Patent ID: 7960329

Claim:
A corrosion inhibiting composition consisting essentially of: a) about 1 to about 65 wt-% of a water soluble calcium salt; b) about 5 to about 75 wt-% of a water soluble magnesium salt selected from the group consisting of magnesium chloride, magnesium sulfate, and mixtures thereof; and c) about 1 to about 85 wt-% alkali metal silicate; wherein the weight ratio of water soluble magnesium salt to the sum of the amount of water soluble calcium salt plus water soluble silicate compound is about 0.5:1 or less, the weight ratio of water soluble calcium salt to water soluble silicate compound salt is about 1-2:2-1, and the composition comprises less than about 0.5 wt-% phosphorous-containing compounds.