CA1340659C - Anti-scale and corrosion inhibitor - Google Patents
Anti-scale and corrosion inhibitorInfo
- Publication number
- CA1340659C CA1340659C CA000554873A CA554873A CA1340659C CA 1340659 C CA1340659 C CA 1340659C CA 000554873 A CA000554873 A CA 000554873A CA 554873 A CA554873 A CA 554873A CA 1340659 C CA1340659 C CA 1340659C
- Authority
- CA
- Canada
- Prior art keywords
- inhibitor
- ppm
- polymer
- aqueous system
- phosphonate
- 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 - Lifetime
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
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F5/00—Softening water; Preventing scale; Adding scale preventatives or scale removers to water, e.g. adding sequestering agents
- C02F5/08—Treatment of water with complexing chemicals or other solubilising agents for softening, scale prevention or scale removal, e.g. adding sequestering agents
- C02F5/10—Treatment of water with complexing chemicals or other solubilising agents for softening, scale prevention or scale removal, e.g. adding sequestering agents using organic substances
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F5/00—Softening water; Preventing scale; Adding scale preventatives or scale removers to water, e.g. adding sequestering agents
- C02F5/08—Treatment of water with complexing chemicals or other solubilising agents for softening, scale prevention or scale removal, e.g. adding sequestering agents
- C02F5/10—Treatment of water with complexing chemicals or other solubilising agents for softening, scale prevention or scale removal, e.g. adding sequestering agents using organic substances
- C02F5/14—Treatment of water with complexing chemicals or other solubilising agents for softening, scale prevention or scale removal, e.g. adding sequestering agents using organic substances containing phosphorus
-
- 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
-
- 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
- C23F14/00—Inhibiting incrustation in apparatus for heating liquids for physical or chemical purposes
- C23F14/02—Inhibiting incrustation in apparatus for heating liquids for physical or chemical purposes by chemical means
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2103/00—Nature of the water, waste water, sewage or sludge to be treated
- C02F2103/02—Non-contaminated water, e.g. for industrial water supply
- C02F2103/023—Water in cooling circuits
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2303/00—Specific treatment goals
- C02F2303/08—Corrosion inhibition
Abstract
The invention provides for a soluble organic corrosion and scale inhibitor for use in aqueous systems. The inhibitor is comprised of a blend of an azole and primary and secondary phosphonates and polymers. To this blend may be added at least one supplemental inhibitor. The invention also provides for a method of inhibiting corrosion and scale formation in aqueous systems.
Description
~34os~~
ANTI-SCALE AND CORROSION INHIBITOR
SPECIFICATION
This invention relates to a corrosion and scale inhibitor for use in an aqueous system (in contact with metallic circulatory components) and to a method of treating an aqueous system utilizing such an inhibitor.
In general, aqueous systems can be considered either scale forming or corrosive. Deposit formation on metal heat transfer surfaces will occur when scale forming waters contact such surfaces. These deposits will reduce the heat transfer efficiency of the equipment and reduce water flow rates. If the deposit layer is non-uniform, porous and contains holidays (breaks in the film) then corrosion will result due to localized hot spots and differential concentration cells. Dissolved corrosives such as chlorides, sulfates, oxygen and carbon dioxide will aggravate the situation by increasing the rate of deterioration or corrosion. In corrosive water, corrosion initially predominates over scale formation. However, once substantial metal loss in the form of metallic ions and oxides occurs and concentrates in the water, deposition of these corrosion products occurs on heat transfer surfaces. Therefore, there is a need for an additive treatment which reduces both scale formation and corrosive attack regardless of whether the aqueous system is scale-forming or corrosive.
Conventional metallic, inorganic inhibitors present an environmental and safety problem. Considerations include transportation, handling, administration and discharge after use into public waterways and water systems of such inhibitors.
There are many known, reported corrosion inhibitors such as chromates, molybdates, nitrites, zinc salts, benzoates, citrates, diamines, sarcosinates, azoles, phosphonates, ortho and polyphosphates. It is also known and reported that many anti-scalants, when used at less than stoichiometric quantities and having either crystal modification properties, sequestration properties and/or increased lag phase induction times for crystallization, can be used in combination with classical corrosion inhibitors, not only to reduce scale formation rates, but also to act synergistically in the reduction of corrosion.
These mixtures, therefore, afford corrosion inhibitory properties equivalent to, or better than, an individual corrosion inhibitor component at a much lower concentration.
Examples of known anti-scalants are: polyphosphates, 1-hydroxylethylidene-1, 1-diphosphonic acid, amino tris (methylene phosphonic acid), 2-phosphonobutane-1, 2, 4-tricarboxylic acid, ethylenediamine tetra (methylene phosphonic acid), polyacrylates, polyacrylamides, polymaleic anhydride, polymethacrylate, polymethylmethacrylates, and phosphino polycarboxylates.
ANTI-SCALE AND CORROSION INHIBITOR
SPECIFICATION
This invention relates to a corrosion and scale inhibitor for use in an aqueous system (in contact with metallic circulatory components) and to a method of treating an aqueous system utilizing such an inhibitor.
In general, aqueous systems can be considered either scale forming or corrosive. Deposit formation on metal heat transfer surfaces will occur when scale forming waters contact such surfaces. These deposits will reduce the heat transfer efficiency of the equipment and reduce water flow rates. If the deposit layer is non-uniform, porous and contains holidays (breaks in the film) then corrosion will result due to localized hot spots and differential concentration cells. Dissolved corrosives such as chlorides, sulfates, oxygen and carbon dioxide will aggravate the situation by increasing the rate of deterioration or corrosion. In corrosive water, corrosion initially predominates over scale formation. However, once substantial metal loss in the form of metallic ions and oxides occurs and concentrates in the water, deposition of these corrosion products occurs on heat transfer surfaces. Therefore, there is a need for an additive treatment which reduces both scale formation and corrosive attack regardless of whether the aqueous system is scale-forming or corrosive.
Conventional metallic, inorganic inhibitors present an environmental and safety problem. Considerations include transportation, handling, administration and discharge after use into public waterways and water systems of such inhibitors.
There are many known, reported corrosion inhibitors such as chromates, molybdates, nitrites, zinc salts, benzoates, citrates, diamines, sarcosinates, azoles, phosphonates, ortho and polyphosphates. It is also known and reported that many anti-scalants, when used at less than stoichiometric quantities and having either crystal modification properties, sequestration properties and/or increased lag phase induction times for crystallization, can be used in combination with classical corrosion inhibitors, not only to reduce scale formation rates, but also to act synergistically in the reduction of corrosion.
These mixtures, therefore, afford corrosion inhibitory properties equivalent to, or better than, an individual corrosion inhibitor component at a much lower concentration.
Examples of known anti-scalants are: polyphosphates, 1-hydroxylethylidene-1, 1-diphosphonic acid, amino tris (methylene phosphonic acid), 2-phosphonobutane-1, 2, 4-tricarboxylic acid, ethylenediamine tetra (methylene phosphonic acid), polyacrylates, polyacrylamides, polymaleic anhydride, polymethacrylate, polymethylmethacrylates, and phosphino polycarboxylates.
It has also been shown in the literature (U. S. patent #4.206,075) that a synergistic blend of phosphonates, namely 1-hydroxylethylidene-1, 1-diphosphonic acid and amino tri (methylene phosphonic acid) can be used as an effective corrosion inhibitor for low carbon steels. Polymers having carboxylate functioning and cationic/non-ionic surfactants have also been shown to provide a synergistic ability to inhibit corrosion. Of the many all-organic and inorganic phosphate-organic scale and corrosion inhibitory blends available, expediency of film repair via metal surface reconditioning and repassivation, has been an application constraint. Their performance in this area compared to a scale and corrosion inhibitory blend containing metallic has always been less effective. Although overall corrosion test coupon rates utilizing the prior art inhibitors have been acceptable, the presence of pitting and coupon gouging has marred their effectiveness. Intermittently run equipment or systems have also encountered corrosion during the stand-off or idle stagnent periods.
The present invention has overcome problems associated with the use of prior art inhibitors by developing a specific organic inhibitor blend which minimizes pitting and coupon gouging while inhibiting corrosion and scale formation.
The present invention provides an organic corrosion and scale inhibitor for use in an aqueous system comprising an azole, primary and secondary phosphonates and primary and secondary polymers.
The present invention has overcome problems associated with the use of prior art inhibitors by developing a specific organic inhibitor blend which minimizes pitting and coupon gouging while inhibiting corrosion and scale formation.
The present invention provides an organic corrosion and scale inhibitor for use in an aqueous system comprising an azole, primary and secondary phosphonates and primary and secondary polymers.
The present invention also provides a method for inhibiting scale and corrosion in an aqueous system comprising the use in said aqueous system of the organic inhibitor according to the instant invention.
According to one aspect of the present invention, there is provided a corrosion and scale inhibitor for use in an aqueous system, said inhibitor comprising: (a) an azole in an amount effective to inhibit corrosion; (b) 3-20 parts by weight per million parts of water of a first phosphonate, 2-hydroxy-phosphono acetic acid; (c) 2-20 parts by weight per million parts of water of a second phosphonate selected from the group consisting of 1-hydroxylethylidene-1,1-diphosphonic acid and 2-phosphonobutane-1,2,4-tricarboxylic acid; (d) 1-16 parts by weight per million parts of water of a first polymer;
(e) 2-16 parts by weight per million parts of water of a second polymer, said first and second polymers being different and both selected from the group consisting of malefic anhydride terpolymer, polyacrylate or polymethacrylate having an average molecular weight of from 1000 to 100, 000. A further aspect of the invention provides a method for using this inhibitor to inhibit scale and corrosion formation in an aqueous system.
According to another aspect of the present invention, there is provided a corrosion inhibitor and scale C.
13406.59 inhibitor for use in an aqueous system comprising: (a) 1-8 parts of an azole, (b) 3-20 parts of a 2-hydroxy-phosphono acetic acid as a first or primary phosphonate, (c) 2-20 parts of second or secondary phosphonate selected from the group consisting of 1-hydroxylethylidene-1,1-diphosphonic acid, 2-phosphonobutane-1,2,4-tricarboxylic acid, and mixtures thereof, (d) 1-16 parts of malefic anhydride terpolymer as a first or primary polymer, (e) 2-16 parts of a second or secondary polymer) such that the weight ratio of (b) to (c) is 1:0.6 to about 0.6:1 and the weight ratio (d) to (e) is from 4:1 to 1:4, wherein said parts is parts by weight per million parts of water. A further aspect of the present invention provides a method for using this inhibitor to inhibit scale and corrosion formation in an aqueous system.
In one embodiment, the inhibitor of the invention comprises an azole, hydroxylated phosphoric acid with carboxylate functioning, an additional phosphonate, malefic anhydride terpolymer and polyacrylate - homopolymer.
In a further embodiment the invention consists of a method of inhibiting corrosion and scale in an aqueous system comprising the utilization in the system of: azole, hydroxylated phosphoric acid with carboxylate functioning, a secondary phosphonate of either 1, hydroxylethylidiene, 1-1, diphosphonic acid or 2-phosphonobutane-1, 2, 4 - tricarboxylic acid, phosphonates, malefic anhydride terpolymer and polyacrylate homopolymer.
- 4a -B.
13~O~a9 The invention utilizes all water soluble organic based inhibitors in a specific blend which provides both scale and corrosion inhibition while allowing for environmental discharge of the inhibitor without regulation. An azole is incorporated in the formula for copper and coFper alloy protection. The blended polymers (primary and secondary) inhibit scale and deposit formation on heat transfer surfaces while also providing a stabilizing effect on calcium phosphonate.
- 4b -~3i' ..
The stabilization of calcium phosphonate is to prevent precipitation from the bulk water onto the heat transfer surfaces as well as low flow areas of the aqueous system. Concurrently, without over-stabilization of calcium phosphonate, the blend allows for a calcium/phosphonate/metallic corrosion inhibitory film to be formed. Therefore, the polymers synergistically enhance the scale and corrosion inhibitory properties of the invention. Operation of the aqueous system with a greater concentration of inhibitor (up to three times the normal operational levels) for a short duration upon initiation will establish a tighter film thus avoiding holidays and undue stress to repair or maintain the inhibitory film integrity. Operation of the aqueous system at higher inhibitor levels for a short duration prior to shut-down of the aqueous system will also extend corrosion inhibitory benefits during the idle, stagnant periods. The inhibitor should be added at least four hours prior to shut-down. The invention can also be used as an adjunct with existing scale and corrosion inhibitory blends thereby minimizing corrosion, during periodic idleness. In this case continuous feeding of the formula into the aqueous system, or slug feeding prior to system shut-down can be performed in order to attain the desired benefits of the invention.
According, to another aspect of the invention, variation in the blend can be made for low alkalinity bearing water (hard water). In this embodiment carbonate alkalinity can be added to the inhibitory blend to supplement system water alkalinity and hence, reduce corrosion of this water. The use of a polymeric iron dispersant such as sulfonated styrene malefic anhydride copolymer or a polyacrylate copolymer and terpolymer of the same has shown to provide no enhancement of corrosion rates. However, they may be used if "ironing out" of iron particulates are required in an aqueous system for increased expediency of control attainment. A non-organic surfactant can also be incorporated to minimize organic loading on the system metal surfaces.
CORROSION INHIBITORY PERFORMANCE
Laboratory tests (see Tables I-X) were carried out on two water compositions (I & IV) under static aeration test procedures at 70°F to 75°F. Two other waters (II & III) were used for dynamic aerated conditions under a recirculatory evaporative cooling process simulation at 95°F to 100°F. Table I
contains the composition of the waters utilized.
The corrosion rates were assessed using the weight loss method. The metal specimens (i.e. National Association of Corrosion Engineers coupons) were precleaned with isopropyl alcohol and a benzene mixture. The coupons were not pretreated with inhibitor, nor were they initially operated in an elevated inhibitor residual environment for a portion of the trial duration (excluding Tables VIII, IX, X, trials).
Various inhibitor blend packages were evaluated utilizing the four water compositions. Some of the blends are identified as being known to the prior art. Table II lists the various inhibitor blends, the composition of each blend, as well as the active residual material present in the test waters. The results of the inhibitory performance of the various mixtures in test waters I, II, III and IV are listed in Tables III, IV, V, VI
and VII. Table VIII outlines the corrosion inhibitory improvement attainable by prefilming the system metal upon start-up of such a programme. The prefilming was accomplished by operating the static aerated test waters at three times the normal operational concentration for the first three days of the ten day trial duration. The test water was discarded after the three days and replenished with the same test water containing inhibitor at the normal operational concentration for the remainder of the trial duration.
Tables IX and X are test data simulating intermittent use systems. The blank provides an untreated system. Inhibitor 37 is a traditional heavy metal inhibitor and inhibitor 22 is a totally organic inhibitor. Static results are listed in Table IX. Here the test water I was aerated for six hours and then capped off to simulate a stagnant condition for the balance of eight days. Referring to Table IX, note the addition of inhibitor blend 22 to the prior art blend 37 resulted in a very substantial reduction in corrosion rate. Dynamic results (Table X) were obtained by operating a simulative, aerated, evaporative recirculatory cooling system. Test water III containing a conventional prior art heavy metal inhibitor (#37) was utilized.
1310~~9 Over the thirty day trial period, inhibitor #22 of the instant invention was 'batch fed' into the aerated recirculatory water four hours prior to shut-down of the system at four times the normal operational concentration. The system remained stagnant for sixty hours, then recirculation and re-aeration were initiated for an additional one hundred and eight hours before shut-down. The process was repeated for a total of approximately seven hundred and twenty hours or thirty days. A simulated system bleed-off was maintained to provide a system retention time of 13.6 hours when recirculating. The bleed-off was discontinued over the shut-down period. The dynamic results listed in Table X. Note the dramatic reduction in corrosion upon the use if inhibitor 22.
Corrosion rate percentage efficiencies on mild steel were calculated as follows:
Untreated Blank mpy - Inhibitor m y x 100 Untreated Blank mpy (mpy = mls. per year or 1/1,OOOth, of an inch metal loss per year) Visual - Microscopic examinations of coupons were made to determine the extent of corrosion. The following qualitative report can be referenced as;
Pitting - Multitude of depressions and carbuncles in the metal coupon surface.
- g _ Generalized - Even corrosion with no depression in the metal coupon surface.
Gouged - Areas of depression which have not been afforded any protection. These areas did not contain any pitting.
Percentages have been given to classify the amount of metal coupon surface affected. The apparently unaffected metal coupon surface percentage is equivalent to 100 less the combined percentage of affected metal coupon surfaces. Hence, even corrosion can be considered as apparently 100 unaffected.
_ g _ TABLE I
TEST WATER COMPOSITION
CONSTITUENT (ppm) I II III IV
Total Hardness as CaC03 188 207 414 232 Calcium Hardness as CaC03 124 186 312 198 Magnesium Hardness as CaC03 64 51 102 34 'M' Alkalinity as CaC03 202 129 258 272 Chloride as "CL" 100 55 96 100 Sulfate as S04 0 50 100 33 Iron as Fe 0.65 0.02 0.05 0.05 Total Dissolved Solids 260 312 624 325 Adjusted pH of Trial Runs 8.3 8.5 8.5 8.5 Temperature (oF) 70-75 95-100 95-100 70-75 Ryznar Index 6.65 6.0 4.91 5.76 Silica as Si02 , 20.0 1.42 2.85 0.95 The mild coupon composition was that of 1,020 military steel specification (C = 0.2~, Mn = 0.2 - 0.6~, P = 0.04, S =
0.05$ Max., Fe = balance) The copper coupon composition was that of electrolytic grade (Federal specification - QQ - C - 576; Cu = 99.9, Ag trace) INHIBITOR COMPOSITION
Inhibitor Component Concentration In Test Waters 1 phosphonate A g ppm (prior art) polymer A 1 ppm tolyltriazole 2 ppm 2 phosphonate B 9 ppm (prior art) polymer A 1 ppm tolyltriazole 2 ppm 3 phosphonate A 6 ppm (prior art) polymer B 15 ppm tolyltriazole 2 ppm 4 phosphonate A 3.0 ppm polymer A 13.5 ppm polymer B 15.0 ppm tolyltriazole 2.0 ppm phosphonate A 3.0 ppm polymer A 5.0 ppm polymer B 6.0 ppm tolyltriazole 2.0 ppm 6 phosphonate A 3.0 ppm (prior art) polymer B 10.0 ppm tolyltriazole 2.0 ppm 7 phosphonate A 5.0 ppm (prior art) polymer A 2.5 ppm tolyltriazole 2.0 ppm 8 phosphonate A 3.0 ppm polymer A 10 ppm tolyltriazole 2 ppm 9 phosphonate A 3.0 ppm polymer A 4.0 ppm polymer C 4.0 ppm tolyltriazole 2.0 ppm phosphonate A 3 ppm polymer A 3 ppm tolyltriazole 2 ppm TABLE II
INHIBITOR COMPOSITION
Inhibitor Component Concentration In Test Waters 11 phosphonate A 3 ppm polymer C 10 ppm tolyltriazole 2 ppm 12 phosphonate A 6 ppm (prior art) polymer A 4 ppm tolyltriazole 2.0, ppm 13 phosphonate A 6 ppm polymer C 5 ppm tolyltriazole 2 ppm 14 phosphonate A 3 ppm polymer C 5 ppm tolyltriazole 2 ppm 15 phosphonate A 3 ppm phosphonate C 5 ppm polymer A 5 ppm polymer B 6 ppm tolyltriazole 2 ppm 16 phosphonate C 5 ppm (prior art) polymer A 1 ppm tolyltriazole 2 ppm 17 phosphonate A 3 ppm phosphonate C 5 ppm polymer B 4 ppm tolyltriazole 2 ppm 18 phosphonate A 3 ppm phosphonate C 5 ppm polymer A 15 ppm tolyltriazole 2 ppm 19 phosphonate A 3 ppm phosphonate C 5 ppm polymer A 2 ppm polymer B 1 ppm tolyltriazole 2 ppm INHIBITOR COMPOSITION
Component Concentration In Test Waters 20 phosphonate A 3 ppm phosphonate C 5 ppm polymer A 2 ppm polymer C 1 ppm tolyltriazole 2 ppm 21 phosphonate A 3 ppm phosphonate C 5 ppm polymer A 2 ppm polymer C 2 ppm tolyltriazole 2 ppm 22 phosphonate A 3 ppm phosphonate C 5 ppm polymer A 2 ppm polymer B 2 ppm tolyltriazole 2 ppm 23 phosphonate A 3 ppm phosphonate C 5 ppm polymer A 1 ppm polymer C 2 ppm polymer D 1 ppm tolyltriazole 2 ppm 24 phosphonate A 3 ppm phosphonate C 5 ppm polymer A 1 ppm polymer B 2 ppm polymer D 1 ppm tolyltriazole 2 ppm 25 phosphonate B 6 ppm polymer C 4 ppm tolyltriazole 2 ppm 26 phosphonate B 6 ppm polymer A 5 ppm polymer B 6 ppm tolyltriazole 2 ppm TABLE II
INHIBITOR COMPOSITION
Inhibitor Component Concentration In Test Waters 27 phosphonate B 6 ppm phosphonate C 5 ppm polymer A 5 ppm polymer B 6 ppm tolyltriazole 2 ppm 28 phosphonate B 4 ppm phosphonate C 5 ppm polymer A 4 ppm tolyltriazole 2 ppm 29 phosphonate B 4 ppm phosphonate C 5 ppm polymer A 2 ppm tolyltriazole 2 ppm 30 phosphonate B 4 ppm phosphonate C 5 ppm polymer A 1 ppm polymer C 2 ppm tolyltriazole 2 ppm 31 phosphonate B 4 ppm phosphonate C 5 ppm polymer A 1 ppm polymer C 2 ppm polymer D 1 ppm tolyltriazole 2 ppm 32 phosphonate B 4 ppm phosphonate C 5 ppm polymer A 1 ppm polymer C 3 ppm tolyltriazole 2 ppm 33 phosphonate B 4 ppm phosphonate C 5 ppm polymer A 1 ppm polymer B 3 ppm tolyltriazole 2 ppm 1340~~9 INHIBITOR COMPOSITION
Component Concentration In Test Waters 34 phosphonate B 4 ppm phosphonate C 5 ppm polymer A 1 ppm polymer B 2 ppm tolyltriazole 2 ppm 35 phosphonate B 4 ppm phosphonate C 5 ppm polymer A 1 ppm polymer B 2 ppm polymer D 1 ppm tolyltriazole 2 ppm 36 phosphonate B 4 ppm phosphonate C 5 ppm polymer A 2 ppm polymer C 1 ppm surfactant A 1 ppm tolyltriazole 2 ppm 37 phosphonate a as HEDP 10 ppm (prior art) zinc chloride as Zn 3 ppm disodium chromate as Cr04 30 ppm 38 phosphonate A 4 ppm phosphonate C 5 ppm polymer A ~ 2 ppm polymer B 2 ppm tolyltriazole 2 ppm 39 phosphonate B 4 ppm phosphonate C 5 ppm polymer A 2 ppm polymer B 2 ppm tolyltriazole 2 ppm 40 phosphonate B 4 ppm phosphonate C 5 ppm polymer A 2 ppm polymer C 2 ppm tolyltriazole 2 ppm TABLE II
INHIBITOR COMPOSITION
Inhibitor Component Concentration In Test Waters 41 phosphonate B 4 ppm phosphonate C 5 ppm polymer A 2 ppm polymer B 1 ppm tolyltriazole 2 ppm 42 phosphonate B 4 ppm phosphonate C 5 ppm polymer A 3 ppm polymer B 1 ppm tolyltriazole 2 ppm NOTE:
phosphonate A = 1-hydroxylethylidene-1, 1-diphosphonic acid phosphonate B = 2-phosphonabutane-1, 2, 4-tricarboxylic acid phosphonate C = 2-hydroxy-phosphono acetic acid polymer A = malefic anhydride terpolymer, 1,000 MW
polymer B = polyacrylate, 4,600 MW
polymer C = polyacrylate copolymer, 4,500 MW
polymer D = sulfonated styrene/maleic anhydride copolymer, 3,000 MW
surfactant A = nonionic polyethoxylate 1340b59 CORROSION RATES USING TEST WATER I
CORROSION RATE OF METAL - MLS. PER YEAR (MPY) TEST DURATION - 7 DAYS, STATIC AERATION CONDITIONS
Inhibitor Mild Steel Coupon Visual ~ Efficiency Blank 12.0 0 3 0.53 25~ Pitting 95.6 4 13.59 25$ Pitting/70$ Gouged N/A
5.9 40~ Pitting/5~ Gouged 50.8 6 0.3 25~ Pitting 97.5 8 3.3 10~ Pitting/35~ Gouged 72.5 9 3.0 10$ Gouged 75.0 10.1 5$ Pitting 15.8 11 0.74 5~ Gouged 93.8 12 13.4 25~ Pitting/50~ Gouged N/A
According to one aspect of the present invention, there is provided a corrosion and scale inhibitor for use in an aqueous system, said inhibitor comprising: (a) an azole in an amount effective to inhibit corrosion; (b) 3-20 parts by weight per million parts of water of a first phosphonate, 2-hydroxy-phosphono acetic acid; (c) 2-20 parts by weight per million parts of water of a second phosphonate selected from the group consisting of 1-hydroxylethylidene-1,1-diphosphonic acid and 2-phosphonobutane-1,2,4-tricarboxylic acid; (d) 1-16 parts by weight per million parts of water of a first polymer;
(e) 2-16 parts by weight per million parts of water of a second polymer, said first and second polymers being different and both selected from the group consisting of malefic anhydride terpolymer, polyacrylate or polymethacrylate having an average molecular weight of from 1000 to 100, 000. A further aspect of the invention provides a method for using this inhibitor to inhibit scale and corrosion formation in an aqueous system.
According to another aspect of the present invention, there is provided a corrosion inhibitor and scale C.
13406.59 inhibitor for use in an aqueous system comprising: (a) 1-8 parts of an azole, (b) 3-20 parts of a 2-hydroxy-phosphono acetic acid as a first or primary phosphonate, (c) 2-20 parts of second or secondary phosphonate selected from the group consisting of 1-hydroxylethylidene-1,1-diphosphonic acid, 2-phosphonobutane-1,2,4-tricarboxylic acid, and mixtures thereof, (d) 1-16 parts of malefic anhydride terpolymer as a first or primary polymer, (e) 2-16 parts of a second or secondary polymer) such that the weight ratio of (b) to (c) is 1:0.6 to about 0.6:1 and the weight ratio (d) to (e) is from 4:1 to 1:4, wherein said parts is parts by weight per million parts of water. A further aspect of the present invention provides a method for using this inhibitor to inhibit scale and corrosion formation in an aqueous system.
In one embodiment, the inhibitor of the invention comprises an azole, hydroxylated phosphoric acid with carboxylate functioning, an additional phosphonate, malefic anhydride terpolymer and polyacrylate - homopolymer.
In a further embodiment the invention consists of a method of inhibiting corrosion and scale in an aqueous system comprising the utilization in the system of: azole, hydroxylated phosphoric acid with carboxylate functioning, a secondary phosphonate of either 1, hydroxylethylidiene, 1-1, diphosphonic acid or 2-phosphonobutane-1, 2, 4 - tricarboxylic acid, phosphonates, malefic anhydride terpolymer and polyacrylate homopolymer.
- 4a -B.
13~O~a9 The invention utilizes all water soluble organic based inhibitors in a specific blend which provides both scale and corrosion inhibition while allowing for environmental discharge of the inhibitor without regulation. An azole is incorporated in the formula for copper and coFper alloy protection. The blended polymers (primary and secondary) inhibit scale and deposit formation on heat transfer surfaces while also providing a stabilizing effect on calcium phosphonate.
- 4b -~3i' ..
The stabilization of calcium phosphonate is to prevent precipitation from the bulk water onto the heat transfer surfaces as well as low flow areas of the aqueous system. Concurrently, without over-stabilization of calcium phosphonate, the blend allows for a calcium/phosphonate/metallic corrosion inhibitory film to be formed. Therefore, the polymers synergistically enhance the scale and corrosion inhibitory properties of the invention. Operation of the aqueous system with a greater concentration of inhibitor (up to three times the normal operational levels) for a short duration upon initiation will establish a tighter film thus avoiding holidays and undue stress to repair or maintain the inhibitory film integrity. Operation of the aqueous system at higher inhibitor levels for a short duration prior to shut-down of the aqueous system will also extend corrosion inhibitory benefits during the idle, stagnant periods. The inhibitor should be added at least four hours prior to shut-down. The invention can also be used as an adjunct with existing scale and corrosion inhibitory blends thereby minimizing corrosion, during periodic idleness. In this case continuous feeding of the formula into the aqueous system, or slug feeding prior to system shut-down can be performed in order to attain the desired benefits of the invention.
According, to another aspect of the invention, variation in the blend can be made for low alkalinity bearing water (hard water). In this embodiment carbonate alkalinity can be added to the inhibitory blend to supplement system water alkalinity and hence, reduce corrosion of this water. The use of a polymeric iron dispersant such as sulfonated styrene malefic anhydride copolymer or a polyacrylate copolymer and terpolymer of the same has shown to provide no enhancement of corrosion rates. However, they may be used if "ironing out" of iron particulates are required in an aqueous system for increased expediency of control attainment. A non-organic surfactant can also be incorporated to minimize organic loading on the system metal surfaces.
CORROSION INHIBITORY PERFORMANCE
Laboratory tests (see Tables I-X) were carried out on two water compositions (I & IV) under static aeration test procedures at 70°F to 75°F. Two other waters (II & III) were used for dynamic aerated conditions under a recirculatory evaporative cooling process simulation at 95°F to 100°F. Table I
contains the composition of the waters utilized.
The corrosion rates were assessed using the weight loss method. The metal specimens (i.e. National Association of Corrosion Engineers coupons) were precleaned with isopropyl alcohol and a benzene mixture. The coupons were not pretreated with inhibitor, nor were they initially operated in an elevated inhibitor residual environment for a portion of the trial duration (excluding Tables VIII, IX, X, trials).
Various inhibitor blend packages were evaluated utilizing the four water compositions. Some of the blends are identified as being known to the prior art. Table II lists the various inhibitor blends, the composition of each blend, as well as the active residual material present in the test waters. The results of the inhibitory performance of the various mixtures in test waters I, II, III and IV are listed in Tables III, IV, V, VI
and VII. Table VIII outlines the corrosion inhibitory improvement attainable by prefilming the system metal upon start-up of such a programme. The prefilming was accomplished by operating the static aerated test waters at three times the normal operational concentration for the first three days of the ten day trial duration. The test water was discarded after the three days and replenished with the same test water containing inhibitor at the normal operational concentration for the remainder of the trial duration.
Tables IX and X are test data simulating intermittent use systems. The blank provides an untreated system. Inhibitor 37 is a traditional heavy metal inhibitor and inhibitor 22 is a totally organic inhibitor. Static results are listed in Table IX. Here the test water I was aerated for six hours and then capped off to simulate a stagnant condition for the balance of eight days. Referring to Table IX, note the addition of inhibitor blend 22 to the prior art blend 37 resulted in a very substantial reduction in corrosion rate. Dynamic results (Table X) were obtained by operating a simulative, aerated, evaporative recirculatory cooling system. Test water III containing a conventional prior art heavy metal inhibitor (#37) was utilized.
1310~~9 Over the thirty day trial period, inhibitor #22 of the instant invention was 'batch fed' into the aerated recirculatory water four hours prior to shut-down of the system at four times the normal operational concentration. The system remained stagnant for sixty hours, then recirculation and re-aeration were initiated for an additional one hundred and eight hours before shut-down. The process was repeated for a total of approximately seven hundred and twenty hours or thirty days. A simulated system bleed-off was maintained to provide a system retention time of 13.6 hours when recirculating. The bleed-off was discontinued over the shut-down period. The dynamic results listed in Table X. Note the dramatic reduction in corrosion upon the use if inhibitor 22.
Corrosion rate percentage efficiencies on mild steel were calculated as follows:
Untreated Blank mpy - Inhibitor m y x 100 Untreated Blank mpy (mpy = mls. per year or 1/1,OOOth, of an inch metal loss per year) Visual - Microscopic examinations of coupons were made to determine the extent of corrosion. The following qualitative report can be referenced as;
Pitting - Multitude of depressions and carbuncles in the metal coupon surface.
- g _ Generalized - Even corrosion with no depression in the metal coupon surface.
Gouged - Areas of depression which have not been afforded any protection. These areas did not contain any pitting.
Percentages have been given to classify the amount of metal coupon surface affected. The apparently unaffected metal coupon surface percentage is equivalent to 100 less the combined percentage of affected metal coupon surfaces. Hence, even corrosion can be considered as apparently 100 unaffected.
_ g _ TABLE I
TEST WATER COMPOSITION
CONSTITUENT (ppm) I II III IV
Total Hardness as CaC03 188 207 414 232 Calcium Hardness as CaC03 124 186 312 198 Magnesium Hardness as CaC03 64 51 102 34 'M' Alkalinity as CaC03 202 129 258 272 Chloride as "CL" 100 55 96 100 Sulfate as S04 0 50 100 33 Iron as Fe 0.65 0.02 0.05 0.05 Total Dissolved Solids 260 312 624 325 Adjusted pH of Trial Runs 8.3 8.5 8.5 8.5 Temperature (oF) 70-75 95-100 95-100 70-75 Ryznar Index 6.65 6.0 4.91 5.76 Silica as Si02 , 20.0 1.42 2.85 0.95 The mild coupon composition was that of 1,020 military steel specification (C = 0.2~, Mn = 0.2 - 0.6~, P = 0.04, S =
0.05$ Max., Fe = balance) The copper coupon composition was that of electrolytic grade (Federal specification - QQ - C - 576; Cu = 99.9, Ag trace) INHIBITOR COMPOSITION
Inhibitor Component Concentration In Test Waters 1 phosphonate A g ppm (prior art) polymer A 1 ppm tolyltriazole 2 ppm 2 phosphonate B 9 ppm (prior art) polymer A 1 ppm tolyltriazole 2 ppm 3 phosphonate A 6 ppm (prior art) polymer B 15 ppm tolyltriazole 2 ppm 4 phosphonate A 3.0 ppm polymer A 13.5 ppm polymer B 15.0 ppm tolyltriazole 2.0 ppm phosphonate A 3.0 ppm polymer A 5.0 ppm polymer B 6.0 ppm tolyltriazole 2.0 ppm 6 phosphonate A 3.0 ppm (prior art) polymer B 10.0 ppm tolyltriazole 2.0 ppm 7 phosphonate A 5.0 ppm (prior art) polymer A 2.5 ppm tolyltriazole 2.0 ppm 8 phosphonate A 3.0 ppm polymer A 10 ppm tolyltriazole 2 ppm 9 phosphonate A 3.0 ppm polymer A 4.0 ppm polymer C 4.0 ppm tolyltriazole 2.0 ppm phosphonate A 3 ppm polymer A 3 ppm tolyltriazole 2 ppm TABLE II
INHIBITOR COMPOSITION
Inhibitor Component Concentration In Test Waters 11 phosphonate A 3 ppm polymer C 10 ppm tolyltriazole 2 ppm 12 phosphonate A 6 ppm (prior art) polymer A 4 ppm tolyltriazole 2.0, ppm 13 phosphonate A 6 ppm polymer C 5 ppm tolyltriazole 2 ppm 14 phosphonate A 3 ppm polymer C 5 ppm tolyltriazole 2 ppm 15 phosphonate A 3 ppm phosphonate C 5 ppm polymer A 5 ppm polymer B 6 ppm tolyltriazole 2 ppm 16 phosphonate C 5 ppm (prior art) polymer A 1 ppm tolyltriazole 2 ppm 17 phosphonate A 3 ppm phosphonate C 5 ppm polymer B 4 ppm tolyltriazole 2 ppm 18 phosphonate A 3 ppm phosphonate C 5 ppm polymer A 15 ppm tolyltriazole 2 ppm 19 phosphonate A 3 ppm phosphonate C 5 ppm polymer A 2 ppm polymer B 1 ppm tolyltriazole 2 ppm INHIBITOR COMPOSITION
Component Concentration In Test Waters 20 phosphonate A 3 ppm phosphonate C 5 ppm polymer A 2 ppm polymer C 1 ppm tolyltriazole 2 ppm 21 phosphonate A 3 ppm phosphonate C 5 ppm polymer A 2 ppm polymer C 2 ppm tolyltriazole 2 ppm 22 phosphonate A 3 ppm phosphonate C 5 ppm polymer A 2 ppm polymer B 2 ppm tolyltriazole 2 ppm 23 phosphonate A 3 ppm phosphonate C 5 ppm polymer A 1 ppm polymer C 2 ppm polymer D 1 ppm tolyltriazole 2 ppm 24 phosphonate A 3 ppm phosphonate C 5 ppm polymer A 1 ppm polymer B 2 ppm polymer D 1 ppm tolyltriazole 2 ppm 25 phosphonate B 6 ppm polymer C 4 ppm tolyltriazole 2 ppm 26 phosphonate B 6 ppm polymer A 5 ppm polymer B 6 ppm tolyltriazole 2 ppm TABLE II
INHIBITOR COMPOSITION
Inhibitor Component Concentration In Test Waters 27 phosphonate B 6 ppm phosphonate C 5 ppm polymer A 5 ppm polymer B 6 ppm tolyltriazole 2 ppm 28 phosphonate B 4 ppm phosphonate C 5 ppm polymer A 4 ppm tolyltriazole 2 ppm 29 phosphonate B 4 ppm phosphonate C 5 ppm polymer A 2 ppm tolyltriazole 2 ppm 30 phosphonate B 4 ppm phosphonate C 5 ppm polymer A 1 ppm polymer C 2 ppm tolyltriazole 2 ppm 31 phosphonate B 4 ppm phosphonate C 5 ppm polymer A 1 ppm polymer C 2 ppm polymer D 1 ppm tolyltriazole 2 ppm 32 phosphonate B 4 ppm phosphonate C 5 ppm polymer A 1 ppm polymer C 3 ppm tolyltriazole 2 ppm 33 phosphonate B 4 ppm phosphonate C 5 ppm polymer A 1 ppm polymer B 3 ppm tolyltriazole 2 ppm 1340~~9 INHIBITOR COMPOSITION
Component Concentration In Test Waters 34 phosphonate B 4 ppm phosphonate C 5 ppm polymer A 1 ppm polymer B 2 ppm tolyltriazole 2 ppm 35 phosphonate B 4 ppm phosphonate C 5 ppm polymer A 1 ppm polymer B 2 ppm polymer D 1 ppm tolyltriazole 2 ppm 36 phosphonate B 4 ppm phosphonate C 5 ppm polymer A 2 ppm polymer C 1 ppm surfactant A 1 ppm tolyltriazole 2 ppm 37 phosphonate a as HEDP 10 ppm (prior art) zinc chloride as Zn 3 ppm disodium chromate as Cr04 30 ppm 38 phosphonate A 4 ppm phosphonate C 5 ppm polymer A ~ 2 ppm polymer B 2 ppm tolyltriazole 2 ppm 39 phosphonate B 4 ppm phosphonate C 5 ppm polymer A 2 ppm polymer B 2 ppm tolyltriazole 2 ppm 40 phosphonate B 4 ppm phosphonate C 5 ppm polymer A 2 ppm polymer C 2 ppm tolyltriazole 2 ppm TABLE II
INHIBITOR COMPOSITION
Inhibitor Component Concentration In Test Waters 41 phosphonate B 4 ppm phosphonate C 5 ppm polymer A 2 ppm polymer B 1 ppm tolyltriazole 2 ppm 42 phosphonate B 4 ppm phosphonate C 5 ppm polymer A 3 ppm polymer B 1 ppm tolyltriazole 2 ppm NOTE:
phosphonate A = 1-hydroxylethylidene-1, 1-diphosphonic acid phosphonate B = 2-phosphonabutane-1, 2, 4-tricarboxylic acid phosphonate C = 2-hydroxy-phosphono acetic acid polymer A = malefic anhydride terpolymer, 1,000 MW
polymer B = polyacrylate, 4,600 MW
polymer C = polyacrylate copolymer, 4,500 MW
polymer D = sulfonated styrene/maleic anhydride copolymer, 3,000 MW
surfactant A = nonionic polyethoxylate 1340b59 CORROSION RATES USING TEST WATER I
CORROSION RATE OF METAL - MLS. PER YEAR (MPY) TEST DURATION - 7 DAYS, STATIC AERATION CONDITIONS
Inhibitor Mild Steel Coupon Visual ~ Efficiency Blank 12.0 0 3 0.53 25~ Pitting 95.6 4 13.59 25$ Pitting/70$ Gouged N/A
5.9 40~ Pitting/5~ Gouged 50.8 6 0.3 25~ Pitting 97.5 8 3.3 10~ Pitting/35~ Gouged 72.5 9 3.0 10$ Gouged 75.0 10.1 5$ Pitting 15.8 11 0.74 5~ Gouged 93.8 12 13.4 25~ Pitting/50~ Gouged N/A
13 5.4 30~ Pitting/5$ Gouged 55.0 14 0.66 5~ Gouged 94.5 12.4 10~ Pitting/20~ Gouged N/A
17 1.9 Generalized 84.2 13.8 10$ Pitting/60~ Gouged N/A
26 14.5 lOg Pitting/60$ Gouged N/A
27 20.0 60g Gouged N/A
28 1.3 Generalized 89.2 5 + 5 ppm 4.0 10$ Pitting/20~ Gouged 66.6 Phosphonate C
TABLE IV
CORROSION RATES USING TEST WATER II
CORROSION RATE OF METAL - MLS. PER YEAR (MPY) TEST DURATION - 18 DAYS; DYNAMIC AERATION CONDITIONS
Inhibitor Copper Coupon Mild Steel Coupon/ Efficiency Visual Blank --- 16.63 / 0 3 A 0.4 2.22 / 86.6 Pitting 4 B 0.05 4.25 / 74.4 Gouged/
Pitting C 0.11 6.43 / 61.3 Gouged/
Pitting NOTE: A average of 2 test runs -B - average of 4 test runs C - average of 3 test runs TABLE V
CORROSION RATES USING TEST ~rVATER III
CORROSION RATE OF METAL - MLS. PER YEAR (MPY) TEST DURATION - 30 DAYS; DYNAMIC AERATION CONDITIONS
AVERAGE OF: (A) 4 EXPERIMENTAL RUNS
(B) 8 EXPERIMENTAL RUNS
Inhibitor Copper Coupon Mild Steel Coupon/ Efficiency Visual (MPY) (MPY) Blank --- 9.96 / 0 25 A 0.014 4.97 / 50.1 Gouged/
Pitting 28 B 0.0073 1.13 / 88.6 Generalized CORROSION RATE USING TEST WATER IV
CORROSION RATE OF METAL - MLS. PER YEAR (MPY) TEST DURATION - 7 DAYS, STATIC AERATION CONDITIONS
Inhibitor Mild Steel Coupon Visual $ Efficiency (MPY) Blank 13.40 p 1 6.99 40~ Pitting 47.8 2 7.60 50~ Pitting 43.3 3 6.88 40~ Pitting 48.6 7 6.16 60~ Pitting 54.0 8 6.11 10~ Pitting/40~ Gouged 54.5 16 9.57 60g Pitting 28.6 17 6.88 25$ Pitting 48.6 18 6.84 35$ Pitting 48.9 19 6.37 25~ Pitting 52.4 20 6.65 20~ Pitting/40$ Gouged 50.4 21 6.99 30~ Pitting/40~ Gouged 47.8 22 5.88 30$ Pitting 56.1 23 6.91 35$ Pitting/40~ Gouged 48.4 24 6.37 35~ Pitting 52.4 28 6.78 30$ Pitting 49.4 29 6.37 25~ Pitting 52.4 30 7.59 25~ Pitting/40$ Gouged 43.3 31 5.29 <5~ Pitting/50~ Gouged 60.5 CORROSION RATE USING TEST WATER IV
Inhibitor Mild Steel Coupon Visual ~ Efficiency 32 4.89 <5~ Pitting 63.5 33 4.46 <5~ Pitting 66.7 34 4.56 10$ Pitting 65.9 35 5.68 15~ Pitting 57.6 36 5.74 5~ Pitting/50~ Gouged 57.1 38 6.97 40~ Pitting 48.0 39 7.40 20$ Pitting/65~ Gouged 44.7 40 6.72 30~ Pitting/60$ Gouged 49.8 CORROSION RATES USING TEST WATER IV
CORROSION RATE OF METAL - MLS. PER YER (MPY) TEST DURATION - 7 DAY INHIBITED TESTS, WATERS CHANGED DAILY DURING
THE DURATION OF THE TEST
Inhibitor Mild Steel Coupon Visual ~ Efficiency Blank 13.30 0 17 1.70 <5~ Pitting 87.2 22 1.10 Generalized 91.7 24 2.50 <5~ Pitting/10~ Gouged 81.2 28 1.58 <2~ Gouged 88.1 33 1.21 Generalized 90.9 34 1.50 <1~ Pitting 88.7 39 1.36 <1$ Pitting 89.7 41 1.42 <1~ Pitting 89.3 42 1.45 <1~ Pitting 89.1 TABLE VIII
CORRISION RATES FOR PREFILMING
CORRISION RATE OF METAL - MLS. PER YEAR (MPY) Inhibitor Mild Steel Coupon ~ Efficiency Blank A 12.0 0 Blank B 13.3 0 9A 3.0 75.0 9A with prefilming 1.12 90.6 17B with prefilming 0.60 95.5 28B with prefilming 0.72 94.5 NOTE: A - blank utilizing test water I
B - blank utilizing test water IV
- prefilming was done at three times the normal inhibitor concentration for 3 days of the total test duration of 10 days. Inhibited test waters were changed daily during the duration of the test.
STATIC CORROSION RATES FOR INTERMITTENT USE SYSTEMS
CORROSION RATE OF METAL - MLS PER YEAR (MPY) Inhibitor Mild Steel Coupon (MPY) $ Efficiency Blank (untreated system) 2.5 0 37 (prior art) 1.1 56 37 + [22] x 4 0.3 88 NOTE: (1) [22] x 4 = 4 times the concentration of Inhibitor 22 (2) Test water I utilized ..-TABLE X
DYNAMIC CORROSION RATES FOR INTERMITTENT USE SYSTEMS
CORROSION RATE OF METAL - MLS. PER YEAR (MPY) Inhibitor Copper Coupon Mild Steel Coupon/$ Efficiency (MPY) (MPY) Blank ---- 9.22 / 0 37 (prior art) 0.13 1.10 / 88.0 37 + [22] x 4 0.020 0.38 / 95.8 NOTE: (1) [22] x 4 = 4 times the concentration of Inhibitor 22 (2) Test water III utilized SCALE INHIBITOR PERFORMANCE
The scale inhibitory performance of the preferred blends was also evaluated. Static tests were performed on calcium carbonate and calcium phosphate precipitation inhibition.
The testing procedures were as follows:
Percent inhibition and percentage efficiency were calculated as follows:
$ Inhibition = Treated Sample Result x 100 Stock Solution Impurity where the impurity is either calcium carbonate, or calcium phosphate $ Efficiency = [Ca2+ treated] - [Ca2+ untreated] x 100 [Ca2+ initial] - (Ca2+ untreated]
for calcium carbonate inhibition tests Efficiency = Inhibitor ~ Inhibition - Blank ~ Inhibition for calcium phosphate inhibition tests CALCIUM CARBONATE (CaC03) PRECIPITATION INHIBITION
STOCK SOLUTION 1: 3.25 g/L CaCl2 ~ 2 H20 adjusted to pH 8.5 STOCK SOLUTION 2: 2.48 g/L Na2C03, adjusted to pH 8.5 ~nnn~r~mD~ .
1. Place the following in a 4-oz. jar:
50 ml Stock Solution 1 50 ml Stock Solution 2 Add inhibitor as specified in Table II
2. Preheat samples in warm (+ 70oC) water for 5 minutes 3. Heat in oven 5 hours at 70°C; remove and cool to room temperature 4. Filter through 0.45 ,txm filter 5. Add 4 ml concentrated HC1 to 25 ml filtrate and allow to stand 15+ minutes 6. Dilute to 50 ml with distilled H20 7. Add 3 ml 50~ NaOH
8. Add Ca+2 indicator 9. Titrate with EDTA to purple-violet endpoint FINAL CONCENTRATION - 958 ppm Ca2+ as CaCo3 i~40659 STANDARD CALCIUM PHOSPHATE PRECIPITATION INHIBITION
1. For each test sample, add the following to a 4-oz. jar:
(a) 50 ml of 12 ppm Na2HP04 as P04-3 (b) Add inhibitor as specified in Table II
(c) 50 ml of 500 ppm CaCl2 as CaC03 (with 5 mg/L Fe+3 added) 2. Adjust each sample to the appropriate pH (8.5) with dilute NaOH ( C1$) 3. Place lid on sample jars and store in a 70oC oven for 17 hours 4. Remove samples from oven one at a time and filter each sample through a 0.22 um millipore filter immediately after it is removed from the oven 5. Allow samples to cool to room temperature 6. Dilute samples by placing 30 ml of test sample into a 100 ml volumetric and QS with distilled H20 7. Spectrophotometrically analyze the dilute samples for p04+3 concentration by the ascorbic acid method (APHA
Standard Methods, 13th. Ed. 532 (1971): Hach spectrophotometer at 700 NM; Phosver III phosphate reagent).
FINAL CONCENTRATIONS:
250 ppm Ca+2, as CaC03 6 ppm P04-3 2.5 ppm Fe+3 The respective results are listed in Tables XI and XII.
~3~os~9 CALCIUM CARBONATE PRECIPITATION RESULTS
Inhibitor Precent Inhibition ~ Efficiency Blank 10.7 0 17 77.0 74.3 22 80.2 77.8 28 84.5 82.7 33 77.0 74.3 34 77.24 74.5 CALCIUM PHOSPHATE PRECIPITATION RESULTS
Inhibitor Precent Inhibition ~ Efficienc Blank 1.6 0 17 25.1 23.5 22 25.4 23.8 28 39.7 38.1 33 25.5 23.9 34 41.6 40.0 The above test results as well as others indicated the following. Generally, a corrosion and scale inhibitor comprising an azole, dual phosphonates and dual polymers showed distinct improvement over prior art inhibitors. Preferrably the azole is selected from 1, 2, 3 tolyltrizole, 1, 2, 3 benzotriazole or sodium 2 mercaptobenzothiazole. However, chlorination destroys sodium mercaptobenzothiazole when used on copper bearing alloys.
Preferrably the concentration of the azole is from 1 to 8 ppm (by weight). Of the dual phosphonates, one is primary and the other secondary. Preferrably both phosphonates are selected from 2-hydroxy-phosphono-acetic acid, 1-hydroxylethylidene-1, 1-diphosphonic acd and 2-phosphonobutane-1, 2, 4-tricarboxylic acid. The most preferred primary phosphonate is 2-hydroxy-phosphono-acetic acid utilized within the blend at a concentration of 3 to 20 ppm by weight.
The most preferred secondary phosphonate is either 1-hydroxylethylidene-1, 1-diphosphonic acid or 2-phosphonobutane -1, 2, 4-tricarboxylic acid utilized within the blend at a concentration of 2 to 20 ppm by weight in water.
It has also been established that the primary to secondary phosphonates should preferrably have a weight ratio of between about 1:0.6 to about 0.6:1.
Preferrably, the dual polymers (primary and secondary) are selected from malefic anhydride terpolymer, polyacrylate or polymethacrylate having an average molecular weight of from 1,000 1340~~9 to 100,000. The preferred primary polymer is malefic anhydride terpolymer utilized in the blend in a concentration of 1 to 16 ppm of water. The preferred secondary polymer is a homopolymer selected from polyacrylates or polymethacrylates and utilized in the blend in a concentration of 2 to 16 ppm of water.
Preferrably the primary and secondary polymers have a weight ratio of between about 4:1 to about 1:4 primary to secondary.
It has been determined that the total phosphonates to total polymers should preferrably have a weight ratio of about 2:1 to about 1:3.
The organic inhibitor blends of the instant invention may also be combined with at least one supplemental inhibitor to achieve improved results over prior art inhibitors. Such supplemental inhibitors are preferrably from the group comprising sulfonated styrene malefic anhydride copolymer, polyacrylate copolymer, nonionic polyethoxylated surfactant and a nonionic tertiary amine oxide utilized in a preferred concentration of 1 to 30 ppm of water.
The method according to the instant invention comprises utilizing the aforesaid blends of inhibitors in an aqueous water system. Of the blends particularized in Table II, numbers 22, 33, 34, 39, 41 and 42 fall within the invention.
While the products and methods of the instant invention have been described and exemplified herein, various .340659 modifications, alterations, and changes should become readily apparent to those skilled in the art without departing from the spirit and scope of the invention.
17 1.9 Generalized 84.2 13.8 10$ Pitting/60~ Gouged N/A
26 14.5 lOg Pitting/60$ Gouged N/A
27 20.0 60g Gouged N/A
28 1.3 Generalized 89.2 5 + 5 ppm 4.0 10$ Pitting/20~ Gouged 66.6 Phosphonate C
TABLE IV
CORROSION RATES USING TEST WATER II
CORROSION RATE OF METAL - MLS. PER YEAR (MPY) TEST DURATION - 18 DAYS; DYNAMIC AERATION CONDITIONS
Inhibitor Copper Coupon Mild Steel Coupon/ Efficiency Visual Blank --- 16.63 / 0 3 A 0.4 2.22 / 86.6 Pitting 4 B 0.05 4.25 / 74.4 Gouged/
Pitting C 0.11 6.43 / 61.3 Gouged/
Pitting NOTE: A average of 2 test runs -B - average of 4 test runs C - average of 3 test runs TABLE V
CORROSION RATES USING TEST ~rVATER III
CORROSION RATE OF METAL - MLS. PER YEAR (MPY) TEST DURATION - 30 DAYS; DYNAMIC AERATION CONDITIONS
AVERAGE OF: (A) 4 EXPERIMENTAL RUNS
(B) 8 EXPERIMENTAL RUNS
Inhibitor Copper Coupon Mild Steel Coupon/ Efficiency Visual (MPY) (MPY) Blank --- 9.96 / 0 25 A 0.014 4.97 / 50.1 Gouged/
Pitting 28 B 0.0073 1.13 / 88.6 Generalized CORROSION RATE USING TEST WATER IV
CORROSION RATE OF METAL - MLS. PER YEAR (MPY) TEST DURATION - 7 DAYS, STATIC AERATION CONDITIONS
Inhibitor Mild Steel Coupon Visual $ Efficiency (MPY) Blank 13.40 p 1 6.99 40~ Pitting 47.8 2 7.60 50~ Pitting 43.3 3 6.88 40~ Pitting 48.6 7 6.16 60~ Pitting 54.0 8 6.11 10~ Pitting/40~ Gouged 54.5 16 9.57 60g Pitting 28.6 17 6.88 25$ Pitting 48.6 18 6.84 35$ Pitting 48.9 19 6.37 25~ Pitting 52.4 20 6.65 20~ Pitting/40$ Gouged 50.4 21 6.99 30~ Pitting/40~ Gouged 47.8 22 5.88 30$ Pitting 56.1 23 6.91 35$ Pitting/40~ Gouged 48.4 24 6.37 35~ Pitting 52.4 28 6.78 30$ Pitting 49.4 29 6.37 25~ Pitting 52.4 30 7.59 25~ Pitting/40$ Gouged 43.3 31 5.29 <5~ Pitting/50~ Gouged 60.5 CORROSION RATE USING TEST WATER IV
Inhibitor Mild Steel Coupon Visual ~ Efficiency 32 4.89 <5~ Pitting 63.5 33 4.46 <5~ Pitting 66.7 34 4.56 10$ Pitting 65.9 35 5.68 15~ Pitting 57.6 36 5.74 5~ Pitting/50~ Gouged 57.1 38 6.97 40~ Pitting 48.0 39 7.40 20$ Pitting/65~ Gouged 44.7 40 6.72 30~ Pitting/60$ Gouged 49.8 CORROSION RATES USING TEST WATER IV
CORROSION RATE OF METAL - MLS. PER YER (MPY) TEST DURATION - 7 DAY INHIBITED TESTS, WATERS CHANGED DAILY DURING
THE DURATION OF THE TEST
Inhibitor Mild Steel Coupon Visual ~ Efficiency Blank 13.30 0 17 1.70 <5~ Pitting 87.2 22 1.10 Generalized 91.7 24 2.50 <5~ Pitting/10~ Gouged 81.2 28 1.58 <2~ Gouged 88.1 33 1.21 Generalized 90.9 34 1.50 <1~ Pitting 88.7 39 1.36 <1$ Pitting 89.7 41 1.42 <1~ Pitting 89.3 42 1.45 <1~ Pitting 89.1 TABLE VIII
CORRISION RATES FOR PREFILMING
CORRISION RATE OF METAL - MLS. PER YEAR (MPY) Inhibitor Mild Steel Coupon ~ Efficiency Blank A 12.0 0 Blank B 13.3 0 9A 3.0 75.0 9A with prefilming 1.12 90.6 17B with prefilming 0.60 95.5 28B with prefilming 0.72 94.5 NOTE: A - blank utilizing test water I
B - blank utilizing test water IV
- prefilming was done at three times the normal inhibitor concentration for 3 days of the total test duration of 10 days. Inhibited test waters were changed daily during the duration of the test.
STATIC CORROSION RATES FOR INTERMITTENT USE SYSTEMS
CORROSION RATE OF METAL - MLS PER YEAR (MPY) Inhibitor Mild Steel Coupon (MPY) $ Efficiency Blank (untreated system) 2.5 0 37 (prior art) 1.1 56 37 + [22] x 4 0.3 88 NOTE: (1) [22] x 4 = 4 times the concentration of Inhibitor 22 (2) Test water I utilized ..-TABLE X
DYNAMIC CORROSION RATES FOR INTERMITTENT USE SYSTEMS
CORROSION RATE OF METAL - MLS. PER YEAR (MPY) Inhibitor Copper Coupon Mild Steel Coupon/$ Efficiency (MPY) (MPY) Blank ---- 9.22 / 0 37 (prior art) 0.13 1.10 / 88.0 37 + [22] x 4 0.020 0.38 / 95.8 NOTE: (1) [22] x 4 = 4 times the concentration of Inhibitor 22 (2) Test water III utilized SCALE INHIBITOR PERFORMANCE
The scale inhibitory performance of the preferred blends was also evaluated. Static tests were performed on calcium carbonate and calcium phosphate precipitation inhibition.
The testing procedures were as follows:
Percent inhibition and percentage efficiency were calculated as follows:
$ Inhibition = Treated Sample Result x 100 Stock Solution Impurity where the impurity is either calcium carbonate, or calcium phosphate $ Efficiency = [Ca2+ treated] - [Ca2+ untreated] x 100 [Ca2+ initial] - (Ca2+ untreated]
for calcium carbonate inhibition tests Efficiency = Inhibitor ~ Inhibition - Blank ~ Inhibition for calcium phosphate inhibition tests CALCIUM CARBONATE (CaC03) PRECIPITATION INHIBITION
STOCK SOLUTION 1: 3.25 g/L CaCl2 ~ 2 H20 adjusted to pH 8.5 STOCK SOLUTION 2: 2.48 g/L Na2C03, adjusted to pH 8.5 ~nnn~r~mD~ .
1. Place the following in a 4-oz. jar:
50 ml Stock Solution 1 50 ml Stock Solution 2 Add inhibitor as specified in Table II
2. Preheat samples in warm (+ 70oC) water for 5 minutes 3. Heat in oven 5 hours at 70°C; remove and cool to room temperature 4. Filter through 0.45 ,txm filter 5. Add 4 ml concentrated HC1 to 25 ml filtrate and allow to stand 15+ minutes 6. Dilute to 50 ml with distilled H20 7. Add 3 ml 50~ NaOH
8. Add Ca+2 indicator 9. Titrate with EDTA to purple-violet endpoint FINAL CONCENTRATION - 958 ppm Ca2+ as CaCo3 i~40659 STANDARD CALCIUM PHOSPHATE PRECIPITATION INHIBITION
1. For each test sample, add the following to a 4-oz. jar:
(a) 50 ml of 12 ppm Na2HP04 as P04-3 (b) Add inhibitor as specified in Table II
(c) 50 ml of 500 ppm CaCl2 as CaC03 (with 5 mg/L Fe+3 added) 2. Adjust each sample to the appropriate pH (8.5) with dilute NaOH ( C1$) 3. Place lid on sample jars and store in a 70oC oven for 17 hours 4. Remove samples from oven one at a time and filter each sample through a 0.22 um millipore filter immediately after it is removed from the oven 5. Allow samples to cool to room temperature 6. Dilute samples by placing 30 ml of test sample into a 100 ml volumetric and QS with distilled H20 7. Spectrophotometrically analyze the dilute samples for p04+3 concentration by the ascorbic acid method (APHA
Standard Methods, 13th. Ed. 532 (1971): Hach spectrophotometer at 700 NM; Phosver III phosphate reagent).
FINAL CONCENTRATIONS:
250 ppm Ca+2, as CaC03 6 ppm P04-3 2.5 ppm Fe+3 The respective results are listed in Tables XI and XII.
~3~os~9 CALCIUM CARBONATE PRECIPITATION RESULTS
Inhibitor Precent Inhibition ~ Efficiency Blank 10.7 0 17 77.0 74.3 22 80.2 77.8 28 84.5 82.7 33 77.0 74.3 34 77.24 74.5 CALCIUM PHOSPHATE PRECIPITATION RESULTS
Inhibitor Precent Inhibition ~ Efficienc Blank 1.6 0 17 25.1 23.5 22 25.4 23.8 28 39.7 38.1 33 25.5 23.9 34 41.6 40.0 The above test results as well as others indicated the following. Generally, a corrosion and scale inhibitor comprising an azole, dual phosphonates and dual polymers showed distinct improvement over prior art inhibitors. Preferrably the azole is selected from 1, 2, 3 tolyltrizole, 1, 2, 3 benzotriazole or sodium 2 mercaptobenzothiazole. However, chlorination destroys sodium mercaptobenzothiazole when used on copper bearing alloys.
Preferrably the concentration of the azole is from 1 to 8 ppm (by weight). Of the dual phosphonates, one is primary and the other secondary. Preferrably both phosphonates are selected from 2-hydroxy-phosphono-acetic acid, 1-hydroxylethylidene-1, 1-diphosphonic acd and 2-phosphonobutane-1, 2, 4-tricarboxylic acid. The most preferred primary phosphonate is 2-hydroxy-phosphono-acetic acid utilized within the blend at a concentration of 3 to 20 ppm by weight.
The most preferred secondary phosphonate is either 1-hydroxylethylidene-1, 1-diphosphonic acid or 2-phosphonobutane -1, 2, 4-tricarboxylic acid utilized within the blend at a concentration of 2 to 20 ppm by weight in water.
It has also been established that the primary to secondary phosphonates should preferrably have a weight ratio of between about 1:0.6 to about 0.6:1.
Preferrably, the dual polymers (primary and secondary) are selected from malefic anhydride terpolymer, polyacrylate or polymethacrylate having an average molecular weight of from 1,000 1340~~9 to 100,000. The preferred primary polymer is malefic anhydride terpolymer utilized in the blend in a concentration of 1 to 16 ppm of water. The preferred secondary polymer is a homopolymer selected from polyacrylates or polymethacrylates and utilized in the blend in a concentration of 2 to 16 ppm of water.
Preferrably the primary and secondary polymers have a weight ratio of between about 4:1 to about 1:4 primary to secondary.
It has been determined that the total phosphonates to total polymers should preferrably have a weight ratio of about 2:1 to about 1:3.
The organic inhibitor blends of the instant invention may also be combined with at least one supplemental inhibitor to achieve improved results over prior art inhibitors. Such supplemental inhibitors are preferrably from the group comprising sulfonated styrene malefic anhydride copolymer, polyacrylate copolymer, nonionic polyethoxylated surfactant and a nonionic tertiary amine oxide utilized in a preferred concentration of 1 to 30 ppm of water.
The method according to the instant invention comprises utilizing the aforesaid blends of inhibitors in an aqueous water system. Of the blends particularized in Table II, numbers 22, 33, 34, 39, 41 and 42 fall within the invention.
While the products and methods of the instant invention have been described and exemplified herein, various .340659 modifications, alterations, and changes should become readily apparent to those skilled in the art without departing from the spirit and scope of the invention.
Claims (31)
1. A corrosion and scale inhibitor for use in an aqueous system, said inhibitor comprising:
(a) an azole in an amount effective to inhibit corrosion;
(b) 3-20 parts by weight per million parts of water of a first phosphonate, 2-hydroxy-phosphono acetic acid;
(c) 2-20 parts by weight per million parts of water of a second phosphonate, which is selected from the group consisting of 1-hydroxylethylidene-1,1-diphosphonic acid and 2-phosphonobutane-1,2,4-tricarboxylic acid;
(d) 1-16 parts by weight per million parts of water of a first polymer;
(e) 2-16 parts by weight per million parts of water of a second polymer, said first and second polymers being different and both selected from the group consisting of malefic anhydride terpolymer, polyacrylate and polymethacrylate having an average molecular weight of from 1000 to 100,000.
(a) an azole in an amount effective to inhibit corrosion;
(b) 3-20 parts by weight per million parts of water of a first phosphonate, 2-hydroxy-phosphono acetic acid;
(c) 2-20 parts by weight per million parts of water of a second phosphonate, which is selected from the group consisting of 1-hydroxylethylidene-1,1-diphosphonic acid and 2-phosphonobutane-1,2,4-tricarboxylic acid;
(d) 1-16 parts by weight per million parts of water of a first polymer;
(e) 2-16 parts by weight per million parts of water of a second polymer, said first and second polymers being different and both selected from the group consisting of malefic anhydride terpolymer, polyacrylate and polymethacrylate having an average molecular weight of from 1000 to 100,000.
2. The inhibitor of claim 1 wherein said azole is selected from the group consisting of 1,2,3-tolyltriazole, 1,2,3-benzotriazole and sodium 2-mercaptobenzothiazole.
3. The inhibitor of claim 1 or 2 wherein the concentration of azole is 1 to 8 parts by weight per million parts of water.
4. The inhibitor of claim 1 wherein a weight ratio of said first phosphonate to said second phosphonate is between about 1:0.6 to about 0.6:1.
5. The inhibitor of claim 1 wherein said first polymer is a maleic anhydride terpolymer.
6. The inhibitor of claim 5 wherein said second polymer is a homopolymer selected from the group consisting of polyacrylate or polymethacrylate.
7. The inhibitor of claim 1, 5 or 6 wherein a weight ratio of said first polymer to said second polymer is between about 4:1 to about 1:4.
8. The inhibitor of claim 1 wherein a weight ratio of said first phosphonate and said second phosphonate to said first polymer and said second polymer is between about 2:1 to about 1:3.
9. The inhibitor of claim 1 including at least one supplemental inhibitor selected from the group consisting of sulfonated styrene malefic anhydride copolymer, polyacrylate copolymer, nonionic polyethoxylated surfactant and a nonionic tertiary amine oxide.
10. The inhibitor of claim 9 wherein said at least one supplemental inhibitor has a concentration of 1 to 30 parts by weight per million parts of water.
11. A method for inhibiting scale and corrosion formation in an aqueous system comprising use of the inhibitor of claim 1 in said aqueous system.
12. The method of claim 11 wherein the inhibitor is added to said aqueous system either continuously or on a supplemental or shock fed basis proportionately to aqueous system water loss.
13. The method of claim 12 wherein the inhibitor provides inhibition of corrosion during stagnant or idle periods of non-recirculation of said aqueous system.
14. The method of claim 12 or 13 wherein said inhibitor is added at least 4 hours prior to shut-down of recirculation of said aqueous system.
15. A method for inhibiting scale and corrosion formation in an aqueous system during periodic idleness comprising use of the inhibitor of claim 1 in combination with existing scale and corrosion inhibitory blends.
16. A method for inhibiting scale and corrosion formation in an aqueous system using a normal operational level of the inhibitor of claim 1, wherein said aqueous system is prefilmed during an initial start up of said aqueous system by using levels in excess of said normal operational level.
17. The method of claim 16 wherein said concentration levels in excess of said normal operational level are up to three times said normal operation level of said inhibitor.
18. A corrosion inhibitor and scale inhibitor for use in an aqueous system comprising:
(a) 1-8 parts of an azole, (b) 3-20 parts of a 2-hydroxy-phosphono acetic acid as a first phosphonate, (c) 2-20 parts of a second phosphonate selected from the group consisting of 1-hydroxylethylidene-1,1-diphosphonic acid, 2-phosphonobutane-1,2,4-tricarboxylic acid, and mixtures thereof, (d) 1-16 parts of maleic anhydride terpolymer as a first polymer, (e) 2-16 parts of a second polymer, such that the weight ratio of (b) to (c) is 1:0.6 to about 0.6:1 and the weight ratio (d) to (e) is from 4:1 to 1:4, wherein said parts is parts by weight per million parts of water.
(a) 1-8 parts of an azole, (b) 3-20 parts of a 2-hydroxy-phosphono acetic acid as a first phosphonate, (c) 2-20 parts of a second phosphonate selected from the group consisting of 1-hydroxylethylidene-1,1-diphosphonic acid, 2-phosphonobutane-1,2,4-tricarboxylic acid, and mixtures thereof, (d) 1-16 parts of maleic anhydride terpolymer as a first polymer, (e) 2-16 parts of a second polymer, such that the weight ratio of (b) to (c) is 1:0.6 to about 0.6:1 and the weight ratio (d) to (e) is from 4:1 to 1:4, wherein said parts is parts by weight per million parts of water.
19. The inhibitor of claim 18 wherein said azole is selected from the group consisting of 1,2,3-tolyltriazole,1,2,3-benzotriazole, and sodium 2-mercaptobenzothiazole.
20. The inhibitor of claim 18 wherein said secondary polymer is a homopolymer selected from the group consisting of polyacrylate and polymethacrylate.
21. The inhibitor of claim 18 or 20 wherein said secondary polymer has an average molecular weight of from 1,000 to 100,000.
22. The inhibitor of claim 18 wherein a weight ratio of said first phosphonate and said second phosphonate to said first polymer and said second polymer is between about 2:1 to about 1:3.
23. The inhibitor of claim 18 including at least one supplemental inhibitor selected from the group consisting of sulfonated styrene maleic anhydride copolymer, polyacrylate copolymer, nonionic polyethoxylated surfactant and a nonionic tertiary amine oxide.
24. The inhibitor of claim 23 wherein said at least one supplemental inhibitor has a concentration of 1 to 30 parts by weight per million parts of water.
25. A method for inhibiting scale and corrosion formation in an aqueous system comprising use of the inhibitor of claim 18 in said aqueous system.
26. The method of claim 25 wherein the inhibitor is added to said aqueous system either continuously or on a supplemental or shock fed basis proportionately to aqueous system water loss.
27. The method of claim 26 wherein the inhibitor provides inhibition of corrosion during stagnant or idle periods of non-recirculation of said aqueous system.
28. The method of claim 26 or 27 wherein said inhibitor is added at least 4 hours prior to shut-down of recirculation of said aqueous system.
29. A method for inhibiting scale and corrosion formation in an aqueous system during periodic idleness comprising use of the inhibitor of claim 18 in combination with existing scale and corrosion inhibitory blends.
30. A method for inhibiting scale and corrosion formation in an aqueous system using a normal operational level of the inhibitor of claim 18, wherein said aqueous system is prefilmed during an initial start up of said aqueous system by using levels in excess of said normal operational level.
31. The method of claim 30 wherein said concentration levels in excess of said normal operational level are up to three times said normal operation level of said inhibitor.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000554873A CA1340659C (en) | 1987-12-18 | 1987-12-18 | Anti-scale and corrosion inhibitor |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000554873A CA1340659C (en) | 1987-12-18 | 1987-12-18 | Anti-scale and corrosion inhibitor |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1340659C true CA1340659C (en) | 1999-07-20 |
Family
ID=33315106
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000554873A Expired - Lifetime CA1340659C (en) | 1987-12-18 | 1987-12-18 | Anti-scale and corrosion inhibitor |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1340659C (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2013020937A1 (en) * | 2011-08-10 | 2013-02-14 | Basf Se | Polymer blends as coating inhibitors in water-carrying systems |
| US20130037491A1 (en) * | 2011-08-10 | 2013-02-14 | Basf Se | Polymer mixtures as deposit inhibitors in water-bearing systems |
| RU2580685C2 (en) * | 2014-07-04 | 2016-04-10 | Акционерное общество "Химический завод им. Л.Я. Карпова" | Corrosion and scaling inhibitor |
| US20210371988A1 (en) * | 2020-05-28 | 2021-12-02 | Ecolab Usa Inc. | Closed loop cooling water corrosion inhibition employing polymaleates and non-borate buffers |
-
1987
- 1987-12-18 CA CA000554873A patent/CA1340659C/en not_active Expired - Lifetime
Cited By (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2013020937A1 (en) * | 2011-08-10 | 2013-02-14 | Basf Se | Polymer blends as coating inhibitors in water-carrying systems |
| US20130037491A1 (en) * | 2011-08-10 | 2013-02-14 | Basf Se | Polymer mixtures as deposit inhibitors in water-bearing systems |
| CN103874663A (en) * | 2011-08-10 | 2014-06-18 | 巴斯夫欧洲公司 | Polymer blends as coating inhibitors in water-carrying systems |
| CN103874663B (en) * | 2011-08-10 | 2016-04-20 | 巴斯夫欧洲公司 | With the polymeric blends of making coatings inhibitor in Aquo System |
| US9382377B2 (en) * | 2011-08-10 | 2016-07-05 | Basf Se | Polymer mixtures as deposit inhibitors in water-bearing systems |
| RU2608409C2 (en) * | 2011-08-10 | 2017-01-18 | Басф Се | Polymer mixtures as deposit inhibitors in water supply systems |
| AU2012293673B2 (en) * | 2011-08-10 | 2017-02-23 | Basf Se | Polymer blends as coating inhibitors in water-carrying systems |
| RU2580685C2 (en) * | 2014-07-04 | 2016-04-10 | Акционерное общество "Химический завод им. Л.Я. Карпова" | Corrosion and scaling inhibitor |
| US20210371988A1 (en) * | 2020-05-28 | 2021-12-02 | Ecolab Usa Inc. | Closed loop cooling water corrosion inhibition employing polymaleates and non-borate buffers |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US4303568A (en) | Corrosion inhibition treatments and method | |
| US4443340A (en) | Control of iron induced fouling in water systems | |
| US5342540A (en) | Compositions for controlling scale formation in aqueous system | |
| CA2162313C (en) | Methods for controlling scale formation in aqueous systems | |
| US4108790A (en) | Corrosion inhibitor | |
| US3960576A (en) | Silicate-based corrosion inhibitor | |
| EP0599485B1 (en) | Method of inhibiting corrosion in aqueous systems | |
| US5866032A (en) | Composition for controlling scale formation in aqueous systems | |
| KR20060123885A (en) | Method of water treatment for preventing corrosion and scale formation of metal | |
| US3803048A (en) | Organic phosphonic acid compound corrosion protection in aqueous systems | |
| EP0077187A1 (en) | Method of inhibiting corrosion and controlling deposition in an aqueous medium | |
| US4057511A (en) | Process for preventing corrosion and the formation of scale in water circulating system | |
| EP0396243A1 (en) | The inhibition of corrosion in aqueous systems | |
| EP0277412B1 (en) | Inhibiting corrosion of iron base metals | |
| US4547540A (en) | Corrosion protection in cooling water systems | |
| US5378390A (en) | Composition for controlling scale formation in aqueous systems | |
| CA1340659C (en) | Anti-scale and corrosion inhibitor | |
| US5002697A (en) | Molybdate-containing corrosion inhibitors | |
| US4778655A (en) | Treatment of aqueous systems | |
| EP0242229B1 (en) | Phosphonic acid/phosphate mixtures for controlling corrosion of metal and inhibiting calcium salt precipitation in aqueous systems | |
| KR20040053571A (en) | Method of water-treatment for preventing corrosion anc scale of metal in cooling system | |
| US5344590A (en) | Method for inhibiting corrosion of metals using polytartaric acids | |
| US3794603A (en) | Zn++-benzotriazole-h2so4 corrosioninhibitor | |
| JPH10509477A (en) | Corrosion inhibiting composition for aqueous system | |
| US4806310A (en) | Corrosion inhibitor |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |
Effective date: 20160720 |