Inert gas purging is essential when welding metal tubes made from titanium, as well as ultra high purity stainless steel joints and just as important when welding those less critical stainless steel and copper nickel pipe joints, in order to achieve non-oxidised, zero colour welds.
PurgExtra™ is the latest weld purging product released by Huntingdon Fusion Techniques HFT® for the purging of tube and pipe joints from 1 – 24” diameter. This range compliments the PurgElite® series, but in addition has extra purge gas inlets and corresponding exhaust ports.
The PurgExtra™ System allows the operator to purge at recommended rates initially and then when it would be an advantage, to introduce additional purge gas to create the desired results.
Typical applications might be:
For extra inert gas with titanium welds to achieve the lower oxygen rates required for welding that material which would be around 20 parts per million.
When welding joints where interpass temperature control is necessary, the cold, extra argon gas will help cooling dramatically.
Removal of additional gases that are expelled by the outgassing that occurs as the metal is being heated. The extra gas flow will prevent these expelled gases from combining with the hot metal and oxidising them, which causes 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 integrated. IntaCal® allows the dams to be inflated correctly and then releases the inert gas to safely purge the space between the dams. IntaCal® replaces the old fashioned, complicated valves, still used by other types of purging devices, that might sometimes fail causing the dams to burst.
The highly flexible hose allows the PurgExtra™ Systems to be pulled or pushed easily around bends and elbows.
In the centre of the hoses between the dams, a strip of RootGlo® material is adhered, allowing the welder to see clearly when the PurgExtra™ System has reached the correct position in the pipe. RootGlo® can be charged by leaving it in daylight for 10 minutes after which it will provide up to 24 hours of bright illumination inside the pipe.
As an option, the PurgeGate® accessory may be fitted to the PurgExtra™ Systems to protect the inflatable dams from accidental or faulty opening of gas supply valves significantly above the recommended flow rate, thus giving further protection to the dams against bursting.
Heat Resistant Covers are also available for PurgExtra™, which fit onto the inflatable dams and allow operation with post-weld heat-treated pipe joints where the temperatures might reach 760°C.