Hydrocarbon Processing - June 2022 - GP-34

INSPECTION & MAINTENANCE
technology. This scenario is a common
occurrence at many oil and gas, refining
and petrochemical sites. Although
the initial cost of low-velocity thermal
spray is often much lower, the long-term
expense far outweighs the short-term
savings. To understand why the low-velocity
system failed, the science behind
various types of materials and application
methodology must be explored.
Standard welding alloys are unsuitFIG.
2. The 2021 inspection of the six columns
coated with a low-velocity thermal spray
showed severe corrosion and risk of failure.
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materials. In the following section, the results
of the application of HVTS on two
of the columns vs. the low-velocity thermal
spray applied by a local contractor on
six of the columns in 2016 are discussed.
The inspections: High-velocity vs.
low-velocity
thermal
sprays. The
first inspection of the two columns protected
by the author's company's HVTS
took place in 2018. No signs of further
corrosion were found, and the protective
cladding was in excellent, as-applied
condition.
An
additional
inspection by
the
plant's senior corrosion engineer in November
2021 revealed a staggering contrast
between the two columns sprayed
with HVTS in 2015 (FIG. 1) and the
other columns applied with the low-velocity
thermal spray in 2016. The HVTS
was still in excellent condition, with no
signs of cracking or failure. However,
the other columns sprayed with the lowvelocity
thermal spray (shown in FIG. 2)
indicated extreme signs of breakdown
of the applied cladding and corrosion
of the substrate, with the wall thickness
loss threatening to exceed its maximum
corrosion allowance.
If left, the continued corrosion could
result in an unplanned shutdown, potentially
costing millions of dollars in lost
revenue. In the best-case scenario, the
column would need to be stripped of the
remaining cladding, undergo mechanical
repairs (which is both costly and time
consuming), and then be protected with
a long-lasting HVTS.
The science behind HVTS, material
modification and application
34 MAY/JUNE 2022 | GasProcessingNews.com
able materials for thermal spray application
in critical internal process equipment,
as the cladding particles form
oxides on their surface in flight, creating
a fundamental weakness in the microstructure
and permeability. The author's
company develops alloys designed and
modified for high-performance thermal
spray application.
The author's company's HVTS conveyance
technologies atomize the bespoke
wire feedstock in a supersonic
gas stream, producing a cladding that
consists of flat and tightly packed microsized
particles. Conventionally available
thermal spray application systems cannot
produce equivalent particle sizes-
they have a more open microstructure
and do not impart sufficient energy to
flatten the particles that are inherently
highly stressed. These shortcomings
lead to premature failure due to permeation
from microstructural weaknesses
and cracking of the coating.
Takeaway. The results seen at this gas
plant confirm the performance difference
between applying an HVTS vs. a
conventional thermal spray, eliminating
the corrosion process. Visually seeing
the difference between the columns in
this case study sprayed in 2015 and the
columns sprayed with a low-velocity
thermal spray is reassuring to owneroperators.
The system and application
process have been successful in preventing
any further degradation or wastage
and resulted in significant savings for
the client. GP
DENNIS SNIJDERS is the Senior
Regional Director, Middle East
and North Africa, for IGS. He has
worked for more than 20 yr in
the corrosion industry, 15 yr of
which have been spent in the
Middle East. In his present
position, he is responsible for managing the
Middle East and North Africa regions for the entire
surface technology solution portfolio of IGS.
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Hydrocarbon Processing - June 2022

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