High strength steel joints must pre-heated prior to welding and also require a post-weld heat treatment. Weld joints of this nature are often purged of oxygen and welded in an inert atmosphere to reduce the risk of ‘sugaring’, an imperfection that could allow metal pieces to break off inside pipework and cause damage to turbines, for example.
With the high temperatures and length of time at such temperatures, most weld purging systems are unsuitable. HotPurge® has been developed by International, an Inflatable Pipe Purging System 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, available in the USA from COB Industries.
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. The Pipe Purging Systems 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.
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.
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 96” (150 to 2,440 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.
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