African Fusion talks to Mwali Kawawa and Michael Ashley of Air Liquide about the advancement of Air Liquide’s ARCAL™ range of gases and the reasons why this set of four exceptional shielding gas mixtures continues to transform the welding market.
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“Our ARCAL™ New Generation gas offer puts the simple back into arc welding, without taking away any of our quality and safety promises. We remain committed to delivering premium quality and high performance, but we see the way forward for advancing the welding industry as coupling these with simplicity,” begins Mwali Kawawa, Air Liquide’s national business developer for welding and cutting.
“At the heart of the ARCAL™ New Generation product line are four shielding gas mixtures: ARCAL™ Prime; ARCAL™ Chrome; ARCAL™ Speed and ARCAL™ Force, which have been meticulously developed over many years to suit the broadest possible spectrum of gas shielded welding applications in industry. We have found that there is now seldom any need to seek out more complicated gas mixtures,” he assures.
“For TIG welding of duplex stainless steel, for example, there is an argument for using 2% nitrogen in an argon gas mixture to improve pitting resistance. We can, of course, still supply this and other special mixes, but for the vast majority of stainless steel fabrication requirements, ARCAL™ Chrome is ideal for MAG welding, while ARCAL™ Prime, our high purity argon gas – more than N5.0 pure – is the established go-to gas for all TIG welding of steels, stainless steels, aluminium and most pure metals and exotic alloys,” Kawawa tells African Fusion.
“Where active gas mixtures are required for the MAG welding of steels, we have discovered that, for almost all applications, three part gas mixes, which typically consists of argon, carbon dioxide and oxygen, are detrimental in some ways and, in most cases, removing the oxygen offers great benefits. None of our ARCAL shielding gas mixtures contains oxygen. The decision to go this route was motivated by a careful R&D programme to evaluate the effects of the elimination of oxygen, which were surprisingly positive,” he relates.
Kawawa says that the first discovery was that oxygen makes it more difficult to weld in overhead and other awkward positions. This is because the oxygen in the gas raises the fluidity of the weld pool, making it more difficult to control the molten metal against gravity.
Oxygen also raises fume emission levels because it readily reacts with high temperature metal oxides to form fume, which can be carcinogenic. By removing the oxygen, therefore, welder safety is improved. In addition, the weld profile oxidation factor of carbon dioxide may be up to tenfold lower than oxygen. A mixture of 5% CO2-3% O2 in argon, for example, has a factor of 5+30 = 35, whereas a simple mixture of 8% CO2 in argon has a factor of only 8. “By removing the oxygen we substantially reduced the tendency to form non-metallic oxides on weld bead surfaces, therefore producing a cleaner and brighter finish that requires very little or no cleaning,” he says.
Oxygen in the shielding gas also raises the concentration of iron oxide. Kawawa explains: “Iron has a high affinity for oxygen thus an undesirable iron oxide FeO can form, which may negatively influence the microstructure of the weld metal, therefore also affecting the mechanical properties of the welded joint,” he adds.
In terms of weld integrity, he explains that research suggests that no negative effects are related to the removal of the oxygen. With welds performed according to approved welding procedures (WPSs), there was no change in the mechanical properties of the welds completed using ARCAL™ gas mixtures compared to welds completed using equivalent three-part shielding gases. This, he assures, has been corroborated many times. “So for most common materials of construction, the simpler ARCAL™ New Generation gases offer several benefits and very few disadvantages,” Kawawa tells African Fusion.
Summarising the specific shielding applications for each of the four ARCAL™ New Generation gas mixtures, Kawawa notes:
ARCAL™ Prime is the primary inert gas solution for a wide range of welding applications, materials and processes, including: TIG and plasma welding of all materials; MIG welding of aluminium and copper alloys; and root shielding and back purging of all materials. This is a very high purity ISO 14175 I1 classification welding gas.
ARCAL™ Chrome is Air Liquide’s ‘brilliant’ gas solution for stainless steels, including: all-purpose MAG welding of austenitic and ferritic stainless steels with chromium compositions of above 10%; and other corrosion resistant materials such as chromium and chromium-nickel alloys. It offers clean and bright weld surfaces and meets the ISO 14175 M12 classification.
ARCAL™ Speed is a high-performance gas solution for high-speed, high deposition rate MAG welding of carbon steels. It offers very low spatter and fume levels and is ideal for spray, pulsed transfer and high speed robot welding. ARCAL™ Speed meets the ISO 14175 M20 classification.
ARCAL™ Force is the ‘powerful’ gas solution for MAG welding of heavy steel structures. It is an all-purpose shielding gas for thicker section carbon steels that is highly tolerant of fit-up variations and rough surface preparations. It is ideal for automated welding in the construction and shipbuilding industries and for use with flux-cored wires. It is an ISO 14175 M21 classification gas.
According to Michael Ashley, by adopting and focusing on this simplified range, Air Liquide is able to offer a more efficient delivery and supply service to its customers. “As the ARCAL™ New Generation range of gases improves and gradually supersedes our more traditional range of gases, we are better able to distribute the range more widely across South and Southern Africa, improving access, availability and delivery efficiencies,” he says.
In a market featuring myriad similar products, he says that Air Liquide aims to go further in helping its customers with smart solutions. “We believe that smart does not have to be complex. In fact, simple is a lot smarter. Our ARCAL™ New Generation gas range enables customers to concentrate on the issues that truly count. We offer the certainty that comes from a gas solution that’s reliable, simple and always high performing,” he assures.
With production efficiency key in modern organisations, Air Liquide’s ARCAL™ New Generation offer also includes several add-ons and different gas delivery options. “While our ARCAL™ gases are freely available in standard cylinders, forward thinking companies will be most interested in our ARCAL™ gas range with EXELTOP™. EXELTOP™ cylinders offer the benefit that they arrive with built in regulators and flowmeters, so there is no need to purchase and manage these separately,” Ashley continues.
EXELTOP™ is a smart gas cylinder that comes with an advanced two-stage built-in regulator; a clearly visible on/off lever for easy shut-off; a permanently attached and protected pressure gauge, all built into a proprietary shock-absorbing protective cap. It also features Air Liquide’s Quick Connect gas hose system and an adjustable handwheel for setting and maintaining a precise flow rate.
“In organisations where production time is meticulously optimised and every kilogram of material is accounted for, ARCAL™ gases in EXELTOP™ cylinders are ideal. Cylinder changeover time, for example, usually involves having to find a spanner to loosen a hose nut and then reconnect it, which we estimate takes 12 to 15 minutes, on average, and production stops for this period. The Quick Connect system on our ARCAL™ EXELTOP™ cylinders allows instant connection, enabling our customers to save almost all of that lost time,” he says.
Various bulk delivery options are also available for ARCAL™ New Generation gases, starting with 16-cylinder manifold bundles of any of the four mixes.
Air Liquide’s dynamic onsite mixers are tamper proof and pre-set to deliver the chosen ARCAL™ gas to within ISO 14175 tolerances. Two thousand litre high purity argon tanks can be coupled to a carbon dioxide manifold. “Our Dynamic On-Site Mixer solutions enable the use of ARCAL™ Prime for TIG welding as well as any one of the active ARCAL™ gas mixtures,” Ashley explains, adding that other mixing panel solutions are also available for those wishing to use more than two of the four gases.
“In collaboration with the SAIW metallurgical testing laboratory, we are continuing to certify our different wire and ARCAL™ gas combinations, which further supports the volumes of global evidence that the ARCAL™ New Generation shielding gas range is of premium-quality.
If used as part of an approved Welding Procedure Specification (WPS), it will consistently deliver clean, bright and flaw-free weld seams that will match or better the quality, weldability and mechanical properties that other gas mixtures can deliver.
ARCAL™ is the future of welding,” Kawawa concludes.