Fast Purging of Heat
Treated Pipework
Chrome steel pipe joints, such as those
used in the power industry for high
pressure, high strength pipework, need to
be pre-heated for welding and also require a
post weld heat treatment. Equally, some high
strength stainless steel weld joints need to
undergo similar heat-treating cycles.
Weld joints of this nature need to be purged of
oxygen and welded in an inert atmosphere, to
prevent the oxidation that would otherwise lead
to loss of corrosion resistance and imperfections in
the joint metallurgy.
With the high temperatures and length of time at
such temperatures, most weld purging systems
are unsuitable. However, Huntingdon Fusion
Techniques HFT® have developed HotPurge®
Inflatable Pipe Purging System for Heat Treated
Chrome and High Strength Stainless Steel Pipe
Joints where the temperatures might be as high as
760OC (1,400 OF) for many hours.
Luke Keane, Distributor Support for HFT® said:
“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.”
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® is manufactured as standard with
PurgeGate® to prevent over inflation of, and
damage to the 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, but allows
the increased flow, should it be required, to
achieve a lower oxygen level, or for faster cooling
of the weld zone.
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 Tube and 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.
The purge space remains tightly sealed at all
times as the inflatable seals 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 the lower oxygen levels faster than with
conventional purging systems. Each HotPurge®
Huntingdon Fusion Techniques HFT® have a
Worldwide Exclusive Distributor network, which
can be found at www.huntingdonfusion.com.
47
TN MAY 2016