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29 June 2016 No Comment

Here, Stewart Jones, Customer Technical Services Manager, Conveyance Tubes at Tata Steel highlights the benefits of hot-finished, multi-certified tube products.

When specifying pipework for the built environment, ensuring that the product is suitably certified and can guarantee a high quality performance is paramount. As tubes are required to perform in a diverse range of applications, such as heating, ventilating and air conditioning (HVAC), steam services and fire protection, deciding on the correct tube specification to use can be both confusing and a challenge.

Influencing factors to consider when choosing a specification include material cost, manufacturing processes and traceability to name but a few. However, key to the specification process, especially in critical environments where health and safety is paramount, is complying with legislation.

BS1387 is still frequently specified for building services pipework, despite this standard being withdrawn from use in 2004 – more than 12 years ago and being replaced by BS EN10255.

BS EN10255, requires CE marking to be applied, which ensures compliance with the European Commission’s Construction Products Regulations (CPR), demonstrating that the products meet specified legislative requirements.

When a welded tube is being used, the manufacturing process also needs to be taken into account. Two options are available – cold-formed or hot-finished, both of which produce products of similar appearance, but there are several key differences to be aware of.

A cold-formed tube is produced from strip that is shaped when cold and High Frequency Welded (HFW) to form the end product. Internal stress is introduced by the cold forming operation and by supplying the tube without any subsequent heat treatment of the weld region. Seam welding changes the microstructure and consequently, a cold-formed tube has what is known as a Heat Affected Zone (HAZ), a harder, less malleable region with a potential risk of cracking and, therefore, a greater possibility of product failure.

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A hot-finished tube undergoes an additional manufacturing process where it is heated to a temperature greater than 850oC. This normalising heat treatment removes the HAZ and refines the microstructure resulting in a uniform, stress-free end product with increased structural integrity and ductility.

The hot-finishing process also provides a tube that is able to withstand higher pressures and can be bent to tighter radii than cold formed products, without the risk of collapsing or creasing. Furthermore, the mechanical properties of hot-finished products remain consistent when undergoing additional processing such as welding or fabrication.

When supply of materials in accordance with the European Pressure Equipment Directive (PED) is specified, cold formed HFW tubes produced against BS EN10217-1 cannot comply with this legislation.

Therefore, to ensure that a suitable product is obtained for the application, it is important to specify a hot-finished tube.

Furthermore, by requesting BS EN 10217-2, a ‘GH’ (Get Hot) grade of hot-finished steel tube will be supplied, offering all the advantages outlined above and hence an increased margin of safety for the application concerned.

To guarantee compliance with the CPR and the PED, both of which are key areas of European legislation, it is necessary to have multi-certified tubes i.e. products that meet both BS EN 10255 and BS EN 10217-2. Such products can be used with confidence, secure in the knowledge that they will be suitable in every case.

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In this respect, Tata Steel, being a forward-thinking manufacturer has developed a range of hot-finished multi-certified branded steel tube products. For building services applications, Tata Steel have Install® Plus 235.

Developed and manufactured within the UK, Install® Plus 235 is suitable for all normal building services applications. As the steel used to make the tube is also produced by Tata Steel, a product of consistently high quality with full traceability can be guaranteed.

By simplifying the specification process, multi-certified products instil a sense of confidence for the project engineer, that the tube is suitable and will perform adequately in service.

The Install® Plus range is ideal for building services applications such as HVAC systems (including chilled water and steam requirements) and low pressure gas.

Drawing on the benefits of hot-finished products whilst utilising a higher grade of steel (235MPa), Tata Steel’s INSTALL PLUS 235 range offers improved pressure integrity compared to alternatives using 195MPa grade steel as per BS 1387.

Based on the next generation EN10255 standard as well as EN 10217-2, INSTALL PLUS tube is CE marked under the CPR to satisfy both CAT3 (fuel, gas and air) and CAT4 (water), and can also be supplied with a Declaration of Performance (DoP), to further satisfy the EU CPR legislative requirements.

In addition, as Tata Steel hot finished tubes are manufactured in accordance with BS EN10217-2, products are fully PED compliant.

Optional additions to further enhance this innovative product include Tata Steel’s own, specially developed, external red paint, which delivers industry leading enhanced corrosion resistance and which is ideal for providing additional protection for longevity in industrial and building service environments.

As well as developing their various ranges of multi-certified steel tubes, Tata Steel, in collaboration with the School of Civil and Building Engineering at Loughborough University, has established the Building and Industrial Services Pipework Academy.

This educational partnership is intended to support the building and industrial services industry by clarifying pipework issues such as the importance of tube specifications, the benefits of using hot-finished tube products and technological advances within the sector, such as the adoption of Building Information Modelling (BIM).

At a time when compliance with European legislation is critical, ensuring that tube and pipework specifications are correct, within an industry still typically referring to standards more than 10 years out of date, can be a daunting task.

However, by using hot-finished, multi-certified products, such as Tata Steel’s Install® Plus 235 range for building services applications, compliance can be ensured providing complete confidence of product suitability.

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For more information on the Building and Industrial Services Pipework Academy, please visit: www.bispa.org

For more information on Tata Steel’s hot-finished tube range and the differences between hot-finished vs cold-formed tubes, please visit: www.tatasteelconstruction.com/hotvscold

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