Upload
ngotuyen
View
216
Download
1
Embed Size (px)
Citation preview
AWI - WeldED Index
Vol 2 2010 WeldED
Sponsors Shindaiwa http://www.shindaiwa.com.au/
South Pacific Welding Group http://www.spwgroup.com.au/home.asp
SafeTac http://www.safetac.com.au
Bureau Veritas http://www.bureauveritas.com.au
Southern Cross Industrial Supplies http://www.scis.com.au
Technoweld http://www.technoweld.com.au
Hardface Technologys http://www.hardface.com.au
3834 Weld Management [email protected]
Cover Page Shindaiwa our new GOLD sponsor. The AWI welcomes Shindaiwa.
Australasian Project Supplies are the sole distributor of
Japanese Shindaiwa welders and generators in Australia.
Originally selling the industry leading DGW400DM 400
Amp dual machine they then diversified their range into a
200Amp welder, 500Amp welder and a range of super
silent environmentally friendly generators custom built for
the Australian market.
AWI operates this service for members. Information and comments in AWI publications are the opinions of specific individuals and companies, and may not reflect the position of AWI or its Directors. Information on procedures and processes herein, as well as any advice given, are not sanctioned by AWI, and AWI makes no representation or warranty as to their validity, nor is AWI liable for any injury or harm arising from such entries or from reliance on any entries. Participants should independently verify the validity of information prior to placing any reliance thereon.
Index Shindaiwa 2 Shindaiwa
Pickling & Passivation 3 Stainless Surface treatment explained
L&A Pressure 8 A snap shot of an AWI member company
The Lighter Side 10 My encounter with HF
AWI Progress 11 Progress Update of the AWI
Defects and Design 13 Case study on how design affects the defect level
Sponsors 17 A thank you to those who brought you "WeldED"
Shindaiwa 2
Vol 2 2010 WeldED
New Shindaiwa Welder hits the ground running
Australasian Project Supplies are the sole distributor of
Japanese Shindaiwa welders and generators in Australia.
Originally selling the industry leading DGW400DM 400
Amp dual machine they then diversified their range into
a 200Amp welder, 500Amp welder and a range of super
silent environmentally friendly generators custom built
for the Australian market.
Over the past 8 years the Shindaiwa and APS team have
spent countless hours making all their welding and
generating machines to not only suit the Australian
conditions and requirements but to exceed them.
Through exceptional build quality, reliability and
performance the Shindaiwa range is suited to even the
harshest Australian environments. Through this
dedication to quality Shindaiwa customers enjoy
machines that are easy to use, maintain and are
economical to own and run.
Last year Shindaiwa released the highly anticipated
DGW500DM/ANZ, featuring a dual welding function
using Wire Feeders or Stick electrodes, 57dbA Super
Silenced enclosure, 18kVA of Auxiliary Power, a 3 Way
Switch and Battery Isolator standard making this the
ultimate diesel welding machine.
The DGW500DM/ANZ has been taken on by hire
companies Tru Blu Hire, Coates Hire and GCS with
excellent utilisation and results on sites such as Gorgan,
South Australian Desalination plant and the Alkimos Pipe
Water treatment plant in Perth. If it is exceptional
welding performance combined with the latest in
Japanese technology you require, look no further than
Shindaiwa.
Please visit the Shindaiwa Australia Webpage for further
product and dealer information:
www.shindaiwa.com.au
Pickling & Passivation 3
Vol 2 2010 WeldED
Pickling & Passivation
Introduction We are all aware that there are many methods of
restoring the corrosion resistance of stainless steels
such as traditional pickling pastes, electro polishing,
mechanical abrasion etc. Each method of restoring
corrosion resistance has its own unique traits and can
be employed in a variety of situations which will have
varying degrees of success. This article will attempt to
explain the various methods available to the
Australian welding and fabrication industry but will
not attempt to rate one method against another.
Instead; it will leave it up to the reader to decide the
best method in any given situation after taking into
account time, cost and safety factors.
Corrosion Resistance Because the corrosion resistance of stainless steels is
due to a ‘passive’, chromium rich oxide layer, the
mechanism by which stainless steels regain this layer
is called ‘passivation’. The corrosion resistance of
stainless steel arises from this oxide film because it
forms a natural protective layer on the surface of the
steel. The oxide layer is extremely thin, but very
tenacious and chemically stable, which is why it is
commonly referred to as ‘passive’. The film is formed
when chromium reacts with oxygen and forms
Chromium Oxide (Cr2O3).The maximum corrosion
resistance of stainless steels can only occur when the
Chromium Oxide layer develops as an unbroken film
across the entire metal surface.
As a word of warning, stainless steels cannot be
considered corrosion resistant in all service
conditions. Depending on the type (composition) of
the steel there will be certain service conditions
where the ‘passive state’ of the stainless steel is
broken down and prevented from reforming. Here the
surface becomes ‘active’ resulting in corrosion. These
conditions occur in small areas, such as at mechanical
joints, tight corners or at incomplete or poorly
finished welds. The result can be a form of localised
attack (crevice or pitting corrosion – Fig 1). Stainless
steel can also corrode in service if there is
contamination of the surface. The high temperature
induced during welding also results in severe
chromium depletion not only at the weld surface but
throughout the heat affected area. Therefore just
removing surface material such as oxide scale is only
half the job as the weld area is still chromium
depleted relative to the parent stainless steel.
Critically when stainless steel is depleted of chromium
its corrosive resistance is severely reduced. The weld
is therefore vulnerable to pitting and crevice
corrosion.
Both pickling and passivation and electro‐polishing are
chemical treatments applied to the surface of
stainless steel to remove contaminants and assist the
formation of a continuous chromium‐oxide, passive
film. There are several methods to restore the
corrosion resistance of stainless steels. Some of these
methods under discussion will also increase the
thickness of the chromium oxide layer.
Methods of Restoring Corrosion Resistance Prior to any attempts to restore the oxide layer,
removal of oil, grease or inorganic contaminants by
degreasing of the material’s surface is an especially
important operation. Acid pickling and electro‐
polishing methods will not break through an oil or
grease barrier and mechanical abrasion methods
(sanding, sand blasting etc) tend to ‘push’ surface
contaminants into the material rather than rid the
surface of them.
Fig 1 Photo revealing localised attack
Pickling & Passivation 4
Vol 2 2010 WeldED
This corrosion resistance can only be achieved if
proper cleaning and finishing operations are carried
out after any fabrication process as there will have
been damage to the surface condition.
The next sections will give some detail on restoring
corrosion resistance.
Auto-passivation Stainless steels will naturally form a chromium‐oxide
layer if the surface is exposed to sufficient oxygen.
This occurs automatically and instantaneously but will
increase in thickness after its initial formation. In this
way stainless steels keep their corrosion resistance
even where mechanical damage (e.g. scratching or
machining) occurs. The chromium in stainless steels is
primarily responsible for the formation of the oxide
layer and for this to occur there must be a minimum
of 10.5% (by weight) of chromium. The mechanism by
which the oxide layer forms is called self‐passivation
or auto passivation.
Passivation As discussed above, passivation naturally occurs on
the surfaces of stainless steels, but it might
sometimes be necessary to assist the process. No
metal is removed during this process. The quality and
thickness of the chromium oxide layer is quickly
developed during acid passivation. The chemical used
is Nitric acid (HNO3) and used alone will only passivate
stainless steel. Common passivation treatments will
clean the steel surface of free iron contaminants. Care
must be taken in selecting and using passivation
treatments to ensure the selected treatment will
target the contaminant. Passivation does not usually
Result in a marked change in appearance of the steel
surface. Stainless parts or surfaces must be rid of
grease and oils that contaminate the surface. The
nitric acid used for this passivation process will not
remove these types of contaminants and the surface
will become mottled and an incomplete passive layer
likely to result.
Pickling and Passivation This method is the most commonly employed in
industry and is the one best known. It is the brush on
paste, where the solution is mixed with an inert
carrier that is used to treat selected areas such as
welds. Spray on treatments is also available for larger
surface areas (Fig 2). Pickling involves the removal of a
thin layer of the stainless steel surface with the use of
strong acids, typically a Nitric and Hydrofluoric (HF)
acid combination. Procedures incorporating pickling
solutions of nitric and hydrofluoric acids remove the
scale and the underlying chromium depleted layer and
restore the corrosion resistance. Pickling solutions
also remove contaminants such as ferrous and ferric
oxide particles.
Pickling solutions other than mixtures of nitric and
hydrofluoric acids exist and can be used for
specialised applications. One example, used in the
wine industry, is for the use of citric acids to treat the
stainless steel surface of the large wine vats.
Fig 3 Before and After treatment
Fig 2 Large vessel being treated
Pickling & Passivation 5
Vol 2 2010 WeldED
Mechanical Cleaning with tools such as mechanically grinding,
buffing, wire brushing and/or polishing the weld is a
surface treatment that is also employed by the
stainless fabrication industry.
Mechanical removal may leave abrasive or other
particles embedded. The corrosion resistance of the
stainless steel is affected by the roughness of the
surface after polishing, with a marked decrease of the
corrosion resistance as the surface roughness
increases above a Ra value of about 0.5 micron
(0.005mm). This roughly corresponds to the surface
produced by grinding with 320 grit abrasives.
Iron‐oxides, polishing compounds and other materials
can then become entrapped in the distorted
structure, creating a vulnerability point for surface
corrosion so mechanical finishing of stainless steel
material is typically a poor corrosive resistant finish.
Electro-Polishing Electro‐polishing is a useful alternative to pickling.
Metal removal is achieved, but usually results in a
bright, smooth and more highly corrosion resistant
finish Pickling is the process where
Research has shown that the best way to post‐weld
finish stainless steel is electro‐polishing, which is an
electrochemical process that increases density of the
chromium throughout the weld surface and therefore
the ability to create the chromium oxide film. Electro‐
polishing provides the most dense and durable
passive film that it is possible to achieve.
Electro‐polishing has two benefits beyond removing
weld scale. One is that it selectively dissolves the
microscopic high points of the stainless and creates a
microscopically smoother surface on which
contaminates can not bind or hide. Figures 3 and 4
reveal this effect.
The second benefit is that it selectively removes iron
at a higher rate than chromium which is why the
chromium density is increased.
Electro‐polishing can be accomplished by immersion of the item in a large, acid‐containing bath. It is impractical to perform this on‐site but it can also be achieved with a portable electro‐polishing machine or weld cleaning machine that runs on a direct current. This method uses an electrochemical cell on the metal surface, akin to electro‐polishing.
The weldment is connected as the anode at which metal is dissolved, removing the oxide layer, leaving a clean surface.
With a direct current and specific solution chemistry, electro‐polishing can occur, which results in a high surface lustre. Figure 5 reveals the results of electro‐polishing on the surface of a vessel.
Fig 3 Material surface before polishing
Fig 4 Material surface after polishing
Fig 5 Photo of tank after immersion
Pickling & Passivation 6
Vol 2 2010 WeldED
Best results are achieved with electro‐polished direct
current which gives a significantly better result than
mechanical cleaning and pickling paste.
It may be advantageous to neutralise the acid with an
alkali before the rinsing step.
Safety Both pickling and passivation solutions can employ
dangerous acids that can damage both the operator
and the environment if not handled correctly. Normal
precautions for safety should be followed and always
consult Materials Safety Data Sheets and product
packaging for detailed advice.
Conclusion In conclusion, it can be stated that from this
discussion, there is a hierarchy of results based on the
process employed to improve the corrosion resistance
of stainless steels. The table below broadly outlines
from worst case to best case.
Process Result
As‐welded Detrimental to corrosion
resistance
Mechanical
polishing/abrasion
May leave abrasive
embedded
Corrosion resistance of the
stainless steel is affected by
the roughness of the
surface
Typically a poor corrosive
resistant finish
Acid Passivation
The quality and thickness of
the chromium oxide layer is
quickly developed
Will clean the steel surface
of free iron contaminants.
Surfaces must be degreased
prior to use
Pickling & Passivation
Solutions of HNO3 and HF
remove scale and the
underlying chromium
depleted layer
Good restoration of
corrosion resistance
Solutions will remove
contaminants
Can be readily used on‐site
and on large and small
surfaces
Electro‐polishing
Best method of post‐weld
finishing stainless steel
Increases density of the
chromium
Creates a microscopically
smoother surface
Minor portability issues,
portable DC
electropolishing machines
are available
Table 1 Hierarchy of results
Pickling & Passivation 7
Vol 2 2010 WeldED
Stainless pickling acids are highly corrosive to carbon
steel. It is essential that all acids are thoroughly
removed by rinsing the component after completing
the process. Residual hydrofluoric acid will initiate
pitting corrosion.
ASTM A380 Standard Practice for Cleaning, Descaling
and Passivation of Stainless Steel Parts, Equipment
and Systems is a valuable source of information on
pickling and passivation treatments.
The two figures below highlight a fabrication that has
undergone a post weld treatment. In a corrosive
environment the item identified in Figure 7 will
significantly outlast the component that has had no
post‐weld finishing.
References 1. Euro Inox –Materials and Applications Series,
Volume 4
2. Stainless Steel Post Weld Finishing/Post
Fabrication Clean up ‐A Technical Review by
Metal Science Technologies August 2010.
3. ASSDA – Australian Stainless Steel
Development Association
Useful Links 1. www.assda.asn.au
2. www.euro-inox.org
3. www.avestawelding.com
4. www.metalscience.com.au
Author:
Alec Kimber IWE
Fig 6 No post‐weld treatment Fig 7 After post‐weld treatment
L&A Pressure 8
Vol 2 2010 WeldED
L&A Pressure Welding Pty Ltd AWI Member Company Overview
L&A Pressure Welding Pty Ltd is an established Sydney based supplier of
pressure equipment and has a long history of providing solutions and equipment
to projects ranging from small maintenance jobs to large LNG developments.
Involvement in several major projects over the last 5 years has been used to
build up the company’s knowledge and services in engineering design, project
and quality system management.
The company operates from a 5700m2 undercover work shop with a base staff of
approximately 45 shop employees.
Figure 1 – 80mm thick boiler
with in‐house lined tubes
Facilities include two PWHT furnaces for equipment up to 20m long x 4.0m in diameter; plate rolling up to 50mm
thick and hydro testing equipment up to 80,000kPa. Overhead cranes provide an 80 tonne lifting capacity; handling
of heavier units has been achieved by utilising jacking systems. An on site machine shop supports the fabrication
process, enabling most activities to be handled in house.
Manufacturing experience covers a range of equipment from typical
pressure vessel, heat exchanger and column design through to specialised
waste heat boiler fabrication. Complete supply, assembly and factory
acceptance testing of multiple air cooler units and piping skids have
recently been executed providing clients with a single delivery option for
their work packages.
Figure 2 – FOB Delivery of assembled skids
Involvement in major project work has extended our design and fabrication scope to include specialised transport
and installation engineering, a service that assists clients requiring free‐
on‐board and site delivery terms.
Extensive involvement in the pressure industry over many years has
created a significant amount of experience in design, covering
equipment that meets all classes of AS1210, ASME VIII and TEMA codes.
Design is carried out using PV Elite and Nozzle pro, drafting is supported
through AutoCAD & Inventor for 3D applications, pipe spooling projects
utilise CADworx. Specialised projects have extended design scope into
areas of high temperature creep and cyclic analysis through FEA.
Figure 3 – loading U‐Tube Bundle
L&A Pressure 9
Vol 2 2010 WeldED
The diverse project scope undertaken over time has exposed our project,
manufacturing and welding personnel to a broad range of materials and
technical challenges. Through in‐house development of welding
procedures the company has established a range of options for welding
exotic materials such as; Super Duplex, Inconel, Titanium, Hastelloy, Monel
and clad plated carbon steels. Construction of heavy wall carbon steel
equipment (150mm thick) has seen the development of specialised
manufacturing and heat treatment processes to achieve low temperature
impact, tensile & hardness requirements.
Design, procurement and manufacturing are supported by a vast
network of specialised engineering and supplier services sourced
both locally and internationally. L&A are also currently supporting
related postgraduate research programs and engineering studies as
well as maintaining a continual training environment for apprentice
boilermakers and welders. L&A Pressure Welding are committed to
supporting Australian manufacturing and are looking forward to
continue support from the oil and gas sector in their development
of Australian resources
Photos of Other Recent Projects
Figure 4 ‐ Inconel 825 Header box Figure 7 ‐ 316 Vessel for Export
Fig 4 SAW on heavy LF2 nozzle to shell joint
Fig 5 Welding on 50mm thick CS vessel
The Lighter Side of Welding 10
Vol 2 2010 WeldED
My encounter with HF
Last weekend as I was walking home from my day at the
shipyard; I saw something at the Pawn Shop that sparked
my interest. Our 22nd wedding anniversary was due and I
was looking for a little something extra for my wife. What I
saw advertised in the window was a 100,000‐volt, purse‐
sized taser. The effects of the taser were supposed to be
short lived, with no long‐term adverse affect on your
assailant, allowing her adequate time to retreat to safety....
WAY TOO COOL!
Long story short, I paid for it and brought it home. I loaded
two AAA batteries in it and pushed the button. Nothing! I
was disappointed. I learned, however, that if I pushed the
button AND pressed it against a metal surface at the same
time; I'd get the blue arch of electricity darting back and
forth between the prongs, just like the high frequency on
my TIG torch……….Awesome!!! Okay, so I was home alone
with this new toy, thinking to myself that it couldn't be all
that bad with only two AAA batteries, right?!! There I sat in
my recliner, my cat Gracie sitting on the arm and looking on
intently (trusting little soul) while I was reading the
directions and thinking that I really needed to try this thing
out on a flesh & blood moving target. I must admit I thought
about zapping Gracie (for a fraction of a second) and
thought better of it. She is such a sweet cat. But, if I was
going to give this thing to my wife to protect herself against
a mugger, I did want some assurance that it would work as
advertised. Was I wrong? So, I’m sat there in a pair of shorts
and my singlet with my reading glasses perched delicately
on the bridge of my nose, directions in one hand, and taser
in another and itching to try it out!!
The directions said that a one‐second burst would shock
and disorient your assailant; a two‐second burst was
supposed to cause muscle spasms and a major loss of bodily
control; a three‐second burst would purportedly make your
assailant flop on the ground like a fish out of water. Any
burst longer than three seconds would be wasting the
batteries. Now I’ve been on the end of those HF tingles and
the damp electrode shocks you get and all the while I'm
looking at this little taser‐thing measuring about 200mm
long, less than 20mm in circumference; pretty cute really
and loaded with ONLY two tiny AAA batteries thinking to
myself, "no possible way!" I'm sitting there alone, Gracie
looking on and I’m thinking that a one‐second burst from
such a tiny little thing couldn't hurt all that bad so I decided
to give myself a one‐second burst just for the hell of it.
What happened next is almost beyond description, but I'll
do my best...
I touched the prongs to my naked thigh, pushed the button,
and……….HOLY MOTHER OF GOD!!!
I'm pretty sure at that VERY SAME MOMENT…..a pack of
Wallabies forwards ran in through the side door, picked me
and the recliner up……and body slammed us both on the
carpet, over and over and over again. I vaguely recall
waking up on my side in the foetal position, with tears
running from my bulging eyeballs, my body was soaking
wet, both of my nipples were on fire and I couldn’t feel
anything from the waist down!!! My left arm was tucked
under my body in the oddest position, and my legs were
kicking imaginary objects!! A minute or so later (I can't be
sure, as time was a relative thing at that point), I collected
what little wits I had left and managed to sit up and survey
the landscape. My bent reading glasses were on the mantel
of the fireplace. How did they up get there???
The cat was making meowing sounds I had never heard
before and seemed to be clinging to the picture rail….half
way up the wall!! The recliner was across the other side of
the room…upside down and I was wet due to a problem I
seemed to have had with my bladder!! My triceps, right
thigh and both nipples were still twitching. My face felt like
it had been shot up with Novocain, and my bottom lip
seemed to weigh 20kgs!!
Note: If you ever feel compelled to "mug" yourself with a
taser, one note of caution: it is DEFINITELY not the same as
a damp electrode or a tingle from a GTAW HF unit!!....and
there is no such thing as a one‐second burst when you zap
yourself. You will not let go of the bloody thing until it is
dislodged from your hand by violently thrashing about on
the floor. A three second burst would be considered
conservative.
Progress Update 11
Vol 2 2010 WeldED
Progress Update on the AWI
Well, it has now been two months since the Australian
Welding Institute has been launched and what an
interesting two months!
In the days after launching, we have received letters,
emails, faxes, phone calls, even personal visits from
people offering all manner of support and
congratulations. This has come not just from the welding
industry itself but from many associated industries such
as mining, NDT, teaching, certification bodies, career
guidance, railways and from the cutting industry, plasma,
gas cutting, grinding etc.
We are amazed at the interest we have received via our
website. Although it is still in its infancy and will develop
over the coming months, the huge number of hits and
downloads has taken us by surprise. We have had to
triple our bandwidth to cope. The interest has not just
been from within Australia. To date, we have had people
from 25 different countries connect to our website.
It seems the most popular downloads have been the
calculators and technical forms in the "Services" and
"Technical Resources" sections.
Shindaiwa has become our first Gold Sponsor. They were
quickly followed by SPW (South Pacific Welding Group)
as our Silver Sponsor with SafeTac, Southern Cross
Industrial Supplies and Bureau Veritas becoming Bronze
Sponsors.
Although membership is currently free of charge, we
have had most people contributing something to the
Institute to become members. While some have not
contributed money, they have offered their time or
expertise to assist in some way. This has been
tremendously encouraging.
All members should by now have received their
membership card. This idea came about after the first
WeldEd had been issued so members were not notified
that they would receive one.
Hopefully it came as a pleasant surprise for everyone.
One eagle‐eyed member pointed out a "deliberate"
mistake in our first technical article on Duplex Steels. OK,
it was a typo. (That's our excuse!).
If you didn't spot it, it was on page 9 under Welding
Methods – GTAW. It should have read “This method of
welding should employ DCEN…..” (direct current
electrode negative) instead of the incorrect DCEP.
Thanks Scott.
We are currently in the process of completing our
Education and Certification working group. We still have
much work to do but we believe this will be up and
running by the time the next WeldEd is out.
While we have received plenty of support, we would
love to see more feedback on what you think would be
interesting or what subjects you want more information
on.
When we contact
people directly, there
is no shortage of ideas
or suggestions on
what direction we
should take or what
aspects of the
industry they would
love to know more about.
This ranges from information on jobs, welding
parameters, what gas to use, AC or DC current, what
Standard applies, where do I get more training, safety
issues etc. etc.
Most people seem to have the same concerns or
interests. This is YOUR institute. Our job is to support
YOU.
Please contact us at [email protected] with
your questions and suggestions (good or bad).
Welding Regards,
The Directors.
Progress Update 12
Vol 2 2010 WeldED
Progress Update on the AWI
Website.
The AWI website has been put together as a portal for
members to access information and technical resources.
It has now been up for approx 8 weeks and the response
has been fantastic, with 40,000 hits in this period. We
have had to upgrade our bandwidth to cope with the
traffic.
There are some fantastic resources available on the
technical resources page such as;
The Cigweld Handbook
Migatronic Technical Sheets
CE Calculator
Heat Input Calculator
Consumable Calculator
The forum has also had a unbelievable launch with many
Q&A being posted. The forum is there so members can
assist one another with technical or other issues. The
Q&A are available indefinitely as a virtual technical
library for members.
We have also registered a Facebook page
www.facebook.com/austwelding giving members
updates on our progress and a media for real time
feedback.
We encourage you to get online and visit
www.austwelding.com.au and have a look for yourself.
To contribute to the technical resource page, please
email any documents, templates or technical
information to [email protected].
Regards
The Directors
AWI
Design and Defects 13
Vol 2 2010 WeldED
Case Study:
How design can contribute to increased costs and rework
Introduction
The purpose of this document is to detail a case
study of how design can contribute to increased
costs and rework, by using inappropriate detailing
and joint configurations.
To achieve welds to an acceptable standard in a
reasonable time period requires good access to
the joints to be welded. Without good access to
the joints the operators struggle to see what they
are doing, struggle to move in a smooth
consistent manner required for producing
acceptable welds, Operator duty cycle (amount of
arc on time) drops dramatically because of
operator fatigue due to cramped conditions and
the likelihood of workplace accidents increases.
The Data
This case study has been developed on data
assembled from my observations of welding
operators trying to weld these joints, from
personal experience trying to get in there myself,
to weld the joints and physical measurements
taken from the job. The data was gathered in the
period of August 2006 – October 2006.
Actual conditions when welding with Gas Metal
Arc Welding (GMA/MIG) were such that, out of
20 qualified and tested operators, only three
where capable of producing AS1554.1 compliant
welds in these very cramped positions, this ratio
would be typical in most engineering workshops.
Images of observations are seen in the examples
and are as follows:
Overall view of
conditions
These images show that a standard welding
helmet cannot get between the members to be
joined
Design and Defects 14
Vol 2 2010 WeldED
The use of special limited access helmets were
used to make access easier, with minimal affect
Actual conditions when operator is welding, this
guy has 82cm waist, right handed.
Considerations:
The larger the operator the lower the access
Consider the use of left and right handed
operators
Image showing you cannot get your head high
enough to get good vision of the joint
Image above showing 82cm waist guy wedged
between members to get access, not only does
it increase difficulty it creates a dangerous
situation due to increased risk of
electrocution, burns, fume inhalation and
physical strain due to ergonomics.
Examples of burns sustained to operators
because they were having to stretch to get
into tight positions when welding resulting in
PPE being less effective (ie jacket riding up)
Design and Defects 15
Vol 2 2010 WeldED
Image showing a larger operator (92cm waist)
trying to access joints in the flat position. Keep
in mind these operators have to be able to
move the hands along a predetermined path
at a rate of about 200 to 300mm per minute
and the operator typically needs their eyes to
be at reading distance from the joint to be
able to focus on what they are doing.
Issues arising from the data
The issue that presented itself when looking at
the data is that in this case the detailing /
product design was such, that access to some
of the joints was very limited.
If you cannot get your head into a position to
see what you are doing when welding you are
fighting an uphill battle, your eyes need to be
at reading distance or it makes welding
operations very difficult. As the data shows the
actual dimension of a welding helmet is
greater than that of the opening the operators
need to get into to see the joint, this is not
something a draftsperson would be aware of.
Seeing the joint is the first requirement, being
able to move along the joint slowly, consistently
and accurately whilst the arc is on is the next
challenge and in these conditions it is nearly
impossible. Indeed some joints were impossible
to weld and had to be modified, where possible,
to suit.
This limited access as seen in this case
contributed to
increased weld discontinuities
therefore increased welding inspection costs to detect discontinuities and sentence to code, to determine defects
increased rework to repair defects
lower operator duty cycle and higher injury rates due to cramped conditions
increased consumable and labour costs because of rework.
Summary
Prior to detailing projects, one must understand
the fabrication and welding processes that will be
used in construction, the processes applications,
limitations and access requirements to ensure the
design is practical and economical to produce.
Fabricators must carefully review drawings at
tender stage to ensure the component they are
about to build is achievable and if there is any
doubt they should go back to the client with their
concerns.
Author:
Graham Fry ‐ Technoweld Pty. Ltd.
Membership Application
Title: (Mr, Mrs, Ms) _______________________________________________________ Name: _____________________________________________________________ Date of Birth: _____________________________________________________________ Company: _____________________________________________________________ Position: _____________________________________________________________ Address: _____________________________________________________________ Suburb: _____________________________________________________________ State: ______________________________ Post Code: _________________________ Email Address: ________________________________________________________ Contact Phone Number: __________________________________________________ Type of Membership: (circle one) Corporate Individual I, the undersigned, agree to be bound by the constitution of the Australian Welding Institute (available by request) Signature: _________________________________ Date: ______________________________________ Please return to your local representative Or email to [email protected] Or Post to PO Box 618, Penrith, NSW 2751
AWI is a Not for Profit Body for the Welding Industry Voluntary Membership Contribution Amount: $________ Membership is free, but if you contribute a voluntary contribution you go into a draw for a Cigweld Inverter (1st prize) and a Sperian Welding Helmet (2nd prize) (both drawn 1/12/10). Contribution can be submitted by direct transfer to Bank: BankWest, Account: Australian Welding Institute, BSB: 302-966 Account Number: 0101604 Remittance: [email protected] Membership is free, with the long term view of charging a minimum value to cover the cost of administration of the organisation as the organisation grows and offers additional services to you as a member. The Directors of the AWI thank you in advance for your support
Membership Benefits
The provision of a professional network for members to exchange information and ideas relating to all things welding
Subscription to the E-News Bulletin “WeldED”
The opportunity to join a national organisation whose main objectives are to:
Promote the advancement of the Australian welding and
fabrication industry Promote its members and their services to others in the welding
industry Create a network of people who are passionate about and want to
aid the Australian welding and fabrication industry Endorsement of Australian welding and inspection qualifications
Encourage participation in working groups to further develop your
knowledge in your area of specialisation and aid other members