. A new flux has been developed making increased SAW productivity possible without introducing the risk of hot cracking. Examples are given for single and multi wire SAW. An alternative option for the vertical welds is semi-automatic or mechanised MIG welding. It will be shown that solid wire MIG welding using new advanced double-pulse power sources can match MMA productivity and provides an increased overall weld quality.