Automatic girth welding process for bimetallic metallurgical composite pipe

Abstract

The application discloses an automatic girth welding process for a bimetal metallurgical composite pipe, which comprises the following steps: S1, bimetal metallurgical composite pipe selection, wherein a base pipe of the bimetal metallurgical composite pipe is an X60 steel pipe, and chemical components of the X60 steel pipe are as follows: C is 0.03-0.05, Si is 0.25-0.35, Mn is 1.40-1.60, P is less than or equal to 0.008, S is less than or equal to 0.005, Cr is less than or equal to 0.30, and the balance is Fe; and a cladding layer is an Incoloy 825 corrosion-resistant alloy, and chemical components of the Incoloy 825 corrosion-resistant alloy are as follows: C is less than or equal to 0.05, Si is less than or equal to 0.50, Mn is less than or equal to 1.0, P is less than or equal to 0.005, S is less than or equal to 0.003, Ni is 38.0-45.0, Cr is 20.0-23.0, Mo is 2.5-3.5, Cu is 1.8-3.0, Ti is 0.6-1.2, Al is less than or equal to 0.15, and the balance is Fe. The application solves the problem of automatic girth welding of the bimetal metallurgical composite pipe. Not only the production cost and the labor intensity of workers are greatly reduced, but also the welding efficiency and the welding quality of the bimetal metallurgical composite pipe are effectively improved. The welded joint has excellent comprehensive mechanical properties and corrosion resistance.

Description

Technical Field

[0001] This invention relates to the field of welding technology for long-distance pipelines, and in particular to an automatic circumferential welding process for bimetallic metallurgical composite pipes. Background Technology

[0002] Bimetallic composite pipes are made by combining two or more different metallic materials through a specific process. They typically consist of a base pipe, a lining steel pipe, or a cladding metal. Composite pipes maximize the complementary advantages of the materials, reduce construction costs, and improve the corrosion resistance and wear resistance of the pipeline while maintaining the performance of the original base pipe, thus extending its service life. They are a substitute for pure stainless steel pipes or corrosion-resistant alloy pipes. Bimetallic composite pipes are currently used in highly corrosive industries such as petroleum, chemical, nuclear, and pharmaceuticals.

[0003] The circumferential weld of bimetallic composite pipes is a crucial step in the construction of corrosion-resistant pipeline projects. If the welding process is improperly chosen, the inner and outer metal layers of the circumferential weld will simultaneously come into contact with corrosive fluids, leading to more severe electrochemical corrosion and consequently, pipe corrosion, leakage, and perforation. Currently, the connection of bimetallic composite pipes requires both efficient welding of the composite pipes and ensuring the integrity and good corrosion resistance of the corrosion-resistant layer at the weld joint, placing high demands on the circumferential weld process. Summary of the Invention

[0004] The purpose of this invention is to address the shortcomings of existing technologies by proposing an automatic circumferential welding process for bimetallic metallurgical composite pipes.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] An automated circumferential welding process for bimetallic composite pipes includes the following steps:

[0007] S1: Selection of bimetallic metallurgical composite pipe. The base pipe of the bimetallic metallurgical composite pipe is X60 steel pipe with the following chemical composition: C: 0.03~0.05, Si: 0.25~0.35, Mn: 1.40~1.60, P: ≤0.008, S: ≤0.005, Cr: ≤0.30, and the balance is Fe; the cladding is Incoloy 825 corrosion-resistant alloy with the following chemical composition: C: ≤0.05, Si: ≤0.50, Mn: ≤1.0, P: ≤0.005, S: ≤0.003, Ni: 38.0-45.0, Cr: 20.0-23.0, Mo: 2.5-3.5, Cu: 1.8-3.0, Ti: 0.6-1.2, Al: ≤0.15, and the balance is Fe.

[0008] S2: Beveling process. A U-shaped bevel is machined on the end of the bimetallic composite pipe, with a bevel angle of 20-40°, a blunt edge of 1.5-1.8mm, a platform of 4.0-6.0mm on the blunt edge, and a transition arc radius of 2.5-3.5mm.

[0009] S3: Welding material selection: For root welding, hot welding, filler welding, and cover welding, use solid welding wire with a diameter of 1.0mm, model AWS5.14ERNiCrMo-3, with a tensile strength of 700~790Mpa, elongation after fracture of 43~48%, and impact energy of 145~165J at -196℃. The chemical composition by weight percentage is: C: 0.01~0.02, Si: ≤0.50, Mn: ≤0.5, P: ≤0.005, S: ≤0.003, Ni: ≥58.0, Cr: 20.0~23.0, Mo: 8.0~10.0, Ti+Nb: 3.2~4.0, with the balance being Fe.

[0010] S4: Root welding parameter settings. The root welding adopts the hot wire tungsten inert gas (TIG) automatic welding process. The shielding gas is argon, the gas flow rate is 5-10 L / min, the welding current is 120-140 A, the welding voltage is 9.0-10.0 V, the wire feed speed is 1.8-2.2 m / min, and the root welding polarity is DC positive.

[0011] S5: Welding parameter settings for hot welding, filler welding, and capping welding. Hot welding, filler welding, and capping welding adopt the automatic welding process of solid welding wire with consumable electrode inert gas shielding. The gas flow rate is 10-15L / min. The welding current for hot welding is 140-180A, the welding voltage is 9.0-10.0V, and the wire feed speed is 2.0-3.0m / min. The welding current for filler welding and capping welding is 150-210A, the welding voltage is 10-18V, and the wire feed speed is 3.0-7.0m / min. The welding polarity for hot welding, filler welding, and capping welding is DC positive polarity, and the wire extension length is 8-15mm.

[0012] S6: Welding. Before welding, the bimetallic composite pipe is first assembled with a gap of 0mm. The bevel position is preheated at 30-50℃ for 3-5 minutes to remove moisture and surface rust. Then, root welding is performed. Before root welding, the composite pipe is filled with argon gas for protection at a flow rate of 5-8L / min. The root weld must be single-sided with double-sided forming. Hot welding, filling and capping welding are performed in sequence, controlling the interpass temperature to be less than 100℃. Multi-layer and multi-pass welding process is used for filling and capping welding. Root welding, hot welding, filling and capping welding are all done using automatic upward welding (from the 6 o'clock position to the 12 o'clock position).

[0013] Furthermore, in S1, Fe is a bimetallic metallurgical composite pipe with the balance being Fe.

[0014] Preferably, the protective gas in S5 is (70% Ar + 30% He) to (90% Ar + 10% He).

[0015] As a further embodiment of the present invention, the diameter of the bimetallic metallurgical composite pipe is 508-813mm, the wall thickness of the base layer is 20-30mm, the wall thickness of the cladding layer is 2-3mm, and during welding, there is 1 root weld, 1-2 hot welds, 7-9 filler welds, and 1-2 cover welds.

[0016] Furthermore, in step S4, the composite pipe is filled with argon gas for protection before root welding, with a gas flow rate of 5-8 L / min. The root weld must be single-sided welded and double-sided formed, and hot welding, filling and capping welding are performed in sequence, controlling the interpass temperature to be less than 100℃.

[0017] The beneficial effects of this invention are:

[0018] 1. This invention solves the problem of automatic circumferential welding of bimetallic composite pipes. It not only significantly reduces production costs and labor intensity, but also effectively improves the welding efficiency and quality of bimetallic composite pipes. The welded joint possesses excellent comprehensive mechanical properties and corrosion resistance. Attached Figure Description

[0019] Figure 1 A schematic diagram of the welding bevel form for an automatic circumferential welding process for bimetallic metallurgical composite pipes;

[0020] Figure 2 A schematic diagram showing the number of welding layers in an automatic circumferential welding process for bimetallic metallurgical composite pipes;

[0021] Figure 3 This is a flowchart of an automatic circumferential welding process for bimetallic metallurgical composite pipes.

[0022] 1. Bevel; 2. Transition fillet; 3. Platform on blunt edge; 4. Blunt edge; 5. Cap weld; 6. Filler weld; 7. Hot weld; 8. Root weld. Detailed Implementation

[0023] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0024] Example 1

[0025] Reference Figure 1-3 An automatic circumferential welding process for bimetallic metallurgical composite pipes includes the following steps:

[0026] S1: Select a bimetallic metallurgical composite pipe with a diameter of 508mm, a base pipe wall thickness of 20mm, and a cladding wall thickness of 2mm. The chemical composition of the base pipe is C: 0.05, Si: 0.25, Mn: 1.50, P: 0.008, S: 0.004, Cr: 0.20, with the balance being Fe; the chemical composition of the cladding is C: 0.03, Si: 0.45, Mn: 0.9, P: 0.005, S: 0.003, Ni: 41.0, Cr: 21.5, Mo: 3.0, Cu: 2.1, Ti: 0.8, Al: 0.1, with the balance being Fe.

[0027] S2: A U-shaped bevel is machined at the end of the composite pipe, with a bevel angle of 20°, a blunt edge of 1.8mm, a platform of 5.0mm on the blunt edge, and a transition arc radius of 2.8mm.

[0028] S3: Select solid welding wire with a diameter of 1.0mm, model AWS 5.14ERNiCrMo-3. The tensile strength of the welding wire is 720Mpa, the elongation after fracture is 45%, the impact energy at -196℃ is 145J, and the chemical composition by weight percentage is C: 0.02, Si: 0.50, Mn: 0.40, P: 0.005, S: 0.003, Ni: 61.0, Cr: 22.0, Mo: 9.0, Ti+Nb: 3.5, and the balance is Fe.

[0029] S4: Root pass welding is performed using a hot-wire tungsten inert gas (TIG) automatic welding process. The shielding gas is argon, with a flow rate of 8 L / min. The welding current is 120–130 A, the welding voltage is 9.5 V, and the wire feed speed is 1.8–1.9 m / min. Hot pass welding, filler weld, and cap pass welding are performed using a gas inert gas (GAG) shielded solid wire automatic welding process. The shielding gas is 80% Ar + 20% He, with a flow rate of 12 L / min. For hot pass welding, the welding current is 140–150 A, the welding voltage is 9.5 V, the wire feed speed is 2.0 m / min, and the wire extension length is 10 mm. For filler weld and cap pass welding, the welding current is 150–170 A, the welding voltage is 10–15 V, the wire feed speed is 6.0 m / min, and the wire extension length is 12 mm. The polarity for hot pass welding, filler weld, and cap pass welding is DC positive polarity.

[0030] S5: Before welding, the bimetallic metallurgical composite pipe is first assembled with a gap of 0mm. The bevel position is preheated and held at 30℃ for 3 minutes to remove moisture and surface rust from the bevel surface.

[0031] S6: The composite tube is filled with argon gas for protection at a flow rate of 8L / min. The oxygen content inside the composite tube is tested using an oxygen analyzer. When the oxygen content drops below 1%, root welding is performed. The root welding must ensure single-sided welding with double-sided forming and control the interpass temperature to be less than 100℃. Hot welding, filling, and capping welding are performed in sequence. Multi-layer, multi-pass welding process is used for filling and capping welding. Root welding, hot welding, filling, and capping welding all use automatic upward welding.

[0032] S7: The circumferential welded joints welded according to the above welding process were subjected to tensile, bending, impact performance tests and intergranular corrosion tests. The tensile strength was 640 MPa, and the fracture occurred in the base material. No cracks were observed during bending. The average impact toughness of the weld at 0℃ was 154 J, and the average value of the heat-affected zone was 99 J, which meets the requirements of DNV F101 standard. The maximum intergranular corrosion rate was 0.294 g / (m2·h), which meets the requirements of ASTM G28 standard.

[0033] The working principle of this embodiment: This invention is a high-quality and efficient new welding process developed based on traditional TIG welding of bimetallic composite pipes. During root pass welding, the welding wire is heated to a certain preheating temperature. Heating the welding wire not only improves welding efficiency but also significantly increases the cladding rate and accelerates the melting speed of the filler wire. During hot welding, filler, and capping welding, a high wire feed rate MIG welding method is used, which reduces the dilution rate of the base material, improves the mechanical properties of the welded joint, and achieves the goal of high-efficiency welding.

[0034] Example 2

[0035] Reference Figure 1-3 An automatic circumferential welding process for bimetallic metallurgical composite pipes includes the following steps:

[0036] S1: Select a bimetallic metallurgical composite pipe with a diameter of 610mm, a base pipe wall thickness of 22mm, and a cladding wall thickness of 3mm. The chemical composition of the base pipe is C: 0.046, Si: 0.33, Mn: 1.48, P: 0.006, S: 0.003, Cr: 0.24, with the balance being Fe; the chemical composition of the cladding is C: 0.023, Si: 0.41, Mn: 0.82, P: 0.005, S: 0.003, Ni: 43.0, Cr: 23.0, Mo: 2.4, Cu: 1.9, Ti: 0.6, Al: 0.07, with the balance being Fe.

[0037] S2: A U-shaped bevel is machined at the end of the composite pipe, with a bevel angle of 30°, a blunt edge of 1.5mm, a platform on the blunt edge of 6.0mm, and a transition arc radius of 3.2mm.

[0038] S3: Select solid welding wire with a diameter of 1.0mm, model AWS 5.14ERNiCrMo-3. The tensile strength of the welding wire is 730Mpa, the elongation after fracture is 44%, the impact energy at -196℃ is 155J, and the chemical composition by weight percentage is C: 0.015, Si: 0.41, Mn: 0.47, P: 0.005, S: 0.003, Ni: 65.0, Cr: 22.0, Mo: 9.4, Ti+Nb: 3.28, and the balance is Fe.

[0039] S4: Root pass welding is performed using a hot-wire tungsten inert gas (TIG) automatic welding process. The shielding gas is argon, with a flow rate of 10 L / min. The welding current is 130–140 A, the welding voltage is 9.5 V, and the wire feed speed is 1.9–2.1 m / min. Hot pass welding, filler weld, and cap pass welding are performed using a consumable electrode inert gas (GAG) shielded solid wire automatic welding process. The shielding gas is 90% Ar + 10% He, with a flow rate of 12 L / min. For hot pass welding, the welding current is 150–160 A, the welding voltage is 9.5 V, the wire feed speed is 2.5 m / min, and the wire extension length is 10 mm. For filler weld and cap pass welding, the welding current is 150–170 A, the welding voltage is 10–15 V, the wire feed speed is 6.8 m / min, and the wire extension length is 11 mm. The polarity for hot pass welding, filler weld, and cap pass welding is DC positive polarity.

[0040] S5: Before welding, the bimetallic metallurgical composite pipe is first assembled with a gap of 0mm. The bevel position is preheated and held at 40℃ for 3 minutes to remove moisture and surface rust from the bevel surface.

[0041] S6: The composite tube is filled with argon gas for protection at a flow rate of 6L / min. The oxygen content inside the composite tube is tested using an oxygen analyzer. When the oxygen content drops below 1%, root welding is performed. The root welding must ensure single-sided welding with double-sided forming and control the interpass temperature to be less than 100℃. Hot welding, filling, and capping welding are performed in sequence. Multi-layer, multi-pass welding process is used for filling and capping welding. Root welding, hot welding, filling, and capping welding all use automatic upward welding.

[0042] S7: The circumferential welded joints welded according to the above welding process were subjected to tensile, bending, impact performance tests and intergranular corrosion tests. The tensile strength was 680 MPa, and the fracture occurred in the base material. No cracks were observed during bending. The average impact toughness of the weld at 0℃ was 149 J, and the average value of the heat-affected zone was 105 J, which meets the requirements of DNV F101 standard. The maximum intergranular corrosion rate was 0.237 g / (m2·h), which meets the requirements of ASTM G28 standard.

[0043] The working principle of this embodiment: This invention is a high-quality and efficient new welding process developed based on traditional TIG welding of bimetallic composite pipes. During root pass welding, the welding wire is heated to a certain preheating temperature. Heating the welding wire not only improves welding efficiency but also significantly increases the cladding rate and accelerates the melting speed of the filler wire. During hot welding, filler, and capping welding, a high wire feed rate MIG welding method is used, which reduces the dilution rate of the base material, improves the mechanical properties of the welded joint, and achieves the goal of high-efficiency welding.

[0044] The foregoing has shown and described the basic principles and main features of the present invention and its advantages. It will be apparent to those skilled in the art that the present invention is not limited to the details of the above exemplary embodiments, and that the present invention can be implemented in other specific forms without departing from the spirit or basic features of the present invention. Therefore, the embodiments should be regarded as exemplary and non-limiting in all respects. The scope of the present invention is defined by the appended claims rather than the foregoing description. Therefore, it is intended that all changes falling within the meaning and scope of the equivalents of the claims be included within the present invention, and no reference numerals in the claims should be regarded as limiting the scope of the claims.

[0045] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A process for automatic girth welding of a bimetallic metallurgical composite pipe, characterized in that, Includes the following steps: S1: Selection of bimetallic metallurgical composite pipe. The base pipe of the bimetallic metallurgical composite pipe is X60 steel pipe with the following chemical composition: C: 0.03~0.05, Si: 0.25~0.35, Mn: 1.40~1.60, P: ≤0.008, S: ≤0.005, Cr: ≤0.30, and the balance is Fe; the cladding is Incoloy 825 corrosion-resistant alloy with the following chemical composition: C: ≤0.05, Si: ≤0.50, Mn: ≤1.0, P: ≤0.005, S: ≤0.003, Ni: 38.0-45.0, Cr: 20.0-23.0, Mo: 2.5-3.5, Cu: 1.8-3.0, Ti: 0.6-1.2, Al: ≤0.15, and the balance is Fe. S2: Beveling process. A U-shaped bevel is machined on the end of the bimetallic composite pipe, with a bevel angle of 20-40°, a blunt edge of 1.5-1.8mm, a platform of 4.0-6.0mm on the blunt edge, and a transition arc radius of 2.5-3.5mm. S3: Welding material selection: For root welding, hot welding, filler welding, and cover welding, use solid welding wire with a diameter of 1.0mm, model AWS 5.14ERNiCrMo-3, with a tensile strength of 700~790Mpa, elongation after fracture of 43~48%, and impact energy of 145~165J at -196℃. The chemical composition by weight percentage is: C: 0.01~0.02, Si: ≤0.50, Mn: ≤0.5, P: ≤0.005, S: ≤0.003, Ni: ≥58.0, Cr: 20.0~23.0, Mo: 8.0~10.0, Ti+Nb: 3.2~4.0, with the balance being Fe. S4: Root welding parameter settings. The root welding adopts the hot wire tungsten inert gas (TIG) automatic welding process. The shielding gas is argon, the gas flow rate is 5-10 L / min, the welding current is 120-140 A, the welding voltage is 9.0-10.0 V, the wire feed speed is 1.8-2.2 m / min, and the root welding polarity is DC positive. S5: Welding parameter settings for hot welding, filler welding, and capping welding. Hot welding, filler welding, and capping welding adopt the automatic welding process of solid welding wire with consumable electrode inert gas shielding. The gas flow rate is 10-15L / min. The welding current for hot welding is 140-180A, the welding voltage is 9.0-10.0V, and the wire feed speed is 2.0-3.0m / min. The welding current for filler welding and capping welding is 150-210A, the welding voltage is 10-18V, and the wire feed speed is 3.0-7.0m / min. The welding polarity for hot welding, filler welding, and capping welding is DC positive polarity, and the wire extension length is 8-15mm. S6: Welding. Before welding, the bimetallic composite pipe is first assembled with a gap of 0mm. The bevel position is preheated at 30-50℃ for 3-5 minutes to remove moisture and surface rust. Then, root welding is performed. Before root welding, the composite pipe is filled with argon gas for protection at a flow rate of 5-8L / min. The root weld must be single-sided with double-sided forming. Hot welding, filling and capping welding are performed in sequence, controlling the interpass temperature to be less than 100℃. Multi-layer and multi-pass welding process is used for filling and capping welding. Root welding, hot welding, filling and capping welding are all done using automatic upward welding (from the 6 o'clock position to the 12 o'clock position).

2. A process for automatic girth welding of a bimetallic metallurgically combined pipe as claimed in claim 1, wherein, In S1, Fe is a bimetallic metallurgical composite pipe with the balance being Fe.

3. A process for automatic girth welding of a bimetallic metallurgically combined pipe as claimed in claim 2, wherein, The protective gas in S5 is (70% Ar + 30% He) to (90% Ar + 10% He).

4. A process for automatic girth welding of a bimetallic metallurgically combined pipe as claimed in claim 3, wherein, The bimetallic composite pipe has a diameter of 508-813mm, a base layer wall thickness of 20-30mm, a cladding wall thickness of 2-3mm, and during welding, there is one root pass, one to two hot passes, seven to nine filler passes, and one to two cap passes.

5. A process for automatic girth welding of a bimetallic metallurgically combined pipe as claimed in claim 4, wherein, Before root welding in S4, the composite pipe is protected by argon gas with a flow rate of 5-8 L / min. The root weld must be single-sided welded and double-sided formed. Hot welding, filling and capping welding are performed in sequence, and the interpass temperature is controlled to be less than 100℃.

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