SZFG supplying grade L485ME hot rolled wide strip as pipe pre-material for the GRTgaz Val de Saône pipeline project

With its technical know-how and high product quality, Salzgitter Flachstahl GmbH (SZFG), in close cooperation with the group affiliate Salzgitter Mannesmann Großrohr GmbH (MGR), is contributing to a secure gas supply in France and Europe.   

The French company GRTgaz SA operates a more than 32,000 kilometer-long pipeline network in Europe for the transport of natural gas, predominantly in France.  The objective of the company’s establishment in 2005 was the standardized operation of what had previously been five gas regions in France. The unified gas market is intended to improve the supply to southern France and to equalize the gas price. The implementation is being expedited by the construction of high performance north-south lines that have already been largely completed in recent years.  

There is currently a gap in the gas supply to central France between the regions of Grand-Est and Burgundy, but plans call for this section to be completed by the end of 2018. An infrastructure project with a total volume of roughly 730 MIL EUR is expected to provide a significantly better connection between the northern and southern sections of the French gas network. To this end, GRTgaz is constructing a 188-km natural gas pipeline from Champagne to Burgundy between Voisines (Departement Haute-Marne) and Etrez (Departement Ain). Not only can this pipeline improve the gas transport from north to south, it can also connect the LNG terminals on the North Sea to those on the Mediterranean.  

For the Val de Saône gas pipeline project, MGR delivered spiral-welded and PE-coated pipes in grade L485ME with a total length of 94 km, which is half of the section’s total length. The pipe’s outer diameter was a uniform 1.219 mm, with a wall thickness of either 13.0 mm, 15.4 mm or 22.7 mm.

SZFG delivered over 45,000 t of hot rolled wide strip as the pre-material to manufacture these gas pipeline pipes. Due to the specific, very demanding material requirements from GRTgaz, it was not possible to use an already existing material to manufacture the up to 22.7 mm-thick hot rolled strips. In cooperation with Salzgitter Mannesmann Forschung (SZMF) and MGR, SZFG developed a new chemical analysis for the pipeline grade L485ME that was customized to meet the GRTgaz requirements.  

The first trial melts were successfully alloyed in the steel mill in the narrowest limits ahead of time and poured as slabs. In order to achieve the required technological properties, these slabs were hot rolled into wide strip using very specific temperature control. This made it possible to deliver a grade L485ME steel that exceeded the GRTgaz specifications in spite of the very tough demands with regard to the strength, particularly in terms of the toughness.  

Series production of the hot rolled wide strip at SZFG and the pipe production by MGR proceeded with close technical and scheduling coordination.  

The subsequent transport of more than 5,000 pipes, each more than 17 m long and weighing up to 9 t, took place in up to four trains a week from the pipe work in Salzgitter to the major construction site’s logistics center in Jura, France from August to November 2016. The pipes were loaded onto trucks at this center and then delivered to the pipeline site.   

GRTgaz commissioned six companies from Belgium, France, Germany, and the Netherlands to lay the pipeline underground with at least 1-m cover.   

Laying the natural gas pipeline involves very extensive work. A total of 66 obstacles, such as the Saône River and the Burgundy Canal, the A6 highway, and other heavily used railway lines and streets have to be crossed.   

Plans call for the pipeline to be commissioned on November 1, 2018, at which time the natural gas line will be operated at a pressure of 68 bar.