CN110699696A - Acid pickling passivation method for stainless steel pipe fitting - Google Patents
Acid pickling passivation method for stainless steel pipe fitting Download PDFInfo
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- CN110699696A CN110699696A CN201911130849.XA CN201911130849A CN110699696A CN 110699696 A CN110699696 A CN 110699696A CN 201911130849 A CN201911130849 A CN 201911130849A CN 110699696 A CN110699696 A CN 110699696A
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- stainless steel
- steel pipe
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- pipe fitting
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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
- 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
- C23G1/14—Cleaning or pickling metallic material with solutions or molten salts with alkaline solutions
- C23G1/19—Iron or steel
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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
- 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
- C23C22/06—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 aqueous acidic solutions with pH less than 6
- C23C22/48—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 aqueous acidic solutions with pH less than 6 not containing phosphates, hexavalent chromium compounds, fluorides or complex fluorides, molybdates, tungstates, vanadates or oxalates
- C23C22/50—Treatment of iron or alloys based thereon
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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
- 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
- C23C22/78—Pretreatment of the material to be coated
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- Chemical & Material Sciences (AREA)
- General Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Mechanical Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Cleaning And De-Greasing Of Metallic Materials By Chemical Methods (AREA)
Abstract
The invention discloses an acid pickling passivation treatment method of stainless steel pipes, which comprises the steps of firstly pre-cleaning with normal-temperature deionized water, and then cleaning with hydrogen peroxide solution; passivating with citric acid solution; then, the test was carried out with a saline solution. According to the invention, hydrogen peroxide is selected to clean the stainless steel pipe fitting under an alkaline condition, so that strong alkali cleaning is replaced, the use amount of strong alkali is reduced, and the probability of harm to a human body is reduced; the citric acid is selected to replace nitric acid to passivate the stainless steel pipe fitting, so that the safety and health of operators are protected, and the environment is protected; the effect is tested by adopting the salt solution, and the method is safe and practical.
Description
Technical Field
The invention relates to the technical field of metal treatment, in particular to an acid pickling passivation method for stainless steel pipes.
Background
The stainless steel has black and yellow scale during processing, and the processed stainless steel needs to be subjected to pickling passivation treatment in order to improve the appearance and corrosion resistance of the stainless steel. The oxide skin generated after welding and high-temperature processing is removed, so that the oxide skin is silvery and bright, and a layer of oxide film taking chromium as a main substance is formed on the surface after processing, secondary oxygen corrosion is not generated, and the passivation purpose is achieved, so that the surface corrosion resistance quality of the stainless steel product is improved, and the service life of equipment is prolonged.
At present, the pickling passivation of stainless steel pipes is usually verified by strong alkali degreasing, nitric acid passivation and potassium ferricyanide solution, and the steps are as follows:
the first step is as follows: cleaning of
1) Pre-cleaning with normal temperature deionized water;
2) washing with alkali liquor with sodium hydroxide solution under heating state;
3) washing with normal-temperature deionized water:
the second step is that: passivation of
1) Passivating the acid solution by using a nitric acid solution under a certain pressure and temperature state;
2) washing with purified water;
3) washing with purified water;
the third step: effect testing
Blue spot test: after the pipeline is dried by argon, 2 g of potassium ferricyanide, 6 ml of 65-85% nitric acid and 200 ml of water are added to prepare a solution, the solution is soaked in filter paper and attached to the surface of the liquid to be detected, and the liquid is observed within 30s, so that the liquid is qualified if no blue spot exists.
However, such a treatment process has the following disadvantages:
1) degreasing and cleaning by strong alkali, so that operators are easy to burn;
2) the passivation by using a dangerous chemical nitric acid and the verification by using a mixed solution of a hypertoxic potassium ferricyanide and nitric acid seriously threaten the safety and health of operators and pollute the environment.
Disclosure of Invention
Aiming at the problems in the prior art, the invention aims to provide a novel stainless steel pickling and passivating treatment method, which is characterized in that hydrogen peroxide is used for degreasing and cleaning stainless steel, citric acid solution is used for passivating, and finally salt solution is used for verification, so that safe and mild reagents are used for replacing strong acid and strong base, the probability of harm to a human body is reduced, and the method is more environment-friendly.
In order to achieve the purpose, the technical scheme of the invention is as follows: an acid pickling passivation treatment method for stainless steel pipes comprises the following specific steps:
step one, cleaning: firstly, pre-cleaning with normal-temperature deionized water, and then cleaning with hydrogen peroxide solution;
and secondly, passivating: passivating with citric acid solution;
step three, checking: after the cleaned stainless steel pipe was blow-dried, the test was carried out with a saline solution.
Wherein the hydrogen peroxide solution is 8% hydrogen peroxide, is added into deionized water, and is added with an alkali solution to adjust the pH value to 9-10. The alkali solution is a sodium hydroxide solution with a volume concentration of 1%.
And heating the hydrogen peroxide solution to 50 ℃, cleaning and soaking the stainless steel pipe fitting for 30 minutes.
Wherein the passivation is performed by using 10% citric acid solution at the temperature of 67 ℃, namely, the stainless steel pipe fitting is soaked in the 10% citric acid solution for at least 120 minutes.
Wherein the test is performed by performing a spray experiment on a stainless steel pipe fitting with a 5% salt solution.
The technical scheme of the invention has the following beneficial effects.
1) Cleaning the stainless steel pipe fitting by using hydrogen peroxide under an alkaline condition (pH is 9-10), replacing strong alkali cleaning, reducing the using amount of strong alkali and reducing the probability of harm to a human body;
2) the stainless steel pipe fitting is passivated by using citric acid instead of nitric acid, so that the safety and health of operators are protected, and the environment is protected;
3) the effect is tested by adopting the saline solution, so that the method is safe and practical;
4) in the whole pickling and passivating process, the adopted medicament is cheap and easily available, is harmless to human bodies and has no influence on the environment, and the aims of safety, high efficiency, environmental protection and energy conservation can be achieved;
5) the reasonable pickling passivation process ensures that the pickling passivation effect meets the requirement.
According to the invention, hydrogen peroxide is selected to clean the stainless steel pipe fitting under an alkaline condition (pH is 9-10), and strong alkali cleaning is replaced, so that the use amount of strong alkali is reduced, and the probability of harm to a human body is reduced; the citric acid is selected to replace nitric acid to passivate the stainless steel pipe fitting, so that the safety and health of operators are protected, and the environment is protected; the effect is tested by adopting the salt solution, and the method is safe and practical.
Drawings
Fig. 1 shows a stainless steel pipe fitting to be cleaned.
FIG. 2 is a view showing a stainless steel pipe after being passivated by the method of the present invention.
Detailed Description
The invention will be further illustrated with reference to the following specific examples. It should be understood that these examples are for illustrative purposes only and are not intended to limit the scope of the present invention. Furthermore, it should be understood that various changes or modifications can be made by those skilled in the art after reading the disclosure of the present invention, and such equivalents also fall within the scope of the invention.
An acid pickling passivation treatment method for stainless steel pipes comprises the following specific steps:
the first step is as follows: cleaning of
1) Pre-cleaning: washing the stainless steel for 2 times by using deionized water to remove dust and particles;
2) cleaning with hydrogen peroxide solution: preparing an 8% hydrogen peroxide reagent, adding the hydrogen peroxide reagent into deionized water, adding an alkali solution to adjust the pH to 9-10, heating the hydrogen peroxide solution to about 50 ℃, putting the stainless steel pipe fitting into the hydrogen peroxide solution, and soaking or performing online circulating flushing for 30 minutes by using a pump; adding acid to make pH be 7, and emptying cleaning solution;
3) washing with deionized water: soaking the stainless steel pipe fitting in deionized water at normal temperature for 30 minutes, and then discharging; then washing with deionized water for 2 times;
the second step is that: passivation of
1) Passivating acid liquor: soaking or circularly washing the stainless steel pipe fitting for 120 minutes by using a 10% citric acid solution prepared from deionized water and citric acid at the temperature of about 67 ℃, and emptying the pickling solution; soaking the stainless steel pipe fitting in deionized water at normal temperature for 5 minutes, and draining; washing with deionized water until the pH value of the washing drainage water is neutral;
the third step: effect testing
And (3) blowing the pipeline with argon, spraying 5% of salt solution on the passivated stainless steel surface, and observing after 2 hours until no rusty spot or stain is formed, so that the stainless steel is qualified.
Example 1
FIG. 1 shows a stainless steel pipe with welded joints which needs to be cleaned, and rust and stains are visible.
Firstly, cleaning the stainless steel pipe fitting.
1. Pre-cleaning
(1) The formula is as follows: deionized water at normal temperature;
(2) the operation procedure is as follows: washing the stainless steel pipe fitting with the welding line for 2 times by using deionized water (for removing dust and particles);
2. cleaning and soaking with hydrogen peroxide
(1) The formula is as follows: preparing 8% hydrogen peroxide reagent, adding the hydrogen peroxide reagent into deionized water, preparing 1% (volume concentration) aqueous alkali by using sodium hydroxide in the deionized water at the temperature of about 50 ℃, mixing the aqueous alkali with the hydrogen peroxide solution, adjusting the pH to 9-10, putting the stainless steel pipe fitting into the deionized water, soaking the stainless steel pipe fitting for 30 minutes, and taking the stainless steel pipe fitting out;
3. soaking in deionized water:
(1) the formula is as follows: soaking the stainless steel pipe fitting in deionized water at normal temperature for 30 minutes, and pouring out the stainless steel pipe fitting; then washing with deionized water for 2 times;
II, passivating
1. Passivation of acid solutions
(1) The formula is as follows: soaking the stainless steel pipe fitting in a 10% citric acid solution prepared from deionized water (at about 67 ℃) and citric acid for 120 minutes, taking out the stainless steel pipe fitting, and pouring out the soaking solution;
(2) the formula is as follows: soaking the stainless steel pipe fitting in deionized water at normal temperature for 5 minutes, and pouring out the stainless steel pipe fitting; then washing with deionized water until the pH value of the washing and draining water is neutral;
thirdly, checking the passivation result
The method comprises the following steps: salt spraying test:
after the pipeline is blown dry by argon, 5% salt solution is sprayed on the passivated pipe fitting, and after 2 hours observation, rust spots and stains are avoided, and the cleaning passivation effect is good. As shown in figure 2, the middle of the stainless steel pipe fitting is a welding line, and after pickling passivation and acceptance spray test, the surface is smooth and has no rusty spots and stains.
According to the invention, hydrogen peroxide is selected to clean the stainless steel pipe fitting under an alkaline condition (pH is 9-10), and strong alkali cleaning is replaced, so that the use amount of strong alkali is reduced, and the probability of harm to a human body is reduced; the citric acid is selected to replace nitric acid to passivate the stainless steel pipe fitting, so that the safety and health of operators are protected, and the environment is protected; the effect is tested by adopting the salt solution, and the method is safe and practical.
The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims (5)
1. The pickling passivation treatment method for the stainless steel pipe fitting is characterized by comprising the following specific steps:
step one, cleaning: firstly, pre-cleaning with normal-temperature deionized water, and then cleaning with hydrogen peroxide solution under an alkaline condition;
and secondly, passivating: passivating with citric acid solution;
step three, checking: after the cleaned stainless steel pipe was blow-dried, the test was carried out with a saline solution.
2. The method for pickling and passivating stainless steel pipes as claimed in claim 1, wherein the hydrogen peroxide solution is 8% hydrogen peroxide added into deionized water, and the pH is adjusted to 9-10 by adding alkali.
3. The method for pickling and passivating stainless steel pipes according to claim 1, wherein the hydrogen peroxide solution is heated to a temperature of 50 ℃ and then cleaned.
4. The method for pickling and passivating stainless steel pipes according to claim 1, wherein the passivation is performed by passivating with 10% citric acid solution at a temperature of 67 ℃.
5. The method for pickling and passivating a stainless steel pipe as claimed in claim 1, wherein the test is performed by performing a spray test on a stainless steel pipe with a 5% salt solution.
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| Application Number | Priority Date | Filing Date | Title |
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| CN201911130849.XA CN110699696A (en) | 2019-11-18 | 2019-11-18 | Acid pickling passivation method for stainless steel pipe fitting |
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| Application Number | Priority Date | Filing Date | Title |
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| CN201911130849.XA CN110699696A (en) | 2019-11-18 | 2019-11-18 | Acid pickling passivation method for stainless steel pipe fitting |
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| CN110699696A true CN110699696A (en) | 2020-01-17 |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112064042A (en) * | 2020-09-03 | 2020-12-11 | 上海朗脉洁净技术股份有限公司 | Pickling passivation solution and pickling passivation process for stainless steel pipeline |
| CN113025445A (en) * | 2021-03-25 | 2021-06-25 | 中核四川环保工程有限责任公司 | Cleaning agent for cleaning high-temperature sintered metal filter |
| CN113201732A (en) * | 2021-04-23 | 2021-08-03 | 江苏盛世华为工程技术有限公司 | Passivation process for injection water and purified water |
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| WO2019160948A1 (en) * | 2018-02-14 | 2019-08-22 | Ecolab Usa Inc. | Compositions and methods for the reduction of biofilm and spores from membranes |
| CN110257812A (en) * | 2019-07-02 | 2019-09-20 | 广汉市恒锐钢球制造有限公司 | A kind of passivating method and passivation workplace of stainless steel product |
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2019
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Patent Citations (5)
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| CN101768746A (en) * | 2008-12-31 | 2010-07-07 | 中国蓝星（集团）股份有限公司 | Cleaning agent special for stainless steel and preparation method and application thereof |
| CN107052046A (en) * | 2016-12-16 | 2017-08-18 | 安徽宝恒新材料科技有限公司 | A kind of high-quality stainless steel cold-rolled plate preparation method |
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| WO2019160948A1 (en) * | 2018-02-14 | 2019-08-22 | Ecolab Usa Inc. | Compositions and methods for the reduction of biofilm and spores from membranes |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112064042A (en) * | 2020-09-03 | 2020-12-11 | 上海朗脉洁净技术股份有限公司 | Pickling passivation solution and pickling passivation process for stainless steel pipeline |
| CN113025445A (en) * | 2021-03-25 | 2021-06-25 | 中核四川环保工程有限责任公司 | Cleaning agent for cleaning high-temperature sintered metal filter |
| CN113201732A (en) * | 2021-04-23 | 2021-08-03 | 江苏盛世华为工程技术有限公司 | Passivation process for injection water and purified water |
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Application publication date: 20200117 |