TUBE NEWS TN February 2018 | Page 12

Bright , Shiny , Oxide-Free Welds with PurgExtra ®

Tubes and pipes made from titanium , stainless steel , chrome / nickel steels are mostly required to be welded in a non-oxidised environment in order to achieve a metallurgically correct , zero colour weld . Best results are obtained by reducing the volume to be purged , with an inflatable Weld Purging System .
Leading the way in Weld Purging Technology , Huntingdon Fusion Techniques HFT ® have developed PurgExtra ®, for purging tube and pipe joints from 1 – 24 ” diameter that provide an extra gas purge hose to speed up the purging process even further .
Additional advantages of this design improvement are that the operator can use the extra purge gas supply for welding reactive metal joints in particular , such as those made from titanium and zirconium . In addition , the extra gas can be used for cooling welded joints faster than normal , where permissible .
Luke Keane , Technical Support for HFT ® said : “ The PurgExtra ® Range complements the PurgElite ® Series that has a single purging inlet and is more appropriate for stainless steel only . PurgExtra ® however , 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 weld zone 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 otherwise cause the metal to discolour and lose its corrosion resistance and possibly introduce defects that would cause loss of joint integrity .
PurgExtra ® comprises 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 and eliminates the need to make adjustments to flow rates .
12 TUBE NEWS February 2018