Process Heating Systems Builder Boosts Welding Productivity by 50 Percent

Sigma Thermal (Marietta, GA) designs, engineers and fabricates thermal oil and thermal fluid heating systems, indirect process bath heaters and electric process heaters for a wide range of process heating applications: from oil and gas operations and power generation to food processing and biomass. They serve customers around the world and have systems installed on six continents. In this highly competitive market, they have differentiated themselves by taking on large and difficult jobs, or others with high specifications. They invest in new welding technologies and processes to stay ahead of competitors and meet customer demands. One recent system they built for the oil fields in Alaska’s North Slope involved a completed unit that weighed 200,000 lb and was shipped from their Marietta headquarters on a 173 ft truck.

“We’re very good at custom engineering and fabrication,” says Tony Driskill, the general manager of Sigma Thermal. “If you want something custom engineered to exactly what you want, nobody’s going to beat us.” The shop typically works on seven or eight projects of varying sizes at any given time. Manufacturing cycles on an average project run from 10 weeks to 12 weeks, though some larger jobs can take up to six months. Being nimble to meet customer timelines is important, but nothing trumps the importance of quality. In looking for equipment and technologies that can help them increase their manufacturing productivity and efficiency, their shop believes it is critical to choose systems that keep quality at the forefront: their addition of PipeWorx 400 multiprocess welding systems from Miller® Electric Mfg. LLC (Appleton, WI), along with their conversion to the Regulated Metal Deposition (RMD®) modified short-circuit MIG process in some welding applications, increased their productivity by 50 percent or more on many jobs.

Sigma Thermal knows that converting to the most productive process is a must, otherwise an operation can get left behind. “I don’t sell equipment; I sell hours. So anything I can do to reduce the number of hours that I put into a piece of equipment, that’s productive to me,” notes Driskill. “We can cut hours off, which means we can cut price down and sell more.”

MULTIPROCESSING WITH FAST ROI
In their manufacturing operation, the shop produces a diverse lineup of process heating systems using many welding processes, including solid wire MIG, MIG with flux-cored wire, pulsed MIG, RMD, TIG and submerged arc. Of their 140 employees, about 40 are welders. “Flexibility and mobility are critical to us,” states Driskill. “Within a week, you may go from building something the size of your desk to something the size of a freight train, and that requires a completely different set of tools.” The shop is ASME certified, with U, S and R stamps for pipe work, and American Welding Society (AWS; Miami, FL) D1.1 certification for structural work. Depending on the customer and the project, specifications and quality testing can be intense.

Welding supplier nexAir LLC (Memphis, TN) partners with the shop to ensure that they are using the most productive technologies and processes for their applications. They assist in selecting equipment that will maximize efficiency, productivity and quality so that the shop stays ahead of the curve. “We know our customers work hard, and we want to help them succeed,” says Jack Bannister, a territory manager at nexAir. “We help them stay on the cutting edge of the industry with the right technology, along with our expertise and support.” Keeping these quality requirements in mind, when the shop tested a PipeWorx 400 system, they already had dozens of XMT® multiprocess welders and a SubArc Digital Series power source from Miller. “Anything that reduces the time between purchase order and delivery, we’re interested,” adds Driskill.

During the day of testing, one welder used an RMD root pass and pulsed MIG fill and cap passes to complete nine 8 in pipe welds with the PipeWorx system – more than double the productivity of another welder who completed four 8 in pipe welds using TIG welding. Even though the welder had only been using the system and the RMD process for one day, the welds passed X-ray inspection with no defects. “The RMD was better than 50 percent faster, which is very impressive, and the quality is just as good,” recalls Driskill. “We were sold right then.”

Using the RMD process for the root pass and pulsed MIG for remaining passes offers faster travel speeds and deposition rates compared to TIG welding all passes as the shop had been doing for pipe welds. The RMD technology improves deposition rates so much in the root pass that it eliminates the need for a second hot pass, saving time and money with every weld. A pump skid welding project that took about 120 hours for welders to complete using TIG was reduced to about 60 hours using RMD and pulsed MIG. “And depending on who is running the RMD and how much prep is done in front of them, we can even cut that time to about 40 hours,” explains Philip Bates, a welder in the shop. “As far as productivity, in my 20 years of welding, I haven’t seen anything to increase your speed that fast.”

Sigma Thermal welders can earn bonuses by completing projects faster than the hours estimated for a job. “This system the top of the line,” adds Bates. “I doubled my speed. It’s that productive.” Faster deposition rates that improve productivity are not the only benefit. The fast process changeover on the PipeWorx system also helps operators save time: welders can switch from RMD to pulsed MIG with the push of a button, and they eliminate the time and hassle of swapping cables and making parameter changes. “The PipeWorx 400 has made my day-to-day work so much easier,” says Sandy Hansen, another welder. “I have to do so many different processes in one day’s time, and this just makes it easy to push a button and switch over. It’s a really good time-saver, much more time efficient, and it still produces a high quality weld, even with the high efficiency.”

Setup time is also greatly reduced with this system because operators have SIM cards with their pre-programmed settings that can be inserted into any PipeWorx machine. “Five minutes here, ten minutes there doesn’t seem long today, but at the end of the year it adds up,” notes Bates. “It shows how much time you’re actually spending just setting your machine up.”

RMD also provides clean penetration, a stable arc and easier puddle control. The process is more forgiving to variations in stickout and contact tip distance to the puddle. The modified short-circuit MIG process precisely controls metal transfer for uniform droplet deposition. “When you’re doing the root with RMD, you have an arc length and you can adjust that to really dial it in with no spatter,” says Daniel Sutton, another welder. “I haven’t had an X-ray failure yet. I’m very confident that it’s the type of quality that I need to produce.” Ensuring a low rate of weld defects and rework saves time and money and helps the shop complete projects faster for customers. “We track X-ray failures very closely, so I know the PipeWorx is a dependable piece of equipment,” says Driskill. “Our failure rate on X-rays is close to zero.”

Experienced welders benefit from this system thanks to improved productivity and efficiency, and because it and the RMD process are user friendly, it also helps the shop train welders with less experience faster: the optimized arc performance for pipe welding, excellent deposition rate and forgiving RMD process result in easier and faster training of welders. “It’s a real consistent bead, so it makes it very user friendly,” explains Bates. “As far as new welders coming in, I would say we’re getting 30 percent to 50 percent less failures on RMD than on TIG. Between that and the time it takes to teach someone how to use this process, it has made us a very competitive company hands down.”

“Technology has changed and the wire processes have come so far,” states Driskill. “If you’re not using this technology for welding pipe, you’re doing it wrong. It’s going to pay for itself. When you’re cutting your weld time down by 50 percent, the ROI is super quick. If you’re not going to take advantage of that, you’re going to get left behind. Business is a competition and technology is a tool. You have to use every tool at your disposal to beat your competition.”

Sigma Thermal, 4875 Deen Road, Marietta, GA 30066, 678-616-2820,
info@sigmathermal.com, www.sigmathermal.com.

Miller Electric Manufacturing LLC, 1635 West Spencer Street, PO Box 1079, Appleton, WI 54912-1079, 920-734-9821, www.millerwelds.com.

nexAir LLC, 1350 Concourse Avenue, Suite 103, Memphis, TN, 38104, 901-396-5050, Fax: 901-396-5020, www.nexair.com.