TPT July 2009

T echnology U pdate

Modernisation of seamless tube rolling mills

EZTM JSC, Russia, designs piercing mills with horizontal rolls. According to engineering processes rolling mills can be equipped with cone and barrel type (cup-

shaped) rolls. When using a billet with diameter smaller than the shell it is advisable to operate cone-roll mills. If billet

andshelldiameters are equal it is wise to use barrel-type rolls. And if the shell diameter is decreased, cup- shaped roll mills are recommended. The exit side of

 Piercing mill

 Reducing mill

first half of 2007. Shells with graduated wall thickness are required in some cases. In particular it is necessary to thin shell bottom end wall thickness to prevent tube ends from triangles. It is advisable to thin shell bottom ends prior to pilger rolling in order to reduce pilger head weight. Wall thinning is accomplished by displacement of the piercing mandrel in the process of rolling. Thus, distance between the mandrel and roll generatrix on its exit taper is varied. Volzhsky Tube Works JSC intends to expand its tube mix rolled in TPA-200 by increasing length up to 12m and decreasing wall thickness. To achieve this, EZTM modified the exit sides of one piercing mill and several reeling mills, in the second half of 2007. In order to extend tube range rolled in TPA-80 operating at Dnepropetrovsk Tube Works, EZTM manufactured equipment for a reducing mill. An existing 15-stand mill was equipped with an independently driven 15-stand mill. As a consequence of such modernisation, a new 30-stand mill was commissioned. The mill is intended for the production of hot rolled tubes of 21 to 89mm in diameter. To improve the quality of rolled tubes, new reducing technology and reducing mill design were introduced. Special technology developed by Ukraine engineers made it possible to decrease the variation of tube wall thickness. This technology allows the substitution of hot-rolled tubes for cold-rolled mix, leading to cost reduction. The mill went into operation in spring 2008. EZTM JSC – Russia

piercing mills (of all types) must allow accurate and rigid centring of a mandrel bar and holding of the rotated shell when piercing. A piercing mill manufactured by EZTM for Seversky Tube Works JSC was commissioned in the

PVDF extruded foam technology now used for tube and pipe

Arkema, France, has made important advances in its Kynar ® and Kynar Flex ® foam technology. The company’s R&D team has developed new, patented technology that allows Kynar closed-cell foams to be extruded into tube, pipe and stock shapes such as rod. Prior to this development, commercial applications for Kynar foam had been limited to foam jacketing for plenum-rated wire and cable. This new application is important as parts made from Kynar ® PVDF foam retain many of the properties of the PVDF resin and are up to 30% lighter than those made from conventional Kynar resin. “Arkema’s research group worked for over a year to improve the processability of Kynar foams before testing outside the lab,” said Mr Guenter Sappelt, Kynar CPI account manager for Europe. “To everyone’s delight, for some customers it took only a few hours to extrude Kynar ® foams with the expected lighter densities and enhanced properties.” Initially developed to lower the cost of Kynar PVDF parts, the new technology has yielded improved Kynar properties like flexibility and easy cutting. It has also maintained many of the properties expected from Kynar resins, like barrier properties, chemical and temperature resistance. Additional patents have been filed. In addition to inherent low smoke and flame properties, Kynar foams are a good choice for harsh industrial applications. With thermal insulating properties, they offer resistance to most solvents and chemicals, gamma and UV radiation. The mechanically tough foams are cut easily and impermeable to fuels, and offer service temperatures from -50°C to +155°C. Arkema produces Kynar PVDF resins at facilities in Calvert City (Kentucky, USA) and Pierre-Bénite (France). A global chemical company and France’s leading chemicals producer, Arkema consists of three businesses: vinyl products, industrial chemicals, and performance products. Arkema – France Fax : +33 1 49 00 83 96 Email : guenter.sappelt@arkema.com • Website : www.arkema.com

Fax : +7 496 577 75 05 Website : www.eztm.ru

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J uly 2009

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