TPT September 2007

T ube M ills: R olling & F orming M ethods

Top grade and high chromium rolls

Hot-rolled seamless steel tubes using pilger mill technology

Shandong Province SiFang Technical Development Co Ltd, China, is a manufacturer of top-grade rolls, with a focus on high chromium rolls. Such rolls are made from high chromium alloy material through casting. The rolls have properties including good wear resistance, uniform hardness from surface to core, and high tenacity. Steel rolled by high chromium rolls also has a brighter surface. High chromium rolls can be used in seamless pipe straightening and ERW pipe welding. Performance results supplied by users show that the service life of high chromium rolls is two to three times that

of forged steel rolls made from traditional materials like 9Cr2Mo, Cr12 and Cr12MoV. According to SiFang, who specialises in producing rolls with high wear resistance capacity, the popularity of high chromium rolls is increasing among companies manufacturing seamless pipes. SiFang also produces high-level rolls for cold bending shape steel and welded pipes. The company manufactures rolls of up to 2m OD and up to 10t in weight. Shandong Province SiFang Technical Development Co Ltd – China

VVT-Vitkovice Valcovna Trub, a division of Trinecke Zelezarny, is one of the largest Czech producers of thick-wall seamless steel tubes. These products are currently manufactured using the Mannesmann technology of hot rolling of seamless steel tubes (pilger mill). The VVT range includes carbon and alloy steel products with an OD range of 60.3mm to 406.4mm and wall thickness 6.3mm and above. With an annual capacity of 100,000t, the company’s entire volume is produced on 2 rolling mills: the ‘big Mannesmann’ for tubes of 168.3-406.4mm OD, and the ‘small Mannesmann’ mill that makes tubes of up to 168.3mm OD. The big Mannesmann line is currently undergoing a large-scale revamp and refurbishment, which will be finished in the second half of 2008. In addition to the overall increase of capacity, the main benefits will be better tube surface quality and dimensional accuracy. Other improvements will include the production of thick-wall tubes in larger lengths and increased capacity of non-destructive testing. The company’s product portfolio will have an increased range of alloy steel tube and OCTG. The Mannesmann technology of seamless steel tube production is composed of four basic operations: preheating of the steel input, perforating on the punching machine, pilger hot rolling and calibrating the hot tube on the sizing line. The periodical rolling process is a discontinuous method achieved against the advance motion, with rolling executed only by the calibration part of the sizing rollers perimeter. A trajectory of the feeding machine motion takes place, in which the mandrel grips the semi-finished product, and leads it into one fi VVT pipe is used for a range of applications, including nuclear, power, chemical and OCTG

Fax : +86 531 8887 6693 Email : sdsf@vip.163.com Website : www.cnsdsf.com

Installed by steel processors worldwide

tank heaters

external heating systems

Tank and vessel heaters for pickling

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Specialists in heating & cooling systems and equipment for highly corrosive liquids…

Liberta House · Sandhurst · Berkshire · GU47 8JR · England Telephone: +44 (0) 1252 876123 • Facsimile: +44 (0) 1252 875281 www. b r a u d e . c o . u k • s a l e s@b r a u d e . c o . u k

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S eptember /O ctober 2007