What's up with helium for welding applications?
As supplies for the welding consumable tighten, welders might consider alternatives
Helium has been hard to get for some, and certainly the consumable gas is more expensive for welders than it used to be. The bad news is that this may be the case for some time. The good news is that alternatives are under development to help welders out as they tackle aluminum and stainless steel welding.
Fabricators that don’t regularly use helium for welding, but might require a bottle for a new job, could run into a strange bit of customer service at the local welding supply shop. They might not get the helium.
If they do, they might be shocked at what they pay, especially if it’s been several years since they bought helium. In fact, one major welding gas supply company announced a price increase on helium and argon, another gas often paired with helium in gas blends, of 10 to 18 percent as of early October. The general belief is that these high prices won’t retreat in a major way anytime soon.
Is it a helium shortage then? That’s probably not totally accurate, according to Nick Haines, head of global helium source development, Linde.
“I would say more than 90 percent of demand is currently being met. The vast majority are getting what they need or close to what they need,” he said.
The supply curve on the helium graph, however, is in a state of flux.
Helium and the World
The U.S. Geological Survey estimates that current global consumption of helium is a little more than 6 billion cubic feet per year. Haines said global demand is likely to grow 2 to 4 percent in the near future. Meanwhile, the U.S. Bureau of Land Management, which governs this country’s helium reserves in Amarillo, Texas, is looking to get out of the helium supply business in the next few years. Considering the Federal Helium Reserve accounts for roughly 30 percent of the world’s helium supply, it’s easy to see how people might be concerned about a possible shortage.
That’s why a lot of helium users view the U.S. government as a scapegoat. The federal government encouraged private sources to sell their helium to it because the element was deemed important to space exploration and military use in the 1950s. Amarillo was selected as the storehouse because that area of Texas has natural gas fields with a very high helium concentration. (Helium is a byproduct of refining natural gas. However, not all natural gas deposits have similar levels of helium concentration.) As a result, the U.S. government has been the main supplier of helium to the world over the past several decades.
What was good for Cold War America didn’t make much sense for a country in the 1990s that was asserting itself into the global marketplace. So in 1996 Congress decided to get out of the helium business, requiring that the reserves be sold off by 2015. The government, in turn, has been raising the price of its helium so that it can pay off the debt incurred when it built its refining plant all those years ago.
The problem is that recoverable helium will remain in the reserve after the 2015 deadline. Testimony before the U.S. Senate Energy and Natural Resources Committee this summer suggested that the “usable life” of the reservoir could be extended to 2018 or possibly even 2020. Some members of Congress have introduced legislation, as late as this fall, that would keep the Federal Helium Reserve open.
In the meantime, the private sector hasn’t stepped up to boost supplies in the face of possible closure of the main source of helium. Plants for refining helium will be coming online soon, but it’s not something that happens overnight.
“You don’t just build a helium plant, like you might choose to build a steel factory or a metal fabricating shop. You can put a helium plant only where there is a helium supply. And there are currently only 14 helium sources in the world, and by ‘sources’ I mean substantial amounts of commercially viable sources of helium,” Haines said.
Natural gas fields with a high concentration of helium can be found in Algeria, Australia, and Qatar, with the latter having a new refining plant coming online in the first half of 2013, according to Haines. Enormous reserves also exist in Russia, but those aren’t yet fully developed. In short, as the U.S. exits the role of helium supplier to the world, other nations will step up.
If you look at the demand side, things have changed as well. Metal fabricating remains a huge consumer of helium as a welding shielding gas (see Helium as a Shielding Gas sidebar), especially with the explosion of more stainless steel and aluminum work taking place in shops. But it’s the emergence of two other sectors—the medical and electronic industries—which have really changed how helium is being consumed.
Ever have a magnetic resonance imaging (MRI) scan? That was made possible because of helium, which can be cooled to 4 degrees Kelvin and is used to remove heat from the huge magnet and superconductive wire as the magnetic field is produced. Haines estimated that the “superconductivity” market uses about 20 percent of the global supply of helium per year.
The electronics sector is another area that is gobbling up a bigger share of helium. LCDs found on monitors, televisions, and even mobile phones all require helium to operate. Just in the last 10 years these items have become ubiquitous, and demand for electronics will grow as emerging economies continue to mature.
Helium in Welding
Needless to say, metal fabricators may not have known all of the reasons for recent helium supply constraints, but they have noticed the price increases. That’s why people are starting to look for alternatives.
One of the most active areas of development is in the welding of stainless steel (see Figure 1). Kevin Lyttle, senior development scientist, Praxair Inc., said this has been the main focus since early on because of the abundance of stainless steel welding applications and the ability to find workable alternatives to helium for those jobs.
“For instance, you can use hydrogen in welding of stainless steels. It has some similar thermal characteristics. But particularly in austenitic, the 300 series stainless steels, it doesn’t create the problems that we might find if it were used on carbon steel,” Lyttle said. “It doesn’t react, and it is kind of soluble in the material.”
He admitted work with aluminum as been more of a challenge. Finding an alternative to the helium/argon mixtures that deliver similar characteristics, such as the thermal conductivity, hasn’t been as successful as the work done with stainless steel.
“There is a reason that people use helium. It has some specific benefits,” Lyttle said.
Perhaps the biggest hope for welders looking to live without, or at least with less, helium rests on the ability to tailor the entire gas metal arc or flux-cored welding process—consumable wire, shielding gas, and power source settings—to a specific welding application. Lyttle said that customized waveforms can pick up the slack where an alternative shielding gas may be lacking.
For instance, thermal conductivity of the shielding gas is important because high heat can influence the shape of the weld bead and the speed of the weld. If a welder elects to use another gas instead of helium, he or she might lose some of that ability to deliver high heat input during the weld. However, Lyttle said a customized waveform might be able to tailor a higher voltage peak during the welding process that can improve the heat-transfer characteristics. This approach also holds hope for some helium alternatives to emerge for aluminum applications as well.
In other areas of manufacturing, the goal may be simply to limit the use of helium. Lyttle pointed out the use of a CO2 laser for welding applications as an example.
Traditionally, helium is used as a shielding gas in CO2 laser welding, but it is supplied in a less-than-efficient manner to the area. In the simplest of descriptions, a copper tube simply floods the welding area with helium when the laser is engaged.
“That’s an expensive way to run the process, but that’s the way that people have been doing it because in the total cost of operation, the helium use wasn’t a significant factor—until recently,” Lyttle said.
To conserve the helium, Lyttle said that researchers are determining whether a small percentage of argon can be added to the shielding gas mix to deliver the same results. They also are looking at new delivery methods, some akin to the nozzles that a welder might use when gas tungsten arc welding.
Even low-profile manufacturing activities such as leak detection are not immune to the helium squeeze. Whereas helium was once the main gas used in leak detection equipment, today equipment-makers are looking at helium/nitrogen blends or hydrogen as alternatives.
Helium availability undoubtedly will improve in the near future, but no one really can be certain how demand will grow over that same time period. That leaves metal fabricators with some decisions to make. Will the current tight supply of helium force the shop to pursue alternatives, or is this temporary shortage just a lot of hot air?
Helium as a Shielding Gas
Helium is an inert gas, which means it doesn’t undergo any chemical changes when exposed to other substances. That trait is especially important in the world of welding shielding gases. Because helium’s performance is consistent, researchers have a good idea of its impact on any type of welding application.
Helium demonstrates good thermal conductivity. That’s why it’s typically used for those weld applications in which higher heat input is needed for improved wetting of the weld bead. The gas also is useful for enabling a higher travel speed.
Helium typically is mixed with varying amounts of argon in shielding gas blends to take advantage of both gases’ good characteristics. For instance, helium as a shielding gas can help to deliver a broader and more shallow penetration pattern during the welding process (see Figure 2). However, helium cannot deliver the cleaning action that argon can.
So metal fabricators typically see argon/helium mixes as part of their work procedures. For gas metal arc welding, helium might make up from 25 percent to 75 percent of the gas mix in a helium/argon blend. By adjusting the composition of the shielding gas mix, the welder can influence the distribution of heat to the weld and, subsequently, the shape of the weld metal cross section and the welding speed.
For gas tungsten arc welding (GTAW), pure argon is more commonly used as a shielding gas. Helium/argon mixtures can be used for applications that require high heat transfer, but those applications aren’t widespread. Pure helium or mixtures with a high percentage of helium sometimes are used with GTAW machines with direct current electrode negative. These applications typically involve seam welding.
Source: ESAB Welding & Cutting Products
The FABRICATOR is North America's leading magazine for the metal forming and fabricating industry. The magazine delivers the news, technical articles, and case histories that enable fabricators to do their jobs more efficiently. The FABRICATOR has served the industry since 1971.