EP1950327A1 - Procédé pour dérouiller des surfaces métalliques - Google Patents

Procédé pour dérouiller des surfaces métalliques Download PDF

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Publication number
EP1950327A1
EP1950327A1 EP07101166A EP07101166A EP1950327A1 EP 1950327 A1 EP1950327 A1 EP 1950327A1 EP 07101166 A EP07101166 A EP 07101166A EP 07101166 A EP07101166 A EP 07101166A EP 1950327 A1 EP1950327 A1 EP 1950327A1
Authority
EP
European Patent Office
Prior art keywords
derusting
lactic acid
buffer
steel
ammonium
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP07101166A
Other languages
German (de)
English (en)
Inventor
Christiaan Reinder Wijnia
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Purac Biochem BV
Original Assignee
Purac Biochem BV
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Purac Biochem BV filed Critical Purac Biochem BV
Priority to EP07101166A priority Critical patent/EP1950327A1/fr
Priority to PCT/EP2008/050893 priority patent/WO2008090219A1/fr
Publication of EP1950327A1 publication Critical patent/EP1950327A1/fr
Withdrawn legal-status Critical Current

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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
    • C23G—CLEANING OR DE-GREASING OF METALLIC MATERIAL BY CHEMICAL METHODS OTHER THAN ELECTROLYSIS
    • C23G1/00—Cleaning or pickling metallic material with solutions or molten salts
    • C23G1/02—Cleaning or pickling metallic material with solutions or molten salts with acid solutions
    • C23G1/08—Iron or steel
    • C23G1/088—Iron or steel solutions containing organic 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
    • C23G—CLEANING OR DE-GREASING OF METALLIC MATERIAL BY CHEMICAL METHODS OTHER THAN ELECTROLYSIS
    • C23G1/00—Cleaning or pickling metallic material with solutions or molten salts
    • C23G1/24—Cleaning or pickling metallic material with solutions or molten salts with neutral solutions
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F28—HEAT EXCHANGE IN GENERAL
    • F28F—DETAILS OF HEAT-EXCHANGE AND HEAT-TRANSFER APPARATUS, OF GENERAL APPLICATION
    • F28F19/00—Preventing the formation of deposits or corrosion, e.g. by using filters or scrapers

Definitions

  • the invention relates to a novel method for derusting metallic surfaces.
  • Rust forming on metal surfaces is a common problem in industry. As a result of the formation of rust deposits, pit corrosion occurs inside steel pipes. Pit corrosion can damage, and causes leakage in pipes. Therefore, cooling installations frequently have to shut down and as a direct result, also the plant for intensive inspection. This all is very time consuming and very expensive. It is known to use lactic acid for rust removal, but this product has the disadvantage that when applied during longer periods itself causes corrosion.
  • citric acid When citric acid is used also the combination citric acid-ammonium citrate-tin sulfate is described.
  • the metal parts are thereby immersed in the derusting solution for about 15 minutes and then rinsed with a basic solution. It was found that this solution is less suitable for plant installations, which cannot be immersed therein but through which the solution must be pumped for a considerable longer time than used in WO 2005/033365 . When used in that manner unacceptable damaging of steel pipes and the like may occur.
  • citric acid is a solid, making dosing and dissolving in cooling water difficult, particularly leading to difficulties at effective pH control.
  • the invention pertains to a method for derusting a metallic surface by bringing the surface in contact with an aqueous solution of a buffer having a pH between 5.1 and 6.5, wherein the buffer comprises lactic acid and the sodium, potassium and/or ammonium salt of lactic acid.
  • the present invention is of particular importance for removing rust within steel pipes as used in plant installations such as cooling installations. Pit corrosion in such pipes can cause serious damage and leakage of the pipes. Prevention is thus of utmost importance to prevent shut down of the installations and intensive inspection.
  • the lactic acid is buffered with its sodium, potassium, and or ammonium salt.
  • a buffer system comprising lactic acid and ammonium lactate is preferred. Such systems do not longer require the presence of zinc sulfate, which is further advantage of the present method.
  • the invention can be performed in the pH range 5.1 to 6.5, but at the higher pH values the derusting process is much slower. For that reason it is preferred to perform the process at a pH between 5.1 and 5.7.
  • the method can be used at ambient temperature but when more quicker removal of rust is required the temperature of the aqueous acid solution may be raised to 70 °C, and if necessary to even higher temperatures until the boiling point of water.
  • the method of the invention is of particular interest for plant cooling systems through which the aqueous acid solution is pumped for usually 4 to 12 hours.
  • the circulation time can be shortened, which is favorable for shortening the shut down time.
  • the panels were partly submerged into a stirred 5% or 10 % (w/w) sodium lactate solution at different concentration and temperatures.
  • the glass beakers, containing the partly submerged panels, were covered with aluminum foil. This simulates a closed system in the daily practice.
  • the panels were lifted out of the test solutions, immediately rinsed with demi-water (to remove the acid), rinsed with acetone, dried with an air hose, weighed, and finally photographed. At every time interval the time was stopped, until the panels were partly submerged in the test solutions again. After 48 hours the test was stopped.
  • Ammonium lactate solution was prepared from commercially available ammonium lactate to obtain a 10.0% (w/w) ammonium lactate solution. This concentration corresponds to a calculated concentration of lactic acid of 8.4% The solution was than brought to pH 5.7 by addition of 0.7% sodium hydroxide.
  • citric acid As comparison (di)ammonium citrate was prepared from citric acid as follows. The weight in amount of citric acid was based on the theoretically starting amount of L(+)-lactic acid in the used ammonium lactate solution. This is 8.4 % (w/w) acid. The citric acid was partly neutralized by adding 6.8% of ammonia, 25% to give pH 5.7. As a result, the calculated concentration of ammonium citrate in this solution was 10% as well.
  • Table 1 shows that both sodium lactate and ammonium lactate are effective in derusting steel panels, the latter being more effective than sodium lactate. Ammonium citrate is not effective at this pH.
  • the prior art pH conditions pH 3-5
  • Table 2 shows that the pH conditions (pH 3-5) according to the prior art lead to substantial more corrosion than the instant invention operating at higher pH.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • General Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Preventing Corrosion Or Incrustation Of Metals (AREA)
EP07101166A 2007-01-25 2007-01-25 Procédé pour dérouiller des surfaces métalliques Withdrawn EP1950327A1 (fr)

Priority Applications (2)

Application Number Priority Date Filing Date Title
EP07101166A EP1950327A1 (fr) 2007-01-25 2007-01-25 Procédé pour dérouiller des surfaces métalliques
PCT/EP2008/050893 WO2008090219A1 (fr) 2007-01-25 2008-01-25 Procédé destiné à dérouiller des surfaces métalliques

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
EP07101166A EP1950327A1 (fr) 2007-01-25 2007-01-25 Procédé pour dérouiller des surfaces métalliques

Publications (1)

Publication Number Publication Date
EP1950327A1 true EP1950327A1 (fr) 2008-07-30

Family

ID=38191070

Family Applications (1)

Application Number Title Priority Date Filing Date
EP07101166A Withdrawn EP1950327A1 (fr) 2007-01-25 2007-01-25 Procédé pour dérouiller des surfaces métalliques

Country Status (2)

Country Link
EP (1) EP1950327A1 (fr)
WO (1) WO2008090219A1 (fr)

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE694237C (de) * 1935-04-18 1940-07-27 Ver Fuer Chemische Und Metallu Mittel zum Entfernen von Bierstein, Milchstein und
DE742477C (de) * 1940-07-20 1943-12-04 Paul Effing Entrostungsmittel zum Entrosten von eisenhaltigen Koerperoberflaechen
US4476930A (en) * 1982-08-23 1984-10-16 Union Oil Company Of California Inhibition of scale deposition from steam generation fluids
DE19721422A1 (de) * 1997-04-05 1998-10-08 Henry Zimzik Verfahren zum Herstellen eines Entrostungsmittel sowie Verwendung desselben
WO2002008127A1 (fr) * 2000-07-20 2002-01-31 Rhodia Consumer Specialties Limited Traitement de dépôts de sulfure de fer
WO2006039983A1 (fr) * 2004-09-25 2006-04-20 Chemetall Gmbh Procede d'elimination de battitures provenant de laser

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE694237C (de) * 1935-04-18 1940-07-27 Ver Fuer Chemische Und Metallu Mittel zum Entfernen von Bierstein, Milchstein und
DE742477C (de) * 1940-07-20 1943-12-04 Paul Effing Entrostungsmittel zum Entrosten von eisenhaltigen Koerperoberflaechen
US4476930A (en) * 1982-08-23 1984-10-16 Union Oil Company Of California Inhibition of scale deposition from steam generation fluids
DE19721422A1 (de) * 1997-04-05 1998-10-08 Henry Zimzik Verfahren zum Herstellen eines Entrostungsmittel sowie Verwendung desselben
WO2002008127A1 (fr) * 2000-07-20 2002-01-31 Rhodia Consumer Specialties Limited Traitement de dépôts de sulfure de fer
WO2006039983A1 (fr) * 2004-09-25 2006-04-20 Chemetall Gmbh Procede d'elimination de battitures provenant de laser

Also Published As

Publication number Publication date
WO2008090219A1 (fr) 2008-07-31

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