Welding method for ocean wind power single-pile foundation super-thick plate

Abstract

The invention relates to the technical field of welding, in particular to an ocean wind power single pile foundation super-thick plate welding method which comprises the steps that X-shaped groove plates are adopted for plate assembly, and the groove angle, the assembly gap and the truncated edge of each plate meet the assembly technical requirements; the plate is subjected to backing welding through a flux-cored wire, and the welding method is semi-automatic gas shielded welding; the plate is filled with solid submerged arc welding wires and subjected to cosmetic welding, and the welding method is double-wire submerged arc welding. Appropriate plates are selected for assembly so as to reduce gaps generated during assembly of the plates and meet technical requirements, deviation of backing welding is reduced through gas shielded welding, then double-wire submerged arc welding is used for filling and cosmetic welding, and meanwhile the problems that weld metal of the double-wire submerged arc welding is low in impact toughness and low in welding quality are solved by setting appropriate welding parameters. The problems that the welding efficiency of an original single wire is low, and the welding material waste is high are solved, and the production cost in the welding work is reduced.

Description

Technical Field

[0001] The present invention relates to the field of welding technology, and particularly to a welding method for ultra-thick plates of a monopile foundation for offshore wind power. Background Art

[0002] Currently, the global offshore wind power industry is booming and has gradually become a force that cannot be ignored in the field of renewable energy. Against this development background, the monopile foundation for offshore wind power, as a key part to support wind power equipment, shows its unique application characteristics, and the wind power monopile foundation is also moving towards ultra-thick plates and large-scale.

[0003] In the welding production process of wind power monopile foundations, for the welding of large-diameter ultra-thick plates, double-sided welding is usually adopted. The first welding process uses CO 2 gas shielded arc welding for backing welding, and then single-wire submerged arc welding is used for filling and surfacing on the first side; after the welding on the first side is completed, carbon arc air gouging is used for root cleaning on the reverse side. After the carbon arc air gouging is completed, the reverse side groove is polished clean and smooth, and then single-wire submerged arc welding is continued for filling and surfacing. Using this welding method for the welding production of ultra-thick plates takes a long time and has low efficiency. At the same time, the increase in the number of welding layers and passes for ultra-thick plates will lead to an increase in the waste of welding materials during the welding process and an increase in production costs. Summary of the Invention

[0004] The purpose of the present invention is to solve the problems of low efficiency and large waste of welding materials in the existing welding technology when welding ultra-thick plates of wind power monopiles, and to provide a welding method for ultra-thick plates of a monopile foundation for offshore wind power, which can improve the welding efficiency of ultra-thick plates of wind power monopiles and reduce the waste of welding materials.

[0005] To achieve the above purpose, the present invention provides a welding method for ultra-thick plates of a monopile foundation for offshore wind power, including the following steps:

[0006] S1. Using X-shaped groove plates for plate assembly, so that the groove angle, assembly gap and root face of the X-shaped groove plates meet the assembly technical requirements;

[0007] S2. Using flux-cored wire for backing welding of the X-shaped groove plates, and the welding method is semi-automatic gas shielded arc welding;

[0008] S3. Using solid submerged arc welding wire for filling and surfacing welding of the X-shaped groove plates, and the welding method is twin-wire submerged arc welding.

[0009] Preferably, the inner groove of the X-shaped groove plate is 50°, the outer groove is 45°, the root faces of the inner groove and the outer groove are both 2 mm, and when assembling, the groove gap between the X-shaped groove plates is 2 mm.

[0010] Preferably, the welding parameters of the semi-automatic gas shielded welding include: the shielding gas is CO 2 , the dry elongation of the welding wire is 15-25 mm, the flow rate of the shielding gas is 15 L / min-20 L / min, the welding current is 180-220 A, the welding voltage is 22-26 V, and the welding heat input is 1.0 KJ / mm-1.3 KJ / mm.

[0011] Preferably, the welding parameters of the twin-wire submerged arc welding include: the current of the front wire with direct current straight polarity is 580-630 A, the voltage of the front wire current is 27-30 V, the current of the rear wire with alternating current is 550-600 A, the voltage of the rear wire current is 29-32 V, the welding speed is 55-70 cm / min, and the welding heat input is 1.3-2.1 KJ / mm.

[0012] Through the above technical solutions, by selecting appropriate X-type groove plates for assembly to reduce the gap generated during the assembly of the plates and meet the technical requirements, the semi-automatic gas shielded welding with flux-cored wire is used to further reduce the deviation during the root pass welding, and then the twin-wire submerged arc welding method is used for filling and capping welding. At the same time, by setting appropriate welding parameters, the problem that the twin-wire submerged arc welding itself may cause the impact toughness of the weld metal to be low and the impact toughness of the welded metal to be unqualified is solved, the problem of low welding efficiency and high waste of welding materials in the original single-wire welding is solved, and the production cost in the welding work is reduced. Brief Description of the Drawings

[0013] Figure 1 is the flowchart of the welding method for the ultra-thick plate of the offshore wind power monopile foundation of the present invention;

[0014] Figure 2 is the groove schematic diagram of the test plate base material of the present invention;

[0015] Figure 3 is the schematic diagram of the distance between the front wire and the rear wire of the submerged arc welding machine of the present invention. Detailed Description of the Preferred Embodiments

[0016] The following detailed description of the specific embodiments of the present invention is provided with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit the present invention.

[0017] Example:

[0018] The welding method for the ultra-thick plate of the offshore wind power monopile foundation proposed in this embodiment, as Figure 1 shown, includes the following steps:

[0019] S1. Use X-type groove plates for plate assembly to make the groove angle, assembly gap and root face of the X-type groove plates meet the assembly technical requirements;

[0020] S2. For the backing welding of the X-type groove plate, a flux-cored wire is used, and the welding method is semi-automatic gas shielded welding;

[0021] S3. For the filling and capping welding of the X-type groove plate, a solid submerged arc welding wire is used, and the welding method is twin-wire submerged arc welding.

[0022] Since the cylinder of the offshore wind power monopile foundation is made of ultra-thick plates with a thickness of not less than 60 mm and the cylinder diameter is large, for such a large structural component, whether it is a longitudinal seam or a circumferential seam, there will inevitably be errors during assembly, resulting in uneven gaps. Therefore, a combined welding method of flux-cored wire gas shielded welding and twin-wire submerged arc welding is used during welding. The backing welding with the flux-cored wire gas shielded welding can adopt a straight welding or oscillating welding technique to compensate for the assembly deviation of inconsistent gaps. The twin-wire submerged arc welding is used for the front and back filling and capping welding, which can give full play to the high efficiency of the twin-wire submerged arc welding.

[0023] In this embodiment, the X-type groove plate selects the EN10025-3 S355ML material, and the factory supply state is TMCP. In order to meet the sampling requirements for the weld quality inspection after welding, two X-type groove plates are selected as the test plate base materials in the embodiment.

[0024] As Figure 2 shown, each X-type groove plate is 1000 mm long, 270 mm wide, and 90 mm thick. After comprehensively considering the test plate thickness and the processing capacity of its own equipment, the X-type groove adopts a 1 / 3 and 2 / 3 ratio distribution. The 1 / 3 side is the outside groove, and the outside groove angle is 45°. The 2 / 3 side is the inside groove, and the inside groove angle is 50°. The groove gap is 2 mm, and the root face is 2 mm.

[0025] In the technical solution provided by the present invention, a combined welding method of flux-cored wire gas shielded welding and twin-wire submerged arc welding is used during welding. The backing welding with the flux-cored wire gas shielded welding can adopt a straight welding or oscillating welding technique to compensate for the assembly deviation of inconsistent gaps caused by the rolling of the test plate base material and the large diameter. The twin-wire submerged arc welding is used for the front and back filling and capping, which can give full play to the high efficiency of the twin-wire submerged arc welding.

[0026] In this embodiment, when using the flux-cored wire for backing welding, a flux-cored wire with the wire grade of GFR-81K2 produced by Kunshan Jingqun Technology Co., Ltd. is selected for semi-automatic gas shielded welding. First, weld the inside groove of the test plate, and then weld the outside groove. When welding the outside groove, use carbon arc air gouging to remove the flux-cored wire backing part at the root of the weld, and grind the inside surface and both sides of the groove with a angle grinder until the groove is completely exposed with metallic luster. The welding parameters include: the shielding gas is CO 2, the dry extension of the welding wire is 15 - 25 mm, the flow rate of the shielding gas is 15 L / min - 20 L / min, the welding current is 180 - 220 A, the welding voltage is 22 - 26 V, and the heat input of welding is 1.0 KJ / mm - 1.3 KJ / mm.

[0027] As Figure 3 shown, when using solid submerged arc welding wire for filling and capping welding, select the submerged arc welding wire produced by Voestalpine Bohler Welding (China) Co., Ltd. with the brand number T Union SANi1 and cooperate with the welding flux UV C 418TT-M for double-wire submerged arc welding. During welding, in order to make the front and rear two welding wires share a common molten pool, the front wire should be vertical and the rear wire should be inclined about 15°, and the distance between the front and rear two welding wires is about 20 mm. In order to reduce the heat input of welding, generally a larger welding speed is adopted during welding to avoid large grains in the weld. The front arc is direct current, with a large current and a low arc voltage, giving full play to the penetration of the direct current arc to obtain a large penetration depth; the rear arc is alternating current, with a relatively small welding current and a large arc voltage to increase the weld width, thus forming a beautiful weld appearance. Among them, the double-wire submerged arc welding parameters include: the current of the front wire with straight polarity is 580 - 630 A, the voltage of the front wire current is 27 - 30 V, the current of the rear wire with alternating current is 550 - 600 A, the voltage of the rear wire current is 29 - 32 V, the welding speed is 55 - 70 cm / min, and the heat input of welding is 1.3 - 2.1 KJ / mm.

[0028] In this embodiment, after the welding of the test plate base metal is completed, first visually inspect the test plate base metal to check the weld reinforcement, width, and whether there are any undercuts or other appearance defects. After inspection, the appearance of the test plate meets the requirements of ISO 5817 Class B. After passing the visual inspection, the test plate is placed at room temperature for 48 hours, and then the NDT inspectors perform magnetic particle inspection and ultrasonic inspection on the test plate. The inspection results meet the requirements of ISO 5817 Class B, and there are no defects exceeding the standard.

[0029] After the NDT inspection of the test plate is completed, send the test plate to the laboratory for sampling according to the ISO 15614-1 standard and conduct tensile, bending, and impact tests. The test results are shown in Table 1.

[0030] Table 1 Summary of the test results of the mechanical properties of the test plate

[0031]

[0032] Among them, FL is the fusion line; FL + 2 mm is the position 2 mm away from the fusion line extending towards the base metal side.

[0033] From the test results in Table 1, it can be seen that the test results of all specimens meet the requirements of DNV-OS-C401, and the mechanical properties are qualified.

[0034] The test results prove that for the test plate with the material S355ML, the flux-cored wire GFR-81K2 is used for the root pass of CO₂ gas shielded welding, and for the multi-wire submerged arc welding, the TUnion SANi1 wire with a diameter of 4 mm is selected to match the welding flux UV C418TT-M for filling and surfacing. The welding can be successfully completed. After non-destructive testing of the welded test plate, no excessive defects are found. Then, through tensile, bending and impact tests and other verifications, the tensile strength of the S355ML test plate is usually between 470 and 630 MPa, and the average tensile strength of the specimen is 578 MPa; when the test temperature of the specimen is -40 °C, the impact value of each specimen reaches more than 100 J. The test results prove that the impact value of the specimen far exceeds the standard requirements, and the comprehensive mechanical properties of the weld are good, and a weld with qualified quality can be obtained. While solving the problem that multi-wire submerged arc welding may lead to relatively low impact toughness of the weld metal, the welding efficiency of the ultra-thick plate of the offshore wind power monopile foundation is also effectively improved.

[0035] The preferred embodiments of the present invention have been described in detail above in conjunction with the accompanying drawings. However, the present invention is not limited thereto. Within the technical concept of the present invention, various simple modifications can be made to the technical solutions of the present invention. To avoid unnecessary repetition, the present invention will not separately describe various possible combinations. But these simple modifications and combinations should also be regarded as the content disclosed by the present invention and fall within the protection scope of the present invention.

Claims

1. A welding method for ultra-thick plates of offshore wind power monopile foundations, characterized in that: The following steps are involved: S1. Use X-shaped grooved plates to assemble plates, so that the groove angle, assembly gap and blunt edge of the X-shaped grooved plates meet the assembly technical requirements; S2, X-type groove plate uses flux-cored wire for base welding, and the welding method is semi-automatic gas shielded welding; S3 and X-type groove plates are filled and covered with solid submerged arc welding wire, and the welding method is double-wire submerged arc welding.

2. The welding method of super-thick plate of offshore wind power monopile foundation according to claim 1 is characterized in that: The inner groove of the X-shaped groove plate is 50°, the outer groove is 45°, the blunt edges of the inner groove and the outer groove are both 2mm, and when assembled, the groove gap of the X-shaped groove plate is 2mm.

3. The welding method of super thick plate of offshore wind power monopile foundation according to claim 1 is characterized in that: The welding parameters of the semi-automatic gas shielded welding include: the shielding gas is CO2, the dry extension of the welding wire is 15 to 25 mm, the shielding gas flow rate is 15 L / min to 20 L / min, the welding current is 180 to 220 A, the welding voltage is 22 to 26 V, and the welding heat input is 1.0 KJ / mm to 1.3 KJ / mm.

4. The method for welding super-thick plates for offshore wind power monopile foundation according to claim 1, characterized in that: The welding parameters of the double-wire submerged arc welding include: the DC positive connection front wire current is 580-630A, the voltage of the front wire current is 27-30V, the AC rear wire current is 550-600A, the voltage of the rear wire current is 29-32V, the welding speed is 55-70cm / min, and the welding heat input is 1.3-2.1KJ / mm.

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