US3400022A - Method for the protection of internal surfaces of the tubes for high-temperature, high-pressure boilers from corrosion - Google Patents

Method for the protection of internal surfaces of the tubes for high-temperature, high-pressure boilers from corrosion Download PDF

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Publication number
US3400022A
US3400022A US635630A US63563067A US3400022A US 3400022 A US3400022 A US 3400022A US 635630 A US635630 A US 635630A US 63563067 A US63563067 A US 63563067A US 3400022 A US3400022 A US 3400022A
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Prior art keywords
corrosion
tubes
solution
treatment
temperature
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Expired - Lifetime
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US635630A
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English (en)
Inventor
Asai Osamu
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Hitachi Ltd
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Hitachi Ltd
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Publication date
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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
    • 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
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C22/00—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
    • C23C22/05—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions
    • C23C22/60—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using alkaline aqueous solutions with pH greater than 8
    • C23C22/62—Treatment of iron or alloys based thereon
    • 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

  • Such a treatment is resorted to because the existence of said adherent substances on the internal surface of the boiler is the principal cause of the above-mentioned corrosion. Since the metallic surface is very susceptible to corrosion after such adherent matters have been removed by pickling, some additional anti-corrosion treatment must be carried out.
  • the simplest method for this latter treatment is to pass an alkaline solution of sodium phosphate, caustic soda, or their mixture with sodiumcarbonate through the metal tubes so as to neutralize the remaining acid liquid and form an anti-corrosion film on the surface of the metal tubes.
  • iron hydroxide will be formed on the internal walls of the'tubes in a steel boiler according to the following formula Next, since the boiler is to be heated to approximately 300 C., the iron hydroxide will decompose in accordance with the following chemical reaction whereby an anti-corrosion film of Fe O forms on the interior surface of the iron tube.
  • An essential object of this invention is to provide a method of protecting the boiler tubes from corrosion without the accompaniment of the above-mentioned various difiiculties.
  • the lithium hydroxide solution to be used as a treatment solution in this invention is contained in conventional alkaline solutions which have been in use heretofore.
  • no study whatsoever has been made of this lithium hydroxide solution, and consequently the remarkable effect derived from said substance has not yet been generally known.
  • the cause of this remarkable effect i.e., the excellent anti-corrosion effect, has not yet been clarified sufficiently, but it is considered that, first of all, the Fe O film obtained by the treatment with lithium hydroxide solution is free from said defects, differing from the Fe O film formed by caustic soda solution.
  • the fact that the film formed by the use of lithium hydroxide has an excellent anti-corrosion property has been confirmed by a large number of experimental data.
  • Corrosion rate Conditions (mg/dm. month) 1. In the case of subjecting to corrosion with l N NaOH at 300 C. (after 200 hrs.) 2. In the case of subjecting to corrosion with l N LiOH at 300 C. (after 200 hrs.) 3. In the case of subjecting to corrosion with 1 N NaOH at 300 C. after treatment with 1 N LiOH at 300 C. for 200 hrs. (after 200 hrs.) 4. In the case of subjecting to corrosion with 5 N NaOH at 300 C. after treatment with 1 N LiOH at 300 C. for 200 hrs. (after 200 hrs.) 5. In the case of subjecting to corrosion with 1 N LiOH at 300 C. after treatment with 1 N NaOH at 300 C. for 200 hrs.
  • the essential point of this invention is to treat first with LiOH solution. If it is uneconomical to carry out the treatment with LiOH alone, the treatment can be carried out first with LiOH solution by the treatment with NaOH, thus the film of Fe O formed on the surface of a steel tube is rendered thicker, whereby the corrosion rate decreases.
  • the drawing clearly shows, when the concentration of the alkaline solution is low, the difference in the corrosion rate between the LiOH and NaOH is not particularly large. However, the drawing also clearly shows that an LiOH solution of as low as 0.1 normality has a better anticorrosive effect than a corresponding NaOH solution.
  • concentration is near 2 N, :the difference between the two solutions is the slightest, but beyond that concentration, the difference in the corrosion rate grows rapidly, the effect of LiOH becoming substantially steady whereas the corrosion rate steeply increases when using NaOH.
  • the method of preventing corrosion according to this invention has a remarkably excellent anti-corrosion effect in comparison with conventional methods and can be used most advantageously, particularly when the water of a boiler, as in the case of a high-temperature, high-pressure boiler, has a tendency to become an alkaline solution of high concentration.
  • a method of protecting the internal wall of evaporative tubes used in a high-temperature, high-pressure boilers which consists essentially of passing "an aqueous solution of lithium hydroxide at least once through said tubes in the course of neutralization of acid liquids and formation of an anti-corrosion film on the internal surface f said tubes, said solution containing a sufficient number of lithium ions to produce an Fe O protective film which is free from defects.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Organic Chemistry (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Inorganic Chemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • General Engineering & Computer Science (AREA)
  • Cleaning And De-Greasing Of Metallic Materials By Chemical Methods (AREA)
  • Preventing Corrosion Or Incrustation Of Metals (AREA)
US635630A 1962-09-10 1967-02-17 Method for the protection of internal surfaces of the tubes for high-temperature, high-pressure boilers from corrosion Expired - Lifetime US3400022A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP3851862 1962-09-10

Publications (1)

Publication Number Publication Date
US3400022A true US3400022A (en) 1968-09-03

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US635630A Expired - Lifetime US3400022A (en) 1962-09-10 1967-02-17 Method for the protection of internal surfaces of the tubes for high-temperature, high-pressure boilers from corrosion

Country Status (4)

Country Link
US (1) US3400022A (de)
CH (1) CH425397A (de)
DE (1) DE1278802B (de)
GB (1) GB1021325A (de)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4364900A (en) * 1977-06-09 1982-12-21 Atomic Energy Of Canada Limited Deposit suppression in the core of water-cooled nuclear reactors
US4532045A (en) * 1982-07-07 1985-07-30 Waterscience, Inc. Bleed-off elimination system and method

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3971628A (en) * 1971-03-09 1976-07-27 Aminkemi Ab Method for inhibiting rust formation on iron-containing articles
DE4117624A1 (de) * 1991-05-29 1992-12-03 Siemens Ag Verfahren zur passivierung einer bauteiloberflaeche

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3173404A (en) * 1963-08-16 1965-03-16 Mortimer C Bloom Protective film formation in high pressure steam generators

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3173404A (en) * 1963-08-16 1965-03-16 Mortimer C Bloom Protective film formation in high pressure steam generators

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4364900A (en) * 1977-06-09 1982-12-21 Atomic Energy Of Canada Limited Deposit suppression in the core of water-cooled nuclear reactors
US4532045A (en) * 1982-07-07 1985-07-30 Waterscience, Inc. Bleed-off elimination system and method

Also Published As

Publication number Publication date
GB1021325A (en) 1966-03-02
DE1278802B (de) 1968-09-26
CH425397A (fr) 1966-11-30

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