Weld purging (removing oxygen from the vicinity of a joint using an inert gas) is essential when welding metal tubes and pipes made from titanium, stainless steel, chrome and nickel steels, where a high strength joint or a clean and smooth joint is needed. The Huntingdon Fusion Techniques (HFT®) PurgExtra® inflatable tube and pipe purging systems provide an extra gas purge for weld purging tube and pipe joints of 1 - 24 in. dia.
Luke Keane, Distributor Support for HFT, said: “The PurgExtra system allows the operator to purge at the recommended rates initially and then, when conditions are correct, to introduce the additional gas at high flowrates. This system is valuable for achieving the lower oxygen levels required for welding materials of approximately 20 parts per million.”
When welding joints where interpass temperature control is necessary, PurgExtra allows extra argon gas into the welding zone, helping to cool the area dramatically. The extra gas also helps to remove the gases that are expelled by the outgassing, which occurs as the metal is being heated. The extra gas flow will prevent these expelled gases from combining with the hot metal and oxidising, which would cause the metal to discolour and lose its corrosion resistance.
PurgExtra comprises of two inflatable dams that are connected by a heat resistant, highly flexible gas hose that has the IntaCal® gas release system. IntaCal allows the dams to be inflated correctly before releasing the inert gas to safely purge the space between the dams. The IntaCal valve replaces bulky complicated valves, which are still used by other types of purging devices.
Being highly flexible, the spinal hose between the dams allows PurgExtra systems to be pulled or pushed easily around bends and elbows. In the centre of the spinal hose, a strip of RootGlo® material is adhered, allowing the welder to see when the PurgExtra system has reached the correct position in the pipe from outside. RootGlo can be charged by exposing it to daylight for 10 min., after which it will provide up to 24 hrs of bright illumination inside the pipe.
Heat resistant covers are also available for PurgExtra, which fit onto the inflatable dams and allow operation with pre-heated and post-weld heat treated pipe joints where temperatures may reach 760°C.
Read the article online at: https://www.worldpipelines.com/product-news/01032017/hft-welcomes-an-extra-gas-purge-for-weld-purging/