TPT July 2007

FQM™: Danieli’s 3-roll pass retained mandrel mill for high quality seamless tube production

By Mr E Cernuschi, Danieli Centro Tube, Italy

1. Background The activities of Danieli in the field of the pipe plant market dates back to the early 1980s, through involvement as a sub-supplier or partner in important contracts for both seamless and welded pipe projects. However, the involvement of Danieli remained marginal until 2003, when the decision was taken to enter new markets. This move was intended to both increase revenues and serve customers better with a more global range of products. In particular, the decision to begin the design and manufacture of seamless pipe plants has been confirmed by the considerable growth in the energy sector, due to increased global oil and gas consumption. Together with the know-how and technology exclusively supplied by Kocks for finish rolling, Danieli Centro Tube can provide the whole technical package – including mechanical, electrical, automation, and reheating systems. This leads to advantages such as smoother coordination through all stages of the project. Danieli Centro Tube provides the process technology and mechanical design of the machines; Danieli Centro Combustion provides heating systems; Danieli Automation develops process automation and related electrical systems; and Danieli Centro Maskin contributes with auxiliary machines. As a result, three large projects are already in progress, while a fourth order has recently been awarded. 2. Seamless tube production overview Over the last 30 years, the state-of-the-art Retained Mandrel Mill (RMM) process has been the most advantageous method for high quality seamless tube manufacture. It holds an extremely competitive position when compared with other processes in corresponding conditions. fi Figure 1 : Danieli’s FQM™ (Fine Quality Mill) can produce superior quality seamless pipes

A universal process, it is highly suitable for all pipe dimensions and steels grades. RMM is also a flexible approach, suitable for high and low tonnage production, with an exceptional capacity to meet a variety of market requirements. With comparatively low cost investment, it provides additional capacity in producing high quality products, both for size tolerances and surface quality. The first generation of the retained mandrel mill, based on 2-roll pass design type technology, is now operating worldwide under the highest possible performance. Meanwhile, the new 3-roll pass design version has made a steady entrance into the market. FQM™ (Fine Quality Mill) is Danieli’s enhanced and progressively modified version of the first generation. 3. FQM™ at a glance – overview The Danieli FQM™ offers process technology able to produce seamless pipes with high quality features (close wall thickness tolerances and very smooth surfaces), at low production cost. The FQM process is based on the continuous rolling principle, with rolling passes on a cylindrical mandrel that moves at a constant controlled speed during the whole rolling phase. Rolling mandrel speed is calculated according to the deformation scheme and is less than the outlet tube speed from the first stand. The material therefore moves faster than the mandrel; consequently friction forces between the material and the mandrel are in the rolling direction versus a longitudinal material flow. The elimination of the transversal metal flow in the roll gap direction and the inline extraction of the tube from the mandrel (immediately after rolling), allow the use of a very close pass design. Moreover, the process offers a high degree of production flexibility, versatility and efficiency fully supported by process control features like automatic gap control and wall thickness in-line measurements. › Figure 2 : With a 3-roll pass design, the Danieli FQM™ process is based on the continuous rolling principle

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J uly /A ugust 2007