Switching to wire processes
Understanding the best practices for welding in-service pipelines can help optimize results. But companies should also consider more holistic changes to processes and equipment that can also save time and money while maintaining high weld quality.
It’s becoming more common — and even a mandate on some jobsites — for contractors to switch from traditional stick welding to wire welding processes for new pipeline construction, though the process change has been slower to take hold for in-service repair work since many of those jobs are one-off projects.
The move away from cellulosic stick in pipeline welding is driven by the process’s higher risk of hydrogen cracking, which results in more time and money spent on rework and repair. Ri’chard reports laying a lot of major pipelines with automated welders that use wire for every pass.
“I haven’t used wire welding for in-service repair yet, but I think it’s coming,” Ri’chard says. “Wire processes help promote stronger welds through higher tensile strength than what’s achieved with cellulosic stick welding.”
Paul Spielbauer, weld engineering manager with Lake Superior Consulting in Duluth, Minnesota, sees more contractors and holding companies making the switch from cellulosic stick to wire processes for new construction of transmission and distribution pipeline.
“Absolutely there is a trend toward adopting more and more wire-feed processes, whether it’s semi-automatic or mechanized,” says Spielbauer, who advises pipeline holding companies on welding best practices and oversees procedure qualifications in the field.
The move is not solely about increasing productivity. It’s also about weld quality.
“It's an increased push from the pipeline owning companies to move toward better welding practices that reduce hydrogen in the weld during construction,” he says. “So obviously moving to a wire process allows that to happen for the contractor, and then simultaneously gives them the benefit of improved construction speeds.”
In addition to high weld quality and productivity benefits, wire processes can also help reduce operator fatigue by reducing the number of passes required, and they allow for easier implementation of higher strength consumables, which is a growing trend in the industry.
Enbridge sees success with a switch
Industry leader Enbridge, Inc., recently made a change to the welding processes used for pipeline repairs and tie-ins on several of its sites, switching from traditional stick welding to advanced wire processes. Productivity improved significantly — with weld time reduced by 40% — allowing Enbridge to meet timelines and complete more projects while maintaining its high safety standards.
In-service repair welding is a critical part of the operation across Enbridge’s entire U.S. system of pipelines — with the company using up to 300 welders in a given construction season.
Wire welding processes were not traditionally used in the field, but the company believed a process change could improve productivity to meet demanding timelines while also meeting the low hydrogen requirements that are critical for pipeline welding.
The company converted from stick welding to advanced wire processes for some of its pipeline repair and tie-ins, using pulsed GMAW and Regulated Metal Deposition (RMD®) processes with XMT® 350 FieldPro™ power sources and Smart Feeders from Miller Electric Mfg. LLC.
With RMD, a modified short-circuit GMAW process, the welding system anticipates and controls the short circuit, then reduces the welding current to create a consistent metal transfer. Precisely controlled metal transfer provides uniform droplet deposition, making it easier for the operator to control the puddle. Advanced welding processes, such as pulsed GMAW or modified short-circuit GMAW, are also more forgiving to variations in stickout and result in a calm stable arc, which makes it easier to control.
Enbridge leaders said the addition of wire welding to the company’s maintenance program resulted in timelines becoming more flexible and arc time decreasing, while still meeting safety standards. That efficiency allowed the company to conduct more projects in a given year.
They also stressed that the productivity gains happened without an impact on weld quality.
Optimizing in-service welds
Welding in-service pipelines can present different challenges compared to other types of pipe welding. It’s important to understand the best practices that can help optimize results for in-service repairs.
As the pipeline industry in general moves toward using wire welding processes more frequently, this is a change that can also offer benefits for in-service welding.
A change in welding processes and investing in new technologies helps companies like Enbridge boost productivity and efficiency — without sacrificing safety or quality on pipeline jobsites.