Not in left field

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by Kip Hanson

Today’s portable welding equipment is lightweight, fast, and cost-effective


Bridge spans, oil and gas pipelines, seagoing vessels–unless you have a shop floor the size of West Edmonton Mall, and more height beneath the hook than Toronto’s First Canadian Place, it’s impossible to weld massive structures like these indoors. Instead, most shops fabricate large products in sections and transport them onsite for final fitting and welding. And in the case of pipelines, the majority of work is done in the field, where environmental conditions take a harsh toll on people and equipment alike.

Wind can be a problem with portable welding systems, says Dave Perkins of ESAB. For TIG and MIG welding, you may need to switch to self-shielding wire or gasless stick electrodes if it's windy.Give Jenny a call
Whether it’s stick, TIG, MIG, or gouging, power is one of the primary considerations for those who must do their welding afield. Not only does the equipment itself require a reliable source of clean, predictable electricity, but the grinders, work lights, and compressors needed to support welding activities are also prodigious power consumers. So when the nearest municipal power source is 50 km away, only a generator or engine-driven welder will do, which use an internal combustion engine powered by diesel fuel, gas, or liquefied propane to operate.

Welding equipment manufacturers offer a wide selection of these devices. Portable self-contained welding machines light enough to be carried by a pair of workers are suitable for repair work and small job sites, while towable units with onboard air compressors generate sufficient power for multiple welders and auxiliary equipment.

Greg Coleman, marketing communications specialist for The Lincoln Electric Company, Cleveland, OH, says experienced cross-country pipeline welders often prefer the arc generated by traditional DC generators, but adds that many of the company’s newest models add more multi-process capability as welders make the transition from stick to wire welding. “These use an alternate technology that makes it much easier to obtain multi-process and multi-mode welding capability, and are designed for those performing TIG and even pulse mode welding. This platform also is capable of generating over 10,000 watts of single-phase or three- phase continuous AC generator power.”

Welding performance may suffer if a generator isn't designed for portable welding, says Joe Ryan of Miller Electric.That’s a lot of juice coming from a unit not much larger than a refrigerator. If more is needed, Coleman says the best bet may be an inverter-based welder, where multiple units are plugged into a rack or tack rig driven by a single dedicated generator. This not only allows multiple operators to work simultaneously, but is less expensive in the long run than buying multiple self-contained welding units.

Keep it clean
Engine-drive welders and generators definitely have their place, but the power coming from older industrial generators might not be all it’s cracked up to be. Marketing segment manager Joe Ryan of Miller Electric Mfg. Co., Appleton, WI, says arc performance may suffer unless the generator is specifically designed for welding. “The output from portable units compared to what comes out of the wall is inherently different. Many of the newer welding technologies help correct issues with arc performance and power stability, but some companies–especially on very large jobs–still opt to have electricity brought out to the site instead of running diesels all the time.”

A hard-wired rack mount
system is a great way to simplify job site mobilization and reduce the number of trips when getting set up, Ryan says. In the case of a multi-system rack, a crane can be used to lift it into position, and the electrician only has to wire up a single rack instead of six or eight individual machines. Not only is this a big time saver, but operators, now free of the power-generating burden, can plug a suitcase-sized machine weighing less than 50 lb. (22 kilos) into a power source and carry it to the work area.

Admittedly, this creates a different challenge: how to control the current, frequency, and other settings when working 60 meters from the power supply? “We offer remote control capabilities on many of our machines,” Ryan says. “These let you communicate back to the power source to adjust weld output and change welding parameters remotely. It’s been very well received.”

The "bug," a semi robotic portable welding system co-developed by Fronius and RMS Welding Systems, Nisku, AB.For those concerned about power drop over long cable lengths with TIG and stick welding, 80 per cent of oil and gas work, according to Ryan, don’t be. Since the machine settings are controlled at the weld joint, it’s easy to identify and compensate for any distance-related problems with amperage or voltage. And for MIG welders, Miller offers its Smart Feeder, which automatically adjusts weld parameters based on feedback from the weld nozzle.

“TIG and stick aren’t going away any time soon, but an increasing number of companies are looking at wire processes for improved productivity in the field,” Ryan says. “There are generally fewer starts and stops with MIG, and therefore less potential for quality issues.”

The four seasons
ESAB Welding and Cutting Products, Florence, SC, is another company with an eye towards mobile welding, offering a number of lightweight machine models as well as automated systems geared towards ship building and offshore use. When asked about portable power generation, Dave Perkins, product technical manager of arc industrial equipment for North America seemed unconcerned. “The electronics available today are night and day compared to five years ago,” he says. “Modern generators, no matter who makes them, put out nice smooth power. It’s nowhere near the problem it used to be.”

What Perkins is concerned with is the weather. Most indoor fab shops are temperature controlled with little chance of precipitation. Field welders should be so lucky. Whether welding a pipe in the oil fields of northern Alberta or laying a bead on a beam 30 stories up, wind, rain and cold are a welder’s worst enemy. Induction heaters can be used to preheat weld joints, and tents are often erected over stationary work zones to keep out the rain. When the wind begins to blow, however, it often spells trouble at the welding site.

“Wind can have a big effect on your weld,” Perkins says. “TIG and MIG both require shielding gas to operate, so you may need to switch to self-shielding wire or gasless stick electrodes if it’s windy. These have the shielding gas built in, and are designed specifically for outdoor use. The performance isn’t quite as good, the consumable costs are higher, and you’re a bit limited on what you can weld, but it’s often the best option for adverse weather conditions.”

Of bugs and backpacks
Ed Molloy, Alberta area sales manager for the Perfect Welding division of Fronius Canada Ltd., says the company makes a portable welding unit that weighs less than his wife’s purse. “We offer the world’s only lithium ion-powered stick welder, the AccuPocket. It weighs 43 lb. (19.5 kg), and with an average output of 140 A, can typically weld up to eight 3 mm. (1/8 in. ) electrodes on a single battery charge. It also operate continuously in hybrid mode, drawing power from a 110 V grid connection or generator.”

Molloy says a welder this small is designed to go places other equipment can’t. “With the oil refinery work in Alberta, construction companies have decided it’s easiest to fabricate refineries in small pieces called ‘modules’ and ship them north for assembly in the field. Modules are usually 14 by 60 ft blocks (4.26 x 18.29 m) and are comprised of metal framing, piperack, and electrical instrumentation. Sometimes they need to weld brackets and other hardware to the modules. It’s easy to send a welder up in a bucket with an AccuPocket, without worrying about running cables or hoses.”

At the other end of the application spectrum sits a semi-robotic, portable system called a ‘bug,’ used for welding pipe seams. The bug carries four Fronius GMAW arctic pipe torches, each with its own generator, and clamps to the outside of large bore pipe to weld the fill and cap. The welding takes place in a shack, which is transported from weld joint to weld joint to protect the arc from the elements.

Molloy says Fronius can take only partial credit for the Bug’s merits, as the system was designed by one of its customers, RMS Welding Systems in Nisku, AB. “These guys are very technically savvy, and have developed something no one else has. It’s an amazing system. The incorporation of Fronius and RMS Systems’ technology results in quality, high speed weld joints.” SMT

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