Patent ID: 8021607

Claim:
In a water system having a total amount of from about 0.1-1.0 ppm of orthophosphate therein, an improved corrosion inhibition method comprising adding to said system an effective amount to inhibit metallurgy in contact with said water system of a hydroxy acid compound having the formula Q′-(R 1) a —(R2) b —(R3) c —COOH wherein a, b, and c are integers of from 0 to 6 with the proviso that (a+b+c>0); R1, R2, and R3 are repeat units in either random or block sequence and are individually chosen from C═O or CY′Z′ wherein Y′ and Z′ are individually selected from the group of H, OH, CHO, COOH, CH 3 , CH 2 OH, CH(OH) 2 , CH 2 (COOH), CH(OH)(COOH), CH 2 (CHO), and CH(OH)CHO so that said B(1) has a minimum of one OH group as written in its fully hydrated form, Q′ is COOH or CH 2 OH, said hydroxy acid being present in an amount of 1 to about 49 ppm said method further comprising adding a poly(epoxysuccinic) acid to said water system in an amount of about 1 to 40 ppm.