The summer heat cooks the outside of the shack as high-powered torches cook the inside, where teams of welders join pipe ends for a big-inch pipeline that will carry crude oil across the North American landscape.
A pipeline is only as strong as its weakest joint. A number of risks threaten the integrity of the welded ends of each length of pipe. The terrain. The environment. The temperature. The metallurgical qualities of the pipe. The speed of the operation. The shortage of people who can do the job. These are all potential pitfalls that could scuttle a strong weld and endanger the public and the surrounding environment.
Safeguarding these critical connections presents one of the key challenges in oil and gas infrastructure construction. Concerns over the quality of the final product and its relation to integrity management, as well as addressing labor shortages, drive welding engineers and equipment manufacturers to improve productivity and efficiency on the jobsite with safety as the No. 1 goal.
To maintain pipeline safety and integrity, industry standards and government regulations demand that welding procedures be prequalified in a shop, testing real-world conditions in a controlled setting to establish a methodology for use in the field. More and more, automated welding systems that can lock in the procedure provide a higher level of quality control for pipeline projects because they can repeat a dialed-in procedure on pipe joint after pipe joint.
“Automation is an area that is becoming more and more commonplace,” says David Freeman, global business segment director for Lincoln Electric’s pipeline industry division. “In the United States, it comes down to a regional decision based on the labor pool, contractors and regulators whether automation may be the preferred way to go. The challenge is whether or not to use traditional welding methods and at the same time maintain quality.”
Different regions have different labor pools, Freeman adds. Depending on the area, contractors or the local unions may have certain welding methods they prefer.
“That’s one of the biggest challenges we deal with,” he says. “The latest technology is bent toward fully automated welding systems, but that high technology is not always applied.”
However, the growing skilled labor shortage in the construction industry as whole in North America will require more contractors to consider a more automated solution. As baby boomers near retirement age, there are not enough younger workers to fill their ranks.
In addition, Freeman adds that increased pipe strength and concerns over integrity are driving the demand for industry regulators to limit the amount of acceptable variation in weld quality in pipeline systems.
“Going forward, the pipe materials themselves, with the increase in mechanical strength, will mandate the requirement for automation,” Freeman says. “Once qualification is done, it’s locked in. That’s not the case with a manual welding system. Variation in weld quality is no longer being accepted. That may be a challenge for the labor pool to accept, but it’s on its way.”
Even working with automated systems, the operators must be proficient on how the machine works, how to monitor seam tracking and how to make sure they’re getting a good weld. It’s not just set it and forget it.
Aging infrastructure also poses a challenge to pipeline welders, according to Scott Funderburk, director of welding engineering at CRC-Evans Pipeline International.
“The news headlines over the last five years have concerned older lines with questionable records keeping and quality of pipe manufacturing process,” Funderburk says. “We as an industry need to continue to bring that up. We have to bring home the importance of maintaining line integrity and how important it is to maintain public safety. People just recently woke up to oil in their backyards in Arkansas. I sure wouldn’t want to wake up to that.”
While Funderburk stresses the importance of building new pipelines to the highest safety standards, he also illustrates the challenge of repairing and maintaining older systems. Repair welds are typically the slowest and require the greatest amount of skill.
“Welding on existing pipelines, the vintage of the pipe is so important in relation to what the effect of the chemistry and the welding arc have on the base material,” he says. “You have to nail down the welding procedure required on in-service lines. For example, if you burn through a pipe, it could result in serious property damage and be very expensive.”
Funderburk believes it’s important that the industry point out the risk of repair welds. These repairs are often to fix hydrogen cracking in weld joints, but repairs can compound this very problem, exponentially increasing the risk of further hydrogen cracking.
Productivity vs. Quality
Contractors are under extreme pressure to deliver projects on time. The focus on productivity seems to fly in the face of ensuring quality and safety on a project, but our sources gave evidence to the contrary.
“The only way to have a very successful project is to realize that efficiency and integrity are not disparate and realize that the proper management of a project and the integrity of the welds is the best way to be successful and efficient,” says Olivier Jouffron, technical manager at Serimax. “A long time ago, some believed that in order to have quality you had to slow down, but I’m convinced that changing this mentality would be more beneficial to the industry.”
Welding procedures are typically qualified using criteria that are more stringent than those found in the field, Jouffron adds. The ability to repeat the same weld over and over again results in higher quality and fewer repairs.
“Controlling the parameter for every weld is the best way to keep a project running and be efficient on site,” says Jouffron, adding that safety, productivity and quality are the three most important components to ensure a successful project.
The good news is that science favors the welders, according to Chris Penniston, P.Eng., a welding and materials engineer for RMS Welding Systems. Speed actually improves the structural integrity of the weld.
“Thankfully, the metallurgy is on our side,” Penniston says. “For mechanized welding, it’s better not to have too much of a melt puddle. Faster weld travel speeds are favorable to the micro structure of the pipe joint.”
All the planning and analysis in advance of the welding operation helps bring together the ideals of high productivity and quality assurance on a project, Funderburk adds. Most pipelines today are designed with API’s engineered critical assessment (ECA) standard in mind, which establishes the acceptance criteria for a weld on a specific pipeline type, whether for crude oil and natural gas.
“All the work is done up front during welding qualification phase,” Funderburk says. “All acceptance criteria are used, and this is done just before construction. All welding procedures are done using the same heat and materials, and we try to reduce uncertainly and variability. A number of things come from this, like qualified weld procedures, the values for tensile strength of the weld material and allowable flaw size. Cracks are never allowed to be left in. The point is that efficiency, productivity, speed and quality are all tied together.”
Where a pipeline project takes place can determine a number of variables for the welding process. Climate and terrain can pose a number of challenges.
“You wouldn’t set the controls on your equipment the same way in winter in Canada as you would in summertime in Saudi Arabia,” Jouffron says. “You have to know how to prepare the equipment to protect it from frost or temperatures in a very hot environment.”
Cooler ambient temperatures present more opportunity for the weld to reach low inter-pass temperatures, potentially leading to high hardness, Penniston says. If the contractor expects the temperature to cool between welding passes or the project requires a number of passes performed at once, the procedure must be qualified using the full range of inter-pass temperatures that may be experienced in the field.
Using pipe with a heavier wall thickness requires additional welding passes, Penniston adds. More passes statistically allow for more opportunity to introduce discontinuity that could pose a risk.
In North America, terrain is not as big of a challenge as other parts of the world, Funderburk says. Temperature and keeping up with quality inspection on the jobsite are bigger issues.
“I see the welder as the first inspector,” he says. “They see it first. There has to be the training there to have the welder make the call if there appears to be a problem. The quality control mentality is part of the jobsite culture that is important to advance.”
A majority of the onsite inspection work is done by automated ultrasonic testing (AUT), which follows the welding crew on a pipeline project to ensure the quality of the pipe joint, Funderburk explains. The AUT team sometimes falls behind while the welding crew continues at a rate of 100 to 150 joints per day with a typical automatic welding system.
“What if there’s an issue? Now you have two miles worth of welding that is of suspect quality,” he says. “Those sections may need to be repaired or cut out and rewelded. It’s a challenge to keep the AUT team close.”
Automatic vs. Manual
Automated welding systems provide a host of benefits, in terms of efficiency and quality control, but there’s one big impediment to these machines taking over: cost. One of the major challenges for equipment manufacturers is to make automatic welding commercially viable for the contractors, Jouffron says. Smaller contractors tend to avoid the high cost of automated systems in favor of manual welding on their projects. The cost just isn’t worth it for some companies.
Although automated welding systems may be higher cost, Jouffron says the increased productivity of the process can help companies win more projects, keeping the equipment in the field longer and thus providing a higher payback
Furthermore, he adds that the repeatability of automatic welding increases efficiency, productivity and integrity. Consistent weld quality saves time compared to manual processes. “Having the welds all done the same way to the same parameters is beneficial to contractors,” he says.
While the cost can be a major hurdle for some contractors, Funderburk says there is a breakeven point where automatic systems make more sense.
“That tends to be 50 miles or greater and somewhere around 30-in. diameter and greater, in terms of productivity cost,” he says. “Some contractors may use automated systems on shorter projects, depending on the availability of welders or maybe for quality purposes.”
As technology continues to evolve, welding manufacturers are developing products and features that marry grunt work to the latest innovations.
Serimax is designing a software program to further improve integrity and efficiency, Jouffron says. By employing a data acquisition program, every type of weld needed is on file and each welding station can be networked together to improve efficiency and better monitor integrity. With this system, any essential variable can be recorded and tracked on a single report, from pipe number to AUT result of the final weld.
RMS has employed data acquisition to capture instantaneous weld parameter data at numerous locations around the pipe on its MOW II system since 2007. The company has also integrated Wi-Fi, for personnel to easily obtain data from networked shacks, and GPS, for tracking welds so that if a problem weld is identified, the entire parameter history can be obtained.
As mentioned earlier in this article, maintaining proper temperature during the welding process is a major priority. Miller Electric Mfg. Co. has developed an induction heating system to keep pipe up to welding temperature to avoid hydrogen cracking, according to Mike MacGillivray, global director for pipelines at ITW Welding, comprised of Miller and Hobart. He cites the pipeline construction in North America to service the shale plays and the need for higher strength pipe.
“From a welding point of view, the challenge of higher strength pipe is there is more possibility of hydrogen-induced cracking, which means traditional welding methods can’t be used,” MacGillivray says. “They require low hydrogen processes, and low hydrogen stick processes are relatively slow. We’re working to create wire processes to be quicker. As for heating pipe in preparation for welding, we’re posing an induction heat system, which offers better heat, is safer and better than fuel sources.”
The induction system allows the pipe to be heated evenly and prevents cooling between weld passes, according to Al Sherrill, regional induction sales specialist for Miller’s pipe welding products. The system places a heating coil around the pipe to maintain heat rather than using a welding arc or other fuel. The heat drives out hydrogen to prevent cracking. The system also monitors the temperature of the pipe and shuts down if it gets too hot.
Another innovation coming to the welding industry is lasers, Funderburk says. Testing shows that laser hybrid welding systems consume less filler metal material and are extremely fast, completing a girth weld on an inch-thick piece of metal in a single pass.
“This technology is maybe 10 years off,” Funderburk says. “What took an hour before is essentially done in 10 minutes. It’s basically science fiction today, but there has been a lot research done on it.”
Such innovations in the welding field will continue to provide new ways of ensuring pipeline integrity and to help solve the challenge of maintaining jobsite productivity one connection at a time.
Bradley Kramer is managing editor of North American Oil & Gas Pipelines. Contact him by email at email@example.com.