CA2074983A1 - Methods for inhibiting metal corrosion in aqueous systems - Google Patents
Methods for inhibiting metal corrosion in aqueous systemsInfo
- Publication number
- CA2074983A1 CA2074983A1 CA 2074983 CA2074983A CA2074983A1 CA 2074983 A1 CA2074983 A1 CA 2074983A1 CA 2074983 CA2074983 CA 2074983 CA 2074983 A CA2074983 A CA 2074983A CA 2074983 A1 CA2074983 A1 CA 2074983A1
- Authority
- CA
- Canada
- Prior art keywords
- corrosion
- methods
- aqueous system
- per million
- benzotriazole compound
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
Classifications
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23F—NON-MECHANICAL REMOVAL OF METALLIC MATERIAL FROM SURFACE; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL; MULTI-STEP PROCESSES FOR SURFACE TREATMENT OF METALLIC MATERIAL INVOLVING AT LEAST ONE PROCESS PROVIDED FOR IN CLASS C23 AND AT LEAST ONE PROCESS COVERED BY SUBCLASS C21D OR C22F OR CLASS C25
- C23F11/00—Inhibiting corrosion of metallic material by applying inhibitors to the surface in danger of corrosion or adding them to the corrosive agent
- C23F11/08—Inhibiting corrosion of metallic material by applying inhibitors to the surface in danger of corrosion or adding them to the corrosive agent in other liquids
- C23F11/10—Inhibiting corrosion of metallic material by applying inhibitors to the surface in danger of corrosion or adding them to the corrosive agent in other liquids using organic inhibitors
- C23F11/14—Nitrogen-containing compounds
- C23F11/149—Heterocyclic compounds containing nitrogen as hetero atom
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Mechanical Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Preventing Corrosion Or Incrustation Of Metals (AREA)
Abstract
ABSTRACT
Methods are provided for inhibiting the corrosion of metals in certain aqueous systems. The methods comprise adding an effective amount of an alkyl benzotriazole compound to the system for which corrosion inhibition is desired.
Methods are provided for inhibiting the corrosion of metals in certain aqueous systems. The methods comprise adding an effective amount of an alkyl benzotriazole compound to the system for which corrosion inhibition is desired.
Description
2~7 ~
METHODS FOR INHIBITING METAL CORROSION IN AQUEOUS SYSTEMS
FIELD OF THE INVENTION
The present invention pertains to methods for inhibiting the corrosion of metals in aqueous systems. The present invention more particularly pertains to simultaneously inhibiting the corrosion of iron-containing and copper-containing metals in cooling water systems that are contaminated by sour leaks.
BACKGROUND OF THE INVENTION
In many refining operations, cooling water systems are often used. Heat exchangers and refrigeration units are commonly used during petrochemical and refining operations. Water is used as the heat exchange fluid.
Iron and/or copper-bearing alloys are commonly the metals of fabrication of heat exchangers, as well as other parts in contact with cooling water, such as pump impellers, stators, and valve parts.
2~)7 ~3 The cooling water systems most often used are of the recirculating type so that the water is used repetitively and remains in contact with the metals of the cooling system. In refinery operations, these cooling waters are often contaminated by "sour" leaks which contain hydrocarbons~ oryanic sulfides and hydrogen sulfide.
These contaminants can be very deleterious if they are left untreated. They will quickly overwhelm any standard oper-ating treatment. The hydrocarbons can coat the metal surfaces of the cooling system and prevent corrosion inhibitors from working correctly. Sulfide ions can cause severe corrosion of metals, which can eventually result in catastrophic failure of metal - components.
Sour leaks and the attendant corrosion and scale problems have been problematic in refineries for years, despite various attempts to inhibit their effects. When these leaks have overwhelmed standard treatments, remedial additive treatments were introduced which typically addressed a specific metallurgy, and at best offered limited improvement. The inventors of the present invention have surprisingly found that the methods described herein provide simultaneously effective inhibition for both iron-containing and copper-containing metals exposed to sour leaks.
207~9~3 SUMMARY OF THE INVENTION
The present invention provides for methods for inhibiting the corrosion of metal in aqueous systems. Alkyl benzotriazole compounds such as butyl benzotriazole have been found to effect-ive1y inhibit the corrosion of iron-containing and copper-con-taining metals in contact with cooling water systems that contain sulfides and hydrocarbons as a result of a sour leak.
DESCRIPTION OF THE RELATED ART
U.S. Patent No. 3,029,202, Brown et a1., Apri1 1962 describes methods of treating water containing sulfur impurities using oxidation catalysts.
U.S. Patent No. 4,6809127, Edmondson, July 1987 discloses a method for reducing the amount of hydrogen sulfide in an aqueous system. The methods provide for adding a combination of glyoxal and formaldehyde or glutaraldehyde or glyoxal a10ne to the aqueous medium.
U.S. Patent No. 4,867,944, Bucher et al., September 1989 discloses a method for inhibiting the corrosion of carbon steel in cooling tower systems. The corrosion inhibiting composition comprises a water soluble zinc compound, a water-soluble molyb-date compound, a water-soluble orthophosphate, a water-soluble polyphosphate and a dispersant.
20rl)~98~
Rogers, M.E., et al., National Association of Corrosion Engineers, Corrosion 87, Conference Paper No. 151 (1987), discloses treating sour leaks in heat exchanger systems. The methods employ triazoles such as benzotriazole in combination with sequestrants to inhibit corrosion in cooling systems. The use of azoles alone yielded inadequate inhibition.
Schreifels, J.A., et al., Corrosion, Vol. ~5(1989)~ pp.
84-91, discloses experimental results for benzotriazole and 2-mercaptothiazole as copper corrosion inhibitors in kerosene.
These compounds did not inhibit copper sulfide formation.
Japanese Patent 51-139,162 discloses making an anti-fouling composition useful in suppressing pitting of a copper alloy by the action of a sulfide comprising treating a water insoluble compound with an organic solvent, a surfactant and a benzotriazole compound.
British Patent No. 1,065,995 teaches that 5-alkyl sub-stituted benzotriazoles are effective in reducing corrosion or tarn;sh of copper items in glycolic solvents or in lubricants, or to resist tarnishin~ in the presence of atmospheric sulfides.
United States No. 4,744,950, Hollander, May 1988 discloses a method of providing a corrosion inhibiting film on copper-containing metals in contact with an open cooling water system. The films,are provided by C3 to C6 substituted alkyl benzotriazoles.
2(37~3~3 DETAILED DESCRIPTION OF THE INVENTION
Methods for inhibiting the corrosion of iron-containing and copper-containing metals in contact with cooling water are described. These methods comprise adding to said cooling water containing sulfides, hydrocarbons and mixtures thereof an effec-tive amount for the purpose of an alkyl benzotriazole compound.
The methods of the present invention are particularly useful when the aqueous system is contaminated by a sour leak.
These aqueous systems are mostly cooling water systems associated with refinery operations. These leaks contain sulfides and hydro-carbons such as crude oil, diesel fuel, naphthas, kerosene and gasoline cut hydrocarbons. In a typical refinery operation, both sulfides and hydrocarbons will be present in a cooling system that is experiencing a sour leak. The introduction of these contaminants will rapidly cause corrosive attack of the iron-containing and copper-containing metals in the cool;ng water system.
The methods of the present invention can be applied to cooling water systems that are not suffering from sour leaks but merely to treat for residual sulfide ions. These methods can also be applied with other corrosion inhibiting agents, as well as microbiological control species such as oxidi7ing and nonoxidizing biocides.
2 V 7 ~
A particular advantage of the present invention is that it maintains low corrosion rates for both iron and copper metal-lurgies simultaneously under the extremely aggressive conditions that occur when both an oxidizing biocide, such as chlorine, and sulfide are present in the system at the same time. In fact, the addition of chlorine is often increased in response to sour leaks.
The preferred alkyl benzotriazole compound is butyl benzotriazole. The compounds may be applied in any conventional manner and can be fed to the cooling water neat or by any suitable carrier means. Water, glycol and polyglycols can be used as the solvent. However, aqueous solutions are preferred.
The addition of the compounds to the cooling water can be either intermittent or continuous, continuous being preferred.
The treatment dosages of the alkyl benzotria701e compounds are dependent upon the severity of the sour leak. Accordingly, a range from about O.l parts per million to about lO0 parts per million alkyl benzotriazole compound should be added. Preferably, the compound should be added from about l part per million to about 15 parts per million.
The data set forth below demonstrate the unexpected results occasioned by use of this invention. The following example is included as being an illustration of the invention and should not be construed as limiting the scope thereof.
.
-7- 20~ 3 EXAMPLE
Chlorinated recirculator testing was performed using the treated water as described in Table A. The sour leak was simulated by the continual feed of the equivalent of 2 parts per million (as H2S) of aqueous sodium sulfide to the recirculator. The temperature was kept at 120F and the pH was actively controlled at 7.2. The condition of chlorination was simulated by the continual fe~d of 0.9% solution of sodium hypochlorite at the rate of 1 ml per hour into the 11 liter system. Butyl benzotriazole was added to the treated water as an additionai inhibitor at a level of 6 parts per million. Both low carbon steel and Admiralty brass coupons were exposed to the water for 7 days. The test results appear in Table I.
2 ~ 7 ~ 3 TABLE A
Ca+2(ppm as CaCD3) 600 Mg+2(ppm as CaCO3 264 Cl- (ppm as Cl~) 555 S04~2(ppm as S04-2) 40Q
Silicate (ppm as SiO2) 50 Orthophosphate (ppm as PO4~3) 12 Pyrophosphate (ppm as PO4~3) 3 Tolyltriazole (ppm) 4 HEDP1 (ppm) 1.6 Active Polymer (ppm) 12 HEDP = 1-hydroxyethylidene-1,1-diphosphonic acid TABLE I
Steel Brass Corrosion Corrosion Additional Rate Rate Leak Condition Inhibitor (mil/vr? ~mil/yr~
Sour leak none 7.4 2.6 Sour leak Butyl-BZT 1.4 0.7 Butyl-BZT = Butyl Benzotriazole Table I indicates the ability to protect both steel and copper containing metals in the presence of sulfides and chlori-nation. The visuàl appearance of the coupons and the heated 2~7L1~3 steel tube present in the experimenti showed less corrosion when butyl benzotriazole was present. These resultâ are totally unexpected considering the seYerity of the laboratory test conditions and actual field experience.
While this invention has been described with respect to particular embodiments thereof, it is apparent that numerous other forms and modifications will be obvious to those skilled in the art. The appended claims generally should be construed to co~er all such Obviouâ forms and modifications which are within the true spirit and scope of the present invention.
METHODS FOR INHIBITING METAL CORROSION IN AQUEOUS SYSTEMS
FIELD OF THE INVENTION
The present invention pertains to methods for inhibiting the corrosion of metals in aqueous systems. The present invention more particularly pertains to simultaneously inhibiting the corrosion of iron-containing and copper-containing metals in cooling water systems that are contaminated by sour leaks.
BACKGROUND OF THE INVENTION
In many refining operations, cooling water systems are often used. Heat exchangers and refrigeration units are commonly used during petrochemical and refining operations. Water is used as the heat exchange fluid.
Iron and/or copper-bearing alloys are commonly the metals of fabrication of heat exchangers, as well as other parts in contact with cooling water, such as pump impellers, stators, and valve parts.
2~)7 ~3 The cooling water systems most often used are of the recirculating type so that the water is used repetitively and remains in contact with the metals of the cooling system. In refinery operations, these cooling waters are often contaminated by "sour" leaks which contain hydrocarbons~ oryanic sulfides and hydrogen sulfide.
These contaminants can be very deleterious if they are left untreated. They will quickly overwhelm any standard oper-ating treatment. The hydrocarbons can coat the metal surfaces of the cooling system and prevent corrosion inhibitors from working correctly. Sulfide ions can cause severe corrosion of metals, which can eventually result in catastrophic failure of metal - components.
Sour leaks and the attendant corrosion and scale problems have been problematic in refineries for years, despite various attempts to inhibit their effects. When these leaks have overwhelmed standard treatments, remedial additive treatments were introduced which typically addressed a specific metallurgy, and at best offered limited improvement. The inventors of the present invention have surprisingly found that the methods described herein provide simultaneously effective inhibition for both iron-containing and copper-containing metals exposed to sour leaks.
207~9~3 SUMMARY OF THE INVENTION
The present invention provides for methods for inhibiting the corrosion of metal in aqueous systems. Alkyl benzotriazole compounds such as butyl benzotriazole have been found to effect-ive1y inhibit the corrosion of iron-containing and copper-con-taining metals in contact with cooling water systems that contain sulfides and hydrocarbons as a result of a sour leak.
DESCRIPTION OF THE RELATED ART
U.S. Patent No. 3,029,202, Brown et a1., Apri1 1962 describes methods of treating water containing sulfur impurities using oxidation catalysts.
U.S. Patent No. 4,6809127, Edmondson, July 1987 discloses a method for reducing the amount of hydrogen sulfide in an aqueous system. The methods provide for adding a combination of glyoxal and formaldehyde or glutaraldehyde or glyoxal a10ne to the aqueous medium.
U.S. Patent No. 4,867,944, Bucher et al., September 1989 discloses a method for inhibiting the corrosion of carbon steel in cooling tower systems. The corrosion inhibiting composition comprises a water soluble zinc compound, a water-soluble molyb-date compound, a water-soluble orthophosphate, a water-soluble polyphosphate and a dispersant.
20rl)~98~
Rogers, M.E., et al., National Association of Corrosion Engineers, Corrosion 87, Conference Paper No. 151 (1987), discloses treating sour leaks in heat exchanger systems. The methods employ triazoles such as benzotriazole in combination with sequestrants to inhibit corrosion in cooling systems. The use of azoles alone yielded inadequate inhibition.
Schreifels, J.A., et al., Corrosion, Vol. ~5(1989)~ pp.
84-91, discloses experimental results for benzotriazole and 2-mercaptothiazole as copper corrosion inhibitors in kerosene.
These compounds did not inhibit copper sulfide formation.
Japanese Patent 51-139,162 discloses making an anti-fouling composition useful in suppressing pitting of a copper alloy by the action of a sulfide comprising treating a water insoluble compound with an organic solvent, a surfactant and a benzotriazole compound.
British Patent No. 1,065,995 teaches that 5-alkyl sub-stituted benzotriazoles are effective in reducing corrosion or tarn;sh of copper items in glycolic solvents or in lubricants, or to resist tarnishin~ in the presence of atmospheric sulfides.
United States No. 4,744,950, Hollander, May 1988 discloses a method of providing a corrosion inhibiting film on copper-containing metals in contact with an open cooling water system. The films,are provided by C3 to C6 substituted alkyl benzotriazoles.
2(37~3~3 DETAILED DESCRIPTION OF THE INVENTION
Methods for inhibiting the corrosion of iron-containing and copper-containing metals in contact with cooling water are described. These methods comprise adding to said cooling water containing sulfides, hydrocarbons and mixtures thereof an effec-tive amount for the purpose of an alkyl benzotriazole compound.
The methods of the present invention are particularly useful when the aqueous system is contaminated by a sour leak.
These aqueous systems are mostly cooling water systems associated with refinery operations. These leaks contain sulfides and hydro-carbons such as crude oil, diesel fuel, naphthas, kerosene and gasoline cut hydrocarbons. In a typical refinery operation, both sulfides and hydrocarbons will be present in a cooling system that is experiencing a sour leak. The introduction of these contaminants will rapidly cause corrosive attack of the iron-containing and copper-containing metals in the cool;ng water system.
The methods of the present invention can be applied to cooling water systems that are not suffering from sour leaks but merely to treat for residual sulfide ions. These methods can also be applied with other corrosion inhibiting agents, as well as microbiological control species such as oxidi7ing and nonoxidizing biocides.
2 V 7 ~
A particular advantage of the present invention is that it maintains low corrosion rates for both iron and copper metal-lurgies simultaneously under the extremely aggressive conditions that occur when both an oxidizing biocide, such as chlorine, and sulfide are present in the system at the same time. In fact, the addition of chlorine is often increased in response to sour leaks.
The preferred alkyl benzotriazole compound is butyl benzotriazole. The compounds may be applied in any conventional manner and can be fed to the cooling water neat or by any suitable carrier means. Water, glycol and polyglycols can be used as the solvent. However, aqueous solutions are preferred.
The addition of the compounds to the cooling water can be either intermittent or continuous, continuous being preferred.
The treatment dosages of the alkyl benzotria701e compounds are dependent upon the severity of the sour leak. Accordingly, a range from about O.l parts per million to about lO0 parts per million alkyl benzotriazole compound should be added. Preferably, the compound should be added from about l part per million to about 15 parts per million.
The data set forth below demonstrate the unexpected results occasioned by use of this invention. The following example is included as being an illustration of the invention and should not be construed as limiting the scope thereof.
.
-7- 20~ 3 EXAMPLE
Chlorinated recirculator testing was performed using the treated water as described in Table A. The sour leak was simulated by the continual feed of the equivalent of 2 parts per million (as H2S) of aqueous sodium sulfide to the recirculator. The temperature was kept at 120F and the pH was actively controlled at 7.2. The condition of chlorination was simulated by the continual fe~d of 0.9% solution of sodium hypochlorite at the rate of 1 ml per hour into the 11 liter system. Butyl benzotriazole was added to the treated water as an additionai inhibitor at a level of 6 parts per million. Both low carbon steel and Admiralty brass coupons were exposed to the water for 7 days. The test results appear in Table I.
2 ~ 7 ~ 3 TABLE A
Ca+2(ppm as CaCD3) 600 Mg+2(ppm as CaCO3 264 Cl- (ppm as Cl~) 555 S04~2(ppm as S04-2) 40Q
Silicate (ppm as SiO2) 50 Orthophosphate (ppm as PO4~3) 12 Pyrophosphate (ppm as PO4~3) 3 Tolyltriazole (ppm) 4 HEDP1 (ppm) 1.6 Active Polymer (ppm) 12 HEDP = 1-hydroxyethylidene-1,1-diphosphonic acid TABLE I
Steel Brass Corrosion Corrosion Additional Rate Rate Leak Condition Inhibitor (mil/vr? ~mil/yr~
Sour leak none 7.4 2.6 Sour leak Butyl-BZT 1.4 0.7 Butyl-BZT = Butyl Benzotriazole Table I indicates the ability to protect both steel and copper containing metals in the presence of sulfides and chlori-nation. The visuàl appearance of the coupons and the heated 2~7L1~3 steel tube present in the experimenti showed less corrosion when butyl benzotriazole was present. These resultâ are totally unexpected considering the seYerity of the laboratory test conditions and actual field experience.
While this invention has been described with respect to particular embodiments thereof, it is apparent that numerous other forms and modifications will be obvious to those skilled in the art. The appended claims generally should be construed to co~er all such Obviouâ forms and modifications which are within the true spirit and scope of the present invention.
Claims (8)
1. A method of simultaneously inhibiting the corrosion of iron-containing and copper-containing metals in contact with an aqueous system containing a contaminant selected from the group consisting of sulfides, hydrocarbons and mixtures thereof comprising adding to said aqueous system an effective amount for the purpose of an alkyl benzotriazole compound.
2. The method as claimed in claim 1 wherein said alkyl benzotriazole compound is butyl benzotriazole.
3. The method as claimed in claim 1 wherein from about 0.1 parts per million to about 100 parts per million of said alkyl benzotriazole compound is added to said aqueous system.
4. The method as claimed in claim 3 wherein from about 1 part per million to about 15 parts per million of said alkyl benzotriazole compound is added to said aqueous system.
5. The method as claimed in claim 1 wherein said alkyl benzotriazole compound is added intermittently.
6. The method as claimed in claim 1 wherein an oxidizing biocide, or a non-oxidizing biocide, or a combination thereof is added to said aqueous system.
7. The method as claimed in claim 6 wherein said oxidizing biocide is chlorine.
8. The method as claimed in claim 1 wherein said aqueous system is a cooling water system.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US76814591A | 1991-09-30 | 1991-09-30 | |
| US07/768,145 | 1991-09-30 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2074983A1 true CA2074983A1 (en) | 1993-03-31 |
Family
ID=25081677
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2074983 Abandoned CA2074983A1 (en) | 1991-09-30 | 1992-07-30 | Methods for inhibiting metal corrosion in aqueous systems |
Country Status (2)
| Country | Link |
|---|---|
| AU (1) | AU655318B2 (en) |
| CA (1) | CA2074983A1 (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2010059897A2 (en) * | 2008-11-20 | 2010-05-27 | Nalco Company | Composition and method for controlling copper discharge and erosion of copper alloys in industrial systems |
| EP3111194A4 (en) * | 2014-02-25 | 2018-03-14 | Jon A. Petty | Corrosion inhibiting hydraulic fluid additive |
| US10669503B2 (en) | 2014-02-25 | 2020-06-02 | Jon A. Petty | Corrosion inhibiting hydraulic fluid additive |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1065995A (en) * | 1963-12-06 | 1967-04-19 | Geigy Uk Ltd | Benzotriazoles and their production |
| US4744950A (en) * | 1984-06-26 | 1988-05-17 | Betz Laboratories, Inc. | Method of inhibiting the corrosion of copper in aqueous mediums |
-
1992
- 1992-07-30 CA CA 2074983 patent/CA2074983A1/en not_active Abandoned
- 1992-09-25 AU AU25360/92A patent/AU655318B2/en not_active Ceased
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2010059897A2 (en) * | 2008-11-20 | 2010-05-27 | Nalco Company | Composition and method for controlling copper discharge and erosion of copper alloys in industrial systems |
| WO2010059897A3 (en) * | 2008-11-20 | 2010-10-14 | Nalco Company | Composition and method for controlling copper discharge and erosion of copper alloys in industrial systems |
| US8470238B2 (en) | 2008-11-20 | 2013-06-25 | Nalco Company | Composition and method for controlling copper discharge and erosion of copper alloys in industrial systems |
| RU2520931C2 (en) * | 2008-11-20 | 2014-06-27 | Налко Компани | Composition and method of control of copper loss and erosion of copper alloys in industrial systems |
| AU2009316522B2 (en) * | 2008-11-20 | 2015-03-19 | Nalco Company | Composition and method for controlling copper discharge and erosion of copper alloys in industrial systems |
| EP3111194A4 (en) * | 2014-02-25 | 2018-03-14 | Jon A. Petty | Corrosion inhibiting hydraulic fluid additive |
| US10669503B2 (en) | 2014-02-25 | 2020-06-02 | Jon A. Petty | Corrosion inhibiting hydraulic fluid additive |
Also Published As
| Publication number | Publication date |
|---|---|
| AU2536092A (en) | 1993-04-01 |
| AU655318B2 (en) | 1994-12-15 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| FZDE | Dead |