The Welding Of LNG Storage Tanks With 9%Ni Steel And Petrifide Installment With Alloy Steel

With the changes in the international energy situation, the demand of state's growing energy and the adjustment of national energy strategies, liquefied natural gas (LNG) is considered the cleanest fossil energy on earth and the most important energy in the 21st century, because it is a high-quality, clean, efficient and convenient "green fuel".With the extensive use of LNG, 9%Ni steel of LNG storage tanks has also very papid development. Currently, The production of 9%Ni steel is mature at abroad. They have had a set of standards with 9%Ni steel, such as, ASTM, EU EN 10028-4, JIS G3127 and so on, this standards involve 9%Ni steel grades, chemical composition, mechanical properties and delivery status. At home, The production of 9%Ni steel start in 2007.It mainly made by Taiyuan and Anshan Iron and Steel Company, the quality has achieved world level.Because 9%Ni steel service under ultralow temperature environment, so the Low Temperature Toughness of Welded Joint of the 9%Ni steel is very important. This article has researched the weldability of imported 9%Ni steels and welding procedure qualification with the entrustment of a petrochemistry company. The 9%Ni stells with thickness of 24mm and 12mm were butt-welded using a sort of filler meteal with Nickel-based alloys. Specifically, we use the Nickel-based wires ERNiCrMo-3(AWS trademark)for manual tungstic electrode argon arc welding (GTAW) and the melting shielded welding (GMAW), the Nickel-based electrodes ENiCrMo-3 for shielded metal arc welding (SMAW), the ERNiCrMo-4 welding wire and the INCOFLUX 9 welding flux submerged-arc welding (SAW).The mechanical properties and micro-structures of welded joints were analysed.Eventually, we evaluted the welding procedures of 9%Ni steel.We often meet the welding of dissimilar welded joints in petrochemical installment. As a result of the physical and chemical performance of dissimilar welded joints exist difference, so the welding of dissimilar welded joints is much more complex than the similar welded joints.This article has researched the weldability of dissimilar welded joints (0Cr18Ni9Ti /12Cr2Mo1) and welding procedure qualification with the entrustment of a petrochemistry company. Using E309L electrode of austenitic grade stainless steel in the welding 12Cr2Mo1 Steel and 0Cr18Ni9Ti dissimilar steel after the surfacing buffer layer. The mechanical properties and micro-structures of welded joints were analysed. The result showed that the mechanical properties of welded joint was good.