Use
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
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.
