Method for inhibiting the corrosion of iron and alloys thereof in an aqueous environment with sulfite compositions

Claim 1

IN A METHOD OF INHIBITING THE CORROSION OF IRON AND ALLOYS THEREOF IN CONTACT WITH AN AQUEOUS SYSTEM CONTAINING DISSOLVED OXYGEN AND A METALLIC CATION SELECTED FROM THE GROUP CONSISTING OF FERROUS, COBALTOUS, NICKELIC, MANGANOUS, CUPRIC, AND MIXTURES THEREOF, COMPRISING ADDING TO SAID SYSTEM AN AQUEOUS SULFITE SOLUTION CONTAINING A SULFITE COMPOUND SELECTED FROM THE GROUP CONSISTING OF ALKALI METAL SULFITES, ALKALI METAL BISULFITES, AMMONIUM SULFITES, AMMONIUM BISULFITES, AND MIXTURES THEREOF, IN AN AMOUNT SUFFICIENT TO PROVIDE A RESIDUAL SULFITE ION CONCENTRATION IN SAID SYSTEM OF FROM 20 TO 100 PPM AFTER SAID ADDED SULFITE COMPOUND AND SAID OXYGEN HAVE REACTED, AND WHEREIN THE CONCENTRATION OF SAID CATION IS SUFFICIENT TO CATALYZE THE REACTION OF SAID SULFITE COMPOUND AND SAID OXYGEN, THE IMPROVEMENT WHICH COMPRISES: ADDING TO SAID AQUEOUS SYSTEM AN AQUEOUS SULFITE SOLUTION, SAID SULFITE SOLUTION BEING COMPOSED OF FROM 5% UP TO SATURATION OF SAID SULFITE COMPOUND, AND A WATER SOLUBLE ORGANIC POLYPHOSPHONATE CONTAINING AT LEAST TWO PHOSPHONIC ACID GROUPS PER MOLECULE, SAID POLYPHOSPHONATE BEING PRESENT IN A CONCENTRATION OF FROM 1-20% BY WEIGHT OF SAID SULFITE COMPOUND IN ORDER TO INHIBIT THE REACTION OF SAID SULFITE COMPOUND WITH ATMOSPHERIC OXYGEN.