The majority of structural applications are manufactured from high-strength steel, such as offshore structures, buildings and shipbuilding. It is therefore important that the steel joint is pre-heated prior to welding and then receives a post-weld heat treatment.
It is also vital that they welds are free from oxidation, however with the high temperatures and length of time at such temperatures, most weld purging systems are unsuitable.
The innovative HotPurge® Pipe Purging System has been developed by Huntingdon Fusion Techniques HFT for Heat-Treated Chrome and High Strength Stainless Steel Pipe Joints where the temperatures might be as high as 760ºC (1,400ºF) for many hours.
Georgia Gascoyne, CEO for HFT® said: “HotPurge® ensures the purge space remains tightly sealed at all times as the inflatable dams maintain an even seal throughout the weld cycle, irrespective of pressure rises or excessive flow rates of argon gas. The large central collar dramatically reduces the space to be purged and makes it easier to reach lower oxygen levels faster than with conventional purging systems.”
“HotPurge® allows the purge to be safely continued for up to 24 hours whilst pre-heating, welding and post weld heat-treating with the purge system remaining in place.”
HotPurge® includes PurgeGate®, a revolutionary device to prevent over inflation of, and damage to the inflatable dams. No matter how high the user increases the pressure, in order to deliver more gas flow, PurgeGate® prevents too much pressure being delivered to the inflatable dams, allowing an increased flow, to achieve a lower oxygen level or faster cooling of the weld zone.
Each HotPurge® System incorporates an innovative central band for easy positioning inside the pipe. This band, known as RootGlo®, will illuminate inside the dark pipe, for up to 20 hours, with only 10 minutes previous exposure to daylight.
HotPurge® Systems are manufactured to suit pipe diameters from 6 to 88” (150 to 2,235 mm) and both inflatable dams have pull handles securely sewn with high temperature resistant Kevlar thread that will withstand a pulling force of 1,000 lb.
These HotPurge® Inflatable Pipe Purging Systems can be used repeatedly for weld purging and will keep the oxygen levels below 100 parts per million (ppm) throughout the welding cycle, ensuring oxide and coke free welds, without the metallurgical imperfections caused by exposure to too much oxygen.