TPi January 2012

products & developments

Composite tubes Hoesch Schwerter Profile GmbH develops its products in collaboration with specific fields of industry and customers. Modern power stations and industrial plants are just two areas where special steel solutions are used that are required to withstand extreme loads. The classic seamless steel tube for pressure vessels represents a key construction element in the building of thermal plants. The requirements for boiler construction steels become significantly more exacting if – instead of conventional boiler fuels such as coal, oil or gas – other sources of energy are used that result in strongly-corrosive combustion products. For instance, boiler tubes in a waste incineration plant are not only exposed to thermal loads, but are also subject to corrosive attack, fundamentally triggered by the chemical element chlorine. For this specific application, the conventional boiler tube used in plant construction with its proven component strength was equipped with a ‘coating’ using a corrosion-resistant austenitic material. The intention behind this combination of materials is to allow the C-steel (carbon steel) to handle the

The composite tube is characterised chiefly by the following properties: • C-steel component and austenitic layer of the extrusion billet are manufactured in a common hot forming process at around 1,150 to 1,250°C. The metallurgical connection between the two materials is achieved in the solid state using pressure- accelerated solid state diffusion • A diffusion zone approximately 10μm thick forms between the materials, which is responsible for a high- strength, oxide-free metallurgical bond of materials • The fine microstructure configuration of the layer and base material is preserved, with no variation in the alloy concentration • Smooth surface structures avoid deposition of corrosion-promoting ash and salt particles from the flue gas • Special cross-section forms such as fin tubes, omega tubes or double omega tubes are possible • Cold bending is possible, since there is no cast structure created by cladding • Internal and external layer possible

thermal-mechanical load on the tube, while the austenite provides protection against corrosion from the prevailing environment. ‘Combined materials’ tubing of this kind is often referred to as composite. If produced using the extrusion process, the term used to describe this is co-extruded tubing. When the corrosion-resistant layer is applied to the tube body by welding, the term used is clad pipe. Clad pipes have one or two layer corrosion-resistant outer covering, approximately 2.5mm thick. This is applied using fusion welding, which creates overlapping welding beads. During welding there is an intermixing of a few tenths of a millimetre between the C-steel and the austenite; in metallurgical terms this is equivalent to a ‘dilution’ of the high-alloy layer material. Since it is obtained via the liquid phase, the layer material is characterised by a casting structure typical of welding. The development of composite tubing pursued by Hoesch Schwerter Profile GmbH was undertaken with the aim of overcoming the known disadvantages peculiar to clad pipes.

Hoesch Schwerter Profile GmbH – Germany

info@hoesch-profile.com www.hoesch-profile.com

A growing perforating business Sönnichsen, Norway, is an established manufacturer and marketer of welded precision tubes in the north European market. The company’s perforating line is the latest stage of a continued expansion of service offering to provide added customer value. The highly automated perforating line is equipped with robots for feeding tubes into the unit, repositioning the tubes if required and handling the perforated tubes. Weld seams are detected by an automated visual detection system, allowing the line to be operated with a minimum of operator assistance.

In the company’s production facilities, located 100km south of Oslo, close to the Swedish border, tubes are produced according to European standard, with a high percentage of the production tailor made to customer specification. While a significant proportion of the production has traditionally been sold cut to length, Sönnichsen’s new perforating line has added an additional service for customers.

Sönnichsen now offers a perforating service

reports that its new service has been well received by customers, particularly in the shop fitting sector.

The perforating line can perforate one to four faces of the tube and accommodate lengths up to approximately 3.2m. The unit can perforate up to four tubes simultaneously and is therefore well suited for long series. The company

Sönnichsen as – Norway oslo@sonnichsen.no www.sonnichsen.no

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January 2012 Tube Products International