TPi April 2010

Current applications and future developments for carbon steel

I ndoor and outdoor applications in which chrome plated carbon steel tubular products are being used are spreading rapidly. Borusan TR currently manufactures round, rectangular and a wide variety of special-shaped sections suitable for chrome plating using convenient carbon steel grades. The company is able to produce a common range of shapes and dimensions made of stainless steel as well. In this paper, the current state and future aspects of electro-chrome plated and decorative industrial painted carbon steel tubular products used in manufacture of heating radiators, steel furniture and some other constructive appliances are highlighted. Besides this, the subject of tube production technology and some electro-chrome-plating process highlights are introduced as well as pre-coating surface treatment topics. Introduction Domestic radiator and (steel) furniture manufacturing industries are the two main areas where carbon steel tubular products are being widely used either as chromium plated or painted. The purpose of chromium plating is to protect the appliances against staining, rust and pitting thus achieving resistance to corrosion and oxidation, ensuring hygiene and enhancing visual appeal to be considered “decorative”. Functionality and appearance are the two main parameters for the so called “high-end” products; heating radiators and steel furniture to be used in residences, houses, offices, schools, hotels, hospitals and such other social buildings. For the applications subject to matter, the production range covers round tubes OD12mm to OD76mm and the equivalent square/rectangular sections beginning from 10x10mm to 60x60mm. Special sections commonly tubular products By Murat Ergin, Borusan Mannesmann Boru – Istanbul, Turkey

used in such applications are: flat-sided oval, elliptical oval, pointed oval, drop shaped, semi-round, tunnel (U) profile and other special sections that lie in the production range of OD12mm to OD76mm round tubes’ equivalent circumference. The hollow sections subject to the discussion in this paper are “as welded” carbon steel tubular products within the scope of EN 10305-3 and EN 10305-5 standards. Technical requirements for tubes suitable for decorative electroplating Generally, two types of surface quality are available; one is suitable for general use involving the decorative painting application, while the other is suitable for electroplating after convenient surface preparation process steps. The latter quality is referred to as “CRP” according to the denomination of Borusan, emphasising that the tubular product is guaranteed to be suitable for electroplating after applying specific

Figure 1 : The amount of metal (0.03mm) that has to be removed from the outer surface of steel tube – by means of grinding – to provide conformity for electroplating

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April 2010 Tube Products International