Classifications

• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23F—NON-MECHANICAL REMOVAL OF METALLIC MATERIAL FROM SURFACE; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL; MULTI-STEP PROCESSES FOR SURFACE TREATMENT OF METALLIC MATERIAL INVOLVING AT LEAST ONE PROCESS PROVIDED FOR IN CLASS C23 AND AT LEAST ONE PROCESS COVERED BY SUBCLASS C21D OR C22F OR CLASS C25
  • C23F11/00—Inhibiting corrosion of metallic material by applying inhibitors to the surface in danger of corrosion or adding them to the corrosive agent
  • C23F11/08—Inhibiting corrosion of metallic material by applying inhibitors to the surface in danger of corrosion or adding them to the corrosive agent in other liquids
  • C23F11/10—Inhibiting corrosion of metallic material by applying inhibitors to the surface in danger of corrosion or adding them to the corrosive agent in other liquids using organic inhibitors
• • C—CHEMISTRY; METALLURGY
  • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F1/00—Treatment of water, waste water, or sewage
  • C02F1/50—Treatment of water, waste water, or sewage by addition or application of a germicide or by oligodynamic treatment
• • 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
  • C02F5/12—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 nitrogen
• • 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
  • C23F11/167—Phosphorus-containing compounds
  • C23F11/1676—Phosphonic acids
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23F—NON-MECHANICAL REMOVAL OF METALLIC MATERIAL FROM SURFACE; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL; MULTI-STEP PROCESSES FOR SURFACE TREATMENT OF METALLIC MATERIAL INVOLVING AT LEAST ONE PROCESS PROVIDED FOR IN CLASS C23 AND AT LEAST ONE PROCESS COVERED BY SUBCLASS C21D OR C22F OR CLASS C25
  • C23F11/00—Inhibiting corrosion of metallic material by applying inhibitors to the surface in danger of corrosion or adding them to the corrosive agent
  • C23F11/08—Inhibiting corrosion of metallic material by applying inhibitors to the surface in danger of corrosion or adding them to the corrosive agent in other liquids
  • C23F11/10—Inhibiting corrosion of metallic material by applying inhibitors to the surface in danger of corrosion or adding them to the corrosive agent in other liquids using organic inhibitors
  • C23F11/173—Macromolecular compounds
• • 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
  • C02F2303/00—Specific treatment goals
  • C02F2303/08—Corrosion inhibition
• • 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
  • C02F2303/22—Eliminating or preventing deposits, scale removal, scale prevention

Definitions

• This invention relates to a treatment composition and method for inhibiting corrosion or white rust on metal components in tow LSI (Langelier Saturation Index) water systems and for inhibiting scale formation in high LSI water systems.
• tow LSI Low Saturation Index
• Various water treatment compositions are used to reduce corrosion, mineral scale, and white rust formation on metal components in contact with an aqueous solution in water systems such as open recirculating systems, closed loop cooling or heating systems, cooling towers and boilers, and help protect the mela! components of these systems.
• the metals typically used in these water systems include ferrous metals, including galvanized steel, aluminum and its alloys, copper and its alloys, lead, and solder.
• any known corrosion inhibitors contain regulated toxic metals, such as zinc, chromate, and molybdate, which are harmful to the environment and increase the costs.
• Zinc is typically used as corrosion inhibitor in water systems with highly corrosive water (low LSI).
• the preferred phosphonic acid in the ⁇ 23 patent is PBTC, but other phosphonic acids, including 1-hydroxyethane 1,1-disphosphonic acid and hydroxyphosphonoacetic acid (HPA) ar also mentioned as suitable.
• HPA hydroxyphosphonoacetic acid
• the corrosion rate results shown in the ⁇ 23 patent based on the use of polyaspartic acid and PBTC are better than other corrosion inhibitors, but there is still a need for even greater corrosion inhibition, particularly in the presence of biocides.
• the scale formation results shown in the ⁇ 23 patent based on the use of polyaspartic acid and PBTC are approximately the same as the results obtained by using PBTC alone, indicating no real improvement in scale inhibition is obtained with the two-component formula of the ⁇ 23 patent
• 6,183,649 discloses a white-rust treatment composition
• a white-rust treatment composition comprising PBTC, sodium polyacryiate, sodium tolytriazoie, an alkali metal motybdate, and an alkali metal bromide for treating circulating water systems.
• the '649 patent also discloses the addition of a 1.5% aqueous solution of decyl thioeihyletheramine (DTEA) at a rate of 25lb/1 ,000 gallons of water/week to the circulating water system prior to adding the white rust treatment composition at a rate of 800 ppm per cycle for ten cycles of recirculation after addition of the DTEA.
• DTEA decyl thioeihyletheramine
• an improved corrosion inhibitor, white rust inhibitor, and scale inhibitor composition comprises an amtno-acid based polymer (AAP), hydroxyphosphonoacetic acid (HPA) or its water soluble salt, and another phosphonic acid or its water soluble salt, Hydroxyphosphonoacetic acid has the following genera! structure:
• the amino-actd based polymer is po!yaspartic acid or its water soluble salt, but other compounds such as polygiycine acid, po!yglutamic acid and their salts may also be used.
• the amino acid based polymer has the followin formula:
• the other phosphonic acid is a phosphonocarboxylic acid or any organic phosphonate may also be used.
• the phosphonocarboxylic acid is 1 -hydroxyethane-1 ,1-diphosphonic acid (HEDP) or 2-phosphonobutene-1 ,2,44ricarboxylic acid (PBTC) or phosphonosuccinic acid.
• HEDP 1 -hydroxyethane-1 ,1-diphosphonic acid
• PBTC 2-phosphonobutene-1 ,2,44ricarboxylic acid
• the weight ratio of AAP to HPA in the inhibitor composition is 90:10 to 10:90 and the ratio of combined AAP and HPA to other phosphonic acid is in the range of 90:10 to 80:40.
• the weight ratio range of AAP to HPA in the inhibitor composition is 80:20 to 80:20 and the ratio of combined AAP and HPA to other phosphonic acid is 80:20 to 70:30, [0012]
• a composition according to a preferred embodiment of the invention is ail organic and does not contain regulated metals such as zinc, chromate, and molybdate and its performance is not affected by addition of biocides.
• a composition according to a preferred embodiment of the invention does not contain tin,
• a preferred composition according to the invention for inhibiting corrosion yields at least 3 ppm active AAP, at least 3 ppm active HPA, and at least 2 ppm of the other phosphorite acid, ore preferably, when added to the water in the water system being treated, a preferred composition yields 3 ppm-50 ppm AAP, 3 ppm- 50 ppm HPA, and 2 ppm-20 ppm of the other phosphonic acid and most preferabfy between 5ppm ⁇ 30ppm AAP, 3ppm-20ppm HPA, and 2 ppm-10 ppm of the other phosphonic acid.
• the combined total of the three components of a preferred composition yields at least 8 ppm active corrosion inhibitors when added to the water being treated.
• the same composition in addition to unexpected and synergistic effect of the inhibitor composition on ferrous metal corrosion inhibition in low LSI water, the same composition also has a positive effect on preventing formation of white rust on galvanized steel.
• Galvanized steel consists of a thin coating of zinc fused to a steel substrate.
• White rust is a rapid, localized corrosion attack on zinc that usually appears as a voluminous white deposit. This rapid corroston can completely remove zinc in a locaitzed area with the resultant reduction in equipment life.
• White rust formation tends to increase with increased alkalinity levels in the water.
• compositions according to the invention may be forming a protective layer on the surface of galvanized steel and reduce white rust formation.
• a composition for treating white rust comprises an amino- acid based polymer and hydroxyphosphonoacetic acid, without another phosphonic acid.
• a composition for treating white rust comprises an amino-acid based polymer, without any hydroxyphosphonoacetic acid. The preferred concentrations and ranges for these components when added to the water being treated for white rust are the same as for inhibiting corrosion.
• LSl ⁇ pH - pHs, where pHs is pH at CaC03 saturation point.
• An LSI > 0 indicates scaling, as scale can form and CaCOS precipitation may occur.
• An LSI ⁇ 0 indicates nonscaling, as there is no potential to scale and the water will dissolve CaCOS.
• LSI is an indication of driving force and not strict quantitative indication of scale formation, which will depend on the water characteristics, temperature, and water systems operations. However, without a scale inhibitor, scale wilt typically precipitate out of water when the LSI is greater than 0.2. Using a treatment composition according to preferred embodiments of the invention, no scale will form (calcium carbonate will not precipitate out of the water) at LSI values of 1-3,
• a preferred composition according to the invention for inhibiting scale yields at least 2 ppm active AAP, at least 2 ppm active HPA, and at least 1 .5 ppm of the other phosphonic acid. More preferably, when added to the water in the water system being treated, a preferred composition yields 2 pprn-50 ppm AAP, 2 ppm-50 ppm HPA, and 1 .5 ppm-20 ppm of the other phosphonic acid and most preferably between 3 ppm ⁇ 30ppm AAP, 2 ppm-20 ppm HPA, and 1.5 ppm-10 ppm of the other phosphonic acid.
• the combined total of the three components of a preferred composition yields at least 6,5 ppm active scaie inhibitors when added to the water being treated.
• Treatment compositions provide an all-in-one treatment that is able to inhibit corrosion of metals such as ferrous metals, aluminum and its alloys, copper and its alloys, zinc and its alloys, galvanized steel (including white rust), lead, or solder, and to prevent mineral scale formation.
• metals such as ferrous metals, aluminum and its alloys, copper and its alloys, zinc and its alloys, galvanized steel (including white rust), lead, or solder, and to prevent mineral scale formation.
• the treatment compositions are particularly useful in water systems such as open recirculating systems, closed loop cooling or heating systems, and boilers that may experience corrosion, white rust, and scale formation during different times of the year or under different operating conditions, including use in both low LSI (high corrosively water) and high LSi (high scale tendency) waters,
• compositions for inhibiting corrosion or white rust or scale also comprise one or more of the following ingredients: a neutralizing amine, chlorine stabilizer, such as monoethanoi amine (MEA); a secondary scale inhibitor (since the composition itself also works as a scale inhibitor) and dispersion agent, such as polycarbo yiate polymer and/or carboxylate/sulfonate functional copolymers (typical examples: poiyacryclic acid (PAA), po!ymethacrylic acid (PMAA), poiymaleic acid (PMA), and copolymers of acrylic acid and 2-acylamido ⁇ methyipropane sulfonic acid (AA A PS); other scale and corrosion inhibitors, cheiant agents; azo!e corrosion inhibitors, such as benzotnazole, alkylfoenzofriazole (to!yltriazole); and/or a fluorescent dye tracer, such as 1 ,3,8,8- Pyrenet
• the overall composition preferably comprises around 2%-15% (by weight) of an amino-acid based polymer (such as poiyaspartic acid), around 2% to 10% (by weight) of hydroxyphosphonoacetic acid, and around 2% to 10% (by weight) of another phosphonic acid.
• an amino-acid based polymer such as poiyaspartic acid
• a treatment composition according to the preferred embodtments of invention as described above is added to the water system.
• a preferred method for corrosion and white rust inhibition comprises feeding the composition info the water at an effective feed rate of 20pprri - 800 ppm, or more preferably 100 - SOOppm, of treatment composition, depending on the treated water chemistry and the amount of optional components in the treatment composition.
• a sufficient amount of treatment composition is added to the water system to provide effective active amounts of one or more of the three treatment components (depending on whether white rust is being treated or both corrosion and white rust) of at least 3 ppm AAP, at feast 3 ppm HPA, and at least 2 ppm of another phosphonic acid, each as concentrations when added to the volume of water in the water system being treated. More preferably, the treatment composition is added in a sufficient amount to provide effective active amounts one or more of the components of between 3 pprn - 50 ppm AAP, between 3pm - 50 ppm HPA, and between 2 ppm - 20 ppm of another phosphonic acid when added to the water in the water system. Most preferably, these effective active amounts are 5ppm - 30 ppm AAP, 3 ppm - 20 ppm HPA, and 2 ppm - 10 ppm other phosphonic acid when added to the water in the water system.
• a preferred method for scale inhibition comprises feeding the composition into the water at an effective feed rate of 20ppm - 600 ppm, or more preferably 50 - SOOppm, of treatment composition, depending on the treated water chemistry and the amount of optional components in the treatment composition.
• a sufficient amount of treatment composition is added to the water system to provide effective active amounts of one or more of the three treatment components of at least 2 ppm AAP, at least 2 ppm HPA, and at least 1.5 ppm of another phosphonic acid, each as concentrations when added to the volume of water in the water system being treated.
• the treatment composition is added in a sufficient amount to provide effective active amounts of the three treatment components of 2 ppm - 50 ppm AAP, 2 ppm - 50 ppm HPA, and 1.5 ppm -20 ppm of another phosphonic acid, each as concentrations when added to the volume of water in the water system being treated.
• the treatment composition is added in a sufficient amount to provide effective active amounts of the three components of between 3 ppm - 30 ppm AAP, between 2pm - 20 ppm HPA, and between 1.5 ppm - 10 ppm of another phosphonic acid when added to the water in the water system.
• FIG. 1 contains photographs showing corrosion levels on steel coupons after spinner tests at flow rates of 3ft sec and 5ft/sec;
• FIG. 2 contains photographs showing corrosion levels on steel coupons after spinner tests run in presence of biocide at flow rates of 3ft/sec and 5 ft/sec;
• FIG, 3 contains photographs showing corrosion levels on steel coupons after spinner tests at a flow rate of 3ft/sec.
• FIG. 4 contains photographs showing white rust levels on galvanized coupons after spinner tests.
• compositions according to the invention were evaluated using spinner tests to simulate flowing water over metal components in a water system.
• Each spinner test set-up comprises a stainless steel container of water with four metal coupons (mild steef coupons (C1010) and copper coupons (CDA 11) were used) suspended in the water in each container from holders hanging from a rotating shaft.
• the shaft rotates the coupons in the water in the stainless steel container at 147 rotations/min, representing a flow rate of 3-5 ft s, depending on coupon distance from center of the rotating shaft.
• the initial volume of water used in each spinner test was characteristic of corrosive, low hardness water typically found in water systems. The water used had the characteristics shown in Table 1 below.
• compositions according to preferred embodiments of the invention (Example os. 1-3 including AAP, HPA, and another phosphonic acid - HEDP) without any added zinc or tin (as shown in Table 2) were compared to compositions using only zinc (Comp. Ex. 4), only tin (Comp, Ex. 5), only AAP (Comp. Ex. 6), only HPA (Comp. Ex.
• ppm concentrations of the various treatments are concentrations when added to the volume of water in the spinner test container.
• the compositions with zinc or tin were for comparison to those without, Zinc is typically used as corrosion inhibitor in water systems with highly corrosive water (Sow LSI). However its usage is undesirable due to toxicity issues and its use face regulations in some locations. Tin has been promoted and patented as a non-toxic alternative to zinc, but it is more expensive.
• ppm active refers to the amount of active raw material, in contrast to ppm which refers to the weight of raw material in mg/L
• HPA is commerctaiiy available as a 50% water solution, so adding 10 ppm raw materia! wili provide 5 ppm active HPA.
• Table 3 Corrosion inhibitor compositions - Comparative Exam p ies
• FIG. 1 shows photographs of a representative mild steel coupon after each spinner test with the control and with Example Composition Nos. 1-9. The amount of corrosion and pitting on the coupons is shown in the photographs. As can be seen, the control coupons show extensive corrosion (dark areas on photographs). The coupons used with compositions according to preferred embodiments of the invention (Ex. Nos, 2-3) show little, if any, corrosion or pitting (very few dark areas on photographs). The coupons used with Ex. No.
• Ex. No. 4 is based on zinc, which is undesirable to use due to toxicity concerns. As with the prior tests, these tests were carried out in presence 4 ppm active AA/AlvlPS copolymer and 4 ppm active TTA. A slug dose of 40ppm of biocide was added at the beginning of each spinner test (after the corrosion inhibition composition was added and the test started) to yield about 1 pm FHR (free halogen residue),
• S. 2 shows photographs of a representative mild steel coupon after each spinner test with the Example Compositions in the presence of biocide.
• the coupons used with compositions according to preferred embodiments of the invention show little, if any, corrosion or pitting, indicating that the functionality of preferred compositions according to the invention is not negatively affected by a biocide.
• the coupons used with the comparative compositions show substantially more corrosion than with Ex. Nos. 2-3. It is noted that Comp. No, 7 was the use of HPA and HEDP, without any AAP, which showed good results without biocide, but significantly more corrosion occurred when a biocide was added.
• Sever pitting a large number of pits (> 50), usually dipper and larger
• compositions according to preferred embodiments of the invention contain organic phosphate from the HPA and from the other phosphonic acid used in these examples (HEDP).
• HEDP phosphonic acid used in these examples
• the organic phosphate is often reverted to orthophosphate, which is not as good in preventing corrosion or scale and also may cause issues with forming calcium phosphate scale.
• AAP.HPA, and HEDP or another phosphonic acid
• virtually no reversion of organic phosphate to orthophosphate was detected.
• Samples from composition Example Nos, 2 and 3 and comparative Example , 7 were tested for the presence of orthophosphates upon mixing of the composition and again after 48 hours.
• Example Nos. 2 and 3 which use AAP, HPA, and HEDP (and contain AA/AMPS and TTA as noted above), showed very little orthophosphate increase over the 48 hour period, but comparative Example No. 7 which contains HPA and HEDP (and contains AA/AMPS and TTA as noted above), but no AAP, showed a substantia! increase.
• a water treatment composition as listed in Table 6 (which is the same as Ex. 2 tested above) is effective at inhibiting corrosion and scale in a water system over a broad range of LSI values (-2.5 to >3) and in the presence of a biocide.
• Active % refers to active weight percent.
• Wt% is raw material weight percent. Most of the raw materials are aqueous soiutions and contain only a certain amount of solids that is the actual chemical component.
• the amount of active (Active %) is calculated based on raw materia! weight percent and the amount of the chemical in the solution per the information provided by the supplier.
• NaOH and/or KOH is preferably also added to the composition according to an embodiment of the invention.
• compositions where TTA is used (as with a preferred embodiment of a composition according to the invention) it is desirable to have higher pH (> 1 1) for the composition in order to ensure solubility of TTA, which has very poor solubility at lower pH.
• Comparative Examples 10, 13, and 15 use AAP, HPA, and HEDP but in amounts less than the preferred concentrations. These examples show increased corrosion (and Comp. Ex, 10 showed moderate pitting) at low ievels of the inhibitors.
• Example Nos. 11-12, 14, and 18 according to preferred embodiments of the invention show good performance (low corrosion rate and no pitting) for different optional components and varying concentrations and ratios of AAP to HPA, The examples also show that the change from HEDP to PBTC (Ex. 16) and reduction of secondary chelates does not affect the corrosion inhibition performance of compositions according to preferred embodiments of the invention.
• Example No. 17 used AAP and HPA, without a second phosphontc acid, similar to the composition described in the ⁇ 23 patent. It shows improved resu!ts in controlling corrosion in iow LSi water, but the results are not as good as in the examples according to preferred embodiments of the invention,
• Example No. 11 which had a corrosion rate of 2.3 MPY using oniy 13.5 ppm total inhibitors (AAP, HPA, HEDP), and Example No. 18, which had a corrosion rate of 2.1 MPY using only 12.6 ppm total inhibitors (AAP, HPA, PBTC).
• AAP, HPA, HEDP oniy 13.5 ppm total inhibitors
• Example No. 18 which had a corrosion rate of 2.1 MPY using only 12.6 ppm total inhibitors (AAP, HPA, PBTC).
• the corrosion rates of Comp. Ex. Nos. 18-19 are comparable to those in Comp. Ex. os, 13 and 15, which use AAP, HPA, and a second phosphonic acid, but the total amount of inhibitor needed to achieve the results in Comp. Ex. Nos, 18-19 (20 ppm total) is much higher than that needed in Nos.
• compositions according to the embodiments of the invention are effective in inhibiting corrosion on metal components in water systems over broad range of LSI values, including LSI ⁇ 0, and without requiring the use of regulated toxic metals. These compositions are also effective at higher pH values (7-9) typically found in water systems, such as cooling towers and boifers, whereas some prior art inhibitors are ineffective or their effectiveness is reduced at such pH levels (for example, a polyaspartic acid/stannous salt treatment is effective only at pH 5-7). These compositions according to the invention also prevent reversion of organic phosphate to orthophosphate to maintain effectiveness in the presence of a biocide.
• FIG, 4 shows photographs of the galvanized coupons after the spinne tests with the compositions described in Table 12, both before and after cleaning.
• the white deposit visible on the coupons before cleaning is white rust.
• the damage of the galvanized layer due to corrosion, shown as dark spots, is visible on the coupons after cleaning.
• the blank (Comp. Ex.
• a preferred composition for treating white rust according to the invention comprises 2-15% amino-acid based polymer, 0-10% HPA, and 0-10% of a second phosphonic acid.
• the amount of active amino-acid based polymer in a treatment composition according to the invention is at least 3ppm, more preferably 3 ppm - 50 ppm, and most preferably 5 ppm - 30 ppm, all as concentrations when added to the volume of water in the water system being treated.
• the AAP is used in conjunction with HPA in an amount of at least 3 ppm, more preferably from 3 ppm - 50 ppm, and most preferably from about 3 ppm - 20 ppm and/or another phosphonic acid in an amount of at least 2 ppm more preferably from 2 ppm- 20 ppm, and most preferably from about 2 ppm - 10 ppm.
• hydroxyphosphonoacetic acid for treating white rust according to the invention, it is preferred to use both hydroxyphosphonoacetic acid and an amino-acid based polymer, and more preferably in conjunction with a second phosphonic acid, in the weight range amounts indicated above, but it has also been found that the use of an amino-acid based polymer or hydroxyphosphonoacetic without the other is beneficial at inhibiting white rust,
• a pilot cooling tower scale test using a composition according to a preferred embodiment of the invention was also conducted to test the ability to inhibit scale formation in high LSI water (LSI >1).
• the objective of the cooling tower scale test was to determine the number of cycles at which the tower can operate without scaling and the LSI limit of treatment in typical water with scaling characteristics as it cycles up.
• the cooling tower pilot test used 4 heat transfer surface rods and a DATS (Deposit Accumulation Testing System) operating at 800 Watts.
• the number of cycles of concentration (GOC) is calculated as the ratio of concentration of any ions in the cooling tower water to the concentration of the same ion in makeup (starting) water. Conductivity ratio can also be used to calculate COC.
• the COC In a cooling tower is maintained at a certain level by measuring water conductivity, bleeding the system when conductivity increases over a set limit and addsng more makeup water.
• the initial volume of water used in the cooling tower pilot test was characteristic of high LSI water having 100 ppm alkalinity as CaCO3 and 100 ppm calcium hardness as CaC03 typically found i cooling tower water systems. The water used had the characteristics shown in Table 12 below.
• the LSi limit (the LSI measurement at which scale will form) can also be determined by monitoring changes in water chemistry, water turbidity and visually by observing scale formation.
• a composition according to Table 6 at a concentration of TOO ppm (when added to the water in the pilot cooiing tower system) was found to increase the operational limit of cooling tower to 8 COC and LSI of 3.2 based on HTR and water chemistry data.
• the pilot cooling tower was operated for 7 days before scale began forming.
• the test was started with high scaling water, LSI around 1 , and was cycled up to 8 COC, which increased LSi to 3.2 before scale began to form.
• a treatment composition according to the invention as described above is added to the water system at an effective feed rate.
• a preferred method for corrosion and white rust inhibition comprises feeding the composition into the wate at an effective feed rate of 20ppm - 600 ppm, or more preferably 100 - 300ppm, of treatment composition, depending on the treated water chemistry and the amount of optional components in the treatment composition.
• a sufficient amount of treatment composition is added to the water system to provide effective active amounts of one or more of the three treatment components (depending on whether white rust is being treated o both corrosion and white) rust of at least 3 ppm AAP, at least 3 ppm HPA, and at least 2 ppm of another phosphonic acid, each as concentrations when added to the volume of water in the water system being treated. More preferably, the treatment composition is added in a sufficient amount to provide effective active amounts one or more of the components of between 3 ppm - 50 ppm AAP, between 3pm - 50 ppm HPA, and between 2 ppm - 20 ppm of another phosphonic acid when added to the water in the water system.
• these effective active amounts are 5pp - 30 ppm AAP, 3 ppm - 20 ppm HPA, and 2 ppm - 10 ppm other phosphonic acid when added to the water in the water system.
• HPA is optional, so the treatment composition used in a preferred method according to the invention may comprise AAP without any HPA and be added in amounts sufficient to provide these same concentration ranges of AAP in the water of the water system being treated.
• a preferred method for scale inhibition comprises feeding the composition into the water at an effective feed rate of 2Qppm - 600 ppm, or more preferably 50 ⁇ 30Qppm, of treatment composition, depending on the treated water chemistry and the amount of optional components in the treatment composition, Preferably, a sufficient amount of treatment composition is added to the water system to provide effective active amounts of one or more of the three treatment components of at least 2 ppm AAP, at least 2 ppm HPA, and at least 1,5 ppm of another phosphonic acid, each as concentrations when added to the volume of water in the water system being treated.
• the treatment composition is added in a sufficient amount to provide effective active amounts of the three treatment components of 2 ppm ⁇ 50 ppm AAP, 2 ppm - 50 ppm HPA, and 1.5 ppm -20 ppm of another phosphonic acid, each as concentrations when added to the volume of water in the water system being treated.
• the treatment composition is added in a sufficient amount to provide effective active amounts of the three components of between 3 ppm - 30 ppm AAP, between 2pm - 20 ppm HPA, and between 1 ,5 ppm - 10 ppm of another phosphonic acid when added to the water in the water system
• the composition added to the water system (for treating corrosion, white rust, and/or scale) comprises a fluorescent tracer so that the level of composition in the wate system can be measured and monitored. Additional treatment composition is added to the water system as needed, based on the tracer measurements, to maintain an effective amount of treatment within the water system.

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