The document outlines ten best practices for weld purging: 1. Continuously monitor oxygen content to save time and prevent bad welds. 2. Enclose the welding area tightly without compromising materials or the weld. 3. Carefully select purge materials to avoid outgassing harmful vapors. 4. Introduce purge gas slowly and from the bottom to displace air efficiently. 5. Wait until oxygen levels stabilize below 0.1% before welding.

1. Webcast
Weld Purging 2011
Ten best Practices

2. ARGWELD ® Weld Purging – Ten best practices 2
1.0 Monitor Oxygen Content continuously to save time and prevent bad welds
2.0 Enclose the volume to be purged as tightly as possible
without prejudicing the materials chosen or the weld itself
3.0 Use the correct materials to enclose the volume around
the weld, for best purging results.
4.0 Introduce your purge gas slowly and at the bottom of the
purge zone created
5.0 Wait until the oxygen level has stabilized at the reading you need
before you start to weld. Usually less than 0.1%
Continued:

3. ARGWELD ® Weld Purging – Ten best practices 3
6.0 Keep the purge gas flowing until the material being welded has fallen
below the oxidation temperature
7.0 Cleanliness is so critical in obtaining a good weld purge
8.0 Purge tack welds to stop contamination getting into the main weld pool
9.0 Use a high quality of purge gas
10.0 Avoid supply pipe leaks to prevent air getting into the purge lines

4. ARGWELD ® Weld Purging – Ten best practices 4
1.0 Monitor Oxygen Content to save time and prevent bad welds
Until 1975, welders purged out the air for test welds in a very inefficient
Manner. They guessed at the time to make a weld.
If the weld was bad, they would wait longer and longer until a good test weld
was made and then use that as the benchmark purging period
So, the world’s first Weld Purge Monitor was designed and developed by
Huntingdon Fusion Techniques Limited.
This cut waiting periods enormously and prevented poor quality welds so
The small cost of the instrument provided payback in less than one weld
and went on to save all users the equivalent of thousands of $’s, €’s or £’s
per job
HFT continued to develop 5 levels of the original MKI Weld Purge Monitor
and in May 2011 launched the PurgEye™ 100 to replace the MKV
Continued:

5. ARGWELD ® Weld Purging – Ten best practices 5
1.0 Monitor Oxygen Content to save time and prevent bad welds
PurgEye™ 100, the 21st Century Weld Purge Monitor™ to ensure your welds
are made efficiently saving you money on every weld.
Push button calibration at atmosphere and the lowest oxygen level
Continued:

6. ARGWELD ® Weld Purging – Ten best practices 6
2.0 Enclose the volume to be purged as tightly as possible without
prejudicing the materials chosen or the weld itself
Reducing the volume to be purged is so critical.
Huntingdon Fusion Techniques Limited has designed and developed a
number of products that will help you save time, save money,
save labour costs and give you quality welds.
The best product for confining the weld zone must be chosen to match the
Conditions ie level of cleanliness, amount of heat generated,
length of time that heat is present
HFT Argweld® range has a product to suit most conditions
Continued:

7. 2.0 Enclose ® Weld Purging – be purged as tightly as possible without
ARGWELD the volume to Ten best practices 7
2
prejudicing the materials chosen or the weld itself
2.1 For tube and pipe welding - Inflatable Pipe Purging System Range
Inflatable system at either HFT designed and developed
Simple inflatable systems Argweld® Quick Purge™ range
end of a lobster back assembly
The HFT concept of two inflatable dams placed either side of
the weld has proved to be the system of choice over a 35 year
period, using HFT ever advancing designs and choice of correct
low outgassing rate materials to prevent weld contamination,
ensures that the job is done quickly saving time and money
Don’t use makeshift devices,
Heat resistant systems for
use the proper tools for the job.
chrome steel pipework
Continued:

8. 2.0 Enclose ® Weld Purging – be purged as tightly as possible without
ARGWELD the volume to Ten best practices 82
prejudicing the materials chosen or the weld itself
2.2 For aerospace component and medical device welding
Standard low cost welding enclosures.
a) Put the components inside using the wide opening zip
b) Expel as much air as possible by squeezing/compressing
the Enclosure downwards and around the parts
c) Introduce the purge gas slowly until a blanket of gas
covers the base, as indicated by your Argweld® PurgEye™
weld purge monitor
d) Turn the purge gas control valve to a higher speed for fast purging without
turbulence and without entraining residual air in the purge gas
(this is achieved because of item c) above, so that your purging takes place in
an established inert gas surrounding)
e) Measure the exhaust gas from the connection at the top of the enclosure with
your PurgEye™ instrument until it reaches your desired level of oxygen.
Continued:

9. ARGWELD ® Weld Purging – Ten best practices 9
3.0 Select materials carefully and wisely
All materials emit gases or vapours and each material has a
‘vapour pressure’, - that is the amount of gas given off per second at
Atmospheric pressure.
At Huntingdon Fusion Techniques Limited our scientific knowledge and
many years serving the weld purging industry has helped us to know
which are the good and the bad materials.
For example, it is well known that paper has a high percentage of water
and will emit water vapour into a weld space, especially as it heats up.
Paper is thus an unwise choice of material in a weld purging situation.
HFT manufacturing techniques eliminate from the Argweld® products, any
material that contains a harmful gas that could be emitted during welding
and thereby contaminate a weld

10. ARGWELD ® Weld Purging – Ten best practices 10
3.0 Select materials carefully and wisely
Paper is not good for a
weld purging environment.
It has a high percentage of
Water and fibres that clog
filters

11. ARGWELD ® Weld Purging – Ten best practices 11
3.0 Select materials carefully and wisely
Argweld® water soluble weld purge
film kit which comes tightly wrapped
in waterproof material and in a
protective cardboard tube along
with two bottles of super adhesive,
a comprehensive set of instructions
for use and a knife to cut dams.
Water soluble weld purge film.
Transparent so that you can
see the weld root clearly

12. ARGWELD ® Weld Purging –Purging Systems
Inflatable Pipe Ten best practices 12 8
Provisional Dam Systems
3.0 Select materials carefully and wisely
Sponge or foam is very porous and
contains masses of air pockets and
with water vapour as well as oxygen
Paper is not good for a
These materials should not be used!
weld purging environment

13. ARGWELD ® Weld Purging – Ten best practices 13
4.0 Introduce your purge gas slowly and at the bottom of the purge zone created
In the case of Argon as a weld purge gas, which is heavier than air, Argon
should be introduced slowly into the weld cavity, as close to the bottom as
possible.
Once an argon blanket covers the base of a purge zone, it travels
upwards pushing the air ahead of it.
The exhaust port in a Weld Purge Cavity should therefore be at the highest
point. The residual air will be pushed out of that orifice, from where it can be
measured with your PurgEye™ Weld Purge Monitor™
By introducing the gas slowly and avoiding turbulence,
you will save enormous volumes of weld purge gas and
The costs resulting

14. ARGWELD ® Weld Purging – Ten best practices 14
4.0 Introduce your purge gas slowly and at the bottom of the purge zone created
A typical inflatable purge dam system

15. ARGWELD ® Weld Purging – Ten best practices 15
5.0 Wait until the oxygen level has stabilised at the reading you need
before you start to weld. Usually less than 0.1%
Since Huntingdon Fusion Techniques Limited, designed, developed and
manufactured the world’s first Weld Purge Monitor, welders no longer
have to guess at the oxygen level, or use archaic methods such as the
extinguishing for a flame when the oxygen level falls.
No more canaries in the box
at the end of a pipe to go to
sleep when the oxygen level
falls 

16. ARGWELD ® Weld Purging – Ten best practices 16
5.0 Wait until the oxygen level has stabilised at the reading you need
before you start to weld. Usually less than 0.1%
PurgEye™ 100 – atmosphere to 0.1%
PurgEye™ 300 – atmosphere to 10 ppm
PurgEye™ 500 – atmosphere to 10 ppm
with integral pump
For stainless steels, duplex steels, Titanium, Nickel alloys and other reactive metals

17. ARGWELD ® Weld Purging – Ten best practices 17
6.0 Keep the purge gas flowing until the material being welded has fallen
below the oxidation temperature
Don’t stop the weld purge gas when the weld has finished !
Wait until the weld zone has cooled below the oxidation temperature.
The Argon or other weld purge gas coming out of the bottle will be very
cold and will help to cool the weld quickly.
Waiting that extra few minutes might save you days of work, cutting out a
badly oxidised weld that happened because the purge gas was turned off
too soon.
Tips like this from Huntingdon Fusion Techniques Limited, world leaders
in the field of weld purging techniques, can save you thousands of
dollars.

18. 18
6.1USINGthe purge gas flowingSYSTEMSmaterial being welded has fallen
Keep PROVISIONAL DAM until the
below the oxidation temperature
Weld appearance when gas Weld with longer wait period
shut off prematurely

19. ARGWELD ® Weld Purging – Ten best practices 19
7.0 Cleanliness is so critical in obtaining a good weld purge
When your weld joint has been prepared for welding, before the two
components are placed together for tack welding, ensure that the area
around the joint has been thoroughly cleaned from machining fluids,
finger greases, grinding dust etc.
All foreign materials will have the capacity to outgas harmful vapours into
your weld joint. This will lead to inclusions, porosity, oxidation,
undesirable nitride formation, coking etc etc.
Information about cleaning materials and processes is available from
Huntingdon Fusion Techniques Limited vast library of technical data on
request.
Tips like this from Huntingdon Fusion Techniques Limited, world leaders
in the field of weld purging techniques, can save you thousands of
dollars.

20. ARGWELD ® Weld Purging – Ten best practices 20
7.1 Cleanliness is so critical in obtaining a good weld purge
There are hundreds of proprietary cleaning materials on the market.
Huntingdon Fusion Techniques Limited can advise you about the best
ones that don’t leave any residue to harm the weld

21. ARGWELD ® Weld Purging – Ten best practices 21
8.0 Purge tack welds to avoid contamination being dragged into the main weld pool
Often overlooked, is the necessity to back purge tack welds!
They may be clean from the front, or torch side, however unless the
backside, or underside is protected, those welds will oxidise heavily and
coke will form.
That oxidation will then be picked up as the seam weld is made and
dragged into the weld pool as a whole.
This will involve expensive cut outs and rewelding.
Tips like this from Huntingdon Fusion Techniques Limited, world leaders
in the field of weld purging techniques, can save you thousands of
dollars.

22. ARGWELD ® Weld Purging – Ten best practices 22
8.1 Purge tack welds to avoid coking being dragged into the main weld pool
These even lightly oxidised tack welds
will allow the oxidation to be dragged
into critical weld pools and contaminate
them.
Tack welds must look bright and shiny
or the oxidation will need to be ground
off, which isn’t always practical inside
pipes etc.
So the weld purging system may need
to be in place prior to tack welding
Tips like this from Huntingdon Fusion Techniques Limited, world leaders
in the field of weld purging techniques, can save you thousands of $’s, €.s
or £’s

23. ARGWELD ® Weld Purging – Ten best practices 23
9.0 Use a quality Purge gas
It is not unusual for the incorrect quality of weld purge gas to be
connected to the purging systems.
It is a wise practice to use your PurgEye™ Weld Purge Monitor to check
the quality of your purging gas before you connect it to the system.
Many hours of heartache can be saved by introducing this short check
into your procedures.
Huntingdon Fusion Techniques Limited has advised thousands of
Companies in the last 35 years and helped them to solve seemingly
impossible problems because of our experience and scientific training.
Tips like this from Huntingdon Fusion Techniques Limited, world leaders
in the field of weld purging techniques, can save you thousands of $’s, €’s
or £’s.

24. ARGWELD ® Weld Purging – Ten best practices 24
9.1 Use the correct quality of Purge gas and test the source before proceeding
Huntingdon Fusion Techniques Limited
can advise you about the correct gas quality for your welding
needs, whatever your materials and weld processes.
Tips like this from Huntingdon Fusion Techniques Limited, world leaders in
the field of weld purging techniques, can save you thousands of $’s, €’s or
£’s.

25. ARGWELD ® Weld Purging – Ten best practices 25
10.0 Gas leaks prevented, drawing oxygen into the purge lines
No matter how carefully you set up your welding equipment, there are
sometimes areas outside of your control that need to be checked.
So many times we have scratched our heads trying to solve our
customers problems, when everything is seemingly perfect.
And so many times, we have decided to pressure test the purge lines
using the simple soapy water test and we have found a leak where
another trustworthy person has made a connection that wasn’t quite right.
Huntingdon Fusion Techniques Limited has advised thousands of
Companies in the last 35 years and helped them to solve seemingly
impossible problems because of our experience and scientific training.
Tips like this from Huntingdon Fusion Techniques Limited, world leaders
in the field of weld purging techniques, can save you thousands of
dollars.

26. ARGWELD ® Weld Purging – Ten best practices 26
10.1 Gas leaks prevented, drawing oxygen into the purge lines
There are many specialised fittings for making
leak tight joints in gas tubing for weld gas purging
lines. In case of need, please contact
Huntingdon Fusion Techniques Limited
and one of our specialists will be pleased to give
you the names of suitable suppliers.
Tips like this from Huntingdon Fusion Techniques Limited, world leaders
in the field of weld purging techniques, can save you thousands of
dollars.

27. ARGWELD ® Weld Purging – Ten best practices 27
These few points are ‘just the tip of the iceberg’ when it comes to weld
purging techniques.
Huntingdon Fusion Techniques Limited has a large volume of other
technical notes concerning weld purging techniques, weld purging
technology and associated best weld practices.
Don’t be swayed by those people offering ‘me too’ products for cheaper
prices. They cannot sustain that activity and they will leave you high and
dry at some time.
Huntingdon Fusion Techniques Limited has its own design and
development staff and its own production lines.
No other Company can offer you our wealth of experience, our technical
support in depth and our large stock levels for immediate delivery of
standard products at all times.

28. Thank You
2011
All photos courtesy of Huntingdon Fusion Techniques Limited, UK.