Antibacterial corrosion conveying welded pipe, manufacturing method thereof and welding material

Abstract

The invention discloses an antibacterial corrosion conveying welded pipe, a manufacturing method of the antibacterial corrosion conveying welded pipe and a welding material. The antibacterial corrosion conveying welded pipe comprises the following chemical elements in percentage by mass: 0.05-0.15% of C, 0.1-0.5% of Si, 0.1-0.5% of Mn, 0-0.02% of P, 0-0.005% of S, 0.15-0.5% of Cu, 0.5-1.5% of Cr and the balance of Fe. And 0.3 lt; ceqlt, Ceqlt; and 0.43%. The method comprises the following steps: continuously casting smelted molten steel into a plate blank; rolling the plate blank at high temperature to prepare a steel plate or a plate coil; and the manufactured steel plate is subjected to coiling forming and welding, chemical elements of a welding material are matched with the welded pipe, and the antibacterial corrosion conveying welded pipe is manufactured. The medium-antibacterial-corrosion conveying welded pipe prepared by the invention has relatively low alloy cost and excellent corrosion resistance and mechanical properties, and can be used in the fields of oil gas fluid conveying and the like.

Description

Technical Field

[0001] The invention belongs to the field of metal materials, in particular to an antibacterial corrosion conveying welded pipe and a manufacturing method and welding material thereof. Background Art

[0002] The medium transported by the oil and gas field gathering pipeline usually contains CO2, H2S, Cl - Corrosive components such as sulphate-reducing bacteria (SRB) and other corrosion components are highly corrosive. Especially as the exploitation of oil and gas fields gradually deepens, the corrosion and perforation of gathering and transportation pipelines caused by electrolyte corrosion promoted by the increase in water content and sulfate-reducing bacteria (SRB) corrosion are becoming more and more frequent. Bacterial corrosion has become an important leading factor in the corrosion of oilfield gathering and transportation pipelines, especially shale gas gathering and transportation pipelines. Bacterial corrosion is usually dominated by rapid pitting corrosion, which is extremely destructive. While the leakage of gathering and transportation pipelines caused by corrosion problems brings huge economic losses to oil and gas fields, the environmental damage caused by oil and gas leakage has also caused great negative social impacts. If corrosion-resistant alloy pipes are directly used to solve such problems, the high price will bring unbearable cost pressure. Due to price reasons, the large-scale application of such pipes is greatly limited. Therefore, oil and gas field companies are eager to obtain a low-cost corrosion-resistant pipeline.

[0003] Cu is an important chemical component that inhibits bacterial corrosion. On the one hand, Cu can significantly improve the resistance of pipelines to CO2 and Cl - On the other hand, Cu is a relatively expensive additive in pipeline steel, and a large amount of addition will greatly increase the construction cost of the pipeline; in addition, in order to avoid Cu brittleness during the rolling process and to ensure the welding and forming performance of the coil / plate, the copper content needs to be limited during the manufacturing of pipeline steel. In view of the existence of the above-mentioned various limiting factors, the oil and gas gathering and transportation industry has not had any relevant research and development and product reports on low-cost anti-bacterial corrosion welded pipes. Summary of the invention

[0004] The purpose of the present invention is to solve the problems in the prior art and provide an antibacterial corrosion transport welded pipe and its manufacturing method and welding material, which are suitable for environments containing water and a small amount of corrosive media and have good corrosion resistance and perforation performance.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] An antibacterial corrosion conveying welded pipe comprises the following chemical elements in the following mass percentages:

[0007] C: 0.05-0.15%, Si: 0.1-0.5%, Mn: 0.1%-0.5%, P: 0-0.02%, S: 0-0.005%, Cu: 0.15-0.5% and Cr: 0.5-1.5%, the balance is Fe;

[0008] And 0.3 < Ceq < 0.43%.

[0009] Furthermore, it further includes the following chemical elements with the following mass percentages: 0 < Ni ≤ 0.3%, and Ni:Cu ≥ 0.5.

[0010] Furthermore, when the mass percentage of the chemical element Cu is 0 - 0.2%, the mass percentage of the chemical element Ni is 0.

[0011] A manufacturing method of the antibacterial and corrosion - resistant conveying welded pipe described above includes the following steps:

[0012] Smelt molten steel according to the ratio of chemical elements C, Si, Mn, P, S, Cu, Cr, and Fe in the welded pipe;

[0013] Continuous - cast the smelted molten steel into a slab;

[0014] Roll the slab at high temperature to make a steel plate or a coil;

[0015] Coil and form the made steel plate, and weld it with welding materials to make an antibacterial and corrosion - resistant conveying welded pipe.

[0016] Furthermore, before the rolling, it further includes a reheating step, the reheating temperature is 1150 - 1280 °C, and the heat - preservation time is 30 - 180 min.

[0017] Furthermore, during the rolling process, the starting rolling temperature is between 1100 - 1270 °C, and the ending rolling temperature is higher than 700 °C.

[0018] Furthermore, during the coiling and forming process, the coiling temperature is 400 - 700 °C.

[0019] Furthermore, the welding materials include the following chemical elements with the following mass percentages:

[0020] C: 0.05 - 0.15%, Mn: 0.1% - 0.5%, Si: 0.1 - 0.5%, P: 0 - 0.005%, S: 0 - 0.004%, Cu: 0.15 - 0.5%, and Cr: 0.5 - 1.5%, and the balance is Fe and inevitable impurities.

[0021] A kind of welding material, which is used to weld the coiled and formed steel plate or coil to make an antibacterial and corrosion - resistant conveying welded pipe;

[0022] It includes the following chemical elements with the following mass percentages:

[0023] C: 0.05 - 0.15%, Mn: 0.1% - 0.5%, Si: 0.1 - 0.5%, P: 0 - 0.005%, S: 0 - 0.004%, Cu: 0.15 - 0.5% and Cr: 0.5 - 1.5%, with the balance being Fe and unavoidable impurities.

[0024] Furthermore, it further includes the following chemical elements with mass percentages as follows: 0 < Ni ≤ 0.5%, and Ni:Cu ≥ 0.5.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] The present invention provides a manufacturing method for an antibacterial and corrosion-resistant conveying welded pipe. By melting the following chemical elements with mass percentages: C: 0.05 - 0.15%, Si: 0.1 - 0.5%, Mn: 0.1% - 0.5%, P: 0 - 0.02%, S: 0 - 0.005%, Cu: 0.15 - 0.5% and Cr: 0.5 - 1.5%, with the balance being Fe; and 0.3 < Ceq < 0.43% into molten steel; continuously casting the molten steel into a slab; rolling the slab at a high temperature to make a steel plate or a coil; coiling and forming the made steel plate, and welding to make an antibacterial and corrosion-resistant conveying welded pipe. At the same time, Ni is added to inhibit the hot working cracking tendency after adding Cu. The yield strength of the made submerged arc welded pipeline pipe reaches above 245 MPa, the tensile strength of the weld reaches above 415 MPa. Under the condition of -40 °C, the average impact energy of the whole size of the pipe body is ≥ 40 J, and the average impact energy of the weld is ≥ 27 J. The performance of the welded pipe manufactured by the present invention meets the requirements of national standards and has excellent low-temperature toughness.

[0027] The antibacterial and corrosion-resistant conveying welded pipe made by the present invention has a relatively low alloy cost and excellent corrosion resistance, and can be used in fields such as oil and gas fluid transportation.

[0028] The present invention also provides a welding material, which is basically matched with the chemical composition of the steel plate / coil used to make the welded pipe. While increasing the contents of Cu, Ni, and Cr, the contents of C and Mn are strictly controlled to ensure the welding performance and welding quality between the welding material and the raw materials of the steel plate / coil. Detailed Embodiments

[0029] To enable those skilled in the art to understand the characteristics and effects of the present invention, the following provides a general description and definition of the terms and expressions mentioned in the specification and claims. Unless otherwise specified, all technical and scientific terms used herein have the ordinary meanings understood by those skilled in the art for the present invention. In case of conflicts, the definitions in this specification shall prevail.

[0030] The theories or mechanisms described and disclosed herein, whether correct or incorrect, should not limit the scope of the present invention in any way, that is, the present invention can be implemented without being limited by any specific theory or mechanism.

[0031] Herein, all features such as values, quantities, contents and concentrations defined in the form of numerical ranges or percentage ranges are for simplicity and convenience only. Accordingly, the description of numerical ranges or percentage ranges should be considered to have included and specifically disclosed all possible secondary ranges and individual values ​​within the range (including integers and fractions).

[0032] In this document, unless otherwise specified, “includes,” “including,” “contains,” “has,” or similar terms cover the meanings of “consisting of” and “mainly consisting of,” for example, “A includes a” covers the meanings of “A includes a and other” and “A only includes a.”

[0033] In this document, in order to make the description concise, not all possible combinations of various technical features in various embodiments or examples are described. Therefore, as long as there is no contradiction in the combination of these technical features, the various technical features in various embodiments or examples can be combined arbitrarily, and all possible combinations should be considered to be within the scope of this specification.

[0034] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms fall within the scope limited by the appended claims of the application equally.

[0035] The following examples use conventional instruments and equipment in the art. The experimental methods in the following examples where specific conditions are not specified are usually carried out under conventional conditions or under conditions recommended by the manufacturer. The various raw materials used in the following examples are conventional commercial products unless otherwise specified, and their specifications are conventional specifications in the art. In the specification of the present invention and the following examples, unless otherwise specified, "%" means weight percentage, "part" means weight part, and ratio means weight ratio.

[0036] The present invention is further described in detail below in conjunction with specific embodiments:

[0037] The present invention provides an antibacterial corrosion transport welded pipe, in which a certain amount of Cr is added to the chemical element composition of the material to improve the resistance to CO2 and Cl -Ability, adding Cu element to improve the H2S corrosion resistance and sulfate-reducing bacteria corrosion resistance of welded pipes, at the same time, adding a small amount of Ni to the raw materials to avoid Cu brittleness during hot rolling, reduce the content of C and Mn, and control the overall carbon equivalent to ensure the welding quality of the raw materials of welded pipes. The chemical composition of the welding wire is controlled at a level close to that of the raw materials of the welded pipes.

[0038] The chemical composition of the raw material coil / steel plate of the antibacterial corrosion conveying welded pipe of the present invention includes:

[0039] C: 0.05-0.15%, Si: 0.1-0.5%, Mn: 0.1%-0.50%, P: 0-0.02%, S: 0-0.005%, Cu: 0.15-0.5%, Ni: Cu≥0.5, and Ni≤0.5%, when Cu<0.2%, Ni can be added without addition, Cr: 0.5-1.5%, the balance is Fe, and no Mo, Nb, V, Ti and other precious alloy elements are intentionally added, and the content is controlled at 0.3 <Ceq<0.43%。

[0040] C is beneficial to improve the strength of steel, but too high C content is easy to precipitate alloy element carbides at the grain boundary, reducing the corrosion resistance of the steel. In addition, C will strongly increase the welding crack sensitivity of steel. Therefore, C must be limited to 0.05-0.15%;

[0041] Si is an effective deoxidizer in steelmaking. In order to improve the strength of steel and ensure the deoxidation effect, its content must be kept above 0.1%. When the content exceeds 0.5%, it will significantly increase the cold brittleness tendency of steel, so the Si content should be limited to below 0.5%.

[0042] Mn has beneficial effects such as expanding austenite phase, increasing hardenability, and refining grains. However, too much Mn has a significant impact on welding performance and hot working performance. According to the present research, it is more appropriate to control the Mn content to 0.1% to 0.50%;

[0043] S is an objective and unavoidable harmful element in steel. Its presence has adverse effects on the corrosion resistance, hot workability, toughness, etc. of steel. Therefore, the S content needs to be limited to less than 0.005%. Preferably, the S content is less than 0.003%.

[0044] P is an objective and unavoidable harmful element in steel. Its presence has an adverse effect on the corrosion resistance and toughness of steel. Therefore, the P content needs to be limited to less than 0.02%. Preferably, the P content is less than 0.012%.

[0045] Cu can improve the atmospheric corrosion resistance and microbiological corrosion resistance of steel. This study found that adding more than 0.15% of Cu can significantly inhibit microbiological corrosion. However, excessive Cu can easily cause cracks during hot working and increase costs at the same time. Therefore, the Cu content needs to be controlled below 0.5%.

[0046] Ni is mainly used to inhibit the tendency of hot working cracking after adding Cu. Generally, it is added at a level of Ni:Cu≥0.5. Considering cost control, the addition amount does not exceed 0.3%. When the Cu content is lower than 0.2%, Ni does not need to be added.

[0047] Adding more than 0.5% of Cr can effectively inhibit CO2 and Cl - corrosion. However, considering weldability and microstructure control, the Cr content needs to be limited within 1.5%.

[0048] The carbon equivalent Ceq = C + Mn / 6 + Cr / 5 + Mo / 5 + Ni / 15 + Cu / 15 + V / 5. On the one hand, to ensure strength, the carbon equivalent needs to be higher than 0.3. On the other hand, to ensure weldability, Ceq needs to be limited below 0.43.

[0049] The rest is Fe.

[0050] The antibacterial and corrosion-resistant conveying welded pipe manufactured by the present invention is in the hot-rolled state in the delivery condition. The manufacturing method includes the following steps:

[0051] According to the mass percentages of each chemical element: C: 0.05 - 0.15%, Si: 0.1 - 0.5%, Mn: 0.1% - 0.5%, P: 0 - 0.02%, S: 0 - 0.005%, Cu: 0.15 - 0.5%, Cr: 0.5 - 1.5%, and the balance is Fe; and smelt the molten steel by controlling 0.3 < Ceq < 0.43%;

[0052] Continuously cast the smelted molten steel into slabs, and then reheat them. The reheating temperature is 1150 - 1280°C, and the holding time is 30 - 180 min;

[0053] Roll the slabs at high temperature to make steel plates or coils;

[0054] Coil and form the made steel plates, and weld them to make antibacterial and corrosion-resistant conveying welded pipes.

[0055] Among them, the compression ratio in the rolling stage (cast slab thickness: finished steel plate thickness) needs to be ≥ 4:1. This is mainly to ensure that the as-cast grains are broken as much as possible and homogenized during rolling. At the same time, grain refinement also helps to improve the strength and low-temperature toughness of the steel plate. In addition, to ensure the grain size of the steel plate, the starting rolling temperature should be between 1100 and 1270 °C, the finishing rolling temperature should be higher than 700 °C, and coiling should be carried out at a temperature of 400 - 700 °C. This is mainly to avoid the appearance of brittle phases such as martensite due to too fast cooling rate in the steel plate.

[0056] The antibacterial and corrosion-resistant transmission welded pipe manufactured by the manufacturing method of the present invention has mechanical properties meeting the requirements of the base material of the L245 steel grade pipeline pipe in GB / T 9711 "Steel Pipes for Pipeline Transportation Systems in the Petroleum and Natural Gas Industries".

[0057] The present invention also provides a welding material, which includes the following chemical elements in mass percentages:

[0058] C: 0.05 - 0.15%, Mn: 0.1% - 0.5%, Si: 0.1 - 0.5%, P: 0 - 0.005%, S: 0 - 0.004%, Cu: 0.15 - 0.5% and Cr: 0.5 - 1.5%, Ni: Cu ≥ 0.5, and 0 < Ni ≤ 0.5%, and the balance is Fe and unavoidable impurities.

[0059] The chemical composition of the welding material is basically kept matching with the chemical composition of the steel plate / coil. While increasing the contents of Cu, Ni, and Cr, the contents of C and Mn are strictly controlled to ensure the welding performance and welding quality between the welding material and the raw materials of the steel plate / coil.

[0060] Taking the production of Φ710×10mm-L245 spiral double-sided submerged arc automatic welding as an example, the production inspection process of the welded pipe is described. The production inspection procedures successively include feeding inspection, welded pipe forming, double-sided submerged arc welding, end facing and sizing, X-ray industrial television inspection, X-ray radiography of the pipe ends, hydrostatic test, automatic ultrasonic flaw detection, manual ultrasonic flaw detection, finished product inspection, and physical and chemical tests of the welded pipe.

[0061] The width of the raw material steel coil for producing the welded pipe is 1500 - 1520mm. The specification of the inner welding wire 1 is Φ4.0mm, the specification of the inner welding wire 2 is Φ3.2mm, the specification of the outer welding wire 1 is Φ4.0mm, the specification of the outer welding wire 2 is Φ3.2mm, the brand of the welding flux is SJ101 G, the welding speed is 1.8 ± 0.18m / min, the welding material adopts the double-wire submerged arc welding process for both inner and outer welding, and the welding current and voltage are shown in Table 1.

[0062] Table 1 Current and voltage of inner and outer welding in submerged arc welding

[0063]

[0064] The components in Examples 1 to 4 and Comparative Examples 1 to 3 are specifically shown in Table 2:

[0065] Table 2 Composition of Examples and Comparative Examples (wt / %)

[0066]

[0067]

[0068] Using the L245 steel grade hot rolled coil and welding wire having the composition in Table 2, a submerged arc welding method was adopted to obtain a submerged arc welded pipeline pipe with a specification of 323.9×8 mm.

[0069] Performance test of submerged arc welded line pipes made in the embodiments of the present invention and the comparative examples:

[0070] The yield strength data is obtained by processing the pipelines made in the embodiments and comparative examples into API arc specimens and taking the average value after testing according to the API standard;

[0071] The full-size Charpy V-type impact absorption energy data is obtained by taking full-size V-type impact specimens with a cross-sectional area of ​​10×10×55 from the line pipes made in the embodiments and comparative examples, and averaging them after testing according to GB / T 229 standard;

[0072] Corrosion test in simulated oil field CO2+Cl - + sulfate-reducing bacteria environment, immerse the sample in liquid at 40°C, Cl - The concentration was 5000 mg / L, the test time was 168 h, and the weight of the samples before and after the test was compared to calculate the uniform corrosion rate. The pitting rate was calculated by cross-sectional analysis of the pitting pits.

[0073] The specific measurement conditions of each data are shown in Table 3:

[0074] Table 3 Mechanical properties and corrosion properties of the embodiments and comparative examples

[0075]

[0076]

[0077] It can be seen from Table 3 that by reasonable alloy combination, ensuring carbon equivalent level, and strictly controlling the addition of P and S, the steel pipe can achieve the required strength and low-temperature toughness; at the same time, compared with the comparative example, the embodiment with appropriate amount of Cu and Cr has significantly reduced uniform corrosion rate and pitting corrosion rate, and has better corrosion resistance. If Cu and Cr exceed the range value limit, the corrosion resistance effect is insufficient, and if C exceeds the range value limit, it affects the low-temperature impact toughness of the base material and the weld, and impurity elements such as P and S exceed the standard, which will also affect the low-temperature impact toughness.

[0078] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. An antibacterial corrosion transport welded pipe, characterized in that: Comprising the following chemical elements in mass percentages: C: 0.05 - 0.15%, Si: 0.1 - 0.5%, Mn: 0.1% - 0.5%, P: 0 - 0.02%, S: 0 - 0.005%, Cu: 0.15 - 0.5% and Cr: 0.5 - 1.5%, with the balance being Fe; And 0.3 < Ceq < 0.43%.

2. The antibacterial corrosion transport welded pipe according to claim 1, characterized in that: Further comprising the following chemical elements in mass percentages: 0 < Ni ≤ 0.3%, and Ni:Cu ≥ 0.

5.

3. The antibacterial corrosion transport welded pipe according to claim 2, characterized in that: When the mass percentage of chemical element Cu is 0 - 0.2%, the mass percentage of chemical element Ni is 0.

4. A method for manufacturing an antibacterial corrosion transport welded pipe according to any one of claims 1 to 3, characterized in that: Including the following steps: Smelting molten steel according to the ratios of chemical elements C, Si, Mn, P, S, Cu, Cr and Fe in the welded pipe; Continuously casting the smelted molten steel into a slab; Rolling the slab at high temperature to make a steel plate or a coil; Coiling and forming the made steel plate, and welding it with welding materials to make an antibacterial and corrosion-resistant conveying welded pipe.

5. The method for manufacturing the antibacterial corrosion transport welded pipe according to claim 4, characterized in that: Before the rolling, there is also a reheating step, the reheating temperature is 1150 - 1280°C, and the heat preservation time is 30 - 180 min.

6. The method for manufacturing the antibacterial corrosion transport welded pipe according to claim 4, characterized in that: During the rolling process, the starting rolling temperature is between 1100 - 1270°C, and the ending rolling temperature is higher than 700°C.

7. The method for manufacturing the antibacterial corrosion transport welded pipe according to claim 4, characterized in that: During the coiling and forming process, the coiling temperature is 400 - 700°C.

8. The method for manufacturing the antibacterial corrosion transport welded pipe according to claim 4, characterized in that: The welding materials comprise the following chemical elements in mass percentages: C: 0.05 - 0.15%, Mn: 0.1% - 0.5%, Si: 0.1 - 0.5%, P: 0 - 0.005%, S: 0 - 0.004%, Cu: 0.15 - 0.5% and Cr: 0.5 - 1.5%, with the balance being Fe and inevitable impurities.

9. A welding material, characterized in that: The welding materials are used to weld the coiled and formed steel plate or coil to make an antibacterial and corrosion-resistant conveying welded pipe; Comprising the following chemical elements in mass percentages: C: 0.05 - 0.15%, Mn: 0.1% - 0.5%, Si: 0.1 - 0.5%, P: 0 - 0.005%, S: 0 - 0.004%, Cu: 0.15 - 0.5% and Cr: 0.5 - 1.5%, with the balance being Fe and inevitable impurities.

10. The welding material according to claim 9, characterized in that: Further comprising the following chemical elements in mass percentages: 0 < Ni ≤ 0.5%, and Ni:Cu ≥ 0.5.

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