Vertical pipe long-fatigue-life welding method of cold metal transition welding process

Abstract

The invention discloses a vertical pipe long-fatigue-life welding method for a cold metal transition welding process, which comprises the following steps of: performing cold metal transition welding on a bottom layer of a marine vertical pipe welding joint, and performing gas metal arc welding on a filling layer and a cover surface layer; the welding method comprises the following steps that a groove used for welding the marine riser is obtained based on the material and the pipe diameter wall thickness of the marine riser; after the two to-be-welded pipeline base materials are assembled, the grooves are cleaned; according to a one-side welding and double-side forming method, multi-layer and multi-pass welding is carried out on the marine riser from the outside, cold metal transition backing welding, gas metal arc welding, filling welding and cosmetic welding are carried out in sequence, and the welded marine riser is obtained. According to the stand pipe long-fatigue-life welding method of the cold metal transition welding process, the root of a weld joint obtained through cold metal transition welding is smooth and attractive, stress concentration is small, and the fatigue life can be effectively prolonged.

Description

Technical Field

[0001] The invention belongs to the technical field of marine riser welding, and in particular relates to a riser high fatigue life welding method using a cold metal transition welding process. Background Art

[0002] In the process of exploration, development and transportation of oil and gas resources in deepwater areas, it is necessary to rely on submarine pipelines and marine risers to achieve long-distance transportation of the exploited oil and gas resources. With the increase of water depth and the increase of riser length, the marine environment will become more complex and harsh. Affected by marine environmental factors such as wind, waves, and currents, the long-term alternating load of the marine riser welded joints will cause fatigue damage, which will significantly shorten the fatigue life and safe service life of the riser. How to improve the fatigue life of the marine riser welded joints has become an urgent problem to be solved in the current deepwater oil and gas resource transportation.

[0003] The welded joint of the marine riser, especially the weld root of the base layer, becomes the main stress concentration area of ​​the welded joint due to its welding structure discontinuity and microstructural inhomogeneity, which promotes the rapid initiation and expansion of fatigue cracks, causing this part to become a potential crack source and preferential failure position of the marine riser, so that fatigue damage often originates here; the current welding method can obtain a well-formed weld, but there are problems and shortcomings such as large root stress concentration, wide heat-affected zone and low welding efficiency, which not only seriously threatens and deteriorates the mechanical properties and fatigue life of the marine riser, but also significantly increases the cost and expense of offshore construction.

[0004] Therefore, it is urgent to design a cold metal transfer welding process for high fatigue life riser welding to solve the above-mentioned problem of marine riser joint welding. Summary of the invention

[0005] In order to solve the problems and shortcomings mentioned in the background technology, such as large stress concentration at the root of the riser, wide heat affected zone and low welding efficiency, which not only seriously threaten and deteriorate the mechanical properties and fatigue life of the marine riser, but also significantly increase the cost and expense of offshore construction, a riser high fatigue life welding method using a cold metal transfer welding process is provided to solve the problem of marine riser joint welding.

[0006] To achieve the above object, the specific technical scheme of the riser high fatigue life welding method of the cold metal transition welding process of the present invention is as follows: A cold metal transfer welding process for a high fatigue life riser welding method, wherein the base layer of the marine riser welding joint is welded by cold metal transfer welding, and the filling layer and the cover layer are welded by metallurgical gas shielding welding, and the welding comprises the following steps: S1. Obtaining a groove for welding the marine riser based on the material, diameter and wall thickness of the marine riser; S2. After assembling the two pipe base materials to be welded, clean the groove; S3. According to the single-sided welding and double-sided forming method, multi-layer and multi-pass welding is performed on the marine riser from the outside, and cold metal transition base welding, metal-conductive gas shielded welding, filling welding and cap welding are performed in sequence to obtain a welded marine riser.

[0007] Furthermore, in S1, in the process of obtaining the groove, the groove is a U-shaped narrow gap groove, the blunt edge thickness is 1.3 to 1.8 mm, the upper groove angle is 3 to 10 degrees, and the R3-R5 transition is adopted.

[0008] Further, in S2, during the process of cleaning the groove, alcohol or acetone is used to wipe the surface of the groove to remove oil stains.

[0009] Further, in S3, during the multi-layer and multi-pass welding of the marine riser from the outside, the layer spacing is 3 to 5 mm, and slag removal is performed after each layer of weld is completed.

[0010] Furthermore, in S3, the welding parameters of the cold metal transition base welding include: welding voltage of 10 to 12 V, welding current of 180 to 200 A, welding speed of 400 to 600 mm / min, wire feeding speed of 6 m / min, shielding gas of 82% argon and 18% carbon dioxide, and gas flow rate of 20 L / min.

[0011] Further, in S3, the welding parameters for filling welding by metal electrode gas shielded welding include: welding voltage of 22 to 24 V, welding current of 220 to 240 A, welding speed of 400 to 600 mm / min, wire feeding speed of 12 to 14 m / min, shielding gas of 82% argon gas + 18% carbon dioxide gas, and gas flow rate of 20 L / min.

[0012] Further, in S3, the welding parameters of the metal electrode gas shielded welding cap layer include: welding voltage of 22 to 24 V, welding current of 170 to 190 A, welding speed of 400 to 600 mm / min, wire feeding speed of 8 to 10 m / min, shielding gas of 82% argon gas + 18% carbon dioxide gas, and gas flow rate of 20 L / min.

[0013] Furthermore, the base layer welding of the marine riser adopts cold metal transition welding for base welding process, and the assembly gap of the marine riser is controlled at 0mm.

[0014] Furthermore, during the process of metal-metal gas shielded welding, the first layer is welded in a single pass, and subsequent weld layers are filled in a multi-pass welding manner to ensure a good weld formation effect.

[0015] Furthermore, before the process of performing cap welding by metal-metal-shielded gas welding, metal-metal-shielded gas welding for cap welding is performed when the weld fills a distance of 1 to 3 mm from the outer wall of the pipeline.

[0016] The high fatigue life welding method of the riser using the cold metal transition welding process of the present invention has the following advantages: Through cold metal transfer welding, the marine riser weld is formed and of good quality. Cold metal transfer welding combines wire feeding movement with short-circuit transition, which can achieve stable arc control and precise energy input. The weld root is smooth and beautiful, the residual height at the weld root is almost 0, the stress concentration is small, the fatigue crack initiation and expansion are difficult, and the fatigue life can be effectively improved.

[0017] The weld grains of the present application are fine and the heat-affected zone is narrow. At the moment of short-circuit transition in cold metal transition welding, the current is 0, and the welding heat input provided is smaller than that of traditional consumable gas shielded welding. The weld grains are finer, the heat-affected zone is narrow, and the microstructure is relatively uniform. The weld root of the base welded by cold metal transition welding has excellent fatigue performance, and the corrosion fatigue performance of the riser joint base welded by cold metal transition welding is greatly improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 A schematic diagram of the groove position of the riser high fatigue life welding method of the cold metal transition welding process of the present invention; Figure 2 A schematic diagram of a weld pass of a riser high fatigue life welding method of a cold metal transition welding process of the present invention; Figure 3 This is an air fatigue test specimen diagram of the riser high fatigue life welding method of the cold metal transfer welding process of the present invention; Figure 4 This is a corrosion fatigue specimen diagram of the riser high fatigue life welding method of the cold metal transfer welding process of the present invention; Figure 5 Comparison chart of air fatigue SN curves of cold metal transfer base welding plus metal arc welding filling and capping and traditional metal arc welding; Figure 6 This is a comparison chart of the corrosion fatigue SN curves of cold metal transfer base welding plus metal arc welding filling and capping and traditional metal arc welding; Figure 7 The present invention is a process flow chart of a method for welding a riser with high fatigue life using a cold metal transition welding process. DETAILED DESCRIPTION

[0019] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0020] Those skilled in the art will appreciate that, although some embodiments herein include certain features included in other embodiments but not other features, the combination of features of different embodiments is meant to be within the scope of the present invention and form different embodiments. For example, in the claims, any one of the claimed embodiments may be used in any combination.

[0021] Please refer to the attached Figure 1 To Attachment Figure 7 The invention discloses a high fatigue life welding method for a riser pipe using a cold metal transfer welding process.

[0022] like Figure 7 As shown, the cold metal transfer welding process of the present invention is a method for welding a riser with high fatigue life. The base layer of the marine riser weld joint is welded by cold metal transfer welding, and the filling layer and the cover layer are welded by metallurgical gas shielded welding. The welding comprises the following steps: S1. Obtaining a groove for welding the marine riser based on the material, diameter and wall thickness of the marine riser; S2. After assembling the two pipe base materials to be welded, clean the groove; S3. According to the single-sided welding and double-sided forming method, multi-layer and multi-pass welding is performed on the marine riser from the outside, and cold metal transition base welding, metal-conductive gas shielded welding, filling welding and cap welding are performed in sequence to obtain a welded marine riser.

[0023] Through cold metal transfer welding, the marine riser weld is formed and of good quality. Cold metal transfer welding combines wire feeding movement with short-circuit transition, which can achieve stable arc control and precise energy input. The weld root is smooth and beautiful, the residual height at the weld root is almost 0, the stress concentration is small, the fatigue crack initiation and expansion are difficult, and the fatigue life can be effectively improved.

[0024] The weld grains of the riser high fatigue life welding method using the cold metal transition welding process are fine and the heat affected zone is narrow. At the moment of short-circuit transition, the current of cold metal transition welding is 0, and the welding heat input provided is smaller than that of traditional consumable gas shielded welding. The weld grains are finer, the heat affected zone is narrower, and the microstructure is relatively uniform. The weld root of the base welded by cold metal transition welding has excellent fatigue performance, and the corrosion fatigue performance of the riser joints using cold metal transition welding for base welding has been greatly improved.

[0025] Further, if Figure 1 and Figure 2 As shown, in S1, in the process of obtaining the groove, the groove is a U-shaped narrow gap groove, the blunt edge thickness is 1.3 to 1.8 mm, the upper groove angle is 3 to 10 degrees, and the R3-R5 transition is adopted; in S2, in the process of cleaning the groove, alcohol or acetone is used to wipe the groove surface to remove oil stains; in S3, in the process of multi-layer and multi-pass welding of the marine riser from the outside, the layer spacing is 3 to 5 mm, and slag removal is performed after each layer of weld is completed.

[0026] In this embodiment, welding equipment is configured, and the welding equipment includes welding wire, a welding robot, a welding machine power supply for cold metal transition base welding, a water tank, and a welding gun for cold metal transition base welding; preferably, the welding equipment is a FRONIUSTPS4000CMTAdvanced welding machine, the welding wire is ER70S-6, and the welding wire diameter is 1 mm.

[0027] Further, if Figures 1 to 4 As shown, in S3, the welding parameters of the cold metal transition base welding include: welding voltage of 10 to 12 V, welding current of 180 to 200 A, welding speed of 400 to 600 mm / min, wire feeding speed of 6 m / min, shielding gas of 82% argon and 18% carbon dioxide, and gas flow rate of 20 L / min.

[0028] In S3, the welding parameters of the filling welding by the metal electrode gas shielded welding include: the welding voltage is 22 to 24V, the welding current is 220 to 240A, the welding speed is 400 to 600mm / min, the wire feeding speed is 12 to 14m / min, the shielding gas is 82% argon + 18% carbon dioxide gas, and the gas flow rate is 20L / min; in S3, the welding parameters of the cap layer by the metal electrode gas shielded welding include: the welding voltage is 22 to 24V, the welding current is 170 to 190A, the welding speed is 400 to 600mm / min, the wire feeding speed is 8 to 10m / min, the shielding gas is 82% argon + 18% carbon dioxide gas, and the gas flow rate is 20L / min.

[0029] In this embodiment, the welding parameters are set, the welding robot is started, and cold metal transition base welding and consumable electrode gas shielded welding are used to perform single-sided welding and double-sided forming on the vertical pipe from the outside. The vertical pipe is welded in multiple layers and multiple passes, and the layer spacing is controlled at 3 to 5 mm. After each layer of weld is completed, slag is removed, and base welding, filling welding and cover welding are performed in sequence.

[0030] Preferably, the welding program is set on the RCU5000 remote control that comes with the welding machine. When editing the welding program on the RCU5000 remote control, follow the following steps: (1) select welding materials; (2) determine the welding wire diameter; (3) confirm the shielding gas; (4) select the welding process.

[0031] Further, if Figures 1 to 4 As shown, the base layer welding of the marine riser adopts cold metal transition welding for the base welding process, and the assembly gap of the marine riser is controlled at 0mm; during the process of gas metal arc welding, the first layer is welded in a single pass, and the subsequent weld layers are filled by separate passes to ensure a good weld forming effect; before the process of cap welding by gas metal arc welding, when the weld fill is 1 to 3mm away from the outer wall of the pipeline, gas metal arc welding for capping is performed.

[0032] In this embodiment, air fatigue specimens of the same size and position are taken from the riser welded by cold metal transfer backing welding plus metal arc welding and the riser welded by conventional metal arc welding, and high cycle fatigue tests are carried out in an air environment to determine the air fatigue performance of the riser weld joints.

[0033] Preferably, the air fatigue test is carried out in a GPS200 electromagnetic resonance high-frequency fatigue testing machine at room temperature, with a stress ratio of 0.1 and a loading frequency of 115 to 135 Hz. The excess height of the cover surface is removed from the sample, and the weld root is retained.

[0034] Corrosion fatigue specimens of the same size and position were taken from the risers with cold metal transfer backing welding plus metallurgical electrode gas shielded welding, filling and capping welding and traditional metallurgical electrode gas shielded welding, and corrosion ring fatigue tests were carried out to determine the corrosion fatigue properties of the riser welded joints.

[0035] Preferably, the corrosion fatigue experiment is carried out in a CORTEST slow strain rate stress corrosion fatigue testing machine at room temperature, the corrosion solution is 0.001M Na2S2O3+NACE A (5% NaCl+0.5% CH3COOH), the stress ratio is 0.1, the loading frequency is 1Hz, the sample removes the cover excess height, and retains the weld root.

[0036] As a preferred embodiment: this example uses cold metal transition backing welding plus metal arc welding filling and capping welding to perform 2G narrow gap welding on φ450mm*30mm X65 pipeline steel, specifically including the following steps: (1) Reasonably design the groove size according to different materials and different pipe diameters and wall thicknesses. The specific groove size is as follows: Figure 1 As shown; (2) Process the groove according to the designed groove, assemble the two pipe base materials 2G to be welded, clean the groove, and wipe the groove surface with alcohol or acetone to remove oil stains; (3) Configure welding equipment, including welding wire, welding robot, welding machine power supply for cold metal transition welding, water tank, and welding gun for cold metal transition welding; (4) According to the process assessment, the welding procedure and welding parameters are pre-set, including cold metal transfer root welding (CMT) and gas shielded arc welding (GMAW). CMT is used for root welding, and the welding voltage is set to 12V, the welding current is 190A, the welding speed is 420mm / min, the wire feeding speed is 6m / min, the shielding gas is 82%Ar+18%CO2, and the gas flow rate is 20L / min; GMAW is used for filling welding, and the welding voltage is set to 22~24V, the welding current is 228A, the welding speed is 600mm / min, the wire feeding speed is 13m / min, the shielding gas is 82%Ar+18%CO2, and the gas flow rate is 20L / min; GMAW is used for cap welding, and the welding voltage is set to 22~24V, the welding current is 175A, the welding speed is 600mm / min, the wire feeding speed is 9m / min, the shielding gas is 82%Ar+18%CO2, and the gas flow rate is 20L / min.

[0037] (5) Multi-layer and multi-pass welding technology is used to perform CMT base welding and GMAW filling and capping welding on the riser in sequence, including 1 layer of base welding, 5 layers of filling and 9 passes, and 1 layer of capping and 2 passes. The spacing between the filling and capping layers is controlled at 3 to 5 mm. After each layer of weld is completed, slag is removed. The specific weld distribution diagram is shown in the figure. Figure 2 As shown; (6) Take an air fatigue test specimen from the obtained riser. The specific dimensions are as follows: Figure 3 As shown, the specimen was subjected to high cycle fatigue test in air environment with the cover excess height removed and the weld root retained, at a stress ratio of 0.1 and a loading frequency of 115-135Hz, to determine the air fatigue performance of the riser weld joint and compare it with the traditional GMAW welded riser. (7) Take corrosion fatigue specimens from the obtained riser. The specific dimensions are as follows: Figure 4As shown, the cover excess height of the sample was removed and the weld root was retained. The corrosion fatigue test was carried out in 0.001M Na2S2O3+NACE A (5%NaCl+0.5%CH3COOH) solution at a stress ratio of 0.1 and a loading frequency of 1Hz to determine the corrosion fatigue performance of the riser weld joint and compare it with the traditional GMAW welded riser.

[0038] The air fatigue performance of the welded joint mentioned in the present invention is excellent: from the air fatigue SN curve ( Figure 5 ) It can be seen that the SN curve of the joint with CMT base welding and GMAW filling and capping welding is above the SN curve of the traditional GMAW welded riser joint. The fatigue performance of the riser joint with CMT base welding has been greatly improved. At the same time, the fatigue performance of the riser joint with CMT base welding is far above the DNV-RP-C203 design curve.

[0039] The corrosion fatigue performance of the welded joint mentioned in the present invention is excellent: from the corrosion fatigue SN curve ( Figure 6 ) It can be seen that the SN curve of the joint with CMT base welding and GMAW filling and capping welding is above the SN curve of the traditional GMAW welded riser joint. The corrosion fatigue performance of the riser joint through CMT base welding has been greatly improved.

[0040] The riser high fatigue life welding method based on cold metal transfer welding process uses cold metal transfer welding to make the marine riser weld shape and quality good. Cold metal transfer welding combines wire feeding movement with short-circuit transition, which can achieve stable arc control and precise energy input. The weld root is smooth and beautiful, the residual height at the weld root is almost 0, the stress concentration is small, the fatigue crack initiation and expansion are difficult, and the fatigue life can be effectively improved.

[0041] The weld grains of the present application are fine and the heat-affected zone is narrow. At the moment of short-circuit transition in cold metal transition welding, the current is 0, and the welding heat input provided is smaller than that of traditional consumable gas shielded welding. The weld grains are finer, the heat-affected zone is narrow, and the microstructure is relatively uniform. The weld root of the base welded by cold metal transition welding has excellent fatigue performance, and the corrosion fatigue performance of the riser joint base welded by cold metal transition welding is greatly improved.

[0042] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the embodiments here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A method for welding a riser with high fatigue life by cold metal transfer welding process, characterized in that: The base layer of the marine riser weld joint is welded by cold metal transfer welding, and the filling layer and the cover layer are welded by metal arc gas shielding. The welding includes the following steps: S1. Obtaining a groove for welding the marine riser based on the material, diameter and wall thickness of the marine riser; S2. After assembling the two pipe base materials to be welded, clean the groove; S3. According to the single-sided welding and double-sided forming method, multi-layer and multi-pass welding is performed on the marine riser from the outside, and cold metal transition base welding, metal-conductive gas shielded welding, filling welding and cap welding are performed in sequence to obtain a welded marine riser.

2. The method for high fatigue life welding of a riser using a cold metal transfer welding process according to claim 1, characterized in that: In S1, during the process of obtaining the groove, the groove is a U-shaped narrow gap groove, the blunt edge thickness is 1.3 to 1.8 mm, the upper groove angle is 3 to 10 degrees, and the R3-R5 transition is adopted.

3. The method for high fatigue life welding of a riser using a cold metal transfer welding process according to claim 1, characterized in that: In S2, during the cleaning of the groove, alcohol or acetone is used to wipe the groove surface to remove oil stains.

4. The method for high fatigue life welding of a riser using a cold metal transfer welding process according to claim 1, characterized in that: In S3, during the multi-layer and multi-pass welding of the marine riser from the outside, the layer spacing is 3 to 5 mm, and slag removal is performed after each layer of weld is completed.

5. The method for high fatigue life welding of a riser using a cold metal transfer welding process according to claim 1, characterized in that: In S3, the welding parameters of cold metal transfer base welding include: welding voltage of 10 to 12 V, welding current of 180 to 200 A, welding speed of 400 to 600 mm / min, wire feeding speed of 6 m / min, shielding gas of 82% argon and 18% carbon dioxide, and gas flow rate of 20 L / min.

6. The method for high fatigue life welding of a riser using a cold metal transfer welding process according to claim 1, characterized in that: In S3, the welding parameters for filling welding by metal electrode gas shielded welding include: welding voltage of 22 to 24 V, welding current of 220 to 240 A, welding speed of 400 to 600 mm / min, wire feeding speed of 12 to 14 m / min, shielding gas of 82% argon gas + 18% carbon dioxide gas, and gas flow rate of 20 L / min.

7. The method for high fatigue life welding of a riser using a cold metal transfer welding process according to claim 1, characterized in that: In S3, the welding parameters of the metal electrode gas shielded welding cap layer include: welding voltage of 22 to 24 V, welding current of 170 to 190 A, welding speed of 400 to 600 mm / min, wire feeding speed of 8 to 10 m / min, shielding gas of 82% argon gas + 18% carbon dioxide gas, and gas flow rate of 20 L / min.

8. The method for high fatigue life welding of a riser using a cold metal transfer welding process according to claim 1, characterized in that: The base layer welding of the marine riser adopts cold metal transition welding for base welding process, and the assembly gap of the marine riser is controlled at 0mm.

9. The method for high fatigue life welding of a riser using a cold metal transfer welding process according to claim 7, characterized in that: During the process of metal-metal gas shielded welding, the first layer is welded in a single pass, and the subsequent layers are filled in by separate passes to ensure a good weld formation effect.

10. The method for high fatigue life welding of a riser using a cold metal transfer welding process according to claim 7, characterized in that: Before the process of cap welding by metal-metal-shielded gas welding, metal-metal-shielded gas cap welding is performed when the weld fill is 1 to 3 mm away from the outer wall of the pipe.

Images