Stability and accuracy
May 1st 2007

ESAB's A2 Multitrac submerged arc welding package has brought a number of benefits to William Hare in the fabrication of structure for the crossrail project

In the UK three ESAB A2 Multitrac submerged arc welding packages have been supplied to William Hare for the fabrication of substantial structures destined for the Paddington section of London's Crossrail project. This investment represents a significant increase in the production capacity at William Hare's Bury facility, and the intention is that the equipment will continue to be used on future contracts after the completion of the Crossrail structures.

William Hare is one of the UK's premier structural steelwork contractors, serving the global market for civil and other structural steelwork.

William Hare has made extensive use of ESAB welding machines before, as Rohan Brandwood, the Welding Engineer, explains: "We have always found ESAB equipment to be both tough and capable of producing high-quality welds; the service and support is also second to none. When the need arose for more sub-arc machines, we had no hesitation in contacting ESAB. Although we did look at other suppliers, we felt that the carriage on the A2 Multitrac was far superior to anything else that was available and, when we visited Waltham Cross to see the machine demonstrated, we particularly liked the four-wheel-drive arrangement that gives stability and accuracy." ESAB's A2 Multitrac is a four-wheel-drive tractor unit capable of being used for submerged arc welding (SAW) or gas metal arc welding (GMAW) in a single- or twin-wire configuration. The single-wire SAW models purchased by William Hare are equipped with ESAB's A2/A6 process controllers type PEH and they are connected to ESAB LAF 1000 power sources. In addition, the tractor units are fitted with flux recovery systems.

One of the advantages of the A2 Multitrac is that although it is extremely robust, it is easily portable so that it can be quickly moved from one welding station to the next.

Once in place it can be rapidly set up and, if required, welding parameters can be recalled from the PEH controller's memory (up to ten sets can be stored). The controller's digital display and pushbutton interface are easy to use, yet rugged enough to survive in heavy-duty fabrication shops.

Similarly, the LAF 1000 power source, which is rated at 1000A at a 60% duty cycle (or 800A at a 100% duty cycle), is robust and user-friendly. The continuously variable voltage control permits very precise adjustments of welding parameters.

So far the new equipment has been used to produce butt and fillet welds on plate girders. Butt welds up to 30mm thick have been produced, as well as multi-pass fillet welds in structures up to 19m long.

Samples of narrow-gap butt welding with an included angle of just 10° have also been produced in sections up to 80mm thick, as welds of this type will be required as part of the Crossrail contract.

While some welding has been performed using solid wires, William Hare is also making use of cored wire submerged arc welding for many joints. In all cases, however, ESAB consumables are being utilised. Where required, technical support and advice is being provided by ESAB's experienced welding experts to help William Hare optimise the welding process, maximise the operational efficiency and ensure the consistent high quality necessary for structural steelwork.

"The new A2 Multitracs have only been in operation for a few weeks, but we are already impressed with their capability and pleased with the investment we have made," comments Rohan Brandwood.

"This equipment will make a major contribution to our output and is therefore very important to the company's business." To request technical datasheets for the A2 Multitrac, A2/A6 process controller type PEH, and the LAF 1000 power sources, call enquire below:

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