A number of state highway departments throughout the country have decreased the use of rock salt and sand on roadways and have increased the use of liquid magnesium chloride as a de-icer or anti-icer. The liquid magnesium chloride is sprayed on dry pavement prior to precipitation or wet pavement prior to freezing temperatures in the winter months to prevent snow and ice from adhering and bonding to the roadway. The application of anti-icers is utilized in an effort to improve highway safety. The use of this product seems to show an improvement in driving conditions during and after freezing precipitation yet it seems to be negatively affecting electric utilities.
Two main issues have been raised regarding the anti-icer magnesium chloride as it relates to electric utilities: contamination of insulators causing tracking and arcing across them, and corrosion of steel and aluminum poles and pole hardware.
The first issue in regard to magnesium chloride relates to the possible increase of outages and pole fires due to tracking and arcing across insulators. There are three cooperatives in Colorado that have seen an increase in outages and pole top fires that have been attributed to insulators becoming coated with magnesium chloride. The insulators become coated as vehicle traffic churns up the magnesium chloride into a fine mist that rises and settles on the pole hardware and insulators. As the solution builds up on the insulators the probability of tracking and arcing increases. An additional safety concern that borrowers should watch for is the possible effects on buckets and booms coated with this material as they may loose their dielectric integrity. Rain assists in removing some of the buildup but utilities have been forced to inspect and clean insulators with a soap and water mixture in certain areas where heavy buildup has occurred. This same inspection and cleaning method may be required for buckets and booms that have been exposed to the magnesium chloride anti-icer.
This is a costly and time-consuming process. In the March 23, 2001, issue of Electric Co-op Today, Jerry Lipson's article "New Winter Road Salt 'Burns' Colorado Co-op Lines" addresses this issue. In an effort to determine whether other cooperatives are experiencing similar problems, RUS asks borrowers to let RUS know whether they have any evidence of increased outages or pole fires in proximity to highways in areas where magnesium chloride is used.
The second issue, corrosion, may also be of concern to cooperatives. In the past, sodium chloride (rock salt) has been used as a de-icer and is known to be a corrosive product. Magnesium chloride is also known as a corrosive agent, but when utilized as a de-icer, other chemical agents are added to reduce and minimize this potential, but the corrosive attributes cannot totally be removed. State Highway departments indicate that they are seeing less evidence of corrosion to their trucks and equipment as well as the steel reinforcing bars inside concrete on roads and bridges when the magnesium chloride de-icer is used in comparison to sodium chloride. A concern still remains on its reaction with aluminum and galvanized steel poles, metal hardware and conductors. There has been some feedback from truckers stating that aluminum components and electrical systems in their vehicles are showing an increased corrosion rate. In an effort to determine whether the magnesium chloride de-icer is creating corrosion problems on electrical equipment, RUS is requesting assistance by asking cooperatives to identifying whether any evidence of corrosion on electrical equipment used in proximity to highways is apparent in areas where this product is used. The amount of corrosion may depend upon the type of anti-corrosive agents added to the magnesium chloride de-icer as well as the chemical reaction to the material utilized by electric utilities.
RUS is requesting any information and experiences that the cooperative can share in regard to magnesium chloride and its effects upon their electric systems. If you have any information to share, would like more information or have any questions, please send the information or contact John Pavek, Chief, Distribution Branch, at 202-720-5082 or jpavek@rus.usda.gov.