Converting to RMD
Sigma Thermal designs, engineers and fabricates process heating systems for a wide range of industries — from oil and gas and power companies to food processing and biomass. If an application uses heat, Sigma Thermal can provide a product that helps. The Marietta, Georgia-based company has customers around the world and products on six continents, including thermal oil and thermal fluid heating systems, indirect process bath heaters, and electric process heaters.
In a highly competitive market, the company has differentiated itself by taking on large and difficult jobs or jobs with high specifications. The company also sees new welding technologies and processes as investments that help them stay ahead in the industry — and meet customer demands. One recent Sigma Thermal product was built for the oil fields in Alaska’s North Slope. The completed unit weighed 200,000 pounds and was shipped from Sigma’s headquarters on a 173-foot truck.
“We’re very good at custom engineering and fabrication,” says Tony Driskill, Sigma Thermal’s general manager. “If you want something custom engineered to exactly what you want, nobody’s going to beat us.”
Sigma typically works on seven or eight projects of varying sizes at any given time. Manufacturing time on an average project runs 10 to 12 weeks, though some larger projects can take up to six months. Being nimble to meet customer timelines is important, but nothing trumps the importance of quality. In looking for products and technologies that can help the company increase productivity and efficiency in the manufacturing operation, it’s critical to choose solutions that keep quality at the forefront.
The addition of Miller® PipeWorx 400 multiprocess welding systems in the shop — and the conversion to the Regulated Metal Deposition (RMD®) modified short-circuit MIG process in some welding applications — increased productivity by 50 percent or more for Sigma Thermal on many jobs. Sigma Thermal leaders know 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,” Driskill says. “We can cut hours off, which means we can cut price down and sell more,”
A multiprocess solution with a fast ROI
In its manufacturing operation, Sigma Thermal produces a diverse lineup of products using many welding processes, including solid wire MIG, MIG with flux-cored wire, pulsed MIG, RMD, TIG and submerged arc. Of the company’s 140 employees, about 40 are welders.
“Flexibility and mobility are critical to us,” Driskill says. “You may go from building something the size of your desk to something the size of a freight train within a week, 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) D1.1 certification for structural work. Depending on the customer and the project, specifications and quality testing can be intense.
Sigma Thermal works with welding supplier nexAir to ensure the shop is using the most productive technologies and processes for its applications. As a partner, nexAir assists Sigma Thermal in selecting equipment that will maximize efficiency, productivity and quality — so the shop stays ahead of the curve.
“We know our customers work hard, and we want to help them succeed,” says Jack Bannister, nexAir territory manager. “We help them stay on the cutting edge of the industry with the right equipment and technology, along with our expertise and support.”
Keeping the quality requirements in mind, Sigma Thermal tested a PipeWorx 400 system from Miller Electric Mfg. LLC. The shop 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,” Driskill says.
During the day of testing, one welder used an RMD root pass and pulsed MIG fill and cap passes to complete nine 8-inch pipe welds with the PipeWorx system — more than double the productivity of another welder who completed four 8-inch 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,” Driskill says. “Right then, we were sold.”
Improving productivity 50 percent or more
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 Sigma Thermal 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 Sigma Thermal 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 you, we can even cut that time to about 40 hours,” says Philip Bates, a welder with Sigma Thermal. “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.
“It’s the top of the line,” Bates says. “I doubled my speed. It’s that productive.”
It’s not only the faster deposition rates that improve productivity for Sigma Thermal. 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. I have to do so many different processes within one day’s time, and it just makes it easy to push a button and switch over,” says Sandy Hansen, a Sigma Thermal welder. “It’s a really good time-saver, much more time efficient, and it’s still a high-quality weld, even with the high efficiency.”
Setup time is also greatly reduced with the system, because operators have SIM cards with their preprogrammed settings that can be inserted into any PipeWorx machine.
“Five minutes here, 10 minutes there doesn’t seem long today, but at the end of the year it adds up,” Bates says. “It shows how much time you’re actually spending just setting your machine up.”
No concerns about quality
In addition to being a productive process with a high deposition rate, 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, a Sigma Thermal 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 for Sigma Thermal, and it helps them complete projects faster for customers.
“We track X-ray failures very closely, so I know the PipeWorx is a dependable piece of equipment,” Driskill says. “Our failure rate on X-rays is close to zero.”
Ease of use and faster training
Welders with experience benefit from the system, thanks to improved productivity and efficiency. Because the system and the RMD process is user friendly, it also helps Sigma Thermal 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,” Bates says. “As far as new welders coming in, I would say we’re getting 30 to 50 percent less failures on RMD than you are on TIG. Between that and the time it takes to teach someone how to use it, hands down it’s made us a very competitive company.”
Conversion delivers a competitive advantage
For Sigma Thermal, staying ahead in a competitive industry means looking for solutions to improve productivity and efficiency, while always placing quality first.
“Technology has changed, and the wire processes have come so far,” Driskill says “If you’re not using this technology for welding pipe, you’re doing it wrong. It’s going to pay for itself.”
Equipment and processes that help welders produce high-quality welds faster — and that ultimately help make the company better — are investments worth making for Sigma Thermal.
“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,” Driskill says. “Business is a competition and technology is a tool. You have to use every tool at your disposal to beat your competition.”