Bump test gas cylinder online shop UK: Pure argon shielding gas will typically produce a completed weld with a brighter, shinier surface appearance. A weld made with a helium/argon mixture would usually require post weld wire brushing to obtain a similar surface appearance. Because of aluminum’s high thermal conductivity, incomplete fusion can be a likely discontinuity. Helium shielding gas mixtures can help to prevent incomplete fusion and incomplete penetration because of the extra heat potential of these gases. Shielding Gas for Gas Tungsten Arc Welding: When considering the shielding gas for gas tungsten arc welding with alternating current (AC), pure argon is the most popular gas used. Pure argon will provide good arc stability, improved cleaning action, and better arc starting characteristics when AC – GTAW aluminum.
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.
The shielding gas does more than protect the finished weld from the effects of oxygen and nitrogen in the atmosphere. It affects the weld’s bead shape and size and its porosity and fusion, as well as the welding speed and amount of spatter. Choose your gas wisely and you’ll achieve strong, tough and corrosion-resistant welds; select poorly and you affect performance: delivering welds that are never quite good enough. See more details on Gas Bump.
A perfect welding result, without impairment of corrosion resistance and mechanical properties, can only be obtained when using a backing gas with very low oxygen content. For best results, a maximum of 20 ppm O2 at the root side can be tolerated. This can be achieved with a purging setup and can be controlled with a modern oxygen meter. Pure argon is by far the most common gas for root protection of stainless steels. Formier gas (N2 + 5 – 12% H2) is an excellent alternative for conventional austenitic steels. The gas contains an active component, H2, which brings down the oxygen level in the weld area. Zero calibration gas is a gas that does not contain flammable gas. You will need this gas in the calibration of analyser’s or gas detectors. Span calibration gases are a more advanced type of calibration gas. They contain a more precise total make up of detectable gases.
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: weldingsuppliesdirect.co.uk.