WSC 8890
corrosion inhibitor provides excellent corrosion and deposit control for a
variety of open recirculating cooling water systems, where deposit and corrosion
free surfaces are required for system life and efficiency.
WSC 8890
is designed to provide minimum environmental impact while providing a highly
effective corrosion control alternative.
WSC 8890
is very effective in low hardness, low alkalinity corrosive waters. It contains
special filming ingredients to establish protective barriers against corrosion
on ferrous metal surfaces. It also contains a proprietary blend of organic and
polymeric sequestrants and dispersants to promote access of the corrosion
control actives to corrosion sites.
WSC 8890
contains no molybdenum or chromate
Features
WSC 8890
is a combination of an organophosphorus compound, zinc and polymer deposit
control agent. This unique blend assures excellent conventional cathodic and
anodic corrosion control.
The organophosphorous act as corrosion inhibitors, absorbing on to metal
surfaces to form a protective film. This film acts as a barrier, denying access
of oxygen to the metal surface, thus stiffling the corrosion process.
The incorporation of zinc into WSC
8890,
gives additional
cathodic metal protection. This results in a much more resistant and adherent
barrier film on the metal surfaces than with other traditional blends.
Effective against primary water stress corrosion cracking (PWSCC)
WSC 8890
is extremely effective against primary water
stress corrosion cracking (PWSCC)
Ample measures have been
taken to cope with this situation, including residual stress relief by heat
treatment, modified scheduled inspections, and the use of tubing materials which
have high resistance to PWSCC in modern power plants.
·
Effect of WSC
8890 addition on PWSCC
WSC 8890
addition is employed to prevent PWSCC in
alloy 600MA tubing
Under simulated primary accelerated corrosion
test conditions at 360°C, the susceptibility of alloy 600MA to PWSCC decreased
with the addition of WSC 8890.
§
Investigation of the
Mechanism of WSC
8890 Inhibition of PWSCC
Since it is considered
that the condition of the surface oxide film may have a close relationship to
the initiation of PWSCC, it is investigated the effect of WSC 8890
addition on the condition of the stainless steel’s alloy 600MA surface oxide
film in detail.
The addition of WSC 8890 thinned the
surface oxide film , and the corrosive products formed on the oxide film also
decreased in quantity.
This result suggests
that WSC 8890 is effective in inhibiting the corrosion reaction.
·
The surface oxide film was of
double-layer structure when WSC 8890 was not added. The outer layer was
rich in iron composition and poor in corrosion resistance, and the inner layer
was rich in chromium and highly corrosion resistant.
·
When WSC 8890 was
added, the outer layer rich in iron content disappeared, leaving only the highly
corrosion resistant chromium layer .
Advantages
·
STABLE even at elevated skin
temperatures.
·
EFFECTIVE corrosion control at
stability indices as high as 10.
·
ANTIFOULANT properties, thus
maximize heat transfer and minimize under-deposit corrosion.
·
PROTECTS
against galvanic corrosion in mixed-metal systems.
·
EXCEPTIONALLY EFFECTIVE control
of pitting of ferrous metals.
·
CONVENIENT single-package
treatment for corrosion and fouling.
Description
Appearance : clear to slightly hazy yellow liquid
Density
(g/lt) : 1200
pH (1% solution) : 2.7
Solubility in water : infinite
Freezing point : <-5°C
These data are to be seen as typical values and should not be considered as
specifications.
Feeding
Recommended feeding of
WSC 8890 is
15-50 ppm in the circulating water.
The pretreatment dosage should be 30-100 ppm for a two week period after which
the concentration may be allowed to revert tot he maintenance level.
The optimum system pH is 7.5 to 8.8.
WSC 8890
should not be used when the stability index of the system water is below 6.0.
The recommended feeding method is continuously as received to an aqueous
dilution to any convenient point, from which good distribution is ensured.
Feeding equipment should be constructed of a suitable plastic material such as
polyethylene, polypropylene or PVC.
WSC
8890 must be fed continuously to
the system by a proportioning pump. Automated systems to control conductivity,
pH, and inhibitor level in the system water are available from Water Services
Ltd, which may include micro-processor control and interfacing with other
computers in the plant.
Transport classifications
A.D.R. : 8-5c
IMDG : 8-8247
U.N.nr : 1840-III
Labelling for handling
Symbol : C, corrosive
R-phrases : 34
S-phrases : 26, 28, 36/37/39
Packaging
WSC 8890 is
packed in 32 and 250 kg PE drums.
