When tubes and pipes of certain materials are welded together it is desirable to purge the oxygen out of the inside of the weld zone to prevent it from reacting with the hot metal and causing oxidation, porosity and corrosion.
Some products available include Inflatable Tube and Pipe Purging Systems PurgElite®, QuickPurge® and HotPurge™. These systems require an open end to enable the system to be retrieved after the weld is finished, meaning it is impossible to use one of these tandem system for closing welds.
To overcome this difficulty Huntingdon Fusion Techniques, HFT® has developed and manufactured Argweld® Weld Purge Film® kits, with water soluble materials that can be used for open assemblies and closing welds. The Film produces an impenetrable purge barrier, but which can easily be washed away when hydrostatically testing the pipe or just by normal wash out.
To obtain a quality purge is not easy and it has been customary to fill pipes with expensive argon gas and keep the gas running at what is thought to be a suitable flow rate for an estimated period of time. In today’s climate of ever improving quality control and increasing demands on procedures with traceability, it is inappropriate to use such hit and miss methods to guarantee a satisfactory purge.
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