Compositions – Preservative agents – Anti-corrosion
Patent
1994-05-06
1996-04-23
Geist, Gary
Compositions
Preservative agents
Anti-corrosion
252394, 2523891, 422 16, 422 19, C23F 1110, C23F 1114
Patent
active
055100570
DESCRIPTION:
BRIEF SUMMARY
This application is a 371 of PCT/US92/09511, filed Nov. 5, 1992, now Publication No. WO/93/09268.
SCOPE OF THE INVENTION
The present invention relates to a method for inhibiting corrosion of corrodible ferrous metal in a water-metal-air contact system by means of a dual corrosion agent system and compositions for the practice of the method.
BACKGROUND OF THE INVENTION
Cooling water tower systems are usually fabricated of ferrous metal. A common problem is severe corrosion which results from water and air contact with the metal, especially in the case where the cooling water is brackish.
Chromate type inhibitors formerly used to reduce corrosion have been banned for use because of environmental impact problems. Consequently, there is a need for a new effective corrosion inhibitor system and, of course, for one which exhibits improved efficiency inhibiting corrosion and which employs materials free of deleterious environmental impact effects.
Inhibitors currently available to the art, for example, phosphate, phosphonate, molybdate, nitrite and zinc types and the like reduce carbon steel corrosion rates in brackish water to an amount on the order of 16 to 35 mills per year (mpy). This is a series rate and one hardly acceptable considering replacement and repair costs for cooling towers.
SUMMARY OF THE INVENTION
The present invention provides a method and compositions useful for inhibiting corrosion of ferrous metal resulting from contact of water and air with the metal. In this method, a stannous salt and a hydrocarbyl substituted succinimide of a polyethylene polyamine are added to the water in minor amounts and cooperatively reduce corrosion of the metal to a substantially zero rate. While the amount of each agent for an effective inhibition is minor, say in the range of from about 0.1 to 100 ppm, a relatively concentrated solution is required for addition to the water. Suitable solvent media include the lower alkanols and mixture thereof with or without added water. Isopropanol is preferred. The solvent component of the compositions varies depending upon the particular imide and/or salt component employed and the concentration desired. In general, the lower alkanol portion of the medium is in the range of from about 15 to 100 volume percent and the water portion is in the range of from about 0 to 85 volume percent. A medium in the range of from about 50 to 67 volume percent water is preferred. The relative amounts of the imide and stannous salt components desirably used varies depending upon the nature of the water in which the agents are employed. Satisfactory relative amounts by weight for each to the other at set forth above, are in the range of from about 0.5 to 10, preferably 0.8 to 2 and more preferably about 1 to 1 weight ratio.
DETAILED DESCRIPTION OF THE INVENTION
The present invention is based upon novel corrosion inhibitor compositions and their cooperative use in a method wherein corrosion of corrodible ferrous metals, e.g., low carbon, silica and mild steels and the like, is reduced to a negligible rate.
The corrosion inhibiting agents required for the practice of the present invention must disperse readily in water, especially brackish water. While the amount of each of the agents required for an effective inhibition is minor, e.g., in the range of from about 0.1 to 100 ppm, preferably 0.5 to 10 ppm, a relatively concentrated solution is required before the solution is added to the water. Suitable solvent media include the lower alkanols, e.g. methanol, ethanol, propanol, isopropanol and mixtures thereof with or without added water. Isopropanol is preferred.
The solvent or medium component of the compositions varies depending upon the particular imide and/or salt component employed and the concentration desired. In general, the lower alkanol portion of the medium is in the range of from about 15 to 100 volume percent and the water portion is in the range of from about 0 to 85 volume percent. A medium in the range of from about 50 to 67 volume percent water is preferred.
The relati
REFERENCES:
patent: 3679579 (1972-07-01), Preusser et al.
patent: 3776835 (1973-12-01), Dvoracek
patent: 4124512 (1978-11-01), Stournas et al.
patent: 4284517 (1981-08-01), Chen et al.
patent: 4440625 (1984-04-01), Go et al.
patent: 4619756 (1986-10-01), Dickakian
patent: 4913830 (1990-04-01), Lundberg
patent: 4937007 (1990-06-01), Damin et al.
patent: 5104518 (1992-04-01), Jager
patent: 5139643 (1992-08-01), Roling et al.
patent: 5171420 (1992-12-01), Forester
patent: 5171421 (1992-12-01), Forester
patent: 5183555 (1993-02-01), Forester
patent: 5194142 (1993-03-01), Forester
patent: 5194620 (1993-03-01), Roling et al.
patent: 5202058 (1993-04-01), Riggs, Jr.
patent: 5211834 (1993-05-01), Forester
patent: 5211835 (1993-05-01), Forester
patent: 5292425 (1994-03-01), Forester
patent: 5342505 (1994-08-01), Forester
Fee Valerie
Geist Gary
Messner Harold D.
LandOfFree
Corrosion inhibiting method and inhibition compositions does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Corrosion inhibiting method and inhibition compositions, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Corrosion inhibiting method and inhibition compositions will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2306211