Huntingdon Fusion Techniques supplied HFT Quick Purge 3 inflatable weld purging systems to a facility in Mangalore, India, for the production of 1,25 million tonnes of terephtalic acid (PTA). The manufacture required a range off stainless steel along with titanium and tantalum alloys, and the bulk of the fabrication involved welding of tubes and pipes. HFT advanced purging system concept has been employed to avoid internal contamination of the pipes during welding and to prevent oxidation of the weld root. The HFT Quick purge 3 was chosen to accomodate pipe sizes between 800 and 1.500 mm.
The company also supplied Purge gate ancillaries, to control and maintain the inflated state of the large diameter inflatable devices, even when the the purge gas flow was interrupted or stopped, for example during shift changes or when work was discontinued overnight. The Purge Gate feature inflates only the dams, effecting a good sealing when the inert gas pressure is set at 0,45 bar, and after inflation the gas flow from the supply stops, with no further consumption, being kept for lengthy periods with any gas loss. Only when gas pressure is increased to 0,5 bar, purging begins, resulting in a significant saving in expensive inert gas. All welds in stainless steel were made using the standard Quick Purge I systems, while in order to guarantee the production of clean and oxide-free welds, even in sensitive materials as titanium alloys, Quick Purge II systems have been added, since this incorporate additional gas purging and gas outlet ports.