Calibration gas cylinder online supplier 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.

Low cost, high quality: Argon is widely used because, like CO2, it is low cost. It is odourless, colourless, and known for not reacting to high levels of elements like oxygen or water. So why use it over CO2? As we mentioned, CO2 yields imperfect results, as it leaves openings for oxygen to compromise the weld. Argon, on the other hand, is much more stable and controllable. It keeps the molten weld from getting damaged, becoming brittle and breaking, and can be used with other gases such as helium to enhance the quality. The perfect choice would be a mix of argon and something else. Argon would always be the gas with the largest quantity though.

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. Read more details at Span Gas Bottle.

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. Calibration gases are split into two categories. These are zero calibration gas and span calibration gas. Calibration gas is used to calibrate gas analyser’s. Calibration gas is in addition used to calibrate Gas detectors. These Gases will also be known as Span Gas and come in a Span Gas cylinder. This product has added one or more component(s).

Chlorinated hydrocarbons, such as trichloroethylene, may be used for degreasing. The radiation from welding arcs causes trichloroethylene vapour to decompose to products that are readily detected by smell. The primary decomposition products are dichloroacetyl chloride and hydrogen chloride but phosgene, which has very low exposure limits (long-term limit 0.02ppm, short-term limit 0.06ppm), is also formed. Fortunately, the smell and lachrymatory properties of the initial breakdown products are sufficient to warn the welder of a problem and welding is likely to be stopped before harmful levels of any product are achieved. Source: www.weldingsuppliesdirect.co.uk.