Flux-Cored Wire Improves Contractor’s Productivity, Meets Strict Seismic Requirements
This article is published in memoriam of Tom Campbell, who passed away unexpectedly only a week after its completion. In addition to being the owner of Campbell's Welding & Machinery, Inc., Tom was a dedicated husband to his devoted wife, Keri and a committed father to his beloved daughter, Jessica. He was also an avid horseman and animal rescue advocate.
Structural steel erection is serious business. Tom Campbell should know. He's been taking on major projects across the East Coast for 23-plus years now. Like many welding operators, Campbell has relied on some of the same, tried-and-true technology to get the job done, particularly stick welding. This process has not only helped him and the other welding operators in his company-Campbell's Welding & Machinery, Inc. of Landing, NJ-meet strict AWS code requirements for their projects, but it's also a process that's familiar. As Campbell says, he and his welders know it.
|The Fabshield self-shielded flux-cored wire offers
excellent out-of- position welding capabilities, as
shown in this overhead weld pass.
Yet, in October 2008 when Campbell was approached to take on a large structural steel project at William Paterson University in Wayne, NJ, he quickly realized that it wasn't going to be any ordinary project-nor could he rely on any ordinary welding technology. The reason: strict new seismic requirements set forth by the American Welding Society (AWS). These new requirements affected all the field-welded moment connections that were specified for the project, each of which would be subject to rigorous post-weld testing.
However, with the help of his local welding supply distributor, Bob Wollsowki of GTS-Welco (A Praxiar Joint Venture), Campbell found the right solution to help him tackle the job: Hobart Brothers new Hobart® Fabshield® XLR-8TM self-shielded flux-cored wire. After some training with Wollsowski and Hobart Brothers, Campbell says that he's certain he found "a wire that is heads and tails better than any other wire [he's] used, in the field or the shop. Hands down."
In fact, since completing the project at William Patterson University, Campbell has relied almost exclusively on Fabshield XLR-8 flux-cored wire for all of his company's projects.
No two jobs that Campbell and his team undertake are the same, but some are decidedly larger than others. The William Patterson University project that led to their discovery of Fabshield XLR-8 was just such one.
"It was a 700-ton structural steel project and took approximately twelve weeks to finish," he says. "For a small-time, open shop contractor like me, that's a pretty good-sized job. And to do it start to finish in that amount of time is pretty respectable as well."
Campbell had a team of approximately a dozen to fourteen welding operators on site daily to accomplish the task, about half of whom he said are certified. Campbell employs around 20 employees total, so having that much of his workforce on a single job attests to his commitment not only to getting it done well, but also on time.
In addition to standard fillet welds, this project largely required field-welded moment frame connections-each of which could meet the strict AWS D1.8 Structural Welding Code for seismic load resistance and Demand Critical Welds. Field-welded moment connections are full penetration welds placed at the beam flanges. To achieve this full penetration, one or both pieces of the structure are beveled (depending on the joint) and the welder places a backer bar under the joint to protect the root pass from oxygen infiltration and subsequent weld contamination. The material on this particular project ranged up to two and one-half inches thick.
Campbell and his team had previously used 1/8- and 5/32-inch AWS 7018 stick electrodes for such welds and for standard fillet welds, in addition to employing various AWS E70T-7 and AWS E71T-11 self-shielded flux-cored wires. The downside for using such filler metals on this project? They wouldn't meet the seismic requirements, nor could they get the job done quickly enough.
"If we used one of our previous wires, it would take us three passes for a 5/16-inch fillet weld. For a 3/8-inch one, it could possibly take up to four passes," explains Campbell.
For the strict timeframe of the William Patterson project, the team needed a wire that could create welds in as little as one or two passes. Fortunately, that's exactly what they got when Wollsowki stepped in with Fabshield XLR-8. Still, the transition to the new wire wasn't without its own challenges.
Like other AWS E71T-8 wires, Fabshield XLR-8 requires a CV (constant voltage) power source, which Campbell obtained in his new Miller Electric XMT® 304 CC/CV multi-process inverters. Campbell also purchased a new diesel-driven CV welding generator and changed to Bernard DurafluxTM self-shielded welding guns. These purchases, while necessary to obtain proper welding performance with the wire, also posed obstacles that he admits were tedious for him and the other welding operators.
"It was very frustrating in the beginning. Changing guns, changing wire and changing power supplies-you're basically taking three out of four tools from a man's hand, giving him something he's never used before and expecting him to do the same quality job. It was difficult," shares Campbell. "Fortunately, we had such good support and training from GTS-Welco and Hobart Brothers. Otherwise, I probably would have pulled the plug on the wire and tried something different," he adds.
That training included, among other factors: using proper gun angles for each welding position, setting the correct welding parameters and employing the various recommended welding techniques-dragging or weaving-to achieve quality welds.
Hobart Brothers' engineers specifically designed Fabshield XLR-8 wire for seismic structural steel projects like those Campbell and other contractors frequently encounter. The wire features an additional D-designation under AWS A5.20/A5.20M:2005 specifications, meaning that it meets strength and toughness requirements, at both high and low heat inputs, for demand critical welds-in particular, those for seismic moment frame connections. Specifically, it offers 58 ksi minimum yield strength and 70 ksi minimum tensile strength, with 22 percent minimum elongation at 2 inches, and provides an impact value of 40 ft•lbs at 70 degrees F. It also provides these properties in all-positions, even when making challenging vertical-up welds, and it creates a low hydrogen weld deposit (less than 8 mL/100g or H8 designation) that provides increased resistance to cracking.
So what benefits do those features translate to for someone like Campbell?
First and foremost, these properties ensure that the welds Campbell and his team make meet the quality requirements for seismic conditions. In fact, the welds (when completed properly) are of X-ray quality. In addition to the specific chemical composition of the wire, this quality is due in part to the fact that Fabshield XLR-8 wire resists the slag inclusions common to other AWS E71T-8 wires, especially when welding vertical-up.
"More often than not," explains Campbell, "the slag will peel off by the time we've hit the end of the weld. If we're welding a 12-inch long vertical fillet weld, say 3/8-inch wide-by the time we get to the top, the bottom half of the slag has fallen right off."
|This photo shows an example of the high-quality
welds Campbell and his team were able to create
with the Fabshield XLR-8 wire.
This attribute not only prevents slag from entering the weld pool and compromising quality, but it also saves Campbell and his team time for post-weld cleaning such as scraping or grinding.
Just as importantly, the wire helps them get the job done faster. According to the recommendations provided by Hobart Brothers, Campbell and his welding operators weld their 5/64-inch diameter Fabshield XLR-8 wire at 22V/255A and use a wire feed speed of approximately 160 IPM (inches per minute). Combined, these parameters provide significant travel speed and deposition rate improvements over both Campbell's previous wires, and especially, the stick electrodes he used before.
In fact, testing by Hobart Brothers' engineers shows that a 5/64 Fabshield XLR-8 wire, like Campbell uses can yield 181 percent and 87 percent increases in deposition rates in the vertical up and overhead positions compared, respectively, to the 1/8- and 5/32-inch diameter stick electrodes he used before.
This increase in deposition rate, in addition to the weld quality and ultimate ease of use after training, was the final selling point for Campbell-and the reason he and his team now use Fabshield XLR-8 almost exclusively for their steel erection projects.
"To anybody who is attempting to make a living in the steel erection business, I would encourage them to contact their distributor for an XLR-8 sample and ask for training on how to use it," says Campbell. " If they do that, they'll never go back."
So what's the bottom line? According to Campbell, the Fabshield XLR-8 wire has helped the company increase productivity between 20 to 25 percent compared to the welding wires and stick electrodes he previously used. The bulk of that increase has resulted not only from faster travel speeds and higher deposition rates, but also from the time Campbell and his welding operators save in clean up.
Generally speaking, Campbell's Welding takes on about five jobs yearly that are similar in size to that of the William Patterson project and often they will tackle two such ones simultaneously. With Fabshield XLR-8 wire, Campbell explains, it's been easier than ever to complete the jobs with the quality they want in the timeframe they need.
"This product single-handedly changed our quality, output and production. It's a huge technological leap as far as I'm concerned-one that's almost too good to be true," explains Campbell. "And for somebody who has done something a certain way for 23 years and has had this wire make such a big impact-well, you couldn't pry it out of my hands now."