South African supplier of welding consumables and equipment ESAB Africa Welding & Cutting, which is the sub-Saharan Africa subsidiary of UK-based industrial company ESAB Holdings, donated more than R200 000 in welding consumables to the institute for training purposes last month.

Further, ESAB Africa Welding & Cutting, which has been a corporate member of the Southern African Institute of Welding (SAIW) since 2009, sponsors various events hosted by the SAIW, including the International Institute of Welding conference, the SAIW Young Welder of the Year Competition and the SAIW’s yearly dinner, besides regularly sponsoring products and consumables.

ESAB Africa Welding & Cutting decided to become a member of the SAIW as it was a natural fit, owing to the similar objectives of the company and the institute.

“We are also at the forefront of major global welding innovations, owing to our ties to ESAB Global, which is one of the leading manufacturers of welding and cutting products, and we can, therefore, assist the SAIW in introducing new technology for the Southern African market,” says ESAB Africa Welding & Cutting MD Chris Eibl.

While ESAB Africa Welding & Cutting is not certified by the SAIW, several company employees have attended courses presented by the institute, with two employees currently completing their international welding training certificate. The course is International Institute of Welding-accredited and aimed at candidates wanting to pursue a career in welding.

A benefit of being a member of the SAIW is that the institute often refers enquiries for the supply of welding products and advanced welding solutions and technology to ESAB Africa Welding & Cutting.

Further, the company is investigating the use of the SAIW’s metallurgical testing laboratory, which was launched in July at the institute’s head office, in City West, Johannesburg, for mech- anical testing services such as impact, hardness, tensile and bend testing.

Turnkey Supply Project
ESAB Africa Welding & Cutting, through its broad-based black economic-empowerment channel partner, Xeon Gas & Welding, was awarded a contract in July by renewable-energy company DCD Wind Towers, a subsidiary of international manufacturing and engineering company DCD.

The contract entails supplying a turnkey solution, comprising cutting, welding, handling and rotating equipment, as well as consumables, to DCD Wind Tower’s R300-million factory, which is under construction in the Coega industrial development zone, outside Port Elizabeth, in the Eastern Cape.

Engineering News reported in May that the wind tower manufacturing facility, which was being established to support the localisation of the wind turbine industry in South Africa, would produce its first units by November and reach full production by February or March next year.

However, DCD Wind Towers MD Rob King told Engineering News at the official sod-turning ceremony of the factory that the facility’s initial capacity of about 110 tubular steel towers a year would be increased to about 180 towers a year should the market be sustainable enough to justify an additional investment.

“What makes this contract and project unique is that it is arguably the largest-ever integrated welding and cutting installation in sub-Saharan Africa,” says Eibl.

“Further, the towers will be manufactured using ESAB Africa Welding & Cutting’s unique growing line concept, as opposed to traditional methods.”

As the factory will not use cranes for manipulation during the welding of the wind tower sections, roller beds, with built-in manipulators, will instead be used to ‘grow’ the line, he explains.

“A set of hydraulically driven transferring rollers lift the wind tower structure clear of the rotating rollers and shuffle it onto a roller bed further up the line, where a new piece of the structure is then loaded and welded, before the whole weldment is moved along the production line a further 3 m, resulting in a complete tower section of up to 38 m in length on a single growing line,” highlights Eibl.

Meanwhile, he says ESAB Africa Welding & Cutting will supply and integrate all the equipment and consumables necessary to fabricate the wind towers, such as cutting machines, manipulators, columns and booms, welding equipment and consumables.

How It Works
At the start of the process, two ESAB Suprarex HD 6000 computer numerically controlled flame cutting machines, each with dimensions of 6 m wide and 38 m long, featuring triple-torch cutting heads, will simul- taneously cut I-, Y- and X-weld preparations and a perfect landing nose in a single operation.

Once profiled, the plate is rolled with equipment, not supplied by ESAB, to form the cir- cular structure and the longitudinal seam is then closed at the first welding station.

DCD has decided to opt for single-wire submerged arc welding to start with; however, tandem, twin-tandem and even integrated cold-electrode options are available should DCD need to increase throughput at a later stage, says Eibl.

The root welds are performed from the inside at ground level. The structure is then rotated 180° to place the seam on top.

Eibl explains that the root weld is undertaken using the ESAB patent-pending Aristo 1000 alternating current/direct current submerged arc power sources, with no back gouging, as punch-through is used and the seam is filled and capped.

The completed 3-m-long structure is then moved along onto the next roller bed where a circular seam-welding system joins it to the previously completed section.

Eibl notes that while differ-ent welding procedures and parameters are required for each seam, the ESAB PEK-branded controller can store up to 255 preprogrammed procedures, enabling many different procedures to be run.

Meanwhile, as the tower’s length increases, increasingly longer lengths have to be rotated. To do this, two parallel rows of roller beds with synchronised speed control and load capacities from 30 t to 90 t stretch the full length of the line rotating the tower.

Once a tower is completed on one of the four growing lines at the manufacturing facility, it is transferred across to a parallel line, which transports the tower back to the start of the line, where it is shot-blasted and painted.