Written by Ed Craig... www.weldreality.com.
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MIG CLAD AND OVERLAY WELDS:
hope your company does not make pulsed MIG Inconel clad welds like this.
|USA power station, boiler water wall being destroyed by poor manual pused MIG clad weld equipment - practices and of course apathetic weld management.
Photo: This sad approach to placing welds on boiler water wall tubes, was
proudly displayed on the cover of a 2008 USA welding magazine. The magazine clad
article was about the wonderful, new, 2008 pulsed MIG equipment available from
Miller Electric and the suitability of this equipment to this Inconel clad application.
The reality is, these clad stringer welds indicate, bad weld practices, this is
not the way to produce water wall clad welds with either Inconel or Stainless
MIG weld wires.
The clad welds in the photo reveal a poor pulsed MIG program,
poor clad weld practices and poor weld techniques. These narrow, clad welds
will create inconsistent, unnecessary weld over lap, poor and excess weld tie
ins, inconsistent clad dilution, excess start stops, and their will be extensive
lack of clad weld fusion. This operation will result in excess distortion, uneven
wear, unnecessary stress risers all leading to reduced boiler operation efficiency
USA / European patented MIG weld process control approach to boiler water wall
weld. These welds were made with a $5000 (2005) pulsed power source.
622 on Boiler Water Walls. Weld section from 300 sq/ft clad section.
Ed's contribution to the
Waste Management Industries.
Welding Services (WSI) now Aquilex Atlanta: WSI is primarily involved in repairs and refurbishment
in the power, waste energy and nuclear industries. In terms of water wall
welding, WSI used to clad approx. 80% of the North American boilers. Each year
WSI uses approx. one million pounds of Inconel 625-622 and 300 series stainless
MIG wires for cladding boiler water wall tubes.
2006: ED WAS REQUESTED TO DEVELOP
A NEW WATER WALL CLAD PATENT: While WSI has produced some of the most innovative, automatic
MIG cladding equipment available in North America, WSI did not have a resident
MIG process control expert who had the expertise necessary to make radical improvements
to it's water wall clad MIG welds. Ed
was contracted for this work by PA the WSI
engineering manager. In less than 6 months, as the following pictures indicate,
Ed dramatically improved the water wall overlay weld quality and a new USA and
European clad weld patent was developed.
AS MOST ARE AWARE, WITH ALL CLAD WELDS, THE MOST DESIRABLE WELD ATTRIBUTE IS THE LEAST POSSIBLE WELD LESS DILUTION:
IMPROVING WATER WALL
BOILER LIFE - OPERATING EFFICIENCY:
many in the power industry are aware, with any water wall clad weld application "less
is always better". With less clad weld shrinkage and less clad weld defects, the boiler water walls will operate more efficiently when the single pass
clad weld surface is as thin as possible and when the clad weld pass thickness is both uniform and free
of weld defects.
The traditional methods of both manual and automated clad welds on boilers would produce clad welds that too often had too much weld filler, lacked uniformity, had poor weld tie ins and had extensive lack of fusio. The Inconel clad filler metals typically can cost over $23 - $26 LB. With these costly weld wires, it makes no sense to produce excess weld and create excess stresses and deformation on the boiler walls. My new clad patent dramatically
improved the single pass clad weld quality and dramatically
reduced the typical
single pass clad weld thickness providing extensive clad cost savings from the reduced weld wire requirements:
REDUCTION IN CONSUMABLE WELD COSTS PER-OPERATION.
With Inconel clad wires at $23 - $26LB and large water wall areas to be clad, the clad weld consumable
costs are typically a large part of the cost of a boiler clad application costs. My new pulsed MIG procedures reduced the amount of clad single pass, clad
weld overlay by approx. 28%.
PASSNCLAD WELDS YOU HAVE TO CONSISTENTLY PROVIDE MINIMUM CLAD WELD DILUTION:
water wall clad applications, the minimum, "single pass" Inconel weld
clad chemistry required is 20% chrome. As the filler metal typically provides approx 21% chrome To attain the minimum chrome requirements,
the pulsed MIG weld procedures with the vertical down clad welds consistently
attained minimum weld dilution < 8%, while achieving consistent weld fusion
on the carbon steel boiler tubes.
WITH LARGE WATER WALL AREAS SOMETIMES OVER 1000 sq/ft, THE CLAD PROCESS NEEDS TO ATTAIN THE HIGHEST POSSIBLE WELD DEPOSITION RATES:
primary part of clad weld costs on large weld areas as found with most clad boiler
wall applications, is dictated by
weld deposition rates attained. Ed's new patented clad procedure with
the unique, WSI automated weld equipment, enabled a single operator controlling
two guns to deposit approx. 28 - 30 lbs/hr.
you sell clad weld consumables, with
clad boiler welds, less is better.
Ed got involved with boiler water wall welds, the picture below was considered an
optimum, Inconel 622,
Vertical Down, Pulsed MIG, water wall, clad application.
Below, untouched the new clad patent showing obvious clad weld quality
a few months of pulsed MIG weld process development.
The final Inconel 622,
single pass, clad
weld results were developed by Ed for WSI in 2006 and the international USA patent was introduced in 2010.
Note the smooth single layer MIG clad surface with optimum weld ties ins. This
clad application was delivered from a low cost, $5000 pulsed MIG power source
in 2006. This clad weld has a smooth finish similar to a $250.000 laser - powder
clad overlay. In contrast to the conventional water wall clad welds, Ed's process
changes required 25 - 28 % less weld metal per sq/ft and for the single pass weld also
produced less weld dilution producing superior clad chemistry.
SPATTER WITH ANY MIG MODE IS USUALLY AN
INDICATION OF LACK OF PROCESS CONTROL
process expertise will always ensure that any
weld process utilized runs
without concern for weld spatter.
2006: Ed's patented weld on the left.
Typical clad welds on the right:
vertical down 622 Inconel / stainless clad MIG welds in Ed's patent were derived from a low cost,
five thousand dollar, pulsed MIG power source and a unique Inconel MIG gas
mix developed by Ed. (See the MIG gas data section at this site).
The patent would not have been possible without the WSI, customized. automated weld equipment that compensated
for the wire stick
out variations that resulted from the water wall curves.
|Why would any respectable engineer allow $23 - $26 LB, POOR Inconel clad welds
like this on a power
station boiler wall that costs million of dollars?.
Ed provided unique MIG Water Wall Clad Welds in the 1980's.
the 1980s, twenty years before the development of decent pulsed MIG equipment, Ed produced the Inconel
622 MIG clad weld shown in the left photo (cross section of a boiler tube). In
his clad weld there was no metallurgical evidence of a heat affected zone as evidence
in the macro.
In contrast on the right photo we have the typical MIG clad
weld fusion profiles
that the power industry and it's water wall boilers were accustomed to in 1980 and in 2008.
Inconel clad weld shown on the left macro was made
by Ed - Zugy without any cooling medium and made
MIG power source and process developed in 1963.
and a Unique Controlled Short Circuit Clad Weld made 1983
Don't try the above weld with your 2013 pulsed MIG power source as you will not achive a clad weld without a heat affected zone. This
622 MIG clad weld made by Ed and and his good buddy Zugy. The macro surprised the Foster
Wheeler senior metallurgist who examined it, as their was no evidence of the 622 weld
dilution with the carbon steel base alloy, and no evidence of the clad weld heat affected
try this in your weld shop..
WITHOUT MIG EQUIPMENT BELLS AND WHISTLES WE PRODUCED SOME REMARKABLE WELDS:
never had MIG equipment bells and whistles in the 1980s, yet we did have weld
process expertise and low cost MIG weld equipment developed in the 1960s. In those
days we were producing welds that are still are not produced 30 years later. In
1980 if you wanted a small vessel made from aluminum bronze you ordered a solid
bar stock and spent many hours ID and OD machining, or you had it cast at a foundry
and waited 6 months. Of course you could have or called Ed and his good buddy
Zugy and they would show you how with a few pounds on alum bronze 0.045 weld wire,
in a few hours you could make the part strictly out of weld metal as shown on the left. If you needed
a small vessel comprised of two different alloys such as the machined piece show above, with this part the customer want one half made out of Hastelloy and the other half made out of 316 stainless. With the Hastelloy - Stainless part, you could have
spent weeks figuring out how to make it and a small fortune in machining, or you
could have called Ed and Zugy and in less than a day the product would have been
made from Hastelloy and stainless MIG weld wire and of course the parts would pass any X-Ray evaluation. Of course if you wanted to find the
holy grail of welding, Ed and Zugy would have taken some Titanium weld wire and
in three hours made the above chalice again free of defects from a Titanium MIG weld
and Hydro-Processing Vessels
347 clad welds. Another common global clad application
overlay application influenced by Ed:
Electro Slag Strip Electrode Process applying ER 347 clad welds.
Above a common Electro Slag Common Application. In
the refinery industry, pressure vessels used in high temperature, high pressure
"hydrogen service" such as hydrocracking and hydrotreating are usually
constructed of Chrome / Molly or Vanadium modified Chrome / Moly steels. To overcome
corrosion areas with these vessels, clad welds of ER 347 alloy are typically applied
to plate or to wasted
areas on pressure vessels.
The most common, global cladding "process"
utilized for plate cladding used for hydrogen service, has been the Electro Slag
Welding (ESW). This process uses strip electrodes two to three inches wide. On
some applications a butter layer of ER 309 is requested followed by a surface
layer of ER 347 for the clad surface. On other applications a single layer of
ER 347 is applied.
the ESW process, high deposition welds result from weld current > 600 amps.
The ESW process has been considered unique in that the large size of the strip
electrode results in low weld current density resulting in "low weld dilution".
The down side of th ESW clad process is;
The ESW is a "single" electrode process,
[b] ESW requires a large equipment package, it's cumbersome
and weld position restricted,
[c] the cost of the ESW clad consumables and
fluxes are high,
[d] there are few companies with ESW expertise.
American vessels are ESW clad in Japan.
a unique MIG weld wire found by Ed, and cladding equipment developed by WSI, Ed produced "single pass", MIG layer clad 347 welds
that met the hydrogen service 347 clad thickness, chemistry and ferrite requirements.
In comparison to the ESW and SAW process, thanks to the large differences in consumable
costs and the multi MIG gun capability, it's now possible in contrast to the ESW process to produce the 347 MIG
clad welds, depending on the application with a 30 to 50% cost reduction.
contrast to the much more costly ESW and SAW processes, the single pass MIG clad
procedure developed by Ed and WSI enables cladding on a much wider range of applications,
and allows the flexibility to provide the vessel cladding at any site locations with the vessel in any position.
This weld flexability dramatically reduces the vessel lead times or shipping costs to have this
clad work done.
MIG PROCESS CONTROL EXPERTISE CHANGED THIS TRADITIONAL
GLOBAL 347 ELECTRO
SLAG AND SAW WELD CLAD APPLICATION.
From ESW to Ed's 347 single pass MIG clad weld.
a clad MIG process that's faster, provides less distortion,
has less heat
effect on the steel, costs less and is much more versatile.
with TiP TiG and some pulsed MIG equipment,
in 2013 we can go where no man has gone before,
if you have to take weld advice from salesman, or your weld personnel "play"
with weld settings, you are no better off than you were in a weld shop in the 1960s and your weld issues may be costly...
you have a clad welding challenges on those ID-OD power plant, refinery, and well
head equipment such as ID welds on adapter flanges,bonnets, studded tees, tree
caps, weld neck flanges, gate valves, please note, you can invest hundreds of
thousands of dollars in sophisticated overlay equipment and never quite get that
application the way it could be. You could ask a salesman for your pulsed clad
MIG advice, or you could learn how to control this important process
and produce clad welds without weld rework.
Keep smiling after all you could be living in Russia.
Russia's solution to their poor quality auto - truch engine problems.
Russian fuel efficient one horse car.
Your keys to MIG weld process
you are teaching your self, or providing weld process control training for others,
the following resources are the key to attaining MIG and flux cored weld process
optimization. Note: Items 2-3-4 are
the most comprehensive process control,
self teaching and training programs ever developed..
The Book: "A Management & Engineers Guide To MIG Weld
Quality, Productivity & Costs"
2. A unique robot MIG training or self teaching
resource. "Optimum Robot MIG Welds from Weld Process Controls".
3. A unique MIG training or self teaching resource.
" Manual MIG Weld Process Optimization from Weld Process Controls".
4. A unique flux cored training or self teaching resource.
"Optimum Manual and Automated Flux Cored Plate and Pipe welds.
5a."Proceso de Soldadura MIG Manual" (MIG Made Simple. Self
teaching in Spanish)
6a. The Self Teaching MIG Book / Video. (MIG
Made Simple in English).
Ed's MIG / flux cored process control books and CD training