Chemical Engineering May 2021 - 40

INDUSTRY EXAMPLES
O
nce the basic concerns and protective mechanisms are understood,
it is helpful to see examples of restoration and
preservation of valves in action. These examples include a
variety of situations that demonstrate how preservation methods can
be similar, yet different from project to project.
Longterm preservation solution
In 2017, an API-accredited (American Petroleum Institute) valve
manufacturer in Dubai needed a corrosion-protection technology
during hydrostatic testing. Due to the harsh climatic conditions, the
valve manufacturer was having a significant problem with flash rust
and needed a way to remove this preexisting rust. The manufacturer
also desired a corrosion inhibitor coating that could be used to preserve
the valves for extended periods of outdoor storage prior to
commissioning. A VCI hydrotest additive was selected that would
deposit a thin protective film during hydrotesting and offer both contact
and vapor-phase protection. Bio-based chemistry was chosen
for rust removal and neutralized with a flash-rust-inhibiting cleaner.
A waxlike removable coating was recommended for outdoor storage
and further protection against salt, humidity, ultraviolet light and
other harsh weather elements [2].
Restoring valve bonnets after over five years in storage
In India, an energy-technology company had valve bonnet spares
that were rusted after more than five years of storage. Corporate
policy did not allow rust removal with phosphating or other harmful
chemical processes, so a bio-based rust remover was applied and
then neutralized with an alkaline cleaner. The valve bonnets were
restored in 45 minutes and ready to use [3].
Often, manufacturing facilities or
warehouses are not air-conditioned,
and these hot, humid environments
can wreak havoc in the form of flash
rust that blossoms on freshly machined
surfaces as the valves await
shipment or the next step in the
manufacturing process.
Once in shipment, whether by land
Protecting spare valves during facility startup
A newly constructed oil-and-gas facility in Alaska experienced problems
with corrosion even in the first month, as it received a large
influx of spare parts. The harsh environment and long delivery times
were to blame, and valves were among the items affected. These
were protected for future use by internally fogging them with VCI.
Machined faces were protected with a waxlike removable coating.
The package was completed by wrapping the entire valve in outdoor-grade
VCI shrink film. Any spares needing rust removal were
soaked in a bio-based rust remover prior to protection [4].
Restoring and protecting valves and other equipment
In 2018, an oil-and-gas company in Indonesia called in a consultant
to help it solve a corrosion problem on critical equipment, such
as valves and flanges. Some of the equipment had already been
used and first required restoration. Because of this, the consultant
broke the process into two steps: (1) surface preparation; and (2)
preservation. Mud or dried soil was cleaned off using a biodegradable,
low-pH organic-salt cleaning alternative to phosphoric and
nitric acid cleaners. A bio-based acidic rust remover was used on
existing corrosion, followed by rinsing with an alkaline flash-rustinhibiting
cleaner. Preservation of the different components varied
depending on the needs of each item. Removable coatings were
applied to some surfaces, while VCI was fogged into voids. Lastly,
the valves and other parts were wrapped in VCI films. The cleaning
procedure was especially efficient and did not require mechanical
grinding or blasting. Preservation of the first container of equipment
finished in November 2019, and the company was involved in processing
a second container of equipment using the same methods
in 2020 [5].

or by sea, the valves face another
challenging time when they are at
heightened risk for corrosion from
fluctuating temperatures, condensation
and possibly even exposure
to high-chloride-content sea spray.
The longer the valve has to remain
in these conditions, the worse the
results can be. Manufacturers must
therefore consider the potential situation
and take appropriate precautions
to avoid spoiled goods.
Cortec Case History 668
FIGURE 2. Wrapping valves prior to storage can
help prevent corrosion-related damage prior to
storage or shipment
40
Corrosion at new facilities
Another time that valves face a special
risk of corrosion is when they
arrive onsite at a new facility under
construction. This process of construction
and gradual startup can
take years, during which time, custom
and standard equipment and
components are delivered. Chances
are high that many of the pieces will
be stored on the grounds until all
components arrive and construction
and installation can be completed.
To avoid possible rusting problems
during storage, precautions can be
taken by the supplier, or by the user
onsite (Figure 2).
Keeping critical spares ready
Even after a plant is up and running,
a similar rust-prevention responsibility
falls on the facility. Best
practices call for making sure that
critical spares are always on hand to
replace a failed component quickly
with as little downtime as possible
(Figure 3). If the spare valves in storage
have rusted, this process will
be interrupted, whether from simply
having to restore the valve or
not being able to restore it at all.
Depending on the criticality of the
valve, this could have an impact
on valve safety in addition to repair
expenses and losses from stalled
production - a price tag that can
quickly add up, especially at chemical
processing facilities. If valves are
properly restored and preserved
ahead of time, the facility can
quickly get back to service using
these emergency backups that are
rust-free and ready to use.
Preserving assets in storage
The decision to shut down a plant
is often combined with plans to preserve
valuable assets until the time
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