Span gas online store UK: Helium / argon mixtures are sometimes used for their higher heat characteristics. Gas mixtures, usually 25% helium and 75% argon are sometimes used and can help to increase travel speeds when AC – gas tungsten arc welding. Mixtures of more than 25% helium for AC – gas tungsten arc welding are used, but not often, as they can tend to produce instability, under certain circumstances, in the AC arc. Pure helium or high percentages of helium (He-90%, Ar-10%) shielding gas are used primarily for gas tungsten arc machine welding with direct current electrode negative (DCEN). Often designed as seam welders, the combination of GTAW – DCEN and the high heat input from the gas used can provide fast welding speeds and outstanding penetration. This configuration is sometimes used to produce full penetration butt welds, welded from one side only, onto temporary baking with no vee-groove preparation, just a square edged plate.
Safety: While argon is a good fit for a variety of welding jobs, it can be a safety risk. As with any gas work, there are steps to take to prevent causing an accident. Argon is stored in high-pressure tanks, and although its inert qualities mean that it doesn’t easily react to other chemicals, it is essential to be fully trained in handling and transporting gases to minimise the risk of accidents and hazards. The risk of gas leaking or spilling needs to be taken seriously; gas should be stored in a well-ventilated room. Argon is colourless and odourless so ensuring ventilation is available and that tanks are sealed adequately is critical.
WSD (weldingsuppliesdirect.co.uk) supplies a wide range of shielding gases specifically designed to optimise performance in particular conditions. In vehicle repair and manufacturing, argon-based gas mixtures are commonly used to MIG weld carbon and low alloy steels. Argoshield Light is one of those choices. It’s ideal if you are welding thinner carbon steel ranging from 0.6 to 5mm in thickness. The addition of oxygen to Argoshield increases arc stability to minimise spatter and fast weld speeds with its low heat input reduce distortion. So it’s perfect for our earlier example where the components of a car are being painted or powder coated after welding. Read extra info at Span Gas.
Nitrogen can be used for duplex steels to avoid nitrogen loss in the weld metal. The purity of the gas used for root protection should be at least 99.995%. When gas purging is impractical, root flux can be an alternative. In submerged-arc welding (SAW) and electro-slag welding (ESW), the shield is achieved by a welding flux, completely covering the consumable, the arc and the molten pool. The flux also stabilizes the electric arc. The flux is fused by the heat of the process, creating a molten slag cover that effectively shields the weld pool from the surrounding atmosphere. Quad gases are mainly used within Marine environments. Quad gases are a four gas mix. Supplied in a range of lightweight cylinders and made from aluminum. Both reactive and non-reactive mixtures are available.
The risk of over-exposure to nitrous gases is considered to be low for oxy-fuel gas cutting, unless the work conditions are unfavourable e.g. hand held cutting in a confined space with a high duty-cycle. Plasma cutting with air or nitrogen generates higher levels of nitrous gases than oxy-fuel gas cutting and there is considerable risk of over-exposure. Free-burning flames generate the highest concentrations of NO and NO2, and the risk of over-exposure is also highest. Caution should be exercised during activities such as flame heating, flame straightening, flame brazing, flame spraying, etc – particularly as emissions from these processes are difficult to control. The flame should be extinguished when not in use. Source: https://www.weldingsuppliesdirect.co.uk/.