CA1293613C - Use of zn (ii) to inhibit sulfide corrosion of cupronickel alloys - Google Patents
Use of zn (ii) to inhibit sulfide corrosion of cupronickel alloysInfo
- Publication number
- CA1293613C CA1293613C CA000514658A CA514658A CA1293613C CA 1293613 C CA1293613 C CA 1293613C CA 000514658 A CA000514658 A CA 000514658A CA 514658 A CA514658 A CA 514658A CA 1293613 C CA1293613 C CA 1293613C
- Authority
- CA
- Canada
- Prior art keywords
- zinc
- acrylic acid
- copolymers
- water
- corrosion
- 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.)
- Expired - Fee Related
Links
Landscapes
- Preventing Corrosion Or Incrustation Of Metals (AREA)
Abstract
ABSTRACT
Low dosages of zinc(II) are capable of preventing the corrosion and pitting of copper and copper alloys exposed to waters containing sulfides.
Low dosages of zinc(II) are capable of preventing the corrosion and pitting of copper and copper alloys exposed to waters containing sulfides.
Description
lZ5'3613 INTRODUCTION
Sulfides present in brackish water and seawater can cause severe corrosion and pitting of copper and its alloys.
This problem applies to such waters used industrially as coolants and for processing materials such as crude oil. There are now only two recognized treatments for this problem. The firs~ is to add tolutriazole (TT) or a similar azole to the water. Although TT protects copper alloys from most corrosion, our work shows it is not very effective against sulfide. The second method is to feed iron (II) to the water. The iron quickly oxidizes to iron (III) and precipitates sulfide in the water as iron sulfide. The disadvantage of this technique is that ferric hydroxide coats the metal surfaces and encourages under-deposit corrosion.
THE INVENTION
This invention resides in treating industrial waters containing sulfides wlth at least 0.1 ppm of zinc(II) to combat the effects of sulfide corrosion on copper and its alloys which contact these waters wherein the zinc(II) is complexed with a low molecular weight water-soluble anionic polymer. When operating at a pH below 8.0, the zinc alone will provide protection from sulfide without causing deposition and under-deposit corrosion.
The zinc(II) may be added to the sulfide containing waters at a dosage ranging between 0.1 - lOppm to reduce the sulfide corrosion of copper and copper alloys in contact with such waters. A preferred dosage is within the range of 0.5 -Sppm. These dosages are on a weight basis.
The zinc may be used in the form of any water-soluble zinc salt such as zinc chloride, zinc sulfate, zinc nitrate, zinc acetate, and the like.
~ 3~i3 Because some waters ln industrial processes are used at a pH over 8.0, it is notfeasible to add 7inc alone to the water. At pH's over 8.0, a polymer-zinc(II) complex must be used to stabilize the Zinc. Without the polymer, the zinc would precipitate as zinc hydroxide and foul the metal surfaces.Several low molecular weight anionic polymers can be used to keep zinc soluble up to pH 9Ø Such polymers are illustratively listed below:
Polymer 1. an 85/15 mole percent acrylic acid/ethyl-acrylate copolymer; Mw 3270.
Polymer 2. an 83/17 mole percent acrylic acid/methyl-acrylate copolymer; Mw 5780.
Polymer 3. a 95/5 mole percent acrylic acid/ NaAMPS
(sodium salt of 2-acrylamide-2-methylpropanesulfonic acid) copolymer; Mw 5100 and 15,300 respectively.
Polymer 4. a 90/10 mole percent acrylic acid/NaAMPS
copolymer; Mw 8280.
Polymer 5. an acrylic acid/NaAMPS copolymer.
Polymer 6. a 67/33 to 75/25 mole percent acrylic acid/hydroxypropylacrylate copolymer; Mw 735C
The use of polymers to complex zinc(IIj so that it may be used at alkaline pH's is the subject of U.S. 4,529,572.
The polymers may be selected from a broad group of acrylic acid containing copolymers with the primary limitation being that the molecular weight be within the range of 500-20,000. The preferred polymers and their use in preparing the zinc complexes are set forth in U.S. 4,529,572.
-i'~ l3 The results of Coupon tests shown below illustrate theeffect of zinc and TT. These coupon tests simulate the conditions of the water used in an industrial cooling tower, where sulfide corrosion was a problem. The addition of 3 and 7 ppm TT not only did not reduce the corrosion rate, it appears to have increased it. The addition of 1 ppm zinc(II), however, does reduce the corrosion rate significantly. The addition of 3 ppm TT and 1 ppmzinc ~II) has the same effect as the zinc alone.
3f~3 Coupon Test Results For these tests, 90/10 cupronickel coupons were placed into concentrated brackish water (1500 ppm Ca; 7000 ppm Mg; pH
8.0; conductivity 55,000 micromhos; and 0.5 ppm sulfide). The water was kept at 120 degrees F for four days. The corrosion rate was determined from the coupon weight loss after cleaning.
Treatment Corrosion Rate, mpY
None 2 5 2.4 2.3 2.6 3 ppm TT 3.5 3.5 7 ppm TT 3.0 2.9 1 ppm Zn 1.8 1.7 1 ppm Zn + 3 ppm TT 1.3 1.4
Sulfides present in brackish water and seawater can cause severe corrosion and pitting of copper and its alloys.
This problem applies to such waters used industrially as coolants and for processing materials such as crude oil. There are now only two recognized treatments for this problem. The firs~ is to add tolutriazole (TT) or a similar azole to the water. Although TT protects copper alloys from most corrosion, our work shows it is not very effective against sulfide. The second method is to feed iron (II) to the water. The iron quickly oxidizes to iron (III) and precipitates sulfide in the water as iron sulfide. The disadvantage of this technique is that ferric hydroxide coats the metal surfaces and encourages under-deposit corrosion.
THE INVENTION
This invention resides in treating industrial waters containing sulfides wlth at least 0.1 ppm of zinc(II) to combat the effects of sulfide corrosion on copper and its alloys which contact these waters wherein the zinc(II) is complexed with a low molecular weight water-soluble anionic polymer. When operating at a pH below 8.0, the zinc alone will provide protection from sulfide without causing deposition and under-deposit corrosion.
The zinc(II) may be added to the sulfide containing waters at a dosage ranging between 0.1 - lOppm to reduce the sulfide corrosion of copper and copper alloys in contact with such waters. A preferred dosage is within the range of 0.5 -Sppm. These dosages are on a weight basis.
The zinc may be used in the form of any water-soluble zinc salt such as zinc chloride, zinc sulfate, zinc nitrate, zinc acetate, and the like.
~ 3~i3 Because some waters ln industrial processes are used at a pH over 8.0, it is notfeasible to add 7inc alone to the water. At pH's over 8.0, a polymer-zinc(II) complex must be used to stabilize the Zinc. Without the polymer, the zinc would precipitate as zinc hydroxide and foul the metal surfaces.Several low molecular weight anionic polymers can be used to keep zinc soluble up to pH 9Ø Such polymers are illustratively listed below:
Polymer 1. an 85/15 mole percent acrylic acid/ethyl-acrylate copolymer; Mw 3270.
Polymer 2. an 83/17 mole percent acrylic acid/methyl-acrylate copolymer; Mw 5780.
Polymer 3. a 95/5 mole percent acrylic acid/ NaAMPS
(sodium salt of 2-acrylamide-2-methylpropanesulfonic acid) copolymer; Mw 5100 and 15,300 respectively.
Polymer 4. a 90/10 mole percent acrylic acid/NaAMPS
copolymer; Mw 8280.
Polymer 5. an acrylic acid/NaAMPS copolymer.
Polymer 6. a 67/33 to 75/25 mole percent acrylic acid/hydroxypropylacrylate copolymer; Mw 735C
The use of polymers to complex zinc(IIj so that it may be used at alkaline pH's is the subject of U.S. 4,529,572.
The polymers may be selected from a broad group of acrylic acid containing copolymers with the primary limitation being that the molecular weight be within the range of 500-20,000. The preferred polymers and their use in preparing the zinc complexes are set forth in U.S. 4,529,572.
-i'~ l3 The results of Coupon tests shown below illustrate theeffect of zinc and TT. These coupon tests simulate the conditions of the water used in an industrial cooling tower, where sulfide corrosion was a problem. The addition of 3 and 7 ppm TT not only did not reduce the corrosion rate, it appears to have increased it. The addition of 1 ppm zinc(II), however, does reduce the corrosion rate significantly. The addition of 3 ppm TT and 1 ppmzinc ~II) has the same effect as the zinc alone.
3f~3 Coupon Test Results For these tests, 90/10 cupronickel coupons were placed into concentrated brackish water (1500 ppm Ca; 7000 ppm Mg; pH
8.0; conductivity 55,000 micromhos; and 0.5 ppm sulfide). The water was kept at 120 degrees F for four days. The corrosion rate was determined from the coupon weight loss after cleaning.
Treatment Corrosion Rate, mpY
None 2 5 2.4 2.3 2.6 3 ppm TT 3.5 3.5 7 ppm TT 3.0 2.9 1 ppm Zn 1.8 1.7 1 ppm Zn + 3 ppm TT 1.3 1.4
Claims (4)
1. A method for preventing the corrosion of copper and copper alloys in contact with corrosive waters containing sulfides which comprises treating such waters with at least 0.1 ppm of zinc(II), on a weight basis; wherein the zinc(II) is complexed with a low molecular weight water-soluble anionic polymer.
2. The method of Claim 1 wherein the said corrosive waters are at a pH of 8 or higher.
3. The method of Claim 1 wherein the amount of zinc(II) is in the range from 0.1 to 10ppm, on a weight basis.
4. The method of Claim 2 or 3 wherein the low molecular weight water-soluble anionic polymer is selected from the group consisting of acrylic acid/ethyl acrylate copolymers, acrylic acid/methyacrylate copolymers, acrylic acid/2-acrylamido-2-methylpropane sulfonic acid copolymers, or acrylic acid/hydroxypropyl acrylate copolymers, said copolymers having a molecular weight within the range of 500 to 20,000 being utilized to confer water-solubility of the zinc(II) up to a pH
of 9Ø
of 9Ø
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US76222385A | 1985-08-05 | 1985-08-05 | |
US762,223 | 1985-08-05 |
Publications (1)
Publication Number | Publication Date |
---|---|
CA1293613C true CA1293613C (en) | 1991-12-31 |
Family
ID=25064442
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
CA000514658A Expired - Fee Related CA1293613C (en) | 1985-08-05 | 1986-07-25 | Use of zn (ii) to inhibit sulfide corrosion of cupronickel alloys |
Country Status (1)
Country | Link |
---|---|
CA (1) | CA1293613C (en) |
-
1986
- 1986-07-25 CA CA000514658A patent/CA1293613C/en not_active Expired - Fee Related
Similar Documents
Publication | Publication Date | Title |
---|---|---|
US4443340A (en) | Control of iron induced fouling in water systems | |
US5130052A (en) | Corrosion inhibition with water-soluble rare earth chelates | |
US5342540A (en) | Compositions for controlling scale formation in aqueous system | |
US3885914A (en) | Polymer-zinc corrosion inhibiting method | |
EP0188884A1 (en) | Method of controlling iron induced fouling in water systems | |
CA1291635C (en) | Composition of corrosion inhibitors for cooling water systems using chemically modified acrylamide or methacrylamide polymers | |
NL8002394A (en) | CORROSION-BRAKING AGENT. | |
US5320779A (en) | Use of molybdate as corrosion inhibitor in a zinc/phosphonate cooling water treatment | |
US2793932A (en) | Corrosion inhibiting | |
US4502978A (en) | Method of improving inhibitor efficiency in hard waters | |
CA1309854C (en) | Inhibiting corrosion of iron base metals | |
US5192447A (en) | Use of molybdate as a cooling water corrosion inhibitor at higher temperatures | |
CA1074552A (en) | Pyrophosphate-zinc corrosion | |
KR890002246B1 (en) | Water treatment agent | |
US4529572A (en) | Polymer-zinc corrosion inhibitor | |
CA1293613C (en) | Use of zn (ii) to inhibit sulfide corrosion of cupronickel alloys | |
EP0311192B1 (en) | Method of controlling corrosion at high ph | |
Rajendran et al. | Synergistic effect of Zn exp 2+ and phenyl phosphonic acid in corrosion inhibition of mild steel in neutral environment | |
KR900003981B1 (en) | Method for corrosion inhibition of metals | |
CA2112642A1 (en) | Method for inhibiting corrosion of metals using polytartaric acids | |
US4105406A (en) | Method of inhibiting corrosion using a hexametaphosphate and a phosphate buffer | |
US4434059A (en) | Polymers for prevention of fouling by iron oxides in cooling systems | |
CA2061249C (en) | Use of cationic alkyl-phosphonium salts as corrosion inhibitors in open recirculating systems | |
EP0339716B1 (en) | Method and compositions for controlling corrosion in low and high hardness water | |
CA1340659C (en) | Anti-scale and corrosion inhibitor |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
MKLA | Lapsed |