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Minimizing Corrosion – Calcium Chloride

Posted By admin On 06/08/2012 @ 12:06 pm In | No Comments

Minimizing Corrosion

Corrosion-Inhibited Calcium Chloride: Liquid Calcium Chloride is hard on ice, but easy on corrosion

The growing need for corrosion-inhibited deicers has prompted manufacturers to explore their production. One example of this is a new corrosion-inhibited grade of liquid calcium chloride introduced by General Chemical Corp. designed to meet or exceed Idaho’s and Washington’s deicer standards in all respects. In addition to providing low corrosion versus salt, it has calcium chloride’s operational benefits in that it continues to melt snow and ice below 20 deg F, the temperature at which salt becomes an inefficient deicer.

The Idaho DOT began using corrosion-inhibited calcium chloride in January 1996 for deicing and anti-icing. Those using the material in Idaho report that it aggressively melts snow and ice, and that it offers operational benefits versus magnesium chloride, which has been the primary deicer used in that state due to local availability.

Evaluations show that 25%, 30% and 32% aqueous solutions of the inhibited liquid calcium chloride produce just 4 to 7 mils/year of corrosion or 80% to 90% less corrosion than sodium chloride (see Figure 1 and Table 1). Testing was done by Control Services, Kerville, Texas, a leading independent corrosion testing laboratory, using the NACE methods in the Washington specification. The tests compared sodium chloride, regular and corrosion-inhibited calcium chloride, and water. Water is taken as the baseline, so its effects were subtracted from the corrosion values of the other materials.

Other advantages of the new corrosion-inhibited calcium chloride are its ability to cut through snow and ice more quickly than salt or magnesium chloride, lack of sediment problems in tanks and easy clean-up of vehicles.

Demand for corrosion-inhibited deicers appears to be here to stay. Washington and Idaho have pioneered programs to limit corrosion through strict specification on the corrosiveness of deicing chemicals, and other states and provinces are exploring its use. The availability of corrosion-inhibited products like the new corrosion-inhibited liquid calcium chloride, offers people an opportunity to move in this direction.

Table 1 Table 2
TYPICAL CORROSION VALUES* TYPICAL ANALYSIS OF CORROSION
Sodium chloride : 41-46 mils/year
Calcium chloride : 18-21 mils/year
Corrosion-inhibited calcium chloride : 4-7 mils/year
*Using the test method defined in the Washington State Department of Transportation deicer specification. Corrosion values reflect a water baseline –i.e., the corrosion of distilled water, taken as 4 mils/year, has been subtracted from all values.
Assay, weight percentage of CaCl2: 30-32
Alkali chlorides as NaCl, weight percentage 0.9
Corrosion inhibitors, percentage 2,000 ppm
Specific gravity 1.295-1.317
Viscosity, cp at 50 deg F 4.35-5.15
pH (5%) 8-10
Total alkalinity (percentage as CaO), percentage 0.01

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