POWER May 2020 - 19

FOCUS ON O&M
area clad with IGS HVTS was no longer affected by corrosion
(Figure 5). Unprotected Alloy 625 WMO and the other vendor's
thermal spray, though, both continued to degrade.
It was decided to extend the scope and apply HVTS alloy cladding
onto an additional ~20 m2
area in 2019. Inspection later that
year, in August, confirmed the following: the areas protected
with HVTS alloy cladding were not exhibiting any pitting corrosion
or wastage. Adjacent unprotected Alloy 625 weld overlay
sections were showing signs of wear and degradation.
Weld Overlay Protection: Inspection and Results
Markus Benz, head of maintenance at Renergia Zentralschweiz
AG, said, " IGS Europe s.r.o. has been selected in November
2017 to apply ~20 m2
of their IGS material using their HVTS technology.
They mobilized efficiently and performed within the tight
4. Like-for-like weld overlay repair is an intensive process. It is designed
to protect the boiler tubes, in this case in a waste-to-energy
(WtE) boiler, from fireside corrosion. It requires preliminary grinding of
the degraded surface layer prior to the application of new weld overlay.
It provides protection, but does not solve the problem of corrosive
media continuing to attack the weld overlay. Courtesy: IGS
the boiler at the same time with no capacity limitations.
Supported by comprehensive laboratory testing and extensive
field experience, IGS HVTS Alloy Cladding has no issues with
permeability or disbondment and can offer lasting protection,
where other technologies fall short. The test application results
and additional references convinced the head of maintenance to
choose IGS HVTS as the solution to the plant's problem.
HVTS Application
IGS HVTS application took place in 2017 on a 20-square-meter
(m2) area located on the left membrane wall, at the very low
furnace of the moving grate WtE boiler above the refractory. The
plant also had a thermal spray coating applied by a different vendor
on the right-hand side of the membrane.
These areas were then inspected in 2018 to determine
whether HVTS and another vendor's thermal spray were successful
at stopping the weld-metal overlay (WMO) degradation.
The inspection of the HVTS/WMO interface showed that the
requested schedule the expected scope of work.
" After 10 months in operation, a short inspection of the wasteto-energy
boiler was performed in September 2018 confirming
the good performance of the coating, " said Benz. " As a result,
another area was ordered for application in January 2019, with
a deeper inspection confirming the good overall behavior of the
cladding after 14 months in operation. "
Benz continued: " The protected area has been doubled so
that we expect to operate safely until our next turnaround in
18 months. IGS has successfully applied the contracted scope
within the critical path in a highly professional manner, with reliable
and transparent communication. "
Ruedi Kummer, director of Renergia Zentralschweiz AG, was
complementary of the process. He commented: " Thank you for
the inspection review. It seems that the idea, to cover Alloy 625
with HVTS overlay, could have enormous potential. " ■
-Marina Silva is international marketing manager for
Integrated Global Services.
5. This illustration shows the sequence of high-velocity alloy cladding
applications and inspections from 2017 to 2019 at the Renergia
WtE plant in Switzerland. The photos show the difference between the
areas in the boiler protected with high-velocity thermal spray (HVTS)
versus the unprotected areas. Courtesy: IGS
May 2020 | POWER
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POWER May 2020

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