Methods for inhibiting intergranular corrosion of metal surfaces

Abstract

The present invention is directed toward the use of a reaction product of an alkynediol and a polyalkylene polyamine to inhibit intergranular corrosion of metal surfaces in industrial processing systems caused by spray water mist or condensation.

What is claimed is:  
     
         1 . A method for inhibiting the intergranular corrosion of metal surfaces in industrial processing systems, which surfaces are in contact with spray water, which comprises adding to the spray water a sufficient corrosion inhibiting amount of the reaction product of an alkynediol and a polyalkylene polyamine.  
     
     
         2 . The method as recited in  claim 1 , wherein said intergranular corrosion is exfoliation corrosion.  
     
     
         3 . The method as recited in  claim 1 , wherein said metal surfaces comprise continuous caster surfaces.  
     
     
         4 . The method as recited in  claim 2 , wherein said exfoliation corrosion occurs on metal surfaces wetted by spray water mist or condensation.  
     
     
         5 . The method as recited in  claim 1 , wherein said alkynediol contains an alkyne group having from about 4 to 12 carbon atoms.  
     
     
         6 . The method as recited in  claim 1 , wherein said alkynediol is butynediol.  
     
     
         7 . The method as recited in  claim 1 , wherein said polyalkylene polyamine contains from 2 to 10 amine groups, each separated from another by an alkylene group having from 1 to 6 carbon atoms.  
     
     
         8 . The method as recited in  claim 1 , wherein said polyalkylene polyamine is pentaethylene hexamine.  
     
     
         9 . The method as recited in  claim 1 , wherein said reaction product is added to said spray water in an amount ranging from 0.5 parts to about 500 parts per million parts water.  
     
     
         10 . The method as recited in  claim 1 , wherein said spray water is at a temperature from about 110° F. to about 180° F.  
     
     
         11 . The method as recited in  claim 1 , wherein said reaction product is added to said spray water in an aqueous solvent.  
     
     
         12 . The method as recited in  claim 1 , wherein said metal surfaces are iron-containing metal surfaces.  
     
     
         13 . The method as recited in  claim 9 , wherein said reaction product is added to said spray water in an amount ranging from 1 parts to about 100 parts per million parts water.  
     
     
         14 . The method as recited in  claim 13 , wherein said reaction product is added to said spray water in an amount ranging from 5 parts to about 10 parts per million parts water.  
     
     
         15 . The method as recited in  claim 1 , wherein said industrial processing systems comprise steam and cooling water systems.