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PULSED
MIG CLAD AND OVERLAY WELDS:
Above:
This sad, manual clad weld photo was taken in 2008 and prodly dispalyed on the
cover of a welding magazine. The Inconel clad welds were made using the latest
2008 pused MIG equipment from Miller. This poor excuse for a weld operation is
not the way to clad weld boiler tubes with Inconel or Stainless MIG weld wires.
Pooe weld settings for Inconel, excess weld heat for the water walls. No weld
dilution or fusion controls. Poor weld overlap. Excess weld start / stops and
a 1000 other weld / boiler issues that will result.
Ed's
weld process control approach to water wall cladd welds,
using 2005 pulsed
MIG equipment
MIG
CLAD APPLICATION.
BOILER
WATER WALLS
Ed's contribution
to the power and
waste management industry
2007:
Welding Services (WSI) Atlanta: WSI is primarily involved in repairs and  refurbishment
in the power, waste energy and nuclear industries. In terms of water wall cladding,
WSI has 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.
CREATED
A NEW 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 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 clad weld patent was developed for
this industry
IMPROVED
BOILER LIFE AND OPERATING EFFICIENCY: As many in the power
industry are aware, with any cladding application "less
is always better". The boilers operate more efficiently when the clad
surface is thinner and the clad weld pass thickness is uniform and free of weld
defects. Ed's new patent dramatically improved the clad weld quality and dramatically
reduced the typical single pass clad weld thickness:
REDUCED
CONSUMABLE WELD COSTS. With Inconel clad wires at approx. $22 per-pound
and large areas to be clad, weld consumables are typically a large part of the
cost of a boiler clad application. Ed's new procedure reduced
the amount of clad weld overlay typically required by approx. 28%.
SINGLE
PASS / DILUTION: With water wall clad applications, the minimum, "single
pass" Inconel weld clad chemistry required is 20% chrome. To attain
the
minimum chrome requirements the pulsed MIG weld procedures had to ensure the weld
dilution was less than 8%. The vertical down clad
welds had to attain minimum weld dilution with consistent weld fusion on the carbon
steel boiler tubes.
COST EFFECTIVE WITH HIGH DEPOSITION
RATES:
Of course when cladding large areas sometimes 1000 to 10.000
sq. feet, the clad weld process improvements must also from a weld deposition
rate perspective be cost affective. Ed's new patented procedure and the WSI unique,
automated weld equipment enabled a single operator controlling two guns to deposit
26 - 28 lbs/hr.
With
Clad welds on boilers, less is always better,
unless you sell the weld consumables.
This
picture was considered an
optimum, Inconel, Vertical Down, Pulsed Clad MIG
weld.
After
pulsed MIG weld process improvements.
The final 622, single pass, clad weld
results were developed by Ed in 2006.
Ed's
MIG clad welds, note the smooth surface and improved weld ties ins.
This application
from a $6000 pulsed MIG power source now
has has a smooth finish similar to
a $250.000 laser / powder overlay.
On
left, traditional clad method for vert down 622 overlay (as welded not cleaned).
On right Ed's process improvements, again both as welded.
Note:
All photos are untouched and no weld cleaning except brushing was provided.
Weld
process expertise will always ensure that any
weld process utilized runs
without weld spatter.
2006: Ed's weld on the left typical
welds on the right:
 The
vertical down 622 Inconel / stainless clad MIG welds were derived from a low cost,
six thousand dollar power source and a MIG gas mix developed
by Ed. (See gas data section). The welds also required an engineering manager
that believed that there was more to MIG welding than asking the advice of a Lincoln
sales rep or an operator throwing a switch that initiates the arc. It also helped
that WSI had excellent, unique automated weld equipment that compensated for the
water wall curves (wire stick out variations). Ed's clad development was complete
in 2006. WSI applied for the Patent during 2006 - 2007.
Cladding
and Hydro-Processing Vessels 
2006:
Another common Global Application
overlay application influenced by Ed:
The
Electro Slag Strip Electrode Process
applying ER 347 clad welds.
The
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.
With
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 this process is;
[a]
its a "single" electrode process,
[b]
It's large, cumbersome and weld position restricted,
[c] the cost of the
clad consumables and flux are high,
[d] there are few companies with expertise.
Many North American vessels are clad in Japan.
Utilizing
a unique MIG weld wire found by Ed, and cladding equipment developed by WSI, has
enabled the ability to produce "single pass",
MIG layer clad 347 welds that meet 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 to produce the 347 MIG clad welds,
depending on the application with a 30 to 50% cost reduction.
In
contrast to the more costly ESW and SAW processes, the 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. This dramatically
reduces the vessel lead times or shipping costs to have this work done.
ED'S
MIG PROCESS EXPERTISE CHANGED
THIS TRADITIONAL GLOBAL 347 ELECTRO SLAG
AND
SAW WELD APPLICATION. 
To
a clad MIG process that's faster, provides less distortion,
has less heat
effect on the steel, costs less and is more versatile.
MIG
Cladding in the 1980's
In the 1980s, before the development of pulsed MIG, Ed produced this Inconel 622
MIG clad weld on a boiler tube. On the right is the clad weld fusion profiles
that the power industry was accustomed to.  
Ed's
Inconel clad weld on the left was made without any cooling medium and made with
a MIG process developed in 1963.
1983
This
clad weld surprised the metallurgist who examined it,
as their was no evidence
of the 622 weld dilution with the base alloy,
or evidence of a weld's heat
affected zone.
The
Clad Weld Challenges
of the next decade.
When
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.
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