Inhibition of corrosion of metal surfaces in contact with corrosive aqueous media

Claim 1

A PROCESS FOR INHIBITING CORROSION OF A SURFACE OF A METAL SELECTED FROM THE GROUP CONSISTING OF FERROUS METALS AND ADMIRALTY METALS IN CONTACT WITH WATER CONTAINING CORROSIVE SALTS WHICH COMPRISES CONTACTING SAID SURFACE FOR A PERIOD OF AT LEAST ONE DAY WITH WATER AT A PH OF 5.5 TO 7.5, CONTAINING AT LEAST ONE MOLECULARLY DEHYDRATED PHOSPHATE AT A CONCENTRATION OF 60-250 P.P.M., EXPRESSED AS PO4, TO FORM A PROTECTIVE PHOPSPHATE COATING ON SAID SURFACE, AND THEREAFTER MAINTAINING SAID PROTECTIVE COATING ON SAID METAL SURFACE DURING CONTACT WITH WATER CONTAINING CORROSIVE SALTS BY MAINTAINING IN SAID WATER A CORROSION INHIBITING COMPOUND SELECTED FROM THE GROUP CONSISTING OF A WATER-SOLUBLE, MOLECULARLY DEHYDRATED PHOSPHATE SALT, A WATER-SOLUBLE CHROMATE SALT, AND A WATER-SOLUBLE DICHROMATE SALT AT A CONCENTRATION OF 10-40 P. P. M. OF SAID PHOSPHATE SALT, EXPRESSED AS PO4 AND 5-30 P. P. M. OF SAID CHROMATE AND DICHROMATE SALTS, EXPRESSED AS CRO4.