Article tech high quality welds on tube and pipework fabrications are mostly made by the tig welding process

1. Inspection, Testing and Quality Control
of stainless steel, titanium and other
reactive metal Tube and Pipe Welding
RAS 19/1/2015
High quality welds on tube and pipework
fabrications are mostly made by the TIG
welding process.
Part of this welding process is to manufacture
clean welds, free of oxidation and
discolouration.
Discoloured welds will have a loss of corrosion
resistance. The greater the discolouration, the
greater the loss of resistance.
With today’s automatic welding technology as
well as with the skills of manual welders, it is
possible to create welds with no other defects,
however if the weld purging procedure is not
controlled and checked discolouration may
appear.
Many welding and quality related personnel
would look at oxidised welds and think, “No
problem, I can have those cleaned!”
•But at what cost -?
There will be other processes. Perhaps

2. Inspection, Testing and Quality Control
of stainless steel, titanium and other
reactive metal Tube and Pipe Welding
RAS 19/1/2015
grinding? Pickling? Polishing?
All extra costs for the Manufacturer.
Welders and Quality Control staff don’t have to
pay the costs of these extra processes
personally and the extra costs go against the
job and reduce the profit for the company.
Financial Controllers of the Companies
fabricating the pipework may not always
realise that extra work was carried out, when
for a little attention and a small cost, it could
have been avoided.
Zero colour welds can be achieved every time
by monitoring the weld purge with a Weld
Purge Monitor®.
Huntingdon Fusion Techniques Limited (HFT)
developed the world’s first Weld Purge
Monitor® in the mid 1970’s and this term is a
registered trademark in the USA and Europe as
belonging to HFT.
Now the HFT is the only company having a
family of seven different instruments, ranging

3. Inspection, Testing and Quality Control
of stainless steel, titanium and other
reactive metal Tube and Pipe Welding
RAS 19/1/2015
from the simple but ubiquitous PurgEye® 100
general-purpose instrument up to the
PurgEye® 1000 remotely reading model.
All of these models will help the operator to
ensure that Zero Coloured welds are produced
and eliminate those wasteful and expensive
additional weld cleaning or even weld cut-out
processes.
Weld Purge Monitors® can be connected to the
exhaust end of any pipe purging system to
check that the residual oxygen is below that
level which causes the permissible amount of
oxidation.
In addition, they can be used to check any gas
supply.
Many welders have reported problems related
to the wrong gas having been delivered or
connected, or even a bad gas bottle that has
somehow escaped the rigorous testing
processes of the gas manufacturers.
With a weld purge monitor used as part of the

4. Inspection, Testing and Quality Control
of stainless steel, titanium and other
reactive metal Tube and Pipe Welding
RAS 19/1/2015
weld set up procedure, the purge gas can be
checked at source and at several places along
the line to ensure that there are no leaks from
the outside and that the gas specification
entering the purge zone, is correct.
The PurgEye® 100 is a hand held battery
operated model that reads down to 100 parts
per million (ppm). It shows when the battery
and sensor need changing and it has an instant
calibration button, allowing the monitor to be
checked prior to welding and checked again
when the ultimate low oxygen level has been
reached.
All other models read very accurately down to
10 parts per million.
The PurgEye® 200 is another hand held model
and has an integral vacuum pump for sample
extraction as well as reading very accurately
down to 10 ppm. Batteries are rechargeable
and a backup pair of batteries with charger is
provided so that the instrument can stay in use.
The PurgEye® 300 Nano is the lowest cost

5. Inspection, Testing and Quality Control
of stainless steel, titanium and other
reactive metal Tube and Pipe Welding
RAS 19/1/2015
mains operated Weld Purge Monitor that can
read down to 10 ppm and for data capture, the
PurgEye® 300 with free PurgeLog software is
the instrument of choice.
For data capture with an integral electro
mechanical vacuum pump to extract gas
samples on a timed basis, the PurgEye® 500 is
available and the top of the range PurgEye®
600 has all the features plus a large size colour
computer screen to automate all processes and
to read from atmosphere very accurately to 10
ppm in one instrument.
The PurgEyes 300, 500 and 600 all have
electronic set points that allows minimum and
maximum oxygen levels to trigger other
electronic devices such as a warning light or an
alarm for instance.
Companies with long distances between the
purging point and the data receiving point, can
use the PurgEye® 1000 that has a sensor at
the purging outlet and the monitor up to 1,000
meters away, but yet gives an instant,
accurate reading via the long electrical cable
instead of having a long purge exhaust tube

6. Inspection, Testing and Quality Control
of stainless steel, titanium and other
reactive metal Tube and Pipe Welding
RAS 19/1/2015
that gives erroneous readings after long
waiting times.
Huntingdon Fusion Techniques also
manufactures Pipe Purging Systems, Trailing
Shields,water soluble purge dam materials and
inflatable single ended purge dams.
The Pipe Purging Systems are divided into
three groups. Simple systems for tube and
pipe diameters from 1 to 24”, the
QuickPurge®III systems for 5 to 96” and the
HotPurge™ systems also in the 5 to 96” range
and suitable for the welding of Chrome Steels
where weld zones need pre- and post-weld
heat treatment cycles.
With 40 years of activity in the Welding Field,
Huntingdon Fusion have become known as the
weld purging guys!