Weld purging is the act of removing oxygen from the vicinity of a joint with an inert gas. It is essential when welding metal tubes and pipes made from titanium, stainless steel, chrome and nickel steels where a high strength joint or an exceptionally clean and smooth joint is needed. For example in power piping and ultra high purity stainless steel joints it is important to have a good weld purge that will provide non-oxidised, zero colour welds.
PurgExtra® Inflatable Tube and Pipe Purging Systems, available from Weld Purging Experts Huntingdon Fusion Techniques HFT®, provides an extra gas purge for weld purging tube and pipe joints from 1 – 24” ø. This range complements the PurgElite® Series that has a single purging inlet.
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 flow rates. This system is especially valuable for achieving the lower oxygen levels required for welding materials around 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 connected by a heat resistant, highly flexible gas hose that has the unique IntaCal® gas release system. IntaCal® allows the dams to be inflated correctly and then releases the inert gas to safely purge the space between the dams. The low profile IntaCal® Valve replaces the old fashioned, bulky complicated valves, which are still used by other types of purging devices.
The highly flexible spinal hose between the dams allows the 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 from outside clearly, when the PurgExtra® System has reached the correct position in the pipe. RootGlo® can be charged by exposing it to daylight for 10 minutes, after which it will provide up to 24 hours of bright illumination inside the pipe.
The innovative PurgeGate® Valve may be fitted to the PurgExtra® Systems as an accessory, to protect the inflatable dams from bursting due to accidental over pressurisation.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 the temperatures might reach 760°C.