Calibration gas cylinder online provider UK: Shielding Gas for Gas Metal Arc Welding: For GMAW the additions of helium range from around 25% helium up to 75% helium in argon. By adjusting the composition of the shielding gas, we can influence the distribution of heat to the weld. This, in turn, can influence the shape of the weld metal cross section and the speed of welding. The increase in welding speed can be substantial, and as labor costs make up a considerable amount of our overall welding costs, this can relate to a potential for significant savings. The weld metal cross section can also be of some consequence in certain applications.
Overall, argon is a standard, low cost but high-quality choice of shielding to use when welding. Although its odourless and colourless properties make it a convenient gas to use, it can also be dangerous if leaks or overexposure when welding occurs. Never forget that you are dealing with a potentially hazardous element, so entrust installation to a specialist gas installer who knows what they are doing.
No shielding gas exists that fits all applications. So the first step is to decide what you want to improve in your welding and match this to the benefits the shielding gas can bring. Just remember the gas may change as the thickness of material increases. For example, with components that have to be painted or coated after MIG welding it is important that the amount of spatter produced is kept to a minimum. Using carbon dioxide can cause large amounts of spatter to be ejected from the weld pool damaging the surface of the component. A change to Argoshield Heavy can halve the amount of spatter produced. Moving to Argoshield Universal can halve it again. See more details at Gas Bump.
The normal gas for TIG welding is argon (Ar). Helium (He) can be added to increase penetration and fluidity of the weld pool. Argon or argon/helium mixtures can be used for welding all grades. In some cases, nitrogen (N2) and/or hydrogen (H2) can be added to achieve special properties. For instance, the addition of hydrogen gives a similar, but much stronger, effect as adding helium. However, hydrogen additions should not be used for welding martensitic, ferritic or duplex grades. Alternatively, if nitrogen is added, the weld deposit properties of nitrogen alloyed grades can be improved. Oxidizing additions are not used because these destroy the tungsten electrode. 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.
For gas shielded welding processes such as TIG, MIG/MAG, FCAW, shielding gases may be inert gases, such as argon, helium and nitrogen, or argon-based mixtures containing carbon dioxide, oxygen or both. Helium may be added to argon/carbon dioxide mixtures to improve productivity. Carbon dioxide (CO2) may be used, on its own, in MAG and FCAW. With the exception of CO2 , these gases are not defined as hazardous to health under the COSHH Regulations but they are asphyxiants. CO2 has a long-term exposure limit of 5000ppm (8-hour TWA reference period) and 15000ppm short-term exposure limit (15-minute reference period). None of the gases can be seen and none have a smell – so their presence in hazardous concentrations is difficult to detect without prior knowledge or measuring equipment. Source: https://www.weldingsuppliesdirect.co.uk/.