A spiral submerged arc welded pipe suitable for hydrogen gas transportation and a method of manufacturing the same

Abstract

The present application belongs to the technical field of spiral submerged arc welding pipe, and particularly relates to a spiral submerged arc welding pipe suitable for hydrogen delivery and a manufacturing method thereof. The chemical element composition of the spiral submerged arc welding pipe suitable for hydrogen delivery is as follows in terms of percentage by weight: C: 0.03-0.06%, Si: 0.05-0.45%, Mn: 0.7-1.45%, S: ≤0.0015%, P: ≤0.008%, Ni: 0.01-0.3%, Cr: 0.01-0.3%, Cu: 0.001-0.15%, Nb: 0.02-0.06%, V: 0.002-0.05%, Ti: ≤0.03%, Mo: ≤0.001%, Al: ≤0.04%, B: ≤0.0003%, and the balance being Fe. The spiral submerged arc welding pipe has the characteristics of small and uniform grain size of pipe body and weld joint, low segregation, high dimensional accuracy of the welded pipe, excellent fracture toughness, excellent hydrogen-induced cracking resistance, small residual stress and the like, and can meet the requirements of hydrogen delivery of pure hydrogen and hydrogen mixed with 20% hydrogen and on-site girth welding butt joint at 6.3 MPa and below.

Description

Technical Field

[0001] This invention belongs to the field of spiral submerged arc welded pipe technology, and specifically relates to a spiral submerged arc welded pipe suitable for hydrogen transportation and its manufacturing method. Background Technology

[0002] Hydrogen energy is a secondary clean energy source and a zero-carbon energy source, possessing four major characteristics: cleanliness, efficiency, safety, and sustainability. It is hailed as the core of the future global energy architecture. Pipeline hydrogen transportation is the safest and most efficient mode of transport, and has become the preferred method for long-distance hydrogen delivery globally. Hydrogen embrittlement is one of the major technical challenges in the research and development of hydrogen transportation pipelines. Hydrogen embrittlement is a general term for the failure phenomenon of pipelines caused by the interaction between hydrogen atoms and the pipeline material. Research shows that the most important failure mode of hydrogen embrittlement is hydrogen-induced cracking, the second most important failure mode is hydrogen bubbling, and another is the degradation of the metal's mechanical properties. Compared with conventional natural gas transportation pipelines, hydrogen transportation pipelines require higher fracture toughness, lower residual stress, and higher requirements for the geometric precision of the pipeline material.

[0003] Currently, seamless pipes are commonly used in hydrogen pipelines, with steel grades below X52 and transport pressures below 4.0 MPa. No research reports have been found on the use of spiral welded pipes for medium- and high-pressure hydrogen pipeline transportation. While seamless pipes are widely used for hydrogen pipeline transportation, their inherent technological characteristics present several challenges. First, the process of heating and piercing steel billets results in significant wall thickness fluctuations and lower dimensional accuracy. Second, the relatively high carbon equivalent of the billet makes it prone to rolling cracks and other defects during the piercing process, which can lead to weld cracks during on-site circumferential welding, making it difficult to guarantee the quality of the circumferential weld joints.

[0004] Spiral welded pipes, with their excellent crack arrest properties, high cost-effectiveness, and mature manufacturing process, are one of the preferred pipes for long-distance pipeline construction. Compared to straight seam welded pipes, the traditional spiral welded pipe manufacturing process lacks a full-body diameter expansion process, resulting in relatively lower dimensional accuracy. Issues such as pipe roundness and bulging can also affect on-site circumferential welding. If spiral submerged arc welded pipes are used for hydrogen transportation, higher requirements are needed for dimensional accuracy and residual stress control to prevent hydrogen atom accumulation in stress concentration micro-regions. Furthermore, existing steel pipe manufacturing processes inevitably introduce hydrogen due to the influence of pipeline steel materials and the presence of welding and hydraulic pressure processes. If the hydrogen content of the steel pipe is not reduced in subsequent processes, hydrogen embrittlement can easily occur, rendering it unsuitable for long-distance safe hydrogen transportation. Summary of the Invention

[0005] To address the aforementioned problems, the present invention aims to provide a spiral submerged arc welded pipe suitable for hydrogen transportation and its manufacturing method. This spiral submerged arc welded pipe features fine and uniform grains and low segregation in the pipe body and weld seam, high dimensional accuracy, excellent fracture toughness, superior resistance to hydrogen-induced cracking, and low residual stress. It can meet the requirements for transportation of pure hydrogen and hydrogen with 20% hydrogen doping at pressures of 6.3 MPa and below, as well as on-site circumferential welding.

[0006] The technical solution of the present invention is as follows: a spiral submerged arc welded pipe suitable for hydrogen transportation, wherein the chemical element composition of the spiral submerged arc welded pipe by weight percentage is: C: 0.03~0.06%, Si: 0.05~0.45%, Mn: 0.7~1.45%, S≤0.0015%, P≤0.008%, Ni: 0.01~0.3%, Cr: 0.01~0.3%, Cu: 0.001~0.15%, Nb: 0.02~0.06%, V: 0.002~0.05%, Ti≤0.03%, Mo≤0.001%, Al≤0.04%, B≤0.0003%, with the balance being Fe.

[0007] The carbon equivalent (CEPcm) of the spiral submerged arc welded pipe is ≤0.11.

[0008] A method for manufacturing a spiral submerged arc welded pipe suitable for hydrogen transportation, comprising uncoiling, leveling, milling, forming, welding, full pipe diameter expansion, continuous X-ray inspection, hydrostatic test, ultrasonic flaw detection of weld and base material, pipe end chamfering, pipe end radiography, whole pipe heat treatment, and finished product inspection.

[0009] The metallographic structure of the spiral submerged arc welded pipe coil selected in the uncoiling process has a non-metallic inclusion level of A, B, C, D, and DS types that is no greater than 1.0, a banded structure that is no greater than 1.5, and a grain size of 9 or above.

[0010] The welding process employs internal and external pre-welding techniques, using mixed gas shielded welding. The mixed gas composition is CO2 (55%~65%) + Ar (35%~45%) by volume, with a flow rate of 100~120 L / min. The welding current I is 540~660 A, the welding voltage U is 20.5~23.5 V, and the welding speed V is 2.5~3.0 m / min. Specifically, the internal welding process uses a dual-wire submerged arc welding system. The first wire uses DC reverse polarity, and the welding process parameters are: current I = 600... The welding process is as follows: the first wire is DC reverse polarity, the second wire is AC, the current I is 360~450A, the voltage U is 33~35V; the welding speed V is 1.6~1.8m / min; the external welding process is as follows: welding is performed using double-wire submerged arc automatic welding. The first wire is DC reverse polarity, and the welding process parameters are: current I is 650~800A, voltage U is 31~35V; the second wire is AC, the current I is 400~500A, voltage U is 33~35V; the welding speed V is 1.6~1.8m / min.

[0011] The full pipe diameter expansion process is as follows: based on the diameter of the spiral welded pipe, a special expansion module for spiral welded pipe is used, and a corresponding expansion head is selected to expand the diameter of the entire spiral welded pipe. The expansion cone head is driven to expand by hydraulic means, and the expansion module expands radially along the steel pipe to avoid the inner weld seam with a certain height, completing one expansion step and realizing the segmented expansion of the pipe body.

[0012] The expansion rate of the entire spiral submerged arc welded pipe is 0.9%~1.1% within 1m of the starting and ending ends, and the pipe body expansion rate is 0.7%~0.9%. The pipe body expansion is carried out in segments, with each segment having an expansion length of about 2.5m and each forward step having a length of 0.8m~1.0m.

[0013] The diameter deviation of the spiral submerged arc welded pipe after full-body expansion is -0.1%D to +0.2%D, with a maximum deviation of 0.5mm; the pipe end circumference difference is <1.5mm; and the pipe end out-of-roundness is <0.7%D. The pipe body diameter deviation is -0.15%D to +0.2%D, with a maximum deviation of 1mm; and the pipe body out-of-roundness is <1.0%D. The straightness deviation along the entire length of the steel pipe exceeds 0.06% of the pipe length, and the local deviation relative to the straight line within a 1.5m length range at each pipe end is <2.8mm. The process of the whole tube heat treatment is as follows: the spiral submerged arc welded pipe is sent into a heating furnace for whole tube heat treatment. The heat treatment process adopts two heat treatments. The temperature of the first heat treatment is controlled between 350℃ and 400℃, and the holding time is between 60min and 70min. After the first heat treatment, the spiral submerged arc welded pipe is placed in another heating furnace for the second heat treatment. The temperature is controlled between 200℃ and 250℃, and the holding time is between 20min and 30min. After the heat treatment is completed, the spiral submerged arc welded pipe is taken out and air-cooled to room temperature.

[0014] The technical effects of this invention are as follows: 1. The spiral submerged arc welded pipe of this invention adopts a composition design with low C, low Mn, low S, and P, and adds appropriate amounts of Si and trace amounts of Mo, Nb, Cr, and other alloying elements. Cr and Mo are strong carbon compounds, which are beneficial to reducing the hydrogen embrittlement sensitivity of pipeline steel, and can also inhibit the formation of banded inclusions, improve segregation, and enhance HIC resistance; 2. In the metallographic structure of the spiral submerged arc welded pipe coil of this invention, the levels of non-metallic inclusions of types A, B, C, D, and DS are all no greater than 1.0, the banded structure is no greater than 1.5, and the grain size is 9 or above. During the rolling process, the size of non-metallic inclusions and banded structures can be effectively reduced, preventing the local accumulation of hydrogen atoms; 3. This invention adopts a full The pipe body expansion process results in high geometric dimensional accuracy of the pipe body and pipe ends, low out-of-roundness of the pipe ends and pipe body, and small straightness deviation, which is conducive to circumferential welding. The diameter deviation of the pipe ends is -0.1%D to +0.2%D, with a maximum deviation of 0.5mm, the circumference difference of the pipe ends is <1.5mm, and the out-of-roundness of the pipe ends is <0.7%D; the diameter deviation of the pipe body is -0.15%D to +0.2%D, with a maximum deviation of 1mm, and the out-of-roundness of the pipe body is <1.0%D; the straightness deviation of the entire length of the steel pipe exceeds 0.06% of the length of the steel pipe, and the local deviation relative to the straight line within a 1.5m length range of each pipe end is <2.8mm, all of which are higher than the standard requirements of conventional spiral welded pipes and can meet the requirements of on-site circumferential welding of pipelines; 4. The spiral submerged arc welded pipe of this invention adopts NACE When the TM0284 standard A solution was used for HIC testing, the crack length ratio (CLR) of the three cross sections was 0, the crack thickness ratio (CTR) was 0, and the crack sensitivity ratio (CSR) was 0, indicating that the welded pipe has excellent resistance to hydrogen-induced cracking; 4. In a 6.3MPa pure hydrogen environment, the spiral submerged arc welded pipe of this invention exhibits a relative shrinkage rate of ≥95% in the slow tensile section of the pipe body and weld, and a fracture toughness K of the pipe body, weld, and heat-affected zone. IH >200MPa·m 1 / 2 Under a total pressure of 6.3 MPa and a hydrogen-doped environment with a hydrogen doping ratio of 20%, the relative shrinkage of the slow tensile section of the pipe body and weld is ≥96%, and the fracture toughness K of the pipe body, weld and heat-affected zone is ≥96%. IH >320MPa·m 1 / 2 It can meet the requirements for transporting pure hydrogen and hydrogen with 20% hydrogen content at pressures of 6.3 MPa and below. Detailed Implementation Example 1

[0015] A spiral submerged arc welded pipe suitable for hydrogen transportation, wherein the chemical element composition of the spiral submerged arc welded pipe by weight percentage is: C: 0.03~0.06%, Si: 0.05~0.45%, Mn: 0.7~1.45%, S≤0.0015%, P≤0.008%, Ni: 0.01~0.3%, Cr: 0.01~0.3%, Cu: 0.001~0.15%, Nb: 0.02~0.06%, V: 0.002~0.05%, Ti≤0.03%, Mo≤0.001%, Al≤0.04%, B≤0.0003%, with the balance being Fe.

[0016] The carbon equivalent (CEPcm) of the spiral submerged arc welded pipe is ≤0.11.

[0017] The spiral submerged arc welded pipe of this invention adopts a composition design with low C, low Mn, low S, and P, and adds appropriate amounts of Si and trace amounts of alloying elements such as Mo, Nb, and Cr. Cr and Mo are strong carbon compounds, which are beneficial to reducing the hydrogen embrittlement sensitivity of pipeline steel. At the same time, they can also inhibit the formation of banded inclusions, improve segregation, and enhance resistance to HIC. Example 2

[0018] A method for manufacturing a spiral submerged arc welded pipe suitable for hydrogen transportation, comprising uncoiling, leveling, milling, forming, welding, full pipe diameter expansion, continuous X-ray inspection, hydrostatic test, ultrasonic flaw detection of weld and base material, pipe end chamfering, pipe end radiography, whole pipe heat treatment, and finished product inspection.

[0019] The metallographic structure of the spiral submerged arc welded pipe coil selected in the uncoiling process has a non-metallic inclusion level of A, B, C, D, and DS types that is no greater than 1.0, a banded structure that is no greater than 1.5, and a grain size of 9 or above.

[0020] The welding process employs internal and external pre-welding techniques, using mixed gas shielded welding. The mixed gas composition is CO2 (55%~65%) + Ar (35%~45%) by volume, with a flow rate of 100~120 L / min. The welding current I is 540~660 A, the welding voltage U is 20.5~23.5 V, and the welding speed V is 2.5~3.0 m / min. Specifically, the internal welding process uses a dual-wire submerged arc welding system. The first wire uses DC reverse polarity, and the welding process parameters are: current I = 600... The welding process is as follows: the first wire is DC reverse polarity, the second wire is AC, the current I is 360~450A, the voltage U is 33~35V; the welding speed V is 1.6~1.8m / min; the external welding process is as follows: welding is performed using double-wire submerged arc automatic welding. The first wire is DC reverse polarity, and the welding process parameters are: current I is 650~800A, voltage U is 31~35V; the second wire is AC, the current I is 400~500A, voltage U is 33~35V; the welding speed V is 1.6~1.8m / min.

[0021] The full pipe diameter expansion process is as follows: based on the diameter of the spiral welded pipe, a special expansion module for spiral welded pipe is used, and a corresponding expansion head is selected to expand the diameter of the entire spiral welded pipe. The expansion cone head is driven to expand by hydraulic means, and the expansion module expands radially along the steel pipe to avoid the inner weld seam with a certain height, completing one expansion step and realizing the segmented expansion of the pipe body.

[0022] The expansion rate of the entire spiral submerged arc welded pipe is 0.9%~1.1% within 1m of the starting and ending ends, and the pipe body expansion rate is 0.7%~0.9%. The pipe body expansion is carried out in segments, with each segment having an expansion length of about 2.5m and each forward step having a length of 0.8m~1.0m.

[0023] The diameter deviation of the spiral submerged arc welded pipe after full-body expansion is -0.1%D to +0.2%D, with a maximum deviation of 0.5mm; the pipe end circumference difference is <1.5mm; and the pipe end out-of-roundness is <0.7%D. The pipe body diameter deviation is -0.15%D to +0.2%D, with a maximum deviation of 1mm; and the pipe body out-of-roundness is <1.0%D. The straightness deviation along the entire length of the steel pipe exceeds 0.06% of the pipe length, and the local deviation relative to the straight line within a 1.5m length range at each pipe end is <2.8mm. The process of the whole tube heat treatment is as follows: the spiral submerged arc welded pipe is sent into a heating furnace for whole tube heat treatment. The heat treatment process adopts two heat treatments. The temperature of the first heat treatment is controlled between 350℃ and 400℃, and the holding time is between 60min and 70min. After the first heat treatment, the spiral submerged arc welded pipe is placed in another heating furnace for the second heat treatment. The temperature is controlled between 200℃ and 250℃, and the holding time is between 20min and 30min. After the heat treatment is completed, the spiral submerged arc welded pipe is taken out and air-cooled to room temperature. Example 3

[0024] According to the spiral submerged arc welded pipe suitable for hydrogen transportation described in Example 1 above, and using the manufacturing method of the spiral submerged arc welded pipe suitable for hydrogen transportation described in Example 2, an L360MH Φ457×8.8mm spiral submerged arc welded pipe for hydrogen transportation is manufactured. The specific process is as follows: (1) Raw material selection: L360MH hot-rolled coil with a wall thickness of 8.8mm is used, and its chemical composition is shown in Table 1 (wt%).

[0025] Table 1 Chemical composition analysis (wt%) of coiled steel for L360MH Φ457×8.8mm spiral welded pipe 1.26 0.18 0.002 0.009 0.008 0.045 0.0003 0.08 0.05 0.14 (2) Pipe manufacturing process: uncoiling, leveling, milling, forming, welding, full pipe diameter expansion, continuous X-ray inspection, hydrostatic test, ultrasonic testing of welds and base material, pipe end chamfering, pipe end radiography, overall pipe heat treatment, and finished product inspection. Specifically: Welding: Pre-welding uses mixed gas shielded welding, with a mixed gas volume fraction of CO2 (55%~65%) + Ar (35%~45%), a mixed gas flow rate of 100~120 L / min, welding current I=580A, welding voltage U=22V, and welding speed V=2.5m / min; Fine welding internal welding process: welding is performed using double-wire submerged arc automatic welding. The first wire uses DC reverse polarity, with welding process parameters of current I=630A and voltage U=32V; the second wire uses AC... The welding parameters are as follows: Current I = 440A, voltage U = 34V; welding speed V = 1.75m / min; the fine welding process is as follows: welding is performed using a double-wire submerged arc automatic welding machine. The first wire uses DC reverse polarity, and the welding process parameters are: current I = 680A, voltage U = 32V; the second wire uses AC, current I = 480A, voltage U = 34V; welding speed V = 1.75m / min. The welding wire type for both internal and external welding is CHW-S1SH, and the flux type is fluorine-alkali type low-hydrogen flux CHF-102SH.

[0026] Full pipe diameter expansion: A special expansion module for spiral welded pipes is used, and a corresponding expansion head is selected to expand the diameter of the entire spiral welded pipe. The expansion cone head is driven to expand by hydraulic means. The expansion module expands radially along the steel pipe, avoiding the inner weld seam with a certain height. The expansion rate is 1% within 1m of the starting and ending ends of the steel pipe expansion, and the pipe body expansion rate is 0.8%. The pipe body expansion is carried out in segments, with each segment expansion length of about 2.5m and each forward step length of 1.0m.

[0027] Heat treatment of the whole pipe: The heat treatment process adopts two heat treatments. The temperature of the first heat treatment is controlled between 350℃ and 400℃ and the holding time is 60 minutes. The temperature of the second heat treatment is controlled between 225℃ and the holding time is 30 minutes. After the heat treatment is completed, the steel pipe is taken out and air-cooled to room temperature.

[0028] Physical and chemical properties: The welded pipe was tested for physical and chemical properties according to CDP-S-NGP-PL-006-2019-4 "Technical Specification for Steel Pipes for Natural Gas Pipeline Engineering". The mechanical properties all meet the standard requirements. The test results are as follows: Pipe body yield strength R... t0.5 420~450MPa; Pipe body tensile strength R m :505~530MPa; pipe body yield ratio R t0.5 / R m 0.83~0.86; Elongation of pipe body A: 42~45%; Tensile strength of weld Rm: 555~573MPa; Transverse impact energy of pipe body at -10℃: 296~314J; Impact energy of weld at -10℃: 218~268J; Impact energy of heat-affected zone at -10℃: 236~288J; Hardness of welded joint: 153~185HV 10 The springback of the spiral welded pipe body measured by cutting the pipe ring was -10mm, indicating low residual stress.

[0029] HIC corrosion resistance: HIC tests were conducted using NACE TM0284 standard solution A. The crack length ratio (CLR) of all three cross sections was 0, the crack thickness ratio (CTR) was 0, and the crack susceptibility ratio (CSR) was 0, indicating excellent HIC corrosion resistance. The test results are shown in Table 2. Table 2. Test Results of HIC Sensitive Parameters for L360MH Φ457×8.8mm Spiral Welded Pipe

[0030] Results of slow strain rate tensile test in hydrogen environment: According to GB / T 34542.2-2018 "Test method for compatibility of metallic materials with hydrogen in hydrogen storage and transportation systems", the welded pipe body and weld were evaluated by slow strain rate tensile test in hydrogen environment. The test results of the pipe body and weld are shown in Table 3. It shows that the L360MH Φ457×8.8mm spiral welded pipe for hydrogen transportation has excellent plasticity in both pure hydrogen environment of 6.3MPa and hydrogen-doped environment of 6.3MPa with a hydrogen doping ratio of 20%.

[0031] Table 3. Results of slow strain rate tensile tests on the body and weld of L360MH Φ457×8.8mm spiral welded pipe.

[0032] Fracture toughness test results in hydrogen environment: The fracture toughness of the welded pipe body and weld was evaluated in a hydrogen environment according to GB / T 34542.2-2018 "Test method for compatibility of metallic materials with hydrogen for hydrogen storage and transportation systems". The test results of the pipe body and weld are shown in Table 4. The results all meet the requirements of ASME B31.12 standard, indicating that the L360MH Φ457×8.8mm spiral welded pipe for hydrogen transportation has excellent toughness in a pure hydrogen environment of 6.3MPa and a hydrogen-doped environment of 6.3MPa with a hydrogen doping ratio of 20%.

[0033] Table 4. Test results of fracture toughness of L360MH Φ457×8.8mm spiral welded pipe body and weld. Example

[0034] According to the spiral submerged arc welded pipe suitable for hydrogen transportation described in Embodiment 1 above, and using the manufacturing method of the spiral submerged arc welded pipe suitable for hydrogen transportation described in Embodiment 2, we take the manufacturing of a spiral submerged arc welded pipe for hydrogen transportation L360MH Φ610×14.3mm as an example.

[0035] (1) Raw material selection: L360MH hot-rolled coil with a wall thickness of 14.3mm is used, and its chemical composition is shown in Table 5 (wt%).

[0036] Table 5 Chemical composition analysis (wt%) of coiled steel for L360MH Φ610×14.3mm spiral welded pipe 1.26 0.18 0.002 0.009 0.008 0.045 0.0003 0.08 0.05 0.14 (2) Pipe manufacturing process: uncoiling, leveling, milling, forming, welding, full pipe diameter expansion, continuous X-ray inspection, hydrostatic test, ultrasonic testing of welds and base material, pipe end chamfering, pipe end radiography, overall pipe heat treatment, and finished product inspection. The specific process is as follows: Welding: Pre-welding uses mixed gas shielded welding, with the gas type being CO2 (55%~65%) + Ar (35%~45%), gas flow rate being 100~120 L / min, welding current I=640A, welding voltage U=23V, and welding speed V=2.5m / min; Fine welding internal welding process: welding is performed using double-wire submerged arc automatic welding. The first wire uses DC reverse polarity, with welding process parameters of: current I=680A, voltage U=32V; the second wire uses AC, with current I... =450A, voltage U=34V; welding speed V=1.7m / min; the fine welding external welding process is as follows: welding is carried out by double-wire submerged arc automatic welding. The first wire adopts DC reverse polarity, and the welding process parameters are: current I=740A, voltage U=33V; the second wire is AC, current I=490A, voltage U=34V; welding speed V=1.7m / min. The welding wire type for both internal and external welding is CHW-S1SH, and the flux type is fluorine-alkali type low hydrogen flux CHF-102SH.

[0037] Full pipe diameter expansion: A special expansion module for spiral welded pipes is used, and a corresponding expansion head is selected to expand the diameter of the entire spiral welded pipe. The expansion cone head is driven to expand by hydraulic means. The expansion module expands radially along the steel pipe, avoiding the inner weld seam with a certain height. The expansion rate is 1% within 1m of the starting and ending ends of the steel pipe expansion, and the pipe body expansion rate is 0.8%. The pipe body expansion is carried out in segments, with each segment expansion length of about 2.5m and each forward step length of 1.0m.

[0038] Heat treatment of the whole pipe: The heat treatment process adopts two heat treatments. The temperature of the first heat treatment is controlled between 350℃ and 400℃ and the holding time is 70 minutes. The temperature of the second heat treatment is controlled between 250℃ and the holding time is 30 minutes. After the heat treatment is completed, the steel pipe is taken out and air-cooled to room temperature.

[0039] Physical and chemical properties: The welded pipe was tested for physical and chemical properties according to CDP-S-NGP-PL-006-2019-4 "Technical Specification for Steel Pipes for Natural Gas Pipeline Engineering". The mechanical properties all meet the standard requirements. The test results are as follows: Pipe body yield strength R... t0.5 415~456MPa; Pipe body tensile strength R m :502~546MPa; pipe body yield ratio R t0.5 / R m 0.83~0.87; Elongation of pipe body A: 41~44%; Tensile strength of weld Rm: 558~577MPa; Transverse impact energy of pipe body at -10℃: 305~326J; Impact energy of weld at -10℃: 235~277J; Impact energy of heat-affected zone at -10℃: 238~290J; Hardness of welded joint: 160~183HV 10 The springback of the spiral welded pipe body measured by cutting the pipe ring was -15mm, indicating low residual stress.

[0040] HIC corrosion resistance: HIC tests were conducted using NACE TM0284 standard solution A. The crack length ratio (CLR) of all three cross sections was 0, the crack thickness ratio (CTR) was 0, and the crack susceptibility ratio (CSR) was 0, demonstrating excellent HIC corrosion resistance. The test results are shown in Table 6. Table 6. Test Results of HIC Sensitive Parameters for L360MH Φ610×14.3mm Spiral Welded Pipe

[0041] Results of slow strain rate tensile test in hydrogen environment: According to GB / T 34542.2-2018 "Test method for compatibility of metallic materials with hydrogen in hydrogen storage and transportation systems", the welded pipe body and weld were evaluated by slow strain rate tensile test in hydrogen environment. The test results of the pipe body and weld are shown in Table 7. It shows that the L360MH Φ610×14.3mm spiral welded pipe for hydrogen transportation has excellent plasticity in both pure hydrogen environment of 6.3MPa and hydrogen-doped environment of 6.3MPa with a hydrogen doping ratio of 20%.

[0042] Table 7 Results of slow strain rate tensile tests on the body and weld of L360MH Φ610×14.3mm spiral welded pipe

[0043] Fracture toughness test results in hydrogen environment: The fracture toughness of the welded pipe body and weld was evaluated in a hydrogen environment according to GB / T 34542.2-2018 "Test method for compatibility of metallic materials with hydrogen for hydrogen storage and transportation systems". The test results of the pipe body and weld are shown in Table 8. The results all meet the requirements of ASME B31.12 standard, indicating that the L360MH Φ610×14.3mm spiral welded pipe for hydrogen transportation has excellent toughness in a pure hydrogen environment of 6.3MPa and a hydrogen-doped environment of 20% with a total pressure of 6.3MPa.

[0044] Table 8. Test results of fracture toughness of L360MH Φ610×14.3mm spiral welded pipe body and weld.

[0045] To further demonstrate the advantages of the technical solution of this invention, a comparative example is used for illustration.

[0046] Comparative Example 1 A spiral submerged arc welded pipe, wherein the chemical element composition of the coil used is as follows by weight percentage: C: 0.12%, Si: 0.4%, Mn: 1.85%, S: 0.002%, P: 0.012%, Ni: 0.005%, Cr: 0.1%, Cu: 0.05%, Nb: 0.004%, V: 0.03%, Ti: 0.02%, Mo: 0.001%, Al: 0.03%, B: 0.0002%, with the balance being Fe.

[0047] In the metallographic structure of spiral submerged arc welded pipe coils, the levels of non-metallic inclusions of types A, B, C, D, and DS are all greater than 1.0, the banded structure is 2.0, and the grain size is 8.

[0048] The product was manufactured using the manufacturing process described in Example 2, and tested according to relevant standards. The results are as follows: Physical and chemical properties: The welded pipe was tested for physical and chemical properties according to CDP-S-NGP-PL-006-2019-4 "Technical Specification for Steel Pipes for Natural Gas Pipeline Engineering". The mechanical properties all meet the standard requirements. The test results are as follows: Pipe body yield strength R... t0.5 426~488MPa; Pipe body tensile strength R m :522~566MPa; pipe body yield ratio R t0.5 / R m 0.85~0.91; Elongation of pipe body A: 41~44%; Tensile strength of weld Rm: 558~585MPa; Transverse impact energy of pipe body at -10℃: 198~289J; Impact energy of weld at -10℃: 78~166J; Impact energy of heat-affected zone at -10℃: 76~178J; Hardness of welded joint: 178~234HV 10 The springback of the spiral welded pipe body measured by cutting the pipe ring was -10mm, indicating low residual stress.

[0049] HIC corrosion resistance: According to the NACE TM0284 standard A solution, the crack length ratio (CLR) of the three sections of the weld is 18% and the crack sensitivity ratio (CSR) is 4%, which is higher than the requirement of cross-sectional crack length ratio (CLR) ≤15% and crack sensitivity ratio (CSR) ≤2%, indicating poor HIC corrosion resistance.

[0050] Results of slow strain rate tensile test in hydrogen environment: The welded pipe body and weld were evaluated by slow strain rate tensile test in hydrogen environment according to GB / T 34542.2-2018 "Test method for compatibility of metallic materials with hydrogen in hydrogen storage and transportation system". The test results of the pipe body and weld are shown in Table 9.

[0051] Table 9 Results of slow strain rate tensile tests on the spiral welded pipe body and weld in Comparative Example 1

[0052] Fracture toughness test results in hydrogen environment: The fracture toughness of the welded pipe body and weld was evaluated in a hydrogen environment according to GB / T 34542.2-2018 "Test method for compatibility of metallic materials with hydrogen in hydrogen storage and transportation systems". The test results of the pipe body and welded joint are shown in Table 10. The fracture toughness of the weld and heat-affected zone does not meet the requirements of ASME B31.12 standard, indicating that the spiral welded pipe in Comparative Example 1 is not suitable for use in a pure hydrogen environment of 6.3MPa and a hydrogen-doped environment with a total pressure of 6.3MPa and a hydrogen doping ratio of 20%.

[0053] Table 10. Test results of fracture toughness of spiral welded pipe body and welded joint in Comparative Example 1

[0054] As can be seen from Comparative Example 1, the chemical composition of the spiral submerged arc welded pipe coil does not conform to the composition range specified in this invention, while the manufacturing process is consistent. In Comparative Example 1, the contents of C, Mn, S, and P elements in the coil are all higher than the composition range specified in this invention, while Nb and Ni are lower than the composition range specified in this invention. C is the main solid solution strengthening element, and the higher its content, the greater the hydrogen embrittlement sensitivity of the steel pipe. Mn and P are elements that are prone to segregation, and they are prone to segregation in the center of the steel plate during the manufacturing process, so their contents should not be too high. S easily causes hydrogen atoms penetrating into the steel to accumulate at the tip of the sulfide, and the resulting hydrogen internal pressure induces hydrogen-induced cracks, so its content should also not be too high.

[0055] Based on the chemical properties, HIC corrosion resistance, slow strain rate tensile testing, and fracture toughness test results of the welded pipe in Comparative Example 1, it can be observed that due to certain differences in the chemical composition of the coiled plate compared to the present invention, the welded pipe weld performance decreases and the hardness increases; the crack length rate and crack sensitivity rate in the HIC corrosion resistance test are higher than the requirements of the hydrogen service environment, making it unsuitable for hydrogen service conditions; the fracture toughness test results are lower than the requirements of ASME B31.12 standard, making it unsuitable for use in a 6.3MPa pure hydrogen environment and a hydrogen-doped environment with a total pressure of 6.3MPa and a hydrogen doping ratio of 20%.

[0056] Comparative Example 2 A spiral submerged arc welded pipe, using the chemical composition described in Example 1 above, and manufactured using the following process, includes uncoiling, leveling, milling, forming, welding, pipe end expansion, continuous X-ray inspection, hydrostatic testing, ultrasonic flaw detection of the weld and base material, pipe end chamfering, pipe end radiography, and finished product inspection. The pipe end expansion process described in Comparative Example 2 involves expanding the pipe end within a 250mm range based on the pipe diameter. This only ensures the accuracy of the pipe end's geometric dimensions; it does not employ a segmented expansion method, thus failing to guarantee the accuracy of the pipe body's geometric dimensions. Comparative Example 2 does not employ a whole-pipe heat treatment process.

[0057] The product was manufactured using the manufacturing process described in Comparative Example 2, and tested according to relevant standards. The results are as follows: Physical and chemical properties: The welded pipe was tested for physical and chemical properties according to CDP-S-NGP-PL-006-2019-4 "Technical Specification for Steel Pipes for Natural Gas Pipeline Engineering". The mechanical properties all meet the standard requirements. The test results are as follows: Pipe body yield strength R... t0.5 416~467MPa; Pipe body tensile strength R m :502~553MPa; pipe body yield ratio R t0.5 / R m 0.83~0.89; Elongation of pipe body A: 42~45%; Tensile strength of weld Rm: 546~583MPa; Transverse impact energy of pipe body at -10℃: 225~323J; Impact energy of weld at -10℃: 178~206J; Impact energy of heat-affected zone at -10℃: 210~289J; Hardness of welded joint: 168~212HV 10 The springback of the spiral welded pipe body measured by cutting the pipe ring was -15mm, indicating low residual stress.

[0058] HIC corrosion resistance: HIC test was conducted according to NACE TM0284 standard A solution. The crack sensitivity rate (CSR) of the three sections of the weld was 3%, which is higher than the requirement of section crack sensitivity rate (CSR) ≤ 2%.

[0059] Results of slow strain rate tensile test in hydrogen environment: The welded pipe body and weld were evaluated by slow strain rate tensile test in hydrogen environment according to GB / T 34542.2-2018 "Test method for compatibility of metallic materials with hydrogen in hydrogen storage and transportation system". The test results of the pipe body and weld are shown in Table 11.

[0060] Table 11 Results of slow strain rate tensile tests on spiral welded pipe body and weld in Comparative Example 2

[0061] Fracture toughness test results in hydrogen environment: The fracture toughness of the welded pipe body and weld was evaluated in a hydrogen environment according to GB / T 34542.2-2018 "Test method for compatibility of metallic materials with hydrogen in hydrogen storage and transportation systems". The test results of the pipe body and welded joint are shown in Table 12. The fracture toughness of the weld and heat-affected zone does not meet the requirements of ASME B31.12 standard, indicating that the spiral welded pipe in Comparative Example 2 is not suitable for use in a pure hydrogen environment of 6.3MPa and a hydrogen-doped environment with a total pressure of 6.3MPa and a hydrogen doping ratio of 20%.

[0062] Table 12. Test results of fracture toughness of spiral welded pipe body and welded joint in Comparative Example 2

[0063] As can be seen from Comparative Example 2, the chemical composition is consistent with the composition range specified in this invention, but the manufacturing process differs. In Comparative Example 2, the pipe diameter was not expanded in sections during expansion, but only within a 250mm range at the pipe end. This cannot guarantee the excellent overall pipe geometry and is prone to defects in welded pipe geometry. At the same time, Comparative Example 2 did not use whole-pipe heat treatment in its manufacturing process. Experiments showed that the welded pipe manufacturing method used in Comparative Example 2 could not effectively reduce the diffusible hydrogen content of the welded pipe, resulting in a crack sensitivity rate higher than the requirements for hydrogen service environment in the HIC corrosion resistance test of the weld, making it unsuitable for hydrogen service conditions. The fracture toughness test results were lower than the requirements of ASME B31.12 standard, making it unsuitable for 6.3MPa pure hydrogen environment and hydrogen-doped environment with a total pressure of 6.3MPa and a hydrogen doping ratio of 20%.

[0064] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A spiral submerged arc welded pipe suitable for hydrogen transportation, characterized in that: The chemical element composition of the spiral submerged arc welded pipe by weight percentage is as follows: C: 0.03~0.06%, Si: 0.05~0.45%, Mn: 0.7~1.45%, S≤0.0015%, P≤0.008%, Ni: 0.01~0.3%, Cr: 0.01~0.3%, Cu: 0.001~0.15%, Nb: 0.02~0.06%, V: 0.002~0.05%, Ti≤0.03%, Mo≤0.001%, Al≤0.04%, B≤0.0003%, with the balance being Fe. The carbon equivalent CEPcm of the spiral submerged arc welded pipe is ≤0.

11.

2. A method for manufacturing a spiral submerged arc welded pipe suitable for hydrogen transportation, comprising manufacturing a spiral submerged arc welded pipe suitable for hydrogen transportation as described in claim 1, characterized in that: The process includes uncoiling, leveling, milling, forming, welding, full pipe diameter expansion, continuous X-ray inspection, hydrostatic testing, ultrasonic testing of welds and base material, pipe end chamfering, pipe end radiography, overall pipe heat treatment, and finished product inspection.

3. The manufacturing method of a spiral submerged arc welded pipe suitable for hydrogen transportation according to claim 2, characterized in that: The metallographic structure of the spiral submerged arc welded pipe coil selected in the uncoiling process has a non-metallic inclusion level of A, B, C, D, and DS types that is no greater than 1.0, a banded structure that is no greater than 1.5, and a grain size of 9 or above.

4. The manufacturing method of a spiral submerged arc welded pipe suitable for hydrogen transportation according to claim 2, characterized in that: The welding process employs internal and external pre-welding techniques, using mixed gas shielded welding. The mixed gas composition is CO2 (55%~65%) + Ar (35%~45%) by volume, with a flow rate of 100~120 L / min. The welding current I is 540~660 A, the welding voltage U is 20.5~23.5 V, and the welding speed V is 2.5~3.0 m / min. Specifically, the internal welding process uses a dual-wire submerged arc welding system. The first wire uses DC reverse polarity, and the welding process parameters are: current I = 600... The welding process is as follows: the first wire is DC reverse polarity, the second wire is AC, the current I is 360~450A, the voltage U is 33~35V; the welding speed V is 1.6~1.8m / min; the external welding process is as follows: welding is performed using double-wire submerged arc automatic welding. The first wire is DC reverse polarity, and the welding process parameters are: current I is 650~800A, voltage U is 31~35V; the second wire is AC, the current I is 400~500A, voltage U is 33~35V; the welding speed V is 1.6~1.8m / min.

5. The manufacturing method of a spiral submerged arc welded pipe suitable for hydrogen transportation according to claim 2, characterized in that: The full pipe diameter expansion process is as follows: based on the diameter of the spiral welded pipe, a special expansion module for spiral welded pipe is used, and a corresponding expansion head is selected to expand the diameter of the entire spiral welded pipe. The expansion cone head is driven to expand by hydraulic means, and the expansion module expands radially along the steel pipe to avoid the inner weld seam with a certain height, completing one expansion step and realizing the segmented expansion of the pipe body.

6. The manufacturing method of a spiral submerged arc welded pipe suitable for hydrogen transportation according to claim 2, characterized in that: The expansion rate of the entire spiral submerged arc welded pipe is 0.9%~1.1% within 1m of the starting and ending ends, and the pipe body expansion rate is 0.7%~0.9%. The pipe body expansion is carried out in segments, with each segment having an expansion length of about 2.5m and each forward step having a length of 0.8m~1.0m.

7. The manufacturing method of a spiral submerged arc welded pipe suitable for hydrogen transportation according to claim 2, characterized in that: The diameter deviation of the spiral submerged arc welded pipe after full diameter expansion is -0.1%D to +0.2%D, with a maximum deviation of 0.5mm; the pipe end circumference difference is <1.5mm; and the pipe end out-of-roundness is <0.7%D. The pipe body diameter deviation is -0.15%D to +0.2%D, with a maximum deviation of 1mm; and the pipe body out-of-roundness is <1.0%D. The straightness deviation of the entire pipe length exceeds 0.06% of the pipe length, and the local deviation relative to the straight line within a 1.5m length range at each pipe end is <2.8mm.

8. The manufacturing method of a spiral submerged arc welded pipe suitable for hydrogen transportation according to claim 2, characterized in that: The process of the whole tube heat treatment is as follows: the spiral submerged arc welded pipe is sent into a heating furnace for whole tube heat treatment. The heat treatment process adopts two heat treatments. The temperature of the first heat treatment is controlled between 350℃ and 400℃, and the holding time is between 60min and 70min. After the first heat treatment, the spiral submerged arc welded pipe is placed in another heating furnace for the second heat treatment. The temperature is controlled between 200℃ and 250℃, and the holding time is between 20min and 30min. After the heat treatment is completed, the spiral submerged arc welded pipe is taken out and air-cooled to room temperature.

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