African Fusion November 2019

nickel-base 625-T1wire; and an experimen- tal manganese-alloyed austenitic 17/15-T1 wire especially developed for welding 5% nickel steels. Based on the present inves- tigation, the following conclusions could be drawn: • Both wires showed good weldability in the vertical-up position and a wire feed rate of 10 m/min was easy to handle manually. This allows for high welding speeds, which in turn enable a reduc- tion in the welding time and improved productivity. • The preferred stick-out length was 15 mm. • All welds were free from defects and irregularities. • When welding the 5% nickel steel, A645 Grade A, both flux-cored wires passed the mechanical requirements in EN 10028-4 and ASME BPVC.II.A, but tensile test fracture occurred in the weldmetal for the 17/1-T1 wire. The A645 Grade A has higher strength than the EN X12Ni5 steel, so it is to be expected that the

Figure 4: Hardness measurements of welded joints: a) 5%Ni+17/15-T1; b) 9%Ni+17/15-T1; c) 5% Ni+625-T1; d) 9% Ni+625-T1.

weldmetal strength exceeds that of the parent material. • Only the nickel-based 625-T1 wire passed all requirements when 9% Ni X7Ni9 plates were joined.

• The austenitic 17/15-T1 wire may be a cost-effective alternative to 625-T1 whenwelding 5%Ni steels for cryogenic applications, but for 9% Ni, nickel-base wire is required.

References [1] Gossl M, Krutzler T, Schieder W, Schindler I, Storch A, Wiesenberger H, Goers S, Lindhofer J, Bruyn K, Luksch C, Tichler R (2013): Beitrag von Fernwärme, Fernkälte und Erdgas zu Energie-und Umweltpolitischen Zielen. Umwelt- bundesamt GmbH Wien. http://www.umweltbundesamt.at/fileadmin/site/ publikationen/DP141.pdf [2] Schier M, Schwarz M (2016): Mid-scale is scaling out! LNG Industry 11, 23-27. [3] Hecking H, Cam E, Schonfisch M, Schulte S (2017): Aktuelle Entwicklungen auf den Kohle-und Gasmärkten und ihre Rückwirkungen auf die Merit Order. ET. Energiewirtschaftliche Tagesfragen. http://www.et-energie-online.de/ Zukunftsfragen/tabid/63/NewsId/3227/Aktuelle- Entwicklungen-auf-den- Kohle-und-Gasmarkten-und-ihre-Ruckwirkungen-auf-die- Merit-Order.aspx. [4] Chen QS, Wegrzyn J, Prasad V (2004): Analysis of temperature and pressure changes inliquefiednaturalgas(LNG)cryogenictanks.Cryogenics44,701–709.

[5] Lin W, Zhang N, Gu A (2010): LNG (liquefied natural gas): A necessary part in China’s future energy infrastructure. Energy 35:4383–4391. [6] Lee DH, HaMK, KimSY, Shin CC (2014): Research of design challenges and new technologies for floating LNG. International Journal of Naval Architecture and Ocean Engineering 6: 317–322. [7] BaumL,FichterV(1992):DerSchutzgasschweißerTeil2:MIG/MAG-Schweißen. 4th Edition, DVS-Verlag Düsseldorf, p88, p212–214. [8] BaumgartnerS,PahrH,SchnitzerR(2016):Creeprupturestrengthofdissimilar CB2-P92 FCW joint welds, in: Viswatha, R (Ed.): Advances inMaterials Technol- ogy for Fossil Power Plants – Proceedings of the 5 th International Conference EPRI, Marco Island, p952. [9] Zhao S, Xie X, Smith GD, Patel SJ (2006): Research and Improvement on struc- turestabilityandcorrosionresistanceofnickel-basesuperalloy INCONELalloy 740. Mater Design 27:1120–1127.

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AFRICAN FUSION