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With the steadily increasing share of wind power in the world’s total energy consumption, windmill fabrication is maturing as an industrial sector. Marcel Stemvers, European Marketing Manager of ESAB, discusses the challenges that producers of wind turbine towers face today and the solutions that are being developed to address them

With the steadily increasing share of wind power in the world’s total energ

Keeping the wind in your sails

Having originated within industries such as offshore and pressure vessel fabrication, many fabricators have converted to fully-fledged producers of windmills, often operating internationally. Today, the windmill industry exists in an extremely competitive environment where fabricators are constantly forced to reconsider their production facilities in order to remain competitive. In welding – one of the most important elements of fabrication – increased productivity is a top priority, along with meeting increased weld quality requirements. ESAB is a leading supplier of welding and cutting solutions that closely follows the progress of the windmill industry, working with fabricators to find solutions for welding demands.

Wind tower production is a typical welding intensive industry segment. The products are voluminous, identical and require a high structural integrity. The production volume needs to pass pre-defined production steps and a limited number of production stations are available. Commonly, each next (welding) step depends on the tolerances and quality delivered from the previous station. Additionally, component size, structural requirements and production volumes increase continuously, putting demands on manufacturing flexibility. The industry is also expanding geographically, requiring new production capacity to be installed close to new markets, as transporting wind towers over long distances is not economically, or practically, viable.

Making decisions for today’s demands does not guarantee success for future requirements, which often have to be

met by upgrading and modifying existing installations or Greenfield production plants. Providing modular solutions and being able to implement the latest welding technologies in existing production installations is important to meet the many requirements in this industry segment.

Tandem-Twin SAW:a major step forward

ESAB supplies complete and productive welding solutions for windmill fabrication to give manufacturers the market strength to remain ahead in one of the world’s most demanding branches of industry. ESAB designs and retrofits column and boom stations for submerged arc welding of circumferential and longitudinal welds – including head and tailstock, automation and integration in existing production lines. These are complemented by welding tractors and equipment for special components.

Developed specifically for the wind tower industry, ESAB’s flux/wire combinations ensure the required weld quality and mechanical properties – be it for land-based, offshore or even arctic wind towers.

Tandem-twin technology is ESAB’s latest development in multi-wire welding heads, providing unsurpassed deposition rates and welding productivity. The Tandem-Twin process, which involves two twin heads placed in sequence, benefits not only windmill fabricators, but all industries that deal with the submerged arc welding of large-scale cylindrical objects. The equipment has been tested on current steel grades for windmill fabrication, new

consumables have been developed and have gained the necessary approvals, and welding procedures have been established. ESAB provides ongoing support for fabricators using this technique, aided by the facilities of its process centre in Gothenburg.

The Tandem-Twin SAW has already been successfully integrated into wind tower production at Sonderjyllands Maskinfabrik and DSSN in Denmark. It brings welding productivity to new levels and can be used for all welds with the accessibility to accommodate the equipment – most importantly, the circumferential welds that make up the majority of weldments in windmill fabrication.

Column and boom

One important component in all automised welding solutions is the manipulator, carrying and transporting the welding head. In wind tower production, the most commonly used manipulator is a column and boom (CaB). ESAB supplies a comprehensive product range of CaBs, from small (3 x 3 m) for light-duty applications, up to heavy-duty types covering 10 x 8 m. For wind tower applications, the ESAB CaB 460 is most commonly used. Working range is from 4 x 4 up to 6 x 6 m. It is a robust, fully modularised product that can be exactly tailored to customer demands. Fabricators have a choice in, for example, size, type of foundation, type of drive unit, camera systems and flux handling systems.

Power sources

ESAB also offers a range of LAF heavy-duty DC power sources, ranging from 635

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to 1600 A, perfectly suited for windmill production and other similar applications. If more than 1600 A is required, special parallel operating systems can be supplied, increasing the output to 3200 A. In addition, two AC power sources are available – TAF 800 and TAF 1250.

Control systems

The control system is an essential component in the total production concept. For the welding process, ESAB utilises sub-bus communication control modules (type PEH). Those units are operated in conjunction with a central control system that handles the overall production. Control systems are often designed specifically to meet individual customer requirements.

Healthy portfolio

TEGOPI of Porto, Portugal, conveniently located only 20 km from the seaport of Leixoes, is a versatile fabricator of windmill towers, civil constructions, and lifting and moving equipment. The company uses several ESAB CaB SAW welding units with single wire, twin arc or tandem heads. For wind tower production, all WPQs above 15 mm are approved down to -50°C, using the flux/wire combination OK Flux 10.72/OK Autrod 12.22.

The Q7 project

ESAB SAW technology has also been crucial in the production of piles and transition pieces for the Q7 North Sea wind farm. Q7 is the largest offshore wind farm in the Dutch sector of the North

Sea and a step forward in the Netherlands’ renewable energy policy to boost wind energy production to 2750 MW by 2020. ESAB’s customer, Sif Group bv (see box out), manufactured the foundation piles and the transition pieces.

The Q7 offshore wind farm is located some 23 km offshore from IJmuiden, in block Q7 of the Dutch continental shelf. It is unique in the sense that it is the world’s first such project located so far from the coast (outside the 12-mile zone) and in deeper waters than ever before (19-24 m). The project comprises 60 wind turbines with a total capacity of 120 MW.

Building on sturdy foundations

ESAB is committed to helping customers increase competitiveness through delivering improved productivity solutions. Being a truly global manufacturer and supplier, ESAB enjoys the unique ability to combine the benefits of international experience with the most extensive range of equipment and consumables available from a single source. ESAB’s long tradition of technical excellence and service to customers continues to be at the heart of operations worldwide. Today, that tradition is being continued with extensive new investments in systems and technologies to enhance the quality and efficiency of services.

In such an industry, the decisions for the welding processes, the welding and handling equipment used, and the expertise on the welding consumables is critical to the success of the company. Much of this expertise has to be available internally and

must be nurtured, as the industry is very competitive. Welding is a key enabler and therefore a critical success factor.

ESAB recognises and understands the challenges its clients face in terms of continuously changing demands for larger sizes, higher mechanical requirements and increasing operational complexity. Being one of the industry’s most favoured suppliers, ESAB must constantly consider opportunities for improvement. The solutions developed are so-called “industry segment solutions”. It is the successful

The Q7 offshore wind farm – a challenging project for Sif Groep bv, which fabricated the foundation piles and transition pieces using ESAB welding technology

“The industry is expanding geographically, requiring new production capacity to be installed close to new markets”

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integration of the processes and process steps that will lead to a harmonised workflow and low-cost production.

ESAB solutions cover cutting processes, engineering of welding automation solutions, standard and engineered equipment components, wind tower specific solutions for product handling and welding, and dedicated welding consumables that meet productivity and structural integrity requirements. The knowledge that comes with these solutions, and the interaction between them, is an area of expertise for ESAB. Being able to deliver turnkey and fully-integrated solutions is seen as essential to success in this industry sector.

Wind towers are constantly growing in size, they are now being placed offshore and in Arctic conditions and their numbers are growing in all regions around the world. This makes wind tower production a dynamic industry with specific requirements. ESAB is committed to retain its leadership position in this industry segment as a complete welding and cutting solution provider. Its global presence and ability to deliver local support and competence, wherever the customer is located, is seen as a key element in maintaining this leadership position. Finally, holding ISO 14001 and OHSAS 18001 certificates, ESAB is making a strong commitment to sustainable development and responsibility towards its products and employees. This dovetails nicely with the social responsibility that comes naturally to the renewable energy sector. ■

A bright future in wind energy

Sif Group bv is an independent company located in Roermond in the south of the Netherlands. The group specialises in the manufacture of tubular structures for a number of markets, including: offshore oil and gas, offshore wind farm foundations, harbour and jetty facilities, pressure vessel shells and cones, and civil and mechanical engineering. Sif has broad experience in bending, welding, heat treatment, non-destructive and destructive testing of various types of steels used in the markets.

By timely investment in new welding technology and production facilities, Sif Group bv has been able to gain a strong foothold in the Western European offshore wind energy market and made a major contribution to the generation of clean energy. With many new wind energy projects anticipated, the future looks bright. Partnered with ESAB for welding technology, the company can be assured of a supplier that understands its needs and can respond to its specific requirements.

For more information on ESAB’s services and current project portfolio, visit www.esab.com

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Top: Foundation pile for Q7 under construction at Sif Groep bvBottom: ESAB tandem-twin technology applied for longitudinal welds

“New ESAB equipment and consumables have made a significant contribution to our objective of manufacturing three complete towers every week” Giuseppe Goffredo, Technical Director of Leucci Construzioni

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Competitiveness in wind tower fabrication is synonymous with the application of productive, high quality welding solutions. With ESAB, you are assured of a partner who understands your challenges and responds with innovative welding and cutting technology.

We design and retrofi t column & boom stations for submerged arc welding of circumferential and longitudinal welds – including head and tailstock, automation and integration in existing production lines. These are complemented by welding tractors and equipment for special components.

Tandem - twin technology is our latest development in multi-wire welding heads providing unsurpassed deposition rates and welding productivity.

Developed specifi cally for your industry, our fl ux/wire combinations ensure the required weld quality and mechanical properties - be it for land-based, offshore or even arctic wind towers.

Visit us at www.esab.com

Excellence in wind tower welding

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