Inhibiting Stress Corrosion Cracking of Metal Exposed to Moderate to High Concentrations of Ethanol

Abstract

An effective stress corrosion cracking (SCC) inhibiting amount of a corrosion inhibitor is added into a blend of fuel and ethanol that contacts a metal, wherein the corrosion inhibitor is an organic acid selected from citric acid, ascorbic acid, succinic acid, pyruvic acid, maleic acid, oxaloacetic acid, oxalosuccinic acid, ketoglutaric acid, isocitric acid, malic acid, aconitic acid, fumaric acid, isomers of these organic acids, and a combination thereof. For example, the corrosion inhibitors inhibit stress corrosion cracking of pipeline grade metal pipe at ethanol concentrations greater than fifteen percent. In one embodiment, the corrosion inhibitor is added into a blend of fuel and ethanol flowing through a pipeline at a plurality of injection points spaced apart along the length of the pipeline. In one option, the corrosion inhibitor is ammoniated to form the ammonium salt of the organic acid. In another option, the foregoing corrosion inhibitors are used in combination with one or more conventional corrosion inhibitors in an amount that is effective to inhibit general corrosion.

1 . A method for inhibiting corrosion of metal exposed to a blend of fuel and ethanol, comprising:
 adding an effective stress corrosion cracking inhibiting amount of a corrosion inhibitor into the blend of fuel and ethanol that contacts the metal, wherein the corrosion inhibitor is an organic acid selected from citric acid, ascorbic acid, succinic acid, pyruvic acid, maleic acid, oxaloacetic acid, oxalosuccinic acid, ketoglutaric acid, isocitric acid, malic acid, aconitic acid, fumaric acid, isomers of these organic acids, and a combination thereof.   
     
     
         2 . The method of  claim 1 , wherein the fuel is selected from gasoline and diesel. 
     
     
         3 . The method of  claim 1 , wherein the corrosion inhibitor is added into the blend of fuel and ethanol in an amount providing between 10 and 1000 ppm of the corrosion inhibitor based on the ethanol content of the blend. 
     
     
         4 . The method of  claim 1 , wherein the corrosion inhibitor is added into the blend of fuel and ethanol in an amount providing between 100 and 600 ppm of the corrosion inhibitor based on the ethanol content of the blend. 
     
     
         5 . The method of  claim 1 , wherein the corrosion inhibitor is added as a solution including a solvent selected from water, methanol, and combinations thereof. 
     
     
         6 . The method of  claim 1 , wherein the ethanol concentration in the blend of fuel and ethanol is greater than fifteen percent. 
     
     
         7 . The method of  claim 1 , wherein the ethanol concentration in the blend of fuel and ethanol is greater than twenty-five percent. 
     
     
         8 . The method of  claim 1 , further comprising:
 flowing the blend of fuel and ethanol through a pipeline including metal exposed to the blend of fuel and ethanol.   
     
     
         9 . The method of  claim 8 , wherein the corrosion inhibitor is added into the flowing blend of fuel and ethanol at a plurality of injection points spaced apart along the length of the pipeline. 
     
     
         10 . The method of  claim 1 , further comprising:
 storing the blend of fuel and ethanol in a storage tank including metal exposed to the blend of fuel and ethanol.   
     
     
         11 . The method of  claim 1 , wherein the corrosion inhibitor includes citric acid. 
     
     
         12 . The method of  claim 1 , wherein the corrosion inhibitor includes ascorbic acid. 
     
     
         13 . The method of  claim 1 , wherein the corrosion inhibitor is ammoniated to form the ammonium salt of the organic acid. 
     
     
         14 . The method of  claim 1 , further comprising:
 adding an effective general corrosion inhibiting amount of a conventional corrosion inhibitor into the blend of fuel and ethanol.   
     
     
         15 . The method of  claim 14 , wherein the conventional corrosion inhibitor is selected from dimer acids, trimer acids, derivatives of succinic anhydride, and combinations thereof. 
     
     
         16 . A method for inhibiting corrosion of metal exposed to a blend of fuel and ethanol, comprising:
 adding an effective stress corrosion cracking inhibiting amount of a corrosion inhibitor into the blend of fuel and ethanol that contacts the metal, wherein the corrosion inhibitor is an organic acid having one or more functional groups selected from carboxylic acids, alkene bonds, hydroxyl groups, and combinations thereof.   
     
     
         17 . The method of  claim 16 , wherein the ethanol concentration in the blend of fuel and ethanol is greater than fifteen percent. 
     
     
         18 . The method of  claim 16 , wherein the corrosion inhibitor is ammoniated to form the ammonium salt of the organic acid. 
     
     
         19 . The method of  claim 16 , further comprising:
 flowing the blend of fuel and ethanol through a pipeline including metal exposed to the blend of fuel and ethanol.   
     
     
         20 . The method of  claim 19 , wherein the corrosion inhibitor is added into the flowing blend of gasoline and ethanol at a plurality of injection points spaced apart along the length of the pipeline. 
     
     
         21 . The method of  claim 16 , further comprising:
 storing the blend of fuel and ethanol in a storage tank including metal exposed to the blend of fuel and ethanol.   
     
     
         22 . The method of  claim 16 , further comprising:
 adding an effective general corrosion inhibiting amount of a convention corrosion inhibitor into the blend of fuel and ethanol.   
     
     
         23 . The method of  claim 22 , wherein the conventional corrosion inhibitor is selected from dimer acids, trimer acids, derivatives of succinic anhydride, and combinations thereof.