Weld Purging World - March 2020

ISSUE 3: MARCH 2020

In March’s Issue:

• Export Business of the Year 2020
• Calendar: Events in the Industry
• Our Upcoming Exhibitions
• Product News: Weld Backing Tape®, PurgEye® 1000
• Technical Article: Tube and Pipe Weld Purging

WELD PURGING PRODUCTS
INNOVATORS, MANUFACTURERS and
INTERNATIONALLY RENOWNED SPECIALIST
MADE IN WALES - MANUFACTURER OF THE YEAR

Huntingdon Fusion Techniques HFT® are proud members of:

www.huntingdonfusion.com

2 CONTENT

WHAT’S IN THIS MONTH’S ISSUE

Export Business of the Year 2020 3

HFT® News 4 - 6

Product News 7-8
9 - 11
Technical Paper:
Principles of Tube and Pipe
Weld Purging

A WELCOME FROM THE EDITOR

Dear Reader,

Welcome to the March Issue of Weld Purging World.

In last month’s issue, we announced that we were Finalists in the Export Business of the Year
Category at the Welsh Business Awards and earlier this month, at the Welsh Business Awards,
not only did we scoop up the award, but our very own Georgia Gascoyne won the Presidents
Award! It was an amazing night and we are all absolutely delighted with the achievement.

Some of the Industry Events have new dates confirmed, so
don’t forget to update your diary with those on page 3. We
also have an exciting new product launched in this month’s
issue … our new range of Inflatable Rubber PetroChem
Stopper.

I’m always on the look out for more exciting content for Weld
Purging World, so if you have any news or would like to be
featured in our magazine, then please get in touch.

Thank you for reading!

Best wishes,
Michaela

Marketing and Social Media Manager
[email protected]

HFT® NEWS 3

EXPORT BUSINESS OF THE YEAR 2020

Early this month, we attended the Welsh Business Awards at
City Hall in Cardiff sponsored by the Welsh Government and
hosted by Gethin Jones.
We were delighted to be named winners of the Export Business
of the Year 2020.
Not only that, but our very own CEO Managing Director, Georgia
Gascoyne scooped the prestigious Presidents Award.
Georgia said: ‘What a night we had at the Welsh Business
Awards and to come away with two top awards is absolutely
fantastic for us. I’m still completely astonished! An amazing
achievement for Huntingdon Fusion Techniques!”
The Welsh Business Awards recognises the very best from
businesses across Wales. Our businesses, whether small,
medium or large, all play a fundamental role in driving the
Welsh economy forward.
1.

CALENDAR: EVENTS IN THE INDUSTRY

Fabtech Mexico Fabtech Canada
12 - 14 May 2020 16 - 18 June 2020
Mexico City, Mexico Toronto, Canada

NEW Date NEW Date
WIN Eurasia TechniShow
HALL 12 A160 1 - 4 September 2020
18 - 21 June 2020 Utrecht, Netherlands
İstanbul, Turkey

Adipec Fabtech
9 - 12 November 2020 18 - 20 November 2020
Abu Dhabi, UAE Las Vegas, USA

NEW Date
Tube
7 - 10 December 2020
Düsseldorf, Germany

4 HFT® NEWS

TWI PRESENTATION

Last week, The Welding Institute (TWI) invited
HFT® to do a presentation on all things Weld
Purging in the Welding Industry at the City of
Bristol College.
It was a great turn out, with HFT®’s Technical
Sales Manager Luke showcasing the solutions
our products have for all weld purging
applications. Luke delivered an interactive
and insightful presentation, with a handful of
HFT®’s Exclusive Distributors, present.
A huge thank you to the City of Bristol College for hosting the event and also to the TWI for the
opportunity.
Look out for more presentations coming soon, including a Lecture at Exeter College!

NEW TRAILING SHIELD

Our re-designed Weld Trailing Shield® is in
production with the first units being shipped to
customers this week.
The Shields feature a unique clip design that
enables the welder to change to a different sized
shield without having to detach the clip from the
welding torch.
The literature is being completed and will be
updated on our website shortly.

HFT® NEWS 5

PIPE FREEZING TRAINING

HFT® and COB Industries recently
held an Exclusive Pipe Freezing
Demonstration and Education Event at
our new training facility in South Wales.

A range of customers from around the
World attended to see theAccu-Freeze™
and Qwik-Freezer™ technology on
display.

HFT®’s Technical Sales Manager Luke, nitrogen in a controlled system to freeze stationary
who carried out the training alongside liquids in a section of pipe or tubing.”
Cletus O’Brien said: “It is essential that
our Customers are able to get hands on
with our Freezing Systems, to ensure
the products can be used to their full
potential. Accu-Freeze™ utilises liquid

“By controlling the surface temperature of the pipe,
Accu-Freeze™ can accurately and safely form an
in-line ice plug, capable of withstanding 138 bar
(2,000 Psi) in pipes up to 36 inch diameter.”

“This temporary plug isolates the section, allowing
repairs or modifications to be made without shutting
off or draining the entire system.”

“Accu-Freeze™ is the World’s only patented,
digitally controlled pipe freezing system thus allowing you to accurately and safely create an ice
plug.”

6 HFT® NEWS

1. Weld Purge Monitor for On-Site Conditions

NEW PRODUCT: RUBBER PETROCHEM STOPPERS

New Inflatable Rubber PetroChem Stoppers.
The Pipestoppers® Division at Huntingdon Fusion
Techniques HFT® have launched new Rubber
PetroChem Stoppers, for pipe stopping where access
is difficult.
CEO Managing Director, Georgia Gascoyne said:
“Our new Rubber PetroChem Stoppers are an easy
way to stop the flow of gas or liquids along a pipe or
duct. Each Stopper has a longer length than diameter,
which prevents them from tipping over and losing their
seal inside the pipe. They are also manufactured with
a ribbing to prevent slipping.”
The Inflatable Rubber PetroChem Stoppers are manufactured from high quality materials, ensuring
a long life span and are resistant to a large number of chemicals and petrochemicals.
The Stoppers are available in five sizes, which will seal pipes from 2” to 12” (50 mm – 300 mm).
Each Stopper is inflated simply using the Schrader Valve.
They’re most commonly used for:
- Construction site drain
testing operations.
- Debris stopping during
machining operations.
- Leak testing of pipework
systems in commercial,
domestic and industrial
applications.
- Low-pressure hydrostatic
tests.
- On-site thermoforming
of bends in ducting and
conduit materials.
- Fibre-optic construction
projects.
- Plumbing operations.
- Reduction of weld purging
volume when welding headers onto stainless steel tanks.
The Pipestoppers® Division at Huntingdon Fusion Techniques HFT® supplies a range of Mechanical,
Inflatable and Solid Rubber Pipestoppers® and Plugs to suit every application.

PRODUCT NEWS 7

BACK PURGING WITH ARGWELD® WELD BACKING TAPE®

Back Purging is the process of protecting and shielding
the back side or under side of the weld during welding to
prevent oxidation.
Back Purging with fiberglass Weld Backing Tape®
supports weld roots and can prevent oxidation, sugaring,
achieving clean, oxide free welds.
Luke Keane®, Technical Sales Manager for Huntingdon
Fusion Techniques HFT® said: “We manufacture a
range of Weld Backing Tape® available up to 600 amps.
This innovative method of back purging will ensure a
high quality finish suitable for plate, sheet and pipe welding.”
Unlike ceramic fibre, Weld Backing Tape® has no true melting point so it works satisfactorily with TIG
or MIG welding (GTAW or GMAW) where temperatures can reach up to 6,000ºC. This overcomes
the concerns associated with ceramic fibre versions that have a melting point of 1,800ºC.
Weld Backing Tape® is a material used for manual and automatic welding. It can help achieve
higher welding speeds and dramatically reduce the amount of post weld cleaning required.
Each tape consists of a 3” (75mm) wide aluminium adhesive tape, in the centre of which is a 1”
(25mm) wide band of woven glass fibre. The glass fibre matting has differing thicknesses to match
the welding current in use.

PurgElite® Inflatable Pipe Weld Purging Systems

Drastically Restrict Weld Purge Volumes

Scientific Developers of Weld Purging Technology and
Manufacturers of Weld Purging Products since 1975

Celebrating our 45th Anniversary

www.huntingdonfusion.com

8 PRODUCT NEWS

DISTANCE WELD PURGE MONITORING

GTA/TIG welding long pipelines made of stainless steel can be found in many different industries
including Oil and Gas, Nuclear and LNG. The use of stainless steel can offer many advantages
including corrosion resistant properties and cost-effectiveness of the alloy.

With Stainless Steel being a reactive material,
the oxygen in the protective gas must be
purged down to under 100 ppm before, during
and after welding, which can cause some
difficulties in long pipelines.

Celebrating their 45th Anniversary in 2020
as International Leaders in Weld Purging,
Huntingdon Fusion Techniques HFT®’s
PurgEye® 1000 Distance Weld Monitor now
makes it possible to have an immediate
reading for the weld purge zone up to 1,000
metres away!

Luke Keane, Technical Sales Manager for HFT® said: “If exhaust gas from a normal weld purge
system is piped down a hose to a distant measuring instrument, it may take many minutes, or even
hours in some cases, to reach the sensor. The exhaust gas may even be contaminated on the way
by outgassing from the walls of the hose material or from air drawn in through a leaky connection.”

“The PurgEye® 1000 Weld Purge Monitor® has been designed and developed specifically to
overcome such difficulties and has a sensor placed immediately next to the weld purge site with
electrical connection to monitoring equipment. This way, the operator can be certain that the weld
purge reading is correct and that the joint will not be adversely affected by oxidation, allowing welders
to achieve that sought-after zero colour weld without loss of corrosion resistance.”

With a unique stainless steel sensing head that can be fitted onto any Pipe Weld Purging System
or simply left in the welding zone, the PurgEye® 1000 can measure oxygen levels up to 1 km away.

The PurgEye® 1000 is one of HFT®’s five Weld Purge
Monitors® to now feature PurgeNet™, a networking
device designed for communicating the current oxygen
reading from the Monitor, to another piece of equipment,
such as the visual warning accessory PurgeAlarm™ or a
Dew Point Monitor with additional inter-pass temperature
monitoring.

The PurgEye® 1000 measures oxygen levels from 1,000
parts per million (ppm), right down to 1 ppm (accurate
to 10 ppm), ideal for welding metals such as stainless
steels, duplex steels, titanium and zirconium where oxide free, zero colour welds are required time
after time.

TECHNICAL ARTICLE - PRINCIPLES OF TUBE AND PIPE .... 9

PRINCIPLES OF TUBE AND PIPE WELD PURGING

Despite the fact that professionally designed weld purging
systems have been available for some time it’s surprising that
fabricators of stainless steel tube and pipework still employ
unreliable home made devices to prevent oxidation of the
weld root.
Even on prestigious and demanding work like LNG storage
and distribution the use of plastic, foam, cardboard and even
screwed up newsprint proliferates.
It’s a fallacy that such relatively archaic practices are more
cost-effective than the use of widely available, proven,
properly engineered systems.
Joints of high quality between stainless steel cylindrical sections such as tubes, pipes and vessels
can only be made by ensuring that atmospheric gases are eliminated.
The presence of oxygen, and to a lesser extent nitrogen, around the molten weld can lead to wide-
ranging defects.
Defining the Problem
Joints of high quality between stainless steel cylindrical sections such as tubes, pipes and vessels
can only be made by ensuring that atmospheric gases are eliminated. The presence of oxygen, and
to a lesser extent nitrogen, around the molten weld can lead to wide-ranging defects.
- Discolouration is unsightly and in some instances might produce metallurgical imbalance, especially
with some stainless steels.
- Gross oxidation inevitably results in reduction of mechanical properties and can cause catastrophic
loss of corrosion resistance.
- Nitrogen contamination can result in brittleness. Gases in the weld may give rise to cracking during
or after cooling.
- Uneven weld root beads caused by gross oxidation can cause entrapment, leading to bacteria
build up and contamination of product flow.
The cost of removing these post-welding imperfections can be time consuming and therefore
expensive.
Pickling through treatment with a mixture of acids is effective but can often not be employed for
reasons of availability, accessibility and environmental protection.
Electrochemical removal of discolouration requires manual operation and is slow; it is generally only
practical for use with smaller products.
Grit blasting and the use of mechanical techniques such as grinding bring with them the risk of
leaving unwanted residual materials behind.
Basic Principles
Weld root quality when making tubular joints can be ensured by applying appropriate safeguards
that are based on removal of air from the fusion zone and the provision of a blanket of inert gas
around it. This is achieved by gas purging.

10 TECHNICAL ARTICLE - PRINCIPLES OF TUBE AND PIPE ....

Purging Gases

Selection of the optimum gas or gas mixture will depend upon many factors but not least the materials
being joined and the welding process employed. Argon is the most widely used as it is completely
inert and the cheapest of all the inert gases.

Even though it is clear that trying to save money using home made devices to prevent oxidation,
operators still attempt to reduce costs further by using a cheaper gases such as nitrogen in the belief
that this too is inert. This rarely the case.

An Examination of Two Types of Tube and Pipe Weld Purging Equipment

Several different principles have been used to provide inert gas coverage of the weld underbead.
We confine ourselves here to an examination of flexible discs and inflatable seals.

Various types of ‘flexible disc’ systems based on natural rubber, silicone rubber and synthetic rubber
discs have been developed specifically for use in weld purging. Persuasive arguments are put
forward by the manufacturers of these systems. They are claimed to be relatively cheap, can be
deployed quickly and removal post-joining is easy since the assembly can be withdrawn past the
weld.

The principles appear sound but the practical aspects render this type of purge equipment unreliable.
Reliability is suspect because disc to pipe sealing depends upon a very small contact area.

If we look at two typical disc concepts in current use it will become clear how unattractive they are
in reality.

Rubber Gasket Dam

A rubber, foam or similar disc can be sandwiched between a pair of
wooden or metal discs and some adjustment to diameter can is
be effected by applying axial pressure. This gasket technique
not collapsible and after welding the discs must be pulled out
past the weld root, an operation that may cause difficulties.
Cheap, yes, Reliable, no!

Multiple and Floppy Discs

Improvements on the compressed gasket have been introduced as cost-effective solutions to weld
purging. None the less, they still only fit a very limited range of internal tube or pipe dimensions
and sealing depends entirely on the disc edge being true - even minor variations in diameter and
roughness cannot be accommodated.
These disc systems also contain numerous metal parts that may scratch polished surfaces. This
can lead to a loss of corrosion resistance. Furthermore, to purchase a disc system for just one
internal diameter of tube or pipe becomes uneconomical, compared to systems that cover a range
of diameters.
Inflatable Seals
The only totally reliable and sufficiently versatile purging systems are those based on inflatable
seals.

TECHNICAL ARTICLE - PRINCIPLES OF TUBE AND PIPE .... 11

Considerable design effort has been applied by the designers and manufacturers to these solutions
over the past decade or so. Currently available systems address the problems of controlled inert
gas pressure and flow, the need for easy and rapid deployment and removal to limit overall welding
time, thermal resistance and leak-tight access for oxygen monitoring equipment. They also provide
a large pipe contact area and therefore excellent and reliable sealing.
Coupled with these advantages comes flexibility to allow access and removal through pipe bends,
abrasion resistance and the use of materials that meet nuclear compliance standards.
The most advanced systems limit the use of metallic materials. This allows post weld radiographic
inspection whilst the purging system remains in place.
The Argweld® range of inflatable systems have set a global standard that no other supplier can
match. They are used by major international fabricators on the most demanding projects.

Argweld® Inflatable Systems cover tube and pipe diameters
from 25 to 1800 mm.
Special materials are used to withstand the higher
temperatures encountered when the inflatable components
are placed closer to the weld zone for reduction of purge
time. In addition, materials with low outgassing rates have
been chosen to further reduce the amount of contaminating
vapour released into the purge volume during welding.
A further reduction of purge time has been achieved by the
central collar that creates a small annulus for purging.
Gas Flow Rates and Pressure
Using proprietary purge systems in conjunction with oxygen monitoring instrumentation the inert
gas pressure and flow rates can be set for maximum efficiency. Indeed with recently introduced
innovative technology, flow rate is pre-set by the manufacturer. Compare this with the guesswork
involved when using plastic foam and similar solutions -to be on the ‘safe side’ gas flow rates are
invariably set far too high to compensate for possible leaks and the additional gas cost can be
very significant. To compound this practice, high flow rates cause turbulence and this leads to poor
welding quality.
Summary
The fact that even very small amounts of oxygen in the purge gas can cause problems makes
it desirable to choose a purging system that ensures a
high level of sealing reliability. In all respects the inflatable
Argweld® systems excel here.
In order to ensure that the oxygen content is maintained at
the appropriate level it is necessary to monitor it.
Two essential characteristics of a suitable instrument are
that it must have an adequate measuring range and it
must sample the purge gas inside the pipe volume. The
sensitivity should be such that an oxygen level as low as
10 ppm (0.001%) can be detected. Instruments that only
display down to 1,000 ppm (0.1%) are totally unsuitable.
A typical high sensitivity instrument will include a sampling tube, gas extraction facility and sensing
electronics that are reliable and repeatable. Such facilities are available with HFT® ‘s advanced
PurgEye® Weld Purge Monitors®.

Replace Foam and other Unsuitable Materials

with Low Cost Weld Purge Dams

Scientific Developers of
Weld Purging Technology and

Manufacturers of
Weld Purging Products since 1975
Celebrating our 45th Anniversary

www.huntingdonfusion.com