Hydrogen-resistant and anti-oxidation method for inner walls of pressure containers, bottles, pipelines and valves

Abstract

The invention discloses a hydrogen resistance and anti-oxidation method for the inner walls of a pressure container, a bottle, a pipeline and a valve, which comprises the following steps of: (1) performing sand blasting or internal grinding treatment on the surface of the inner wall of a high-pressure hydrogen storage container, and removing oxide skin; (2) vacuumizing the treated container to 0.1-1.0 MPa or replacing with N2, and introducing a mixed gas composed of 75-85% by volume of fluorine and 15-25% by volume of nitrogen; (3) rotating the container at a constant speed of 5-20 revolutions per minute for 30-120 minutes, so that the mixed gas is uniformly attached to the surface of the inner wall to form a fluoride protective film; and (4) standing for 24 hours, exhausting gas, and introducing the exhausted gas into a calcium hydroxide solution at 20-60 DEG C to react to generate marble. According to the 30CrMo steel treated through the method, after a 72-hour hydrogen permeation test, the corrosion rate is reduced to 0.01 mm / a or below, and the hydrogen permeability is reduced by 92%; the tensile strength retention rate of the substrate is greater than or equal to 95% and is superior to that of a high- The friction coefficient of the fluoride film is less than or equal to 0.1 and is obviously reduced compared with nickel-plated Marble generated from tail gas can be recycled, and fluorine-free gas is directly discharged.

Description

Technical Field

[0001] This invention belongs to the field of corrosion protection technology for pressure vessels, bottles, pipelines and valves, and in particular relates to a method for preventing hydrogen and oxidation on the inner wall of pressure vessels, bottles, pipelines and valves. Background Technology

[0002] In existing technologies, the inner walls of alloy steel hydrogen storage containers often suffer from hydrogen embrittlement corrosion due to hydrogen infiltration (e.g., 30CrMo steel corrodes to a depth of 50 μm after 72 hours in a high-pressure hydrogen environment). While high-nickel-based materials have good resistance to hydrogen embrittlement, their tensile strength is insufficient (e.g., the strength of Inconel 718 alloy is only about 850 MPa). Furthermore, traditional plating (e.g., nickel alloy plating) or polymer coatings (e.g., EVOH / PEI-GO composite layer) suffer from problems such as low adhesion and poor temperature resistance. This invention generates a fluoride film in situ using fluorine gas, which combines high corrosion resistance, low friction, and high strength retention. Summary of the Invention

[0003] The purpose of this invention is to provide a hydrogen-blocking and oxidation-preventing inner wall for pressure vessels, bottles, pipes, and valves. By forming a fluoride protective film on the inner wall of alloy steel, hydrogen gas is effectively prevented from contacting the metal, thus solving the problem of hydrogen embrittlement and corrosion and completely overcoming the shortcomings of the prior art.

[0004] The objective of this invention is achieved through the following technical solution:

[0005] A method for preventing hydrogen contamination and oxidation on the inner wall of pressure vessels, bottles, pipes, and valves, comprising the following steps:

[0006] (1) Sandblasting or internal grinding is performed on the inner wall surface of pressure vessels, bottles, pipes and valves to remove oxide scale;

[0007] (2) Evacuate the treated container to 0.1-1.0 MPa or replace it with N2, and introduce a mixed gas consisting of 75-85% volume of fluorine gas and 15-25% volume of nitrogen gas;

[0008] (3) Rotate the container at a constant speed of 5-20 revolutions / minute for 30-120 minutes to make the mixed gas evenly adhere to the inner wall surface and form a fluoride protective film.

[0009] (4) After standing for 24 hours, the gas is discharged and then passed into a calcium hydroxide solution at 20-60℃ to react and generate marble.

[0010] Preferably, in step (3), the thickness of the fluoride film is 0.1-5 μm, and the film composition includes one or more of FeF2, CrF3 or TaF5.

[0011] Preferably, the inner wall material of the container is 30CrMo or 4130X alloy steel with a tensile strength ≥800MPa, and the hydrogen permeation rate is reduced by ≥90% after treatment.

[0012] Preferably, the marble after tail gas treatment in step (4) has a purity of 95-99%, which can be recycled as a raw material for fluorochemicals.

[0013] Preferably, the reaction temperature of the discharged gas with the calcium hydroxide solution in step (4) is 20-60℃.

[0014] Compared with the prior art, the present invention has the following beneficial effects:

[0015] Corrosion resistance: After 72 hours of hydrogen permeation test, the corrosion rate of 30CrMo steel and 4130X alloy steel treated by this invention dropped to below 0.01 mm / a (0.12 mm / a for untreated sample), and the hydrogen permeability was reduced by 92%.

[0016] Mechanical properties: The tensile strength retention rate of the base material is ≥95% (e.g., the strength of 4130X steel is still 1020MPa after treatment), which is better than high nickel-based materials (e.g., the strength of Inconel 718 is only 850MPa);

[0017] Low friction characteristics: The coefficient of friction of the fluoride film is ≤0.1 (sliding friction test), which is significantly lower than that of nickel-plated alloy (coefficient of friction 0.2-0.3).

[0018] Environmentally friendly and safe: The exhaust gas produces marble (CaF2), which can be recycled and reused, and there is no direct emission of fluorine gas. Attached Figure Description

[0019] Figure 1 It is a process flow chart of the present invention. Detailed Implementation

[0020] The present invention will be further described below with reference to specific embodiments and accompanying drawings.

[0021] like Figure 1 As shown, a pressure vessel, bottle, pipe, and valve include the following steps:

[0022] (1) Sandblasting or internal grinding is performed on the inner wall surface of the high-pressure hydrogen storage container to remove the oxide scale;

[0023] (2) Evacuate the treated container to 0.1-1.0 MPa or replace it with N2, and introduce a mixed gas consisting of 75-85% volume of fluorine gas and 15-25% volume of nitrogen gas to reduce the risk of explosion by diluting with nitrogen gas;

[0024] (3) Rotate the container at a constant speed of 5-20 revolutions / minute for 30-120 minutes to make the mixed gas evenly adhere to the inner wall surface and form a fluoride protective film.

[0025] (4) After standing for 24 hours, the gas is discharged and then passed into a calcium hydroxide solution at 20-60℃ to react and generate marble.

[0026] In step (2), the container can be evacuated by N2 replacement.

[0027] In step (3), the thickness of the fluoride film is 0.1-5 μm, and the film composition includes one or more of FeF2, CrF3 or TaF5.

[0028] The inner wall material of the container is 30CrMo or 4130X alloy steel with a tensile strength ≥800MPa, and the hydrogen permeation rate is reduced by ≥90% after treatment.

[0029] The purity of the marble after tail gas treatment in step (4) is 95-99%, which can be recycled as a raw material for fluorochemicals.

[0030] The reaction temperature between the discharged gas and the calcium hydroxide solution in step (4) is 20-60℃.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] Corrosion resistance: After 72 hours of hydrogen permeation test, the corrosion rate of 30CrMo steel, 4130X alloy steel and other alloy steel treated by this invention dropped to below 0.01 mm / a (0.12 mm / a for untreated samples), and the hydrogen permeability was reduced by 92%.

[0033] Mechanical properties: The tensile strength retention rate of the base material is ≥95% (e.g., the strength of 4130X steel is still 1020MPa after treatment), which is better than high nickel-based materials (e.g., the strength of Inconel 718 is only 850MPa);

[0034] Low friction characteristics: The coefficient of friction of the fluoride film is ≤0.1 (sliding friction test), which is significantly lower than that of nickel-plated alloy (coefficient of friction 0.2-0.3).

[0035] Environmentally friendly and safe: The exhaust gas produces marble (CaF2), which can be recycled and reused, and there is no direct emission of fluorine gas.

[0036] Example 1

[0037] 1. Substrate treatment: The inner wall of the 4130X alloy steel container is sandblasted with 18-mesh quartz sand, with a roughness Ra of 1.2μm.

[0038] 2. Fluorine treatment: Evacuate to 0.5MPa or replace with N2, introduce 80% fluorine gas + 20% nitrogen gas, rotate at 10 revolutions per minute for 60 minutes, with a total pressure of 0.5MPa.

[0039] 3. Film formation and detection:

[0040] XRD analysis showed that the film contained FeF2 (65%) and CrF3 (35%).

[0041] SEM observation showed the film thickness to be 1.5 μm, indicating it was dense and crack-free.

[0042] No surface corrosion was observed after a 72-hour hydrogen permeation test, and the coefficient of friction was 0.08.

[0043] 4. Exhaust gas treatment: The exhaust gas reacts with Ca(OH)2 to generate CaF2 (marble), with a recovery rate of ≥95%, avoiding fluorine pollution.

[0044] Comparative Example 1

[0045] Untreated 4130X steel under the same conditions under hydrogen permeation for 72 hours showed a corrosion depth of 45μm and dense cracks on the surface.

[0046] Example 2

[0047] 1. Take a 30CrMo alloy steel hydrogen storage container, and sandblast the inner wall with 20-mesh quartz sand.

[0048] 2. Evacuate to 0.1 MPa, introduce 80% fluorine gas + 20% nitrogen gas (total pressure 0.5 MPa), and rotate at 10 revolutions per minute for 60 minutes.

[0049] 3. After standing for 24 hours, the gas is released and passed into a 25℃ saturated Ca(OH)2 solution to generate marble.

[0050] 4. Testing: The thickness of the fluoride film on the inner wall is 1.2 μm, the coefficient of friction is 0.08, and no corrosion was observed in the 72-hour hydrogen permeation test.

[0051] Comparative Example 2

[0052] After 72 hours of hydrogen permeation under the same conditions, the surface of the untreated 30CrMo container developed dense cracks with a corrosion depth of 50 μm.

[0053] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preventing hydrogen absorption and oxidation on the inner wall of pressure vessels, bottles, pipes, and valves, characterized in that, Includes the following steps: (1) Sandblasting or internal grinding is performed on the inner wall surface of the high-pressure hydrogen storage container to remove the oxide scale; (2) Evacuate the treated container to 0.1-1.0 MPa or replace it with N2, and introduce a mixed gas consisting of 75-85% volume of fluorine gas and 15-25% volume of nitrogen gas; (3) Rotate the container at a constant speed of 5-20 revolutions / minute for 30-120 minutes to make the mixed gas evenly adhere to the inner wall surface and form a fluoride protective film. (4) After standing for 24 hours, the gas is discharged and then passed into a calcium hydroxide solution at 20-60℃ to react and generate marble.

2. The method according to claim 1, characterized in that: In step (3), the thickness of the fluoride film is 0.1-5 μm, and the film composition includes one or more of FeF2, CrF3 or TaF5.

3. The method according to claim 1, characterized in that: The inner wall material of the container is 30CrMo or 4130X alloy steel with a tensile strength ≥800MPa, and the hydrogen permeation rate is reduced by ≥90% after treatment.

4. The method according to claim 1, characterized in that: The purity of the marble after tail gas treatment in step (4) is 95-99%, which can be recycled as a raw material for fluorochemicals.

5. The method according to claim 1, characterized in that: The reaction temperature between the discharged gas and the calcium hydroxide solution in step (4) is 20-60℃.

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