Welded and seamless pipes are used as billets for rolling in mills of XPT and XPT types. Seamless stainless tubes, which are needed for HRPT mills, and welded tubes are made by various methods of pressing and hot rolling. Let's take a look at some of them.

Types of billets

Billets for HRT mills (medium or small sizes) are tubing rolled in larger sizes, as well as cold drawn stainless steel tubing. Billets for HPTP mills are welded and drawn tubes from HPT mills and tubes from larger HPTP mills. Each billet package must have a special label, which will indicate the size of the tube, steel grade, open-hearth furnace number, package number of tube welding, pipe rolling mill, route number, open-hearth furnace number and package number of tube drawing mill.

Billet Quality

The surface of a tube billet must be free of cracks, opalines, tears, foils, shells, rolls and dirt. The ends should be trimmed without burrs, perpendicular to the axis of the pipes. Pipes shall also be straight. Supply pipes are regulated by the following GOST: seamless stainless steel pipes - 9940-72, seamless hot-rolled pipes - 8732-70, electric-welded pipes -10 704-63, welded pipes - 3262-75.

Tolerances

Tubes of intermediate sizes, made of alloyed or carbon steel, used for drawing and subsequent cold rolling have bigger tolerances for wall thickness and diameter than the respective tolerances for finished tubes. For example, tubes of intermediate sizes in stainless steel have a wall thickness tolerance of +12.5 (or 10%), while tubestubes up to 3.2 cm in diameter have an outside diameter tolerance of 0.5 to 1 mm, while tubes of larger diameters have an outside diameter tolerance of 0.5 to 1.6 mm. When rolling a dimensional intermediate billet with a deviation of the average actual wall thickness (Sfact) from the nominal (Snom), given the nominal length of the billet (Lnom), its actual length (Lfact) is determined according to the formula: Lfact = Lnom x Snom / Sfact. For billets for mills HTRP have the following tolerances for all sizes of pipes: the wall thickness of ±0.1 mm, the outside diameter of +0.5 - 0.2 mm.

Buy, price

Evek GmbH always in stock high-quality rolled steel. We offer stainless steel tubes at the best prices. It is formed taking into account the technological features of production and does not include additional costs. All products are certified. The terms of fulfilment of orders are minimal. Wholesalers get preferential discounts.