Nickel-based alloy composite pipe welding process and application of nickel-based alloy composite pipe welding process in submarine pipeline welding

Abstract

The invention discloses a nickel-based alloy composite pipe welding process and application thereof in submarine pipeline welding, and belongs to the technical field of welding. The welding procedure comprises the steps that firstly, groove machining is conducted on the two alloy pipes, then the two alloy pipes are welded at the grooves, and the pipe wall of each alloy pipe is composed of a base layer and a covering layer; the base layer is carbon steel, and the coating layer is nickel-based alloy; in the groove processing step, the sections of the two alloy pipes are respectively processed to obtain grooves; the groove is composed of a slope surface A located on the base layer, a slope surface B located on the covering layer and a slope surface C located on the covering layer in sequence. According to the method, narrow-gap all-position welding is adopted, the thickness of a welding groove and the thickness of a nickel-based alloy isolation layer are reduced, the welding efficiency can be obviously improved, and meanwhile welding materials are saved; the automatic welding device is high in efficiency, wide in application range, low in welding material consumption, stable in welding quality, relatively simple in process control and suitable for narrow-gap all-position automatic welding of the nickel-based alloy composite pipe.

Description

Technical Field

[0001] The invention relates to a nickel-based alloy composite pipe welding process and application thereof in submarine pipeline welding, in particular to a full-position direct current automatic argon arc welding process method for a nickel-based alloy N06625 and low alloy steel composite pipe, belonging to the technical field of welding. Background Art

[0002] Nickel-based alloy composite pipe is a new type of pipe for conveying high-pressure and high-sulfur medium. This pipe consists of two layers. The base layer is made of carbon steel (seamless steel or welded steel) and the cladding is nickel-based alloy. It has strong corrosion resistance (resistance to H2S, CO2 and Cl-), good toughness, high strength, high temperature and low temperature resistance. However, the chemical composition of the base layer and the cladding of the nickel-based alloy composite pipe is very different, and the linear expansion coefficient and thermal conductivity are also quite different. During welding, impurities such as S and P are segregated in the weld metal, and the nickel-based alloy is easily oxidized to form refractory Cr oxides. If the welding process is improperly selected and the protection effect is not good, the welding of nickel-based alloy composite pipes is prone to dilution of alloy elements, thermal cracks, pores, poor weld formation and other problems. Therefore, it is necessary to solve the welding quality problem and study efficient and fully automatic welding processes to improve the efficiency of welding construction. Summary of the invention

[0003] The purpose of the present invention is to provide a nickel-based alloy composite pipe welding process with high efficiency, wide adaptability, low welding material consumption, stable welding quality and relatively simple process control, so as to realize full-position DC automatic argon arc welding of nickel-based alloy composite pipe submarine pipelines.

[0004] To achieve the above purpose, the present invention provides a nickel-based alloy composite pipe welding process on one hand, which welds two alloy pipes with cross sections; the welding process includes firstly processing the two alloy pipes with grooves, and then welding the two alloy pipes at the grooves, wherein the pipe wall of the alloy pipe is composed of a base layer and a cladding layer; the base layer is carbon steel, and the cladding layer is a nickel-based alloy; the groove processing is to process the cross sections of the two alloy pipes respectively to obtain the groove; the groove is composed of a slope surface A located at the base layer, a slope surface B located at the cladding layer, and a slope surface C located at the cladding layer in sequence; the slope surface A is a plane, and the angle between the slope surface A and the radial surface of the alloy pipe is α, α=8°; the slope surface B is a concave surface, and the curvature radius of the slope surface B is R, R=4.6mm; the slope surface C is a plane, and the slope surface C is parallel to the radial surface of the alloy pipe; the slope surface A is inwardly connected with the slope surface B.

[0005] As a preferred technical solution, the thickness of the slope surface C in the radial direction of the alloy tube is p, where p=1.6-1.8 mm.

[0006] As a preferred technical solution, during the welding, the distance between the slope surfaces C of the two alloy tubes is b, where b=0-1 mm.

[0007] As a preferred technical solution, the welding includes: preheating, base welding, hot welding, filling welding and capping welding.

[0008] As a preferred technical solution, the preheating temperature is 60°C to 80°C.

[0009] As a preferred technical solution, argon protection is performed during the base welding and hot welding processes; the argon protection is on the inner wall side of the alloy tube; preferably, the purity of the argon is ≥99.99%, and the oxygen content on the inner wall side of the alloy tube is <500ppm; the argon flow rate is 15-20L / min.

[0010] As an optimal technical solution, the parameters of the base welding include: the thickness of the base welding is 2 mm; the diameter of the base welding wire is 1 mm; the current is 125-135 A; the voltage is 8-11 V; the wire feeding speed is 1.8-2.8 m / min; the welding speed is 15-18 cm / min, the swing angle is 2-8°, and the edge dwell time is 0.2-0.4 s.

[0011] As an optimal technical solution, the parameters of the hot welding include: current 210-220A, voltage 10-12V; wire feeding speed 2.4-3.6m / min; welding speed 10-15cm / min; swing angle 8-18°, edge dwell time 0.4-0.5s.

[0012] As an optimal technical solution, the parameters of the filling welding include: current 260-290A, voltage 10-15V, shielding gas is argon, argon content Ar ≥ 99.99%, shielding gas flow rate 15-20L / min, wire feeding speed 3.5-6.1m / min, welding speed 10-15cm / min, swing angle 14-30°, edge residence time 0.4-0.5s, and multiple filling layers are obtained in sequence after filling welding.

[0013] As an optimal technical solution, the parameters of the cap welding include: current 235-240A, voltage 10-15V, shielding gas is argon, argon content Ar≥99.99%, shielding gas flow rate 15-20L / min, wire feeding speed 2.8-4.7m / min, welding speed 10-15cm / min, swing width 10-13mm, edge residence time 0-0.3s, and after cap welding, a cap layer is obtained.

[0014] As a preferred technical solution, after welding, the weld surface excess height is 0 to 2.0 mm, the misalignment is ≤ 1 mm, and the weld width is 0.5 to 2.0 mm greater than the outermost edge of the groove on each side.

[0015] The present invention also provides application of the above nickel-based alloy composite pipe welding process in submarine pipeline welding.

[0016] The present invention adopts narrow gap full-position welding, reduces the welding groove and the thickness of the nickel-based alloy isolation layer, can significantly improve the welding efficiency, and save welding materials at the same time; it has high efficiency, wide adaptability, low welding material consumption, stable welding quality and relatively simple process control, and is suitable for automatic welding of nickel-based alloy composite pipes in narrow gaps and full positions. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a schematic diagram of the all-position welding butt joint of nickel-based alloy composite pipes;

[0018] Figure 2 This is an enlarged schematic diagram of a single-side slope;

[0019] Figure 3 Schematic diagram of U-shaped groove for pipe butt joint;

[0020] Figure 4 Welding process layer diagram;

[0021] Figure 5 This is a schematic diagram of pipe grinding;

[0022] In the figure, T is the coating thickness, L is the base thickness, α is the groove surface angle; p is the blunt edge length, R is the arc radius, 1 is the root weld layer; 2 is the hot weld layer, 3, 4, 5, 6 are the filling layers; 7 is the cover layer. DETAILED DESCRIPTION

[0023] The welding process is implemented in the following manner.

[0024] The first step: Use DPFM1224 special internal expansion beveling machine to bevel the pipe section of the nickel-based alloy composite steel pipe. The pipe wall of the nickel-based alloy composite steel pipe is composed of a base layer and a cladding layer. There is no requirement for the thickness of the base pipe, and the thickness of the cladding layer is 2 to 4 mm. The base layer is carbon steel, and the cladding layer is nickel-based alloy; the groove processing is to process the cross sections of the two alloy pipes respectively to obtain the groove; the groove is composed of a slope surface A located at the base layer, a slope surface B located at the cladding layer, and a slope surface C located at the cladding layer in sequence; the slope surface A is a plane, and the angle between the slope surface A and the radial surface of the alloy pipe is α, α=8°; the slope surface B is a concave surface, and the curvature radius of the slope surface B is R, R=4.6mm; the slope surface C is a plane, and the slope surface C is parallel to the radial surface of the alloy pipe; the slope surface A is inwardly connected to the slope surface B; after the two pipes are butt-jointed, the narrow gap groove surface extends outward from the center of the pipe to form a U-shape; the groove dimensions are: b=0-1mm; p=1.6-1.8mm; the groove surface angle α=8°; R=4.6mm.

[0025] Step 2: Grind the straight weld of the pipe 200mm away from the groove, and make the straight weld position of the pipe flush with the surface of the pipe after grinding.

[0026] Step 3: Use Taipu DN350 special stainless steel internal jointer for assembly.

[0027] Step 4: Preheat the nickel-based alloy composite pipe at a temperature of 60°C to 80°C.

[0028] Step 5: Root welding: The root of the welding pipe is filled with argon gas for protection, Ar≥99.99%, and the oxygen content in the back argon space is <500ppm;

[0029] Step 6: Use DC argon arc welding process for all-position root welding and hot welding. The welding wire uses Exaton Ni60 TIG welding wire produced by ESAB. The root welding thickness is 2mm and the welding wire diameter is 1mm.

[0030] Backing welding parameters: current 125-135A, voltage 8-11V, shielding gas is argon, argon content Ar ≥ 99.99%, shielding gas flow 15-20L / min, wire feeding speed 1.8-2.8m / min, welding speed 15-18cm / min, swing angle 2-8°, edge dwell time 0.2-0.4s;

[0031] Hot welding parameters: current 210-220A, voltage 10-12V, shielding gas is argon, argon content Ar≥99.99%, shielding gas flow rate 15-20L / min, wire feeding speed 2.4-3.6m / min, welding speed 10-15cm / min, swing angle 8-18°, edge dwell time 0.4-0.5s.

[0032] Step 7: Remove the argon gas at the inner wall weld root.

[0033] Step 8: Use DC argon arc welding process to fill and cover the surface in all positions. The welding wire is Exaton Ni60 TIG welding wire produced by ESAB. The welds are arranged one layer at a time. During the welding process, stainless steel grinding sheets are used to grind the weld surface to remove oxides on the weld surface.

[0034] Filling parameters: current 260-290A, voltage 10-15V, shielding gas is argon, argon content Ar≥99.99%, shielding gas flow 15-20L / min, wire feeding speed 3.5-6.1m / min, welding speed 10-15cm / min, swing angle 14-30°, edge dwell time 0.4-0.5s;

[0035] Covering parameters: current 235-240A, voltage 10-15V, shielding gas is argon, argon content Ar≥99.99%, shielding gas flow rate 15-20L / min, wire feeding speed 2.8-4.7m / min, welding speed 10-15cm / min, swing width 10-13mm, edge residence time 0-0.3s.

[0036] Step 9: After the weld is completed, it is naturally cooled to below 150°C and then cooled to room temperature by water.

[0037] Example 1

[0038] like Figure 1 , Figure 2 , Figure 3 , Figure 4 , Figure 5 As shown, the tube wall of the nickel-based alloy composite steel pipe is composed of a base layer and a cladding layer; the base layer is carbon steel, and the cladding layer is a nickel-based alloy (N06625); the groove processing is to process the cross sections of the two alloy pipes respectively to obtain the groove; the groove is composed of a slope surface A located at the base layer, a slope surface B located at the cladding layer, and a slope surface C located at the cladding layer in sequence; the slope surface A is a plane, and the angle between the slope surface A and the radial surface of the alloy pipe is α, α = 8°; the slope surface B is a concave surface, and the curvature radius of the slope surface B is R, R = 4.6mm; the slope surface C is a plane, and the slope surface C is parallel to the radial surface of the alloy pipe; the slope surface A is inwardly connected to the slope surface B; after the two pipes are butt-jointed, the narrow gap groove surface extends outward from the center of the pipe into a U-shape.

[0039] Steps:

[0040] Step 1: Use DPFM1224 special internal expansion groove machine to groove the pipe section of nickel-based alloy composite steel pipe. The groove form of the two sides of the pipe is a narrow gap groove surface extending from the center of the pipe to the outside U shape. The groove size is b = 0.5mm; p = 1.6mm; the groove surface angle α = 8°; R = 4.6mm; the groove form and parameters are inspected;

[0041] Step 2: Grind the straight weld of the pipe 200mm away from the groove, and make the weld position flush with the parent material;

[0042] Step 3: Use Taipu DN350 special stainless steel internal jointer for assembly;

[0043] Step 4: preheat the nickel-based alloy composite tube at a temperature of 69°C;

[0044] Step 5: Root welding: The root of the welding pipe is filled with argon gas for protection, Ar≥99.99%, and the oxygen content in the back argon space is <500ppm;

[0045] Step 6: Use DC argon arc welding process for all-position root welding, hot welding, filling and covering. The welding wire uses Exaton Ni60 TIG welding wire produced by ESAB. The root welding thickness is 2mm and the welding wire diameter is 1mm.

[0046] Backing welding parameters: the shielding gas is argon, the argon content Ar≥99.99%, the current, voltage, wire feeding speed, welding speed, swing angle, edge dwell time and other parameters are shown in Table 1;

[0047] Hot welding parameters: the shielding gas is argon, the argon content Ar≥99.99%, the current, voltage, wire feeding speed, welding speed, swing angle, edge dwell time and other parameters are shown in Table 1;

[0048] Step 7: Remove the argon gas at the inner wall weld root.

[0049] Step 8: Use DC argon arc welding process to fill and cover the surface in all positions. The welding wire is Exaton Ni60 TIG welding wire produced by ESAB. The welds are arranged one layer at a time. During the welding process, stainless steel grinding sheets are used to grind the weld surface to remove oxides on the weld surface.

[0050] Filling parameters: the shielding gas is argon, the argon content Ar≥99.99%, the current, voltage, wire feeding speed, welding speed, swing angle, edge dwell time and other parameters are shown in Table 1;

[0051] Covering parameters: the shielding gas is argon, the argon content Ar≥99.99%, the current, voltage, wire feeding speed, welding speed, swing angle, edge dwell time and other parameters are shown in Table 1;

[0052] Step 9: After the weld is completed, cool it naturally to below 150°C. Use water cooling to cool it down to room temperature;

[0053] Step 10: Welding appearance inspection;

[0054] Step 11: Nondestructive testing.

[0055] In Table 1, one filling gives Figure 5 Filling layer 3 in the middle; secondary filling to obtain Figure 5 Filling layer 4 in the middle; three fillings to obtain Figure 5 Filling layer 5 in the middle; four fillings give Figure 5 The filling layer in 6.

[0056] Effect verification: After welding using the process of Example 1, the weld was visually inspected. The weld appearance was uniform and there were no cracks, unfused welds, pores, slag inclusions and other defects on the weld and its surrounding surfaces. The weld surface excess height could be controlled within 0 to 2.0 mm, and the misalignment after welding was less than or equal to 1 mm. The weld width was increased by 0.5 to 2.0 mm on each side of the outer surface groove, and there was no undercut depth.

[0057] Table 1 Welding process parameters of Example 1

[0058]

[0059] After the appearance inspection is qualified, non-destructive testing, radiographic testing and penetration testing are carried out in accordance with

[0060] DNV-OS-F101-2013 standard requirements. After mechanical property tests, its tensile, bending, impact test, Vickers hardness, macro-metallography and micro-metallography meet the standard requirements of ISO6892-1:2016, ISO5178:2001, ISO5173:2009, ASTM A370-19e1, ISO6507-1:2018, GB / T26955-2011, DNV-OS-F101:2013, ISO17781:2017(E), GB233.62-1988, ASTM E1019-18, ASTM E2594-09(2014), intergranular corrosion-A: ferric sulfate sulfuric acid corrosion test meets the standard requirements of ASTM G28-02(2015), and ferric chloride pitting test meets the standard requirements of ASTM G46-94(2018) and ASTM G48-11(2015). The groove gap only needs 0-1mm, the weld pool is more intuitive, the weld forming quality is easy to control, the welding forming is beautiful and the welding material consumption is small. Because nickel-based alloys have good toughness and high strength, the requirements for welding material selection and welding process parameters are more refined. Control welding with small heat input to ensure better welding coverage and stronger welding crack resistance. The welding test results show that after welding according to the selected automatic welding process, all welding properties of the welding test meet the requirements and the welding strength meets the standards. The all-position DC automatic argon arc welding process has been verified to be technically feasible, with reliable welding quality and significant economic benefits, filling the gap in welding technology at home and abroad.

Claims

1. Nickel-based alloy composite pipe welding process, characterized in that: Welding two alloy tubes with cross sections; the welding process includes firstly beveling the two alloy tubes, and then welding the two alloy tubes at the bevel, the tube wall of the alloy tube is composed of a base layer and a cladding layer; the base layer is carbon steel, and the cladding layer is a nickel-based alloy; The groove processing is to process the cross sections of the two alloy tubes respectively to obtain the grooves; The groove is composed of a slope surface A located at the base layer, a slope surface B located at the covering layer, and a slope surface C located at the covering layer in sequence; The slope surface A is a plane, and the angle between the slope surface A and the radial surface of the alloy tube is α, α=8°; The slope surface B is a concave surface, and the curvature radius of the slope surface B is R, R=4.6 mm; The slope surface C is a plane, and the slope surface C is parallel to the radial surface of the alloy tube; The slope surface A and the slope surface B are inwardly connected.

2. The nickel-based alloy composite pipe welding process according to claim 1, characterized in that: The thickness of the slope surface C in the radial direction of the alloy tube is p, where p=1.6-1.8 mm.

3. The nickel-based alloy composite pipe welding process according to claim 1, characterized in that: During the welding, the distance between the slope surfaces C of the two alloy tubes is b, where b=0-1 mm.

4. The nickel-based alloy composite pipe welding process according to claim 1, characterized in that: The welding includes: preheating, base welding, hot welding, filling welding and capping welding; The preheating temperature is 60°C to 80°C.

5. The nickel-based alloy composite pipe welding process according to claim 4, characterized in that: Argon protection is performed during the base welding and hot welding process; the argon protection is on the inner wall side of the alloy tube; preferably, the purity of the argon is ≥99.99%, and the oxygen content on the inner wall side of the alloy tube is <500ppm; the argon flow rate is 15-20L / min.

6. The nickel-based alloy composite pipe welding process according to claim 4, characterized in that: The parameters of the base welding include: the thickness of the base welding is 2 mm; the diameter of the base welding wire is 1 mm; the current is 125-135 A; the voltage is 8-11 V; the wire feeding speed is 1.8-2.8 m / min; the welding speed is 15-18 cm / min, the swing angle is 2-8°, and the edge dwell time is 0.2-0.4 s.

7. The nickel-based alloy composite pipe welding process according to claim 4, characterized in that: The parameters of the hot welding include: current 210-220A, voltage 10-12V; wire feeding speed 2.4-3.6m / min; welding speed 10-15cm / min; swing angle 8-18°, edge dwell time 0.4-0.5s.

8. The nickel-based alloy composite pipe welding process according to claim 4, characterized in that: The parameters of the filling welding include: current 260-290A, voltage 10-15V, shielding gas is argon, argon content Ar≥99.99%, shielding gas flow rate 15-20L / min, wire feeding speed 3.5-6.1m / min, welding speed 10-15cm / min, swing angle 14-30°, edge dwell time 0.4-0.5s; And / or, the parameters of the cap welding include: current 235-240A, voltage 10-15V, shielding gas is argon, argon content Ar≥99.99%, shielding gas flow rate 15-20L / min, wire feeding speed 2.8-4.7m / min, welding speed 10-15cm / min, swing width 10-13mm, edge residence time 0-0.3s.

9. The nickel-based alloy composite pipe welding process according to claim 4, characterized in that: After the capping welding, a capping layer is obtained, wherein the surface excess height of the capping layer is 0 to 2.0 mm, and the misalignment is ≤ 1 mm; The capping layer is wider than the distance between the slope surfaces A of the two alloy tubes, preferably increasing by 0.5 to 2.0 mm on each side.

10. Application of the nickel-based alloy composite pipe welding process according to claims 1 to 9 in submarine pipeline welding.

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