Improvements at Fos-sur-Mer meet customer demand for variable thickness coils
One of the four coilers in the ArcelorMittal Fos-sur-Mer rolling mill
The changes build on ArcelorMittal’s current offer of True Taper coils which have a maximum thickness variation of up to 0.9 mm. When the changes are fully implemented at the end of 2019, the mill will be able to produce Taper XR coils with thickness variations of between 0.8 and 2.4 mm along the length of the coil. The steel grades used can have a tensile strength of up to 1000 MPa – a world first.
Both True Taper and Taper XR coils are rolled so that they are thicker at one end than at the other. Thickness decreases evenly across the length of the coil.
The decision to make changes to the finishing mill in Fos-sur-Mer was taken following requests from customers, as Cedric D. Williams, sales engineer for Quality Tubing explains: “Our clients came to us with a request to have more rapid thickness transitions in the hot rolled coils which are used to make our coiled tubing. The Fos team responded with a capital expenditure project that will allow the manufacture of hot rolled coils with over 2 mm of taper. ArcelorMittal is the first steelmaker to offer such a large taper in our industry.”
Coiled tubing ready to be deployed
Rapid taper coils allow OEMs such as Quality Tubing to produce extremely long lengths of tubular products – known as strings – which have fewer welds. The strings are used to extract oil and gas, and maintain the health of wells. As welds are the weak spot for fatigue resistance, this increases the strength of the tube where it is needed in the well and ensures a longer life.
Strips of Taper XR only require one weld to form a pipe, enhancing fatigue resistance
The changes at Fos-sur-Mer have required an investment of €6 million. The first phase of the upgrade was completed during a scheduled shutdown at the plant during November 2018. “The work is continuing during 2019 and will enable us to produce coils with even higher thickness variations than we can achieve now,” says Jean-Claude Jouvenel, process manager at the hot strip mill in Fos-sur-Mer.
The cooling table at the exit of the hot rolling mill ensures the variation in mechanical properties remains minimal along the length of the coil