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  • Rapid taper

Improvements at Fos-sur-Mer meet customer demand for variable thickness coils

An improvement programme at ArcelorMittal Fos-sur-Mer (France) will allow the mill to produce coils with a rapid taper, known as Taper XR. The coils have highly controlled thickness variations from end to end. While Taper XR products have applications in the energy industry, the process improvements made at Fos will also benefit a wide range of demanding applications, particularly in automotive where tight gauge and thickness control is vital.

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. Until now, the maximum variation in thickness ArcelorMittal Fos-sur-Mer has been able to achieve is 0.9 mm. But with the installation of a new automation system in the finishing mill, variations of 1.2, 1.173, and 2.39 mm will be possible along the length of the coil.


Customer-driven changes to mill

The decision to make changes to the finishing mill in Fos-sur-Mer (a part of the ArcelorMittal Méditerranée network) 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.”

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. “Welding similar gauge material eliminates stress concentrations, which is one of the main advantages of having a variable wall transition,” says Kevin Elliott product engineering manager at Quality Tubing. “That means our customers can run more jobs before retiring a string which improves their economics. The use of variable tapers also reduces the number of bias welds in the string which reduces manufacturing time.”

Upgrade to be complete by end of 2019

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. “This will help us to answer new market requirements from our customers.”

While the main market for tapered coils is in the oil and gas industry, Jean-Claude Jouvenel believes the changes in Fos will make them attractive to customers in other sectors: “The improvements will benefit customers in sectors where OEMs need to achieve tight gauge and thickness control. Twist beams and control arms for automotive chassis are obvious examples.”

Along with True Taper and Taper XR coils, ArcelorMittal Fos-sur-Mer can also produce coils with a U-taper. These coils are the same thickness at each end, but are thinner in the middle. Their main application is in specialist coiled tubing products for the oil and gas industry.
The new rapid taper coils will allow customers such as Quality Tubing to improve their position in several key markets notes Cedric D. Williams: “Right now the oil and gas market is still a somewhat soft. But with ArcelorMittal as our development partner, we feel confident that we can thrive even in this challenging market.”

“This project has given the team at Fos a unique opportunity to establish a direct technical exchange between our customer and our process team at the hot rolling mill,” notes Henri Olivier, ArcelorMittal International account manager for Quality Tubing. “This is the ultimate way to ensure the mill perfectly understands the needs of the market. Later this year we will introduce a breakthrough steel grade which will also be offered in a Taper XR version.”
This project would not have been possible without the support of ArcelorMittal’s New Products Team,” says Pierre Fize, oil and gas pipelines sales manager for ArcelorMittal International. “They spent countless hours on the line to follow up the trials. We will continue to hold direct discussions between our team and Quality Tubing at least once a year in Fos-sur-Mer.”


Coiled tubing ready to be deployed 

About Quality Tubing

Quality Tubing has been the leader in coiled tubing manufacturing for the past 40 years. The company excels in the welding, manufacture, and testing of continuously-milled tubing, resulting in the highest quality product. Quality Tubing products are typically used by oil and gas service companies and well owners.

More info: www.nov.com/qualitytubing


Strips of Taper XR only require one weld to form a pipe, enhancing fatigue resistance 


As part of the improvements, the reaction time of actuators on the roughing stands has been revamped to handle drastic thickness variations 


The hot rolling mill at ArcelorMittal Fos-sur-Mer

Copyright images: ArcelorMittal, Quality Tubing