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Laser-hybrid welding for pipe production and pipe laying of thick large diameter pipes

: Rethmeier, Michael; Gumenyuk, Andrey; Gook, Sergej

Singapore Weldings Society -SWS-; International Institute of Welding -IIW-:
Recent Development in Welding and Joining Technologies. CD-ROM : Proceedings of the 7th Asia-Pacific International IIW Congress; 8th - 10th July 2013, Singapore; Programme & Abstracts
London: IIW, 2013
International Institute of Welding (IIW International Congress) <7, 2013, Singapore>
Conference Paper
Fraunhofer IPK ()
high strength steel; laser hybrid welding; longitudinal weld; pipeline

New brilliant high-power lasers such as disc laser and fibre laser open up new fields of applications for laser-hybrid welding, e.g. power generation, shipbuilding and pipeline construction. To a large extend, longitudinally welded large-diameter pipes are used for modern oil- und gas-pipelines. New material trends are high strength steel grades API-X80 or higher. For the production of such pipes a large plate is first formed to an open ring. Subsequent, it is continuously tacked by means of metal active gas (GMA) welding process. The remaining double-sided joint gaps are filled up by cost-intensive multiple-wire submerged arc welding (SAW) processes. For reasons of economy the GMA tackweld process can be replaced by the laser-GMA-hybrid welding process, whereby as primary objective sufficient weld metal toughness for low temperature applications down to 60C is pursued. Results are discussed in the light of achievable toughness of the welded joints and their accordance with the requirements demanded in the standards. It could be shown that the penetration depth of filler material is rather independent of the kind of arc used and does not exceed 13 mm. A second interesting aspect is the use of laser-hybrid welding in pipe laying, insensibility towards tolerances and the possibility of orbital welding are very important factors in addition to the weld seam quality. First promising results for laser-hybrid welding of thick materials could be demonstrated. Half-orbital welds could be demonstrated for a single pass weld in 16 mm thick large-diameter pipes.