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ZMR2-07.CHP:Corel VENTURA
Accelerated Corrosion of Ferrous Metals Resulting from
Zebra Mussel Infestations and Control Measures
Purpose
The purpose of this note is to discuss the relationship between zebra mussel
macrofouling and the degradation of ferrous metal surfaces.
Additional
information
For more information, contact the author of this note, Mr. Tim Race, (217) 373-
6769, U.S. Army Construction Engineering Research Laboratories. Dr. Ed
Theriot, U.S. Army Engineer Waterways Experiment Station (WES), (601) 634-
2678, is Manager of the Zebra Mussel Research Program.
Description
Accelerated corrosion of ferrous metals can occur directly as a result of zebra
mussel infestation or as a result of treatments used to prevent fouling. For ex-
ample, chlorine is being used to control and prevent zebra mussel infestations.
High chloride content of water is a direct cause of corrosion of stainless and
mild steels. High chloride environments also are more corrosive to steels pro-
tected with coatings. Thermal backflushing systems are also used to eradicate
zebra mussel infestations. The rate of corrosion is directly proportional to
water temperature. Degradation of protective coatings can also be affected by
water temperature and thermal cycling.
Some facilities manage their zebra mussel problems by performing periodic
cleaning. Mechanical cleaning methods such as high-pressure water blasting or
scraping can damage the protective coating system, resulting in increased corro-
sion if the damage is not repaired before returning the item to service.
The buildup of a heavy layer of zebra mussels on a surface can produce anaero-
bic conditions at the substrate. Microbiologically induced corrosion (MIC) is
caused by many types of anaerobic bacteria. Stainless steel weldments are par-
ticularly susceptible to MIC. Oxygen concentration cells may be caused by ze-
bra mussel infestations. This effect will establish corrosion cells, which may
accelerate corrosion of both coated and bare ferrous substrates.
Recommendations
Methods for cleaning fouled substrates and for preventing infestations should
be selected that minimize coating damage and corrosion. Ferrous metal sys-
tems and components likely to be fouled by zebra mussels should be designed
with an understanding of the added potential for severe corrosion problems.
Uncoated sheet piling and welded stainless steel construction are particularly
US Army Corps
of Engineers
Waterways Experiment
Station
Prepared and published by the Zebra Mussel Research Program, U.S. Army Engineer Waterways Experiment Station, 3909
Halls Ferry Road, Vicksburg, MS
39180-6199.
Z
ebra
M
ussel
R
esearch
Technical Notes
Section 2 Control Methods
Technical Note ZMR-2-07
July 1992 susceptible to MIC. Protective coating systems subjected to chlorine or other
biocides often have to be repaired or replaced more frequently.
Technical Note ZMR-2-07
July 1992
Zebra Mussel Research Technical Notes
2