CA2066991A1 - Synergistic combination of sodium silicate and orthophosphate for controlling carbon steel corrosion - Google Patents
Synergistic combination of sodium silicate and orthophosphate for controlling carbon steel corrosionInfo
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- CA2066991A1 CA2066991A1 CA002066991A CA2066991A CA2066991A1 CA 2066991 A1 CA2066991 A1 CA 2066991A1 CA 002066991 A CA002066991 A CA 002066991A CA 2066991 A CA2066991 A CA 2066991A CA 2066991 A1 CA2066991 A1 CA 2066991A1
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- Prior art keywords
- orthophosphate
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- weight
- corrosion
- sodium silicate
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- 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
- C23F11/18—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 inorganic inhibitors
- C23F11/187—Mixtures of inorganic inhibitors
- C23F11/188—Mixtures of inorganic inhibitors containing phosphates
-
- 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
- C02F5/083—Mineral agents
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- Environmental & Geological Engineering (AREA)
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- General Chemical & Material Sciences (AREA)
- Water Supply & Treatment (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Inorganic Chemistry (AREA)
- Materials Engineering (AREA)
- Mechanical Engineering (AREA)
- Metallurgy (AREA)
- Preventing Corrosion Or Incrustation Of Metals (AREA)
- Anti-Oxidant Or Stabilizer Compositions (AREA)
Abstract
TITLE OF THE INVENTION
SYNERGISTIC COMBINATION OF SODIUM SILICATE AND ORTHO-PHOSPHATE FOR CONTROLLING CARBON STEEL CORROSION
ABSTRACT OF THE DISCLOSURE
An orthophosphate salt and sodium silicate, when used in a 3:1 ratio by weight, and in a concentration of 0.1 to 100 mg/L, are found to have a synergietic effect in controlling the corrosion of carbon steel in an aqueous system, e.g., a municipal water supply system. The synergistic combination is also useful in reducing lead solubility and leaching, and in stabilizing soluble iron and manganese and their reaction products.
SYNERGISTIC COMBINATION OF SODIUM SILICATE AND ORTHO-PHOSPHATE FOR CONTROLLING CARBON STEEL CORROSION
ABSTRACT OF THE DISCLOSURE
An orthophosphate salt and sodium silicate, when used in a 3:1 ratio by weight, and in a concentration of 0.1 to 100 mg/L, are found to have a synergietic effect in controlling the corrosion of carbon steel in an aqueous system, e.g., a municipal water supply system. The synergistic combination is also useful in reducing lead solubility and leaching, and in stabilizing soluble iron and manganese and their reaction products.
Description
2 ~
TITLE OF THE INVENTION
SYNERGISTIC COMBINATION OF SODIUM SILICATE AND ORTHO-PHOSPHATE FOR CONTROLLING CARBON STEEL CORROSION
BACKGROUND OF THE INVENTION
1. Field of the Invention CORROSION - The present invention relates to a method for inhibiting the corrosion of metallic surfaces, especially those made of carbon steel, in contact with aqueous systems, and to compositions for use in such a method, particularly where the water o~
the aqueous system is oxygen-bearing. More particularly, the present invention relates to a ~ynergistic composition comprising about 3 parts by weight of orthophosphate and about 1 part by weight of sodium silicate. In particular, sodium phosphate tribasic is the preferred form of orthophosphate.
The term "aqueous system" as used herein, is intended to describe any system which contains water in any physical state, includi.ng water which contains one or more dissolved or dispersed substances such a~
inorganic salts. Typical sys~ems include, but are not limited to, cooling water s~stems including cooling towers, boiler water systems, desalination systems, gas scrubber units, blast furnaces, sewage sludge dewatering systems, thermal conditioning lo equipment, reverse osmosis units, sugar evaporators, paper processing systems, mining circuits, and the like. Where the aqueous system is a potable water source, it may be any type of drinking water system or source.
The term "carbon steel" as used herein is intended to include ferrous and ferrous-containing materials alloyed with small quantities of carbon and optionally ~:mall amounts of other metals, but to exclude those stee~ alloys of the type commonly ~ re~erred to as ~stainless~, which contain nickel and/or chromium.
The corrosion of a metallic surface in an aqueous system consists of the destruction of the ferrous metal by chemical or electrochemical reaction of the metal with its immediate environment.
Where the corrosion is electrochemical in nature, a transfer or exchange of electrons is necessary for the corrosion reaction to proceed. When corrosion of the metal takes place, at least two electrochemical processes occur, and must occur, simultaneously.
There is an anodic oxidation reaction in which metal 03041H -3- C~
ions go into solution, leaving behind electrons; and at least one cathodic reduction reaction in which species in solution are reduced by consuming the electrons produced by the anodic reaction. With respect to errous or ferrous containing materials, when the water contains oxygen and i~ at a neutral pH
or above, these processes may be illustrated by the following equations:
Anodic oxidation:
Fe -~ Fe~2 ~ 2e~
Cathodic reaction:
H20 + 2 + 4e -~ 40H
The two ionic reaction products, ferrous ion and hydroxyl ion, combine to form ferrous hydroxide, Fe(0~)2, which is then oxidized to form ferric hydroxide, Fe(OH)3(rust). For ferrous or ferrous-containing materials as well as other metals in agueous systems, the principle factors influencing the corrosion process are the characteristics o~ the water in the system, including but not limited to the rate of water flow, the temperature of the system and contact between dissimilar me~als in the system.
Variable characteristics of the water which impact upon its corrosiveness are its dissolved oxygen concentration, carbon dioxide contant, p~ and hardness.
The presence of dissolved oxygen in the water of an aqueous system iæ primarily the result of contact between the water and the atmosphere. The oxy~en 2 ~
solubility in water is temperature and pressure dependent, with increases in pressure increasing solubility and increases in t~emperature lowering oxygen solubility.
Corroslon produced by the presence of oxygen in the water of an aqueous system can take place in the form of small pits or depressions and/or in the form of general metal loss. As a corrosive process continues, pits or depressions generally increase in depth. The corrosive attack is more severe when it causes pits or depressions, since the deeper penetration of the metal causes more rapid failure at lo these points.
MANGANESE AND IRON STABILIZATION - The synergistic combination of the present invention is also useful in stabilizing soluble manganese and iron ions and their reaction products in desirable ~orms and reduced particle sizes. Manganous ions are often found in well waters while cooling waters contain primarily the manganic species. Ferrous and ferric ions are o~ten found in well waters while cooling waters contain primarily the ferric species. Anionic species of carbonate, bicarbonate, ~ulfite, fluoride, chloride, sulfate, and so forth, and dissolved oxygen may be present in both waters. Oxygen reaction products of manganese and iron can collect on metal surfaces and accelerate corrosion and reduce heat transfer.
LEAD LEAC~ING - The synergistic combination of the present invention is further useful for preventing or reducing levels of lead in potable water sources, i.e., drinking water. It has long been known that there is a strong link between lead contamination in drinking water and adverse health ~ 3 ~J ,~
03041H -~- C-1531 effects in humans.
2. Brief Description of the Prior ~rt A variety of compostions have been employed in the art for the purpose of inhibiting corrosion of surfaces in water-carrying systems where the cause of corrosion i6 dissolved oxygen. Polyphosphates such as sodium tripolyphophate are widely used in the treatment of once-through systems. See U.S. Pat. No.
2,742,369. Silicates, for example sodium silicate, have also found acceptance.
lo U.S. Pat. No. 3,483,133 discloses a corrosion inhibiting composition comprising amino-tris (methylene phosphonic) acid compounds in combination with water soluble zinc salts.
Other conventional inhibitors such as zinc, soluble zinc salts, chromates, benzotriazole, tolytriazole or mercaptobenzothiazole may be added to the final formulation in varying amounts to improve its usefulness in a wider variety of industrial applications where both low carbon steel and copper or its alloys are present in the same system.
Similarly, polymeric dispersants such as polyacrylates, polyacrylamides or polymers of 2-acrylamidomethylpropane sulfonic acid may also be incorporated in the final formulation in varying amounts. The molecular weights of these dispersants may vary from as low as less than 1000 to as high as several million.
Still other compositions for inhibiting corro~ion are known. See, e.g., Boffardi US 4,798,683 (molybdate compositions); Ralston US 3,589,858 (readily soluble phosphate glasses); ~ollingshad US
d, ~
TITLE OF THE INVENTION
SYNERGISTIC COMBINATION OF SODIUM SILICATE AND ORTHO-PHOSPHATE FOR CONTROLLING CARBON STEEL CORROSION
BACKGROUND OF THE INVENTION
1. Field of the Invention CORROSION - The present invention relates to a method for inhibiting the corrosion of metallic surfaces, especially those made of carbon steel, in contact with aqueous systems, and to compositions for use in such a method, particularly where the water o~
the aqueous system is oxygen-bearing. More particularly, the present invention relates to a ~ynergistic composition comprising about 3 parts by weight of orthophosphate and about 1 part by weight of sodium silicate. In particular, sodium phosphate tribasic is the preferred form of orthophosphate.
The term "aqueous system" as used herein, is intended to describe any system which contains water in any physical state, includi.ng water which contains one or more dissolved or dispersed substances such a~
inorganic salts. Typical sys~ems include, but are not limited to, cooling water s~stems including cooling towers, boiler water systems, desalination systems, gas scrubber units, blast furnaces, sewage sludge dewatering systems, thermal conditioning lo equipment, reverse osmosis units, sugar evaporators, paper processing systems, mining circuits, and the like. Where the aqueous system is a potable water source, it may be any type of drinking water system or source.
The term "carbon steel" as used herein is intended to include ferrous and ferrous-containing materials alloyed with small quantities of carbon and optionally ~:mall amounts of other metals, but to exclude those stee~ alloys of the type commonly ~ re~erred to as ~stainless~, which contain nickel and/or chromium.
The corrosion of a metallic surface in an aqueous system consists of the destruction of the ferrous metal by chemical or electrochemical reaction of the metal with its immediate environment.
Where the corrosion is electrochemical in nature, a transfer or exchange of electrons is necessary for the corrosion reaction to proceed. When corrosion of the metal takes place, at least two electrochemical processes occur, and must occur, simultaneously.
There is an anodic oxidation reaction in which metal 03041H -3- C~
ions go into solution, leaving behind electrons; and at least one cathodic reduction reaction in which species in solution are reduced by consuming the electrons produced by the anodic reaction. With respect to errous or ferrous containing materials, when the water contains oxygen and i~ at a neutral pH
or above, these processes may be illustrated by the following equations:
Anodic oxidation:
Fe -~ Fe~2 ~ 2e~
Cathodic reaction:
H20 + 2 + 4e -~ 40H
The two ionic reaction products, ferrous ion and hydroxyl ion, combine to form ferrous hydroxide, Fe(0~)2, which is then oxidized to form ferric hydroxide, Fe(OH)3(rust). For ferrous or ferrous-containing materials as well as other metals in agueous systems, the principle factors influencing the corrosion process are the characteristics o~ the water in the system, including but not limited to the rate of water flow, the temperature of the system and contact between dissimilar me~als in the system.
Variable characteristics of the water which impact upon its corrosiveness are its dissolved oxygen concentration, carbon dioxide contant, p~ and hardness.
The presence of dissolved oxygen in the water of an aqueous system iæ primarily the result of contact between the water and the atmosphere. The oxy~en 2 ~
solubility in water is temperature and pressure dependent, with increases in pressure increasing solubility and increases in t~emperature lowering oxygen solubility.
Corroslon produced by the presence of oxygen in the water of an aqueous system can take place in the form of small pits or depressions and/or in the form of general metal loss. As a corrosive process continues, pits or depressions generally increase in depth. The corrosive attack is more severe when it causes pits or depressions, since the deeper penetration of the metal causes more rapid failure at lo these points.
MANGANESE AND IRON STABILIZATION - The synergistic combination of the present invention is also useful in stabilizing soluble manganese and iron ions and their reaction products in desirable ~orms and reduced particle sizes. Manganous ions are often found in well waters while cooling waters contain primarily the manganic species. Ferrous and ferric ions are o~ten found in well waters while cooling waters contain primarily the ferric species. Anionic species of carbonate, bicarbonate, ~ulfite, fluoride, chloride, sulfate, and so forth, and dissolved oxygen may be present in both waters. Oxygen reaction products of manganese and iron can collect on metal surfaces and accelerate corrosion and reduce heat transfer.
LEAD LEAC~ING - The synergistic combination of the present invention is further useful for preventing or reducing levels of lead in potable water sources, i.e., drinking water. It has long been known that there is a strong link between lead contamination in drinking water and adverse health ~ 3 ~J ,~
03041H -~- C-1531 effects in humans.
2. Brief Description of the Prior ~rt A variety of compostions have been employed in the art for the purpose of inhibiting corrosion of surfaces in water-carrying systems where the cause of corrosion i6 dissolved oxygen. Polyphosphates such as sodium tripolyphophate are widely used in the treatment of once-through systems. See U.S. Pat. No.
2,742,369. Silicates, for example sodium silicate, have also found acceptance.
lo U.S. Pat. No. 3,483,133 discloses a corrosion inhibiting composition comprising amino-tris (methylene phosphonic) acid compounds in combination with water soluble zinc salts.
Other conventional inhibitors such as zinc, soluble zinc salts, chromates, benzotriazole, tolytriazole or mercaptobenzothiazole may be added to the final formulation in varying amounts to improve its usefulness in a wider variety of industrial applications where both low carbon steel and copper or its alloys are present in the same system.
Similarly, polymeric dispersants such as polyacrylates, polyacrylamides or polymers of 2-acrylamidomethylpropane sulfonic acid may also be incorporated in the final formulation in varying amounts. The molecular weights of these dispersants may vary from as low as less than 1000 to as high as several million.
Still other compositions for inhibiting corro~ion are known. See, e.g., Boffardi US 4,798,683 (molybdate compositions); Ralston US 3,589,858 (readily soluble phosphate glasses); ~ollingshad US
d, ~
3,885,914 (low molecular weight polymers and zinc);
Ralston US 4,018,701 (phosphorous acid and zinc);
~atch US 3,532,639 (zinc salts and derivatives of methanol phosphonic or diphosphonic acid); and Hatch U~ 3,022,133 (chromates/dichromates and zinc).
One method for removing soluble manganese by precipitation and removal involves the addition of a salt of iron, copper, or cobalt and any compound yielding bisulfite ions in ~olution to the manganese-containing water. See Hatch - US 3,349,031.
Soluble manganese ion and its reaction products have been stabilized in water systems using lo carboxylic acid/sulphonic acid copolymers. See Ralston - US 4,552,6~5.
The use of orthophosphate has reduced lead solubility in both low- and high-alkalinity waters.
An orthophosphate concentration of approximately 1 to 2 mg/L PO4 can be effective in reducing lead solubility over a much lower pH range than would be possible by using pH-carbonate adjustment.
Adding zinc/polyphosphate to municipal distribution systems has been an effective treatment program for controlling corrosion, as well as stabilizing iron and manganese. Although polyphosphates are not as effective as orthophosphate in reducing lead solubility, the use of zinc/polyphosphate has broad applicability. The effective pH range is 6 to 7.5, but maintaining the pH above neutral i~ recommended.
Treatments utilizing silicates appear to have a ret~rding effect on lead solubility, but require a relatively long period of time, approximately 8 to 9 months, to show reductions in lead concentrations.
This long-term effect can be explained by the slow 2 ~ 3 ~
formation of a ~inetically-inhibited lead silicate film. Silicate treatments, however, are not recommended for control of lead solubility in distribution systems.
SUMMARY OF THE INVENTION
The present invention relates to a carbon steel corrosion inhibiting composition comprising about 3 parts by weight of orthophosphate and about 1 part by weight of sodium silicate. In particular, sodium phosphate t:ribasic is the preferred form of orthophosphate.
The present invention further relates to a method of inhibiting the corrosion of carbon steel in an a~ueous system comprising the step of treating said system with an effective corrosion-inhibiting amount of a composition comprising about 3 parts by weight of orthophosphate and about 1 part by weight of sodium silicate. In particular, the present invention relates to such a treatment method in which sodium phosphate tribasic is preferred as the orthophosphate, and the composition is used in an amount ~ufficient to achieve a concentration of the total composition of from 0.1 to 100 mg/L in said aqueous system, preferably from 1.0 to 50 mg/L, and most preferably from 2 to 25 mg/L.
The present invention further relates to a method of inhibiting the precipitation of dissolved manganese and iron ions and their reaction products in an a~ueous system, comprising the step of treating said system with an effective precipitation-inhibiting amount of a composition 2 ~
comprising about 3 parts by weight of orthophosphate and about 1 part by weight of sodium silicate. In particular, the present invention relates to such a treatment method in which sodium phosphate tribasic is preferred as the orthophosphate, and the composition is used in an amount sufficient to achieve a concentration of from 0.1 to 50 mg/L in said aqueous system, preferably from 1.0 to 50 mg/L, and most preferably from 2 to 25 mg/L.
The present invention still further relates to a method of reducing the amount of soluble lead in a potable water source comprising treating said water with an effective amount of a composition comprising about 3 parts by weight of orthophosphate and about 1 part by weight of sodium silicate. In particular, the present invention relates to such a treatment method in which sodium phosphate tribasic is preferred as the orthophosphate, and the composition is used in an amount sufficient to achieve a concentration of from 0.1 to 100 mg/L in said aqueous system, preferably from 1.0 to 50 mg/L, and most preferably from 2 to 25 mg/L.
DETAILED DESCRIPTION OF THE INV~NTION
The orthophosphates useful in the compositions ~5 and methods of the present invention all have PO4 as the anion portion of the total salt, i.e., a salt of orthophosphoric arid. This is the active ionic component with respect to providing the benefits of the methods of the present invention in inhibiting carbon steel corrosion, and inhibiting the precipitation of manganese and iron ions and their 2~$~
03041~ -9- C-1531 reaction products, and also red~cing lead solubility in said water. The cation portion of the total salt is relatively unimportant, e~:cept with respect to solubility, which, it will ~e appreciated, is critical to the method of the present invention, since it requires the addition of the orthophosphate salt to an aqueous system being treated, including a potable water source. Thus, the most soluble salt forms will generally be the most preferred for use in the methods of the present invention.
The cation portion is selected from the alkali metals Li, Na, K and NH4, or combinations of these lo with the alkaline earth metals M~, Ca and Ba. Since the P04 anion portion has a 3 valency, the most commcn alkali metal salt forms will simply have three cations of the same metal, e.g., Na3P04. This form, which is often referred to as sodium phosphate lS tribasic, is the most common form and the most preferred form for use in the method of the present invention.
The alkali metals may be different, e.g., LiNa2P04 or NaK2P04. Where the alkaline earth metals are present, usually only one will be present because they have a ~2 valency, and there will usually be an alkali metal preæent to balance ~alencies. Thus, MgNaP04 may be used. Other combinations of the alkali and alkaline earth metals are possible, e.g., Na2Mg2(P04)2, but these are less preferred forms.
The most preferred orthophosphate for use in the methods of the present invention, aodium phosphate tribasic, or trisodium orthophosphate, crystallizeæ ~ith 8 and 12 mols of ~2 The dodecahydrate is in the form of colorless or white crystals which, when rapidly heated, melts at about 75 C. It is soluble in 3.5 parts of 03041~ -10- C-1531 water. Accordingly, such a material can be added directly to an aqueous system to be treated, including a potable water source in the amount required to inhibit carbon steel corrosion, and inhibit precipitation of manganese and iron ions and their reaction products, as well as to reduce lead leaching.
The orthophosphate is used in the composition of the present invention in an amount which gives a weight ratio to sodium silicate of about 3:1. The weight of P04 only is used in this calculation, and not the weight of the total orthophosphate salt. The term "about" means that amounts more than or less than the precise amount which lo gives the 3:1 ratio are also a part of the present invention so long as the synergistic effect of the combination is obtained. It is contemplated that in practice the amounts thus included will normally between 2.85:1 and 3.15:1.
The sodium silicate which is used in the compositions and methods of the present invention, has one or more of the compositions shown by the formulas: Na~SiO3, Na6Si207, and Na2Si307, and is also known as water glass and sodium metasilicate. It is preferred for practical reasons to use the sodium silicate in liquid form, i.e., as an aqueous solution, which may consist of varying compositions with respect to the ratlo between sodium and silica, as well as being of various densities.
The sodium silicate is used in the composition of the present invention in an amount which gives a weight ratio to orthophosphate o~ about 1:3. The weight of ~iO2 only is used in this calculation, and not the weight of the sodium portion of the salt. The term "about" means that amounts more than or less than the precise amount which gives the 1:3 ratio are also a part of the present invention so long as the synergistic effect of the combination is obtained. It is contemplated that in practice the amounts thus included will normally between 0.85:3 and 1.15:3.
The amounts of the 3:1 orthophosphate: sodium silicate composition of the present invention, that are required to be added for the desired maximum inhibition of carbon steel corrosion will be such as to provide an ultimate concentration of the total composition of the present invention in the aqueous system being treated of between 0.1 and 100 mg/L, and preferably this concentration will be between 1.0 and 50 mg/L. Most preferably the concentration will be between ~ and 25 mg/L, although it is understood that man~ factors, of the type which have been explained in detail with regard to the background to the present invention, will determine the actual amount of the composition of the present invention which will be added to any particular aqueous system in order to achieve the maximum amount of inhibition of carbon steel corrosion in that aqueouæ system. The calculation of those amounts will be well within the skill of the artisan in this field.
The amounts of the 3:1 orthophosphate: sodium silicate composition of the present invention, that are required to be added for the desired maximum inhibition of precipitation of manganese and iron ions and their reaction products will be such as to provide an ultimate concentration of the total composition of the present invention in the aqueous system being treated of between 0.1 and 100 mg/L, and 2 ~ .J~
03041~ -12- C-1531 preferably this concentration will be between 1.0 and 50 mg/L. Mos-t preferably the concentration will be between 2 and 25 mg/L, altho~lgh it is understood that many factors, of the type which have been explained in detail with regard to the ~ackground to the present invention, will determine the actual a~ount of the total composition of t:he present invention which wil~ be added to any particular aqueous sys~em in order to achieve the maximum amount of inhibition of precipitation of manganese and iron ions and their reaction products in that aqueous system. The calculation of those amounts will be well within the 0 skill of the artisan in this field.
The manner of addition of the orthophosphate and sodium silicate composition of the present invention to an aqueous system, including a potable water source, will also be straightforward to a person of ordinary skill in this art. It may be added in finely subdivided solid form by mechanical dispensers of known de~ign. It may also be added in solid form, but in the form of a matrix in which solid particles of the active ingredient are bonded or ~ound together by a material which is water soluble, or optionally, does not dissolve at all. Such a matrix allows for regular leaching out or dissolving of the active ingredient particles, whereby it is possible to obtain a sustained release and more unvarying concentration of the orthophosphate and sodium silicate composition in the water being treated. In the preferred manner of addition, the orthophosphate and sodium silicate composition of the present invention is made up in the form of concentrated solutions for dispensing in liquid form ~rom dispensers well known in the art. The orthophosphate 03041H -13- C-~ J ~ ~Qy and sodium silicate composition of the present invention may also be combined with other chemical treatment agents for di~pensing to the aqueous system, including a potable ~ater source; and these in combination may be dispensed in solid or liguid form.
Where the aqueous system is a potable water 5 source, it may be as simple as a well, municipal plant or private water company supplying a single residence, the water of which is treated for the purpose of softening, etc., and there is then added to the chemical agents used in the water treatment, lo the orthophosphate and sodium silicate composition, in accordance with the present invention. Where the potable water source is a major distribution system such as a municipal plant or a private water company, economies of scale can be realized using the methods of the present invention.
EXAMPLES OF PREFERRED EMBODIMENTS
The following examples demonstrate the effectiveness of the treatment methods of the present in~ention in synergistically inhibiting corrosion of carbon steel in water. These examples are illustrative only, and are not intended to be a limitation of the present invention.
Corrosion Inhibition TEST PROTOCOL FOR MUNICIPAL CORROSION STUDY: the 03041H -14- C-~ J
test consisted of large a bath with a capacity of 42 liters. The solution composition listed in Table 1 below was used. A constant temperature immersion circulator was used to control the solution temperature and agitate the controlled bath.
Temperature was maintained at 25OC. The pH of the solution was controlled with a p~ stat at 7.5. The bath was continuously aerated through a medium porosity gas dispersion tube to ensure air saturation.
Two carbon steel coupons (SAE-1010) having a surface area of 4.2 square inches were suspended in the 42 liters of water. After seven days the coupons were removed, cleaned, and weighed to determine corrosion rate in mils per year.
Each test contained a different ratio of SiO2:PO4. The orthophosphate content was obtained from sodium phosphate tribasic. The SiO~
content was obtained from type N silicate from the PQ
corporation.
Solution Composition SPECIES CONCENTRATION mg/L
Calcium 4.4 Magnesium 1.2 Bicarbonate 25 Chloride 3.5 Sulfate 16.4 Total hardness as CaCO3 16.Q
The following solutes were then prepared:
03041H -15- C- ~
0 g/L SiO2 = 1~ g/L SiO2_ = 34.84 g/L type N silica 0.287 % Si~
in type N sllica g/L PO4 = 8 g/L PO4 = 32.02 g/L sodium phosphate O.2498 %-PO4 in sodium phosphate tribasic Bath Conditions Bath No. 1 10 ppm SiO2 41.6 ml 10 g/L SiO2 Bath No. 2 7.5 ppm SiO2 : 2.5 ppm PO4 31.2 ml 10 g/L SiO2; 13.0 ml 8 g/L PO4 Bath No. 3 5.0 ppm SiO2 : 5.0 ppm PO4 20.8 ml 10 g/L SiO~; 26.0 ml 8 g/L PO4 Bath No. 4 2.5 ppm SiO2 : 7.5 ppm PO4 10.5 ml 10 g/L SiO2; 39.0 ml 8 g/L PO4 Bath No. 5 10 ppm PO4 52.0 ml 8 g/L PO4 Coupons of carbon steel were placed in baths of the above compositions for slightly over 7 days, with the results described below.
Test Results - Weight Loss BATH CORROSION INHIBITOR
COUPON COMPOSITION WEI~HT LOSS (G~
251 A 10 ppm SiO2 0.19287 B ~l " ll 0.19875 2 A 7.5/2.5 ppm Sio2:po4 0.09257 ~ " " " " " 0.04530 3 A 5.0/5.0 ppm Sio2:po4 0.02283 B 1' " " " " 0.02746 4 A 2.5/7.5 ppm Sio2:po4 0.01646 ~ " " " " " 0.01685 305 A 10 ppm PO4 0.05750 B " " " 0.02020 03041H -16- 2 ~ ~ ~ `3 ~ ~ C-1531 The corrosion rate was ca].culated in accordance with the following equation: ¦
CORROSION 534 X ~ WEGHT (MG) RATE DENSITY (cc) X AREA (IN2) X TIME (~RS) where DENSITY = 7.84 cc; AREA = 4.3 in2; TIME = 160.50 hrs.
Test Results - Corrosion Rate BATH CORROSION
COUPON BAT~ CONDITIONS RATE (MPY) AVERAGE
1 A 10 ppm SiO2 19.03 19.32 B .. .. " 19.61 2 A 7.5 ppm SiO2 9.14 6.81 B 2.5 ppm P04 4.47 3 A 5 ppm SiO2 2.25 2.48 B 5 ppm P04 2.71 154 A 2.5 ppm SiO2 1.62 1.64 B 7.5 ppm P04 1.66 5 A 10 ppm P04 5.67 3.83 B " ll ll 1.99
Ralston US 4,018,701 (phosphorous acid and zinc);
~atch US 3,532,639 (zinc salts and derivatives of methanol phosphonic or diphosphonic acid); and Hatch U~ 3,022,133 (chromates/dichromates and zinc).
One method for removing soluble manganese by precipitation and removal involves the addition of a salt of iron, copper, or cobalt and any compound yielding bisulfite ions in ~olution to the manganese-containing water. See Hatch - US 3,349,031.
Soluble manganese ion and its reaction products have been stabilized in water systems using lo carboxylic acid/sulphonic acid copolymers. See Ralston - US 4,552,6~5.
The use of orthophosphate has reduced lead solubility in both low- and high-alkalinity waters.
An orthophosphate concentration of approximately 1 to 2 mg/L PO4 can be effective in reducing lead solubility over a much lower pH range than would be possible by using pH-carbonate adjustment.
Adding zinc/polyphosphate to municipal distribution systems has been an effective treatment program for controlling corrosion, as well as stabilizing iron and manganese. Although polyphosphates are not as effective as orthophosphate in reducing lead solubility, the use of zinc/polyphosphate has broad applicability. The effective pH range is 6 to 7.5, but maintaining the pH above neutral i~ recommended.
Treatments utilizing silicates appear to have a ret~rding effect on lead solubility, but require a relatively long period of time, approximately 8 to 9 months, to show reductions in lead concentrations.
This long-term effect can be explained by the slow 2 ~ 3 ~
formation of a ~inetically-inhibited lead silicate film. Silicate treatments, however, are not recommended for control of lead solubility in distribution systems.
SUMMARY OF THE INVENTION
The present invention relates to a carbon steel corrosion inhibiting composition comprising about 3 parts by weight of orthophosphate and about 1 part by weight of sodium silicate. In particular, sodium phosphate t:ribasic is the preferred form of orthophosphate.
The present invention further relates to a method of inhibiting the corrosion of carbon steel in an a~ueous system comprising the step of treating said system with an effective corrosion-inhibiting amount of a composition comprising about 3 parts by weight of orthophosphate and about 1 part by weight of sodium silicate. In particular, the present invention relates to such a treatment method in which sodium phosphate tribasic is preferred as the orthophosphate, and the composition is used in an amount ~ufficient to achieve a concentration of the total composition of from 0.1 to 100 mg/L in said aqueous system, preferably from 1.0 to 50 mg/L, and most preferably from 2 to 25 mg/L.
The present invention further relates to a method of inhibiting the precipitation of dissolved manganese and iron ions and their reaction products in an a~ueous system, comprising the step of treating said system with an effective precipitation-inhibiting amount of a composition 2 ~
comprising about 3 parts by weight of orthophosphate and about 1 part by weight of sodium silicate. In particular, the present invention relates to such a treatment method in which sodium phosphate tribasic is preferred as the orthophosphate, and the composition is used in an amount sufficient to achieve a concentration of from 0.1 to 50 mg/L in said aqueous system, preferably from 1.0 to 50 mg/L, and most preferably from 2 to 25 mg/L.
The present invention still further relates to a method of reducing the amount of soluble lead in a potable water source comprising treating said water with an effective amount of a composition comprising about 3 parts by weight of orthophosphate and about 1 part by weight of sodium silicate. In particular, the present invention relates to such a treatment method in which sodium phosphate tribasic is preferred as the orthophosphate, and the composition is used in an amount sufficient to achieve a concentration of from 0.1 to 100 mg/L in said aqueous system, preferably from 1.0 to 50 mg/L, and most preferably from 2 to 25 mg/L.
DETAILED DESCRIPTION OF THE INV~NTION
The orthophosphates useful in the compositions ~5 and methods of the present invention all have PO4 as the anion portion of the total salt, i.e., a salt of orthophosphoric arid. This is the active ionic component with respect to providing the benefits of the methods of the present invention in inhibiting carbon steel corrosion, and inhibiting the precipitation of manganese and iron ions and their 2~$~
03041~ -9- C-1531 reaction products, and also red~cing lead solubility in said water. The cation portion of the total salt is relatively unimportant, e~:cept with respect to solubility, which, it will ~e appreciated, is critical to the method of the present invention, since it requires the addition of the orthophosphate salt to an aqueous system being treated, including a potable water source. Thus, the most soluble salt forms will generally be the most preferred for use in the methods of the present invention.
The cation portion is selected from the alkali metals Li, Na, K and NH4, or combinations of these lo with the alkaline earth metals M~, Ca and Ba. Since the P04 anion portion has a 3 valency, the most commcn alkali metal salt forms will simply have three cations of the same metal, e.g., Na3P04. This form, which is often referred to as sodium phosphate lS tribasic, is the most common form and the most preferred form for use in the method of the present invention.
The alkali metals may be different, e.g., LiNa2P04 or NaK2P04. Where the alkaline earth metals are present, usually only one will be present because they have a ~2 valency, and there will usually be an alkali metal preæent to balance ~alencies. Thus, MgNaP04 may be used. Other combinations of the alkali and alkaline earth metals are possible, e.g., Na2Mg2(P04)2, but these are less preferred forms.
The most preferred orthophosphate for use in the methods of the present invention, aodium phosphate tribasic, or trisodium orthophosphate, crystallizeæ ~ith 8 and 12 mols of ~2 The dodecahydrate is in the form of colorless or white crystals which, when rapidly heated, melts at about 75 C. It is soluble in 3.5 parts of 03041~ -10- C-1531 water. Accordingly, such a material can be added directly to an aqueous system to be treated, including a potable water source in the amount required to inhibit carbon steel corrosion, and inhibit precipitation of manganese and iron ions and their reaction products, as well as to reduce lead leaching.
The orthophosphate is used in the composition of the present invention in an amount which gives a weight ratio to sodium silicate of about 3:1. The weight of P04 only is used in this calculation, and not the weight of the total orthophosphate salt. The term "about" means that amounts more than or less than the precise amount which lo gives the 3:1 ratio are also a part of the present invention so long as the synergistic effect of the combination is obtained. It is contemplated that in practice the amounts thus included will normally between 2.85:1 and 3.15:1.
The sodium silicate which is used in the compositions and methods of the present invention, has one or more of the compositions shown by the formulas: Na~SiO3, Na6Si207, and Na2Si307, and is also known as water glass and sodium metasilicate. It is preferred for practical reasons to use the sodium silicate in liquid form, i.e., as an aqueous solution, which may consist of varying compositions with respect to the ratlo between sodium and silica, as well as being of various densities.
The sodium silicate is used in the composition of the present invention in an amount which gives a weight ratio to orthophosphate o~ about 1:3. The weight of ~iO2 only is used in this calculation, and not the weight of the sodium portion of the salt. The term "about" means that amounts more than or less than the precise amount which gives the 1:3 ratio are also a part of the present invention so long as the synergistic effect of the combination is obtained. It is contemplated that in practice the amounts thus included will normally between 0.85:3 and 1.15:3.
The amounts of the 3:1 orthophosphate: sodium silicate composition of the present invention, that are required to be added for the desired maximum inhibition of carbon steel corrosion will be such as to provide an ultimate concentration of the total composition of the present invention in the aqueous system being treated of between 0.1 and 100 mg/L, and preferably this concentration will be between 1.0 and 50 mg/L. Most preferably the concentration will be between ~ and 25 mg/L, although it is understood that man~ factors, of the type which have been explained in detail with regard to the background to the present invention, will determine the actual amount of the composition of the present invention which will be added to any particular aqueous system in order to achieve the maximum amount of inhibition of carbon steel corrosion in that aqueouæ system. The calculation of those amounts will be well within the skill of the artisan in this field.
The amounts of the 3:1 orthophosphate: sodium silicate composition of the present invention, that are required to be added for the desired maximum inhibition of precipitation of manganese and iron ions and their reaction products will be such as to provide an ultimate concentration of the total composition of the present invention in the aqueous system being treated of between 0.1 and 100 mg/L, and 2 ~ .J~
03041~ -12- C-1531 preferably this concentration will be between 1.0 and 50 mg/L. Mos-t preferably the concentration will be between 2 and 25 mg/L, altho~lgh it is understood that many factors, of the type which have been explained in detail with regard to the ~ackground to the present invention, will determine the actual a~ount of the total composition of t:he present invention which wil~ be added to any particular aqueous sys~em in order to achieve the maximum amount of inhibition of precipitation of manganese and iron ions and their reaction products in that aqueous system. The calculation of those amounts will be well within the 0 skill of the artisan in this field.
The manner of addition of the orthophosphate and sodium silicate composition of the present invention to an aqueous system, including a potable water source, will also be straightforward to a person of ordinary skill in this art. It may be added in finely subdivided solid form by mechanical dispensers of known de~ign. It may also be added in solid form, but in the form of a matrix in which solid particles of the active ingredient are bonded or ~ound together by a material which is water soluble, or optionally, does not dissolve at all. Such a matrix allows for regular leaching out or dissolving of the active ingredient particles, whereby it is possible to obtain a sustained release and more unvarying concentration of the orthophosphate and sodium silicate composition in the water being treated. In the preferred manner of addition, the orthophosphate and sodium silicate composition of the present invention is made up in the form of concentrated solutions for dispensing in liquid form ~rom dispensers well known in the art. The orthophosphate 03041H -13- C-~ J ~ ~Qy and sodium silicate composition of the present invention may also be combined with other chemical treatment agents for di~pensing to the aqueous system, including a potable ~ater source; and these in combination may be dispensed in solid or liguid form.
Where the aqueous system is a potable water 5 source, it may be as simple as a well, municipal plant or private water company supplying a single residence, the water of which is treated for the purpose of softening, etc., and there is then added to the chemical agents used in the water treatment, lo the orthophosphate and sodium silicate composition, in accordance with the present invention. Where the potable water source is a major distribution system such as a municipal plant or a private water company, economies of scale can be realized using the methods of the present invention.
EXAMPLES OF PREFERRED EMBODIMENTS
The following examples demonstrate the effectiveness of the treatment methods of the present in~ention in synergistically inhibiting corrosion of carbon steel in water. These examples are illustrative only, and are not intended to be a limitation of the present invention.
Corrosion Inhibition TEST PROTOCOL FOR MUNICIPAL CORROSION STUDY: the 03041H -14- C-~ J
test consisted of large a bath with a capacity of 42 liters. The solution composition listed in Table 1 below was used. A constant temperature immersion circulator was used to control the solution temperature and agitate the controlled bath.
Temperature was maintained at 25OC. The pH of the solution was controlled with a p~ stat at 7.5. The bath was continuously aerated through a medium porosity gas dispersion tube to ensure air saturation.
Two carbon steel coupons (SAE-1010) having a surface area of 4.2 square inches were suspended in the 42 liters of water. After seven days the coupons were removed, cleaned, and weighed to determine corrosion rate in mils per year.
Each test contained a different ratio of SiO2:PO4. The orthophosphate content was obtained from sodium phosphate tribasic. The SiO~
content was obtained from type N silicate from the PQ
corporation.
Solution Composition SPECIES CONCENTRATION mg/L
Calcium 4.4 Magnesium 1.2 Bicarbonate 25 Chloride 3.5 Sulfate 16.4 Total hardness as CaCO3 16.Q
The following solutes were then prepared:
03041H -15- C- ~
0 g/L SiO2 = 1~ g/L SiO2_ = 34.84 g/L type N silica 0.287 % Si~
in type N sllica g/L PO4 = 8 g/L PO4 = 32.02 g/L sodium phosphate O.2498 %-PO4 in sodium phosphate tribasic Bath Conditions Bath No. 1 10 ppm SiO2 41.6 ml 10 g/L SiO2 Bath No. 2 7.5 ppm SiO2 : 2.5 ppm PO4 31.2 ml 10 g/L SiO2; 13.0 ml 8 g/L PO4 Bath No. 3 5.0 ppm SiO2 : 5.0 ppm PO4 20.8 ml 10 g/L SiO~; 26.0 ml 8 g/L PO4 Bath No. 4 2.5 ppm SiO2 : 7.5 ppm PO4 10.5 ml 10 g/L SiO2; 39.0 ml 8 g/L PO4 Bath No. 5 10 ppm PO4 52.0 ml 8 g/L PO4 Coupons of carbon steel were placed in baths of the above compositions for slightly over 7 days, with the results described below.
Test Results - Weight Loss BATH CORROSION INHIBITOR
COUPON COMPOSITION WEI~HT LOSS (G~
251 A 10 ppm SiO2 0.19287 B ~l " ll 0.19875 2 A 7.5/2.5 ppm Sio2:po4 0.09257 ~ " " " " " 0.04530 3 A 5.0/5.0 ppm Sio2:po4 0.02283 B 1' " " " " 0.02746 4 A 2.5/7.5 ppm Sio2:po4 0.01646 ~ " " " " " 0.01685 305 A 10 ppm PO4 0.05750 B " " " 0.02020 03041H -16- 2 ~ ~ ~ `3 ~ ~ C-1531 The corrosion rate was ca].culated in accordance with the following equation: ¦
CORROSION 534 X ~ WEGHT (MG) RATE DENSITY (cc) X AREA (IN2) X TIME (~RS) where DENSITY = 7.84 cc; AREA = 4.3 in2; TIME = 160.50 hrs.
Test Results - Corrosion Rate BATH CORROSION
COUPON BAT~ CONDITIONS RATE (MPY) AVERAGE
1 A 10 ppm SiO2 19.03 19.32 B .. .. " 19.61 2 A 7.5 ppm SiO2 9.14 6.81 B 2.5 ppm P04 4.47 3 A 5 ppm SiO2 2.25 2.48 B 5 ppm P04 2.71 154 A 2.5 ppm SiO2 1.62 1.64 B 7.5 ppm P04 1.66 5 A 10 ppm P04 5.67 3.83 B " ll ll 1.99
Claims (10)
1. A carbon steel corrosion inhibiting composition for use in potable water systems, consisting essentially of [comprising] about 3 parts by weight orthophosphate and about 1 part by weight of sodium silicate, wherein said weights are based on PO4 and SiO2, respectively.
2. A composition according to Claim 1 wherein the orthophosphate is sodium phosphate tribasic.
3. A method of inhibiting the corrosion of carbon steel from which a potable water distribution [in an aqueous] system is constructed, comprising the step of treating said system with an effective corrosion-inhibiting amount of a composition [comprising] consisting essentially of about 3 parts by weight of orthophosphate and about 1 part by weight of sodium silicate, wherein said weights are based on PO4 and SiO2, respectively.
4. A method according to Claim 3 wherein the orthophosphate is sodium phosphate tribasic.
5. A method according to Claim 3 wherein the composition is used in an amount sufficient to achieve a concentration of the total composition of from 0.1 to 100 mg/L in said aqueous system.
6. A method according to Claim 5 wherein the concentration of the composition in the aqueous system is from 1.0 to 50 mg/L.
7. A method of inhibiting the precipitation of dissolved manganese and iron ions and their reaction products in [an aqueous] a potable water system, comprising the step of treating said system with an effective precipitation-inhibiting amount of a composition [comprising] consisting essentially of about 3 parts by weight of orthophosphate and about 1 part by weight of sodium silicate, wherein said weights are based on PO4 and SiO2, respectively.
8. A method according to Claim 8 wherein the orthophosphate is sodium phosphate tribasic and the composition is used in an amount sufficient to achieve a concentration of the total composition of from 0.1 to 100 mg/L in said aqueous system.
9. A method of reducing the [amount] solubilzation of soluble lead in a potable water source including a water distribution system wherein said solubilzation results from the corrosive action of said water on lead-containing materials from which the water distribution system included in said potable water source is constructed, comprising treating said water with an [effective] amount effective to reduce said corrosion, of a composition [comprising] consisting essentially of about 3 parts by weight of orthophosphate and about 1 part by weight of sodium silicate, wherein said weights are based on PO4 and SiO2, respectively.
10. A method according to Claim 10 wherein the orthophosphate is sodium phosphate tribasic, and the composition is used in an amount sufficient to achieve a concentration of from 0.1 to 100 mg/L in said aqueous system.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US07/690,876 US5137657A (en) | 1991-04-24 | 1991-04-24 | Synergistic combination of sodium silicate and orthophosphate for controlling carbon steel corrosion |
| US690,876 | 1991-04-24 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2066991A1 true CA2066991A1 (en) | 1992-10-25 |
Family
ID=24774341
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002066991A Abandoned CA2066991A1 (en) | 1991-04-24 | 1992-04-24 | Synergistic combination of sodium silicate and orthophosphate for controlling carbon steel corrosion |
Country Status (6)
| Country | Link |
|---|---|
| US (1) | US5137657A (en) |
| EP (1) | EP0510989A1 (en) |
| JP (1) | JPH05230676A (en) |
| AU (1) | AU1506492A (en) |
| CA (1) | CA2066991A1 (en) |
| NZ (1) | NZ242457A (en) |
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|---|---|---|---|---|
| DE4321883C2 (en) * | 1993-07-01 | 2003-05-15 | Henkel Kgaa | Aqueous silicate solutions with high orthophosphate contents and processes for the corrosion protection treatment of drinking water pipes |
| GB9409811D0 (en) * | 1994-05-17 | 1994-07-06 | Imi Yorkshire Fittings | Improvements in copper alloy water fittings |
| US5478604A (en) * | 1994-06-07 | 1995-12-26 | Actinic, Inc. | Composition and method for preventing lead intoxication |
| AU711992B2 (en) * | 1995-08-03 | 1999-10-28 | Europa Metalli S.P.A. | Low lead release plumbing components made of copper based alloys containing lead, and a method for obtaining the same |
| DE19706410C2 (en) * | 1997-02-19 | 2001-04-05 | Metakorin Wasser Chemie Gmbh | Process and agent for the anti-corrosion treatment of water-bearing metal systems |
| US6461534B2 (en) | 1997-11-19 | 2002-10-08 | Europa Metalli S. P. A. | Low lead release plumbing components made of copper based alloys containing lead, and a method for obtaining the same |
| US6096197A (en) * | 1997-12-11 | 2000-08-01 | Hughes; Douglass E. | Shower filter for chlorine removal and scale deposit prevention |
| DE19755622C2 (en) * | 1997-12-13 | 2001-08-16 | Kodiak Wasser Technologie Gmbh | Liquid aqueous concentrates for corrosion protection |
| US6585933B1 (en) | 1999-05-03 | 2003-07-01 | Betzdearborn, Inc. | Method and composition for inhibiting corrosion in aqueous systems |
| US20080257831A1 (en) * | 2005-03-30 | 2008-10-23 | Junichi Nakajima | Water Treating Agent and Water Treatment Method |
| DE102005050200A1 (en) * | 2005-10-18 | 2007-04-19 | Henkel Kgaa | Corrosion protection for metallic water supply systems, comprises dosing silicates and supplement materials into the water stream |
| DE102008039411A1 (en) * | 2008-08-12 | 2010-02-18 | Alfred Kärcher Gmbh & Co. Kg | Care products, in particular for hot water high pressure cleaners |
| US9144958B2 (en) * | 2009-10-28 | 2015-09-29 | Fenwal, Inc. | Sheets for use with medical containers |
| JP6437536B2 (en) * | 2013-09-27 | 2018-12-12 | ビーエーエスエフ ソシエタス・ヨーロピアＢａｓｆ Ｓｅ | Corrosion inhibitors for Fe2P structure magnetocaloric materials in water |
| US11149202B1 (en) | 2016-12-13 | 2021-10-19 | Ecolab Usa Inc. | Tetracarboxylic acid combinations for corrosion inhibition |
| US11879094B2 (en) | 2022-06-03 | 2024-01-23 | Halliburton Energy Services, Inc. | Enhancing friction reduction and protection of wellbore equipment during hydraulic fracturing |
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| GB491237A (en) * | 1935-12-13 | 1938-08-25 | Michelin & Cie | Improvements in or relating to the conditioning of water |
| GB559697A (en) * | 1942-08-26 | 1944-03-01 | John Eric Edwards | Improvements in or relating to the prevention of scale formation from water |
| DE1048759B (en) * | 1954-05-12 | 1959-01-15 | ]oh A Benckiser GmbH Che mische labrik Ludw igshafen Rhein | I Process for the prevention of corrosion on objects that contain copper, especially in combination with iron |
| US3022133A (en) * | 1959-04-23 | 1962-02-20 | Hagan Chemicals & Controls Inc | Methods of inhibiting the pitting of iron and steel |
| US3337496A (en) * | 1961-04-26 | 1967-08-22 | Union Carbide Corp | Novel organosiloxane-silicate copolymers |
| FR1364106A (en) * | 1963-05-09 | 1964-06-19 | Baele Gangloff Ste Nouvelle | Descaling unit and its manufacturing process |
| DE1517496A1 (en) * | 1963-11-07 | 1969-11-27 | Rww Filter Gmbh | Process for the protection of cold and hot water piping systems, especially against oxygen and carbonic acid corrosion |
| US3589858A (en) * | 1965-08-20 | 1971-06-29 | Calgon Corp | Inhibiting the corrosion of metals in a water system |
| US3349031A (en) * | 1965-08-20 | 1967-10-24 | Calgon Corp | Method and composition for removal of manganese from water |
| US3507807A (en) * | 1966-12-12 | 1970-04-21 | Taito Herman Rikhard Palikko | Corrosion inhibiting composition containing a potassium soap of tall oil,toluene,alkali metal phosphate,and alkali metal silicate |
| DE1621529A1 (en) * | 1967-03-09 | 1971-05-06 | Wasserversorgung Abwasse | Process for the formation of protective layers on the steel parts of submersible motors to increase the service life of submersible motor pumps |
| US3483133A (en) * | 1967-08-25 | 1969-12-09 | Calgon C0Rp | Method of inhibiting corrosion with aminomethylphosphonic acid compositions |
| US3532639A (en) * | 1968-03-04 | 1970-10-06 | Calgon C0Rp | Corrosion inhibiting with combinations of zinc salts,and derivatives of methanol phosphonic acid |
| US3580855A (en) * | 1969-04-09 | 1971-05-25 | Rohm & Haas | Process for inhibition of scale and corrosion using a polyfunctional phosphated polyol ester having at least 75% primary phosphate ester groups |
| US3711246A (en) * | 1971-01-06 | 1973-01-16 | Exxon Research Engineering Co | Inhibition of corrosion in cooling water systems with mixtures of gluconate salts and silicate salts |
| US3885914A (en) * | 1973-06-04 | 1975-05-27 | Calgon Corp | Polymer-zinc corrosion inhibiting method |
| US3965027A (en) * | 1974-03-11 | 1976-06-22 | Calgon Corporation | Scale inhibition and corrosion inhibition |
| US4018701A (en) * | 1975-07-31 | 1977-04-19 | Calgon Corporation | Phosphorous acid and zinc corrosion inhibiting compositions and methods for using same |
| US4172032A (en) * | 1976-10-15 | 1979-10-23 | Nalco Chemical Company | Polyphosphate-based industrial cooling water treatment |
| US4210549A (en) * | 1979-01-02 | 1980-07-01 | Basf Wyandotte Corporation | Hydroxybenzoic acid as pH buffer and corrosion inhibitor for alkali metal silicate-containing antifreeze compositions |
| US4241014A (en) * | 1979-10-09 | 1980-12-23 | Basf Wyandotte Corporation | Hydroxybenzoic acid as pH buffer and corrosion inhibitor for alkali metal silicate-containing antifreeze compositions |
| NL8000920A (en) * | 1980-02-14 | 1981-09-16 | Gram Cornelis H De | METHOD FOR PROTECTING THE PIPING SYSTEM OF A HEATING SYSTEM, AND METHOD FOR PREPARING A WATERY MIXTURE FOR IT |
| DE3232615A1 (en) * | 1982-09-02 | 1984-03-08 | Henkel KGaA, 4000 Düsseldorf | METHOD FOR THE CORROSION PROTECTION TREATMENT OF WATER-CONTAINING SYSTEMS |
| US4936987A (en) * | 1983-03-07 | 1990-06-26 | Calgon Corporation | Synergistic scale and corrosion inhibiting admixtures containing carboxylic acid/sulfonic acid polymers |
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| US4640793A (en) * | 1984-02-14 | 1987-02-03 | Calgon Corporation | Synergistic scale and corrosion inhibiting admixtures containing carboxylic acid/sulfonic acid polymers |
| US4552665A (en) * | 1984-05-04 | 1985-11-12 | Calgon Corporation | Stabilization of soluble manganese and its reaction products |
| FR2571745B1 (en) * | 1984-10-17 | 1988-10-28 | Trest Juzhvodoprovod | ANTI-CORROSIVE FOR PROTECTING THE INTERNAL SURFACE OF A CORROSION PIPE, METHOD FOR OBTAINING THIS ANTI-CORROSIVE AND METHOD FOR PROTECTING THE INTERNAL SURFACE OF A CORROSION PIPE USING THIS ANTI-CORROSION |
| KR950010657B1 (en) * | 1987-02-18 | 1995-09-21 | 닛뽕 베인또가부시기가이샤 | Corrosion preventing pigment |
| US4867944A (en) * | 1988-01-13 | 1989-09-19 | Gulf Coast Performance Chemical, Inc. | Method of preventing corrosion by contaminated cooling tower waters |
| US4798683A (en) * | 1988-04-21 | 1989-01-17 | Calgon Corporation | Method for controlling corrosion using molybdate compositions |
| US5076941A (en) * | 1990-10-15 | 1991-12-31 | Calgon Corp. | Monofluorophosphate solubility inhibitor for lead in potable water sources |
-
1991
- 1991-04-24 US US07/690,876 patent/US5137657A/en not_active Expired - Fee Related
-
1992
- 1992-04-23 NZ NZ242457A patent/NZ242457A/en unknown
- 1992-04-23 AU AU15064/92A patent/AU1506492A/en not_active Withdrawn
- 1992-04-24 EP EP92303688A patent/EP0510989A1/en not_active Withdrawn
- 1992-04-24 JP JP4149803A patent/JPH05230676A/en active Pending
- 1992-04-24 CA CA002066991A patent/CA2066991A1/en not_active Abandoned
Also Published As
| Publication number | Publication date |
|---|---|
| AU1506492A (en) | 1992-10-29 |
| JPH05230676A (en) | 1993-09-07 |
| NZ242457A (en) | 1993-11-25 |
| EP0510989A1 (en) | 1992-10-28 |
| US5137657A (en) | 1992-08-11 |
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