High-steel-grade pipeline welding process based on ultra-small dip angle butt joint
By adopting ultra-small inclination butt technology and shallow groove design in welding of high-wall thick pipes, the problems of high difficulty and cost of welding of large wall thickness pipes are solved, and efficient and low-cost welding results are achieved.
Patent Information
- Application Number
- CN202510756171.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-06-08
- Publication Date
- 2025-08-12
AI Technical Summary
The increase in wall thickness of high-steel pipes leads to high welding difficulty and cost, and the inclination design of existing welding technical standards leads to the problem of large amount of welding materials and low welding efficiency.
The welding process of high-steel pipes with ultra-small inclination angle is adopted. By setting shallow grooves in the bevel and filling welding is performed under specific welding process parameters, the thickness of single-layer welding and the order of multi-layer welding is controlled to reduce the amount of welding material and improve welding efficiency.
Significantly reduce the welding cost and difficulty of high-steel grade pipes with large wall thickness, improve welding efficiency, and ensure weld quality.
Smart Images
Figure CN120460853A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of pipeline welding, and in particular to a high-grade steel pipeline welding process based on ultra-small angle butt welding. Background Art
[0002] In recent years, the increasing demand for high-pressure gas transmission through pipelines has driven the development of high-grade steel pipelines, enabling the transportation of natural gas at even higher pressures. High-grade steel pipelines include X52, X60, X65, X70, and X80. Currently, most gas pipeline projects utilize X70 and X80 steel grades.
[0003] Although the wall thickness of high-grade steel pipes is trending toward thinner walls in the natural gas transmission sector, ultra-high-pressure fluid transportation still requires thicker wall thicknesses (no less than 13 mm, and even up to 20 mm or more) to meet pressure requirements. However, every approximately 2 mm increase in wall thickness significantly increases welding difficulty and cost. This is particularly true for high-grade steel pipes with a wall thickness of 18 mm or more, which can lead to extremely low welding efficiency and high costs. Furthermore, current welding standards specify the types and angles of pipe weld grooves (i.e., the inclination angle, commonly referred to as the groove angle, in this context). For example, for V-grooves with wall thicknesses of 9-26 mm, the lower limit is 55°. However, for high-grade steel pipes with large wall thicknesses, welds corresponding to this inclination angle require a large amount of welding material. Therefore, it is necessary to develop a high-grade steel pipe welding process based on ultra-low inclination (this invention defines an inclination angle as at least 3° below the existing lower limit). Summary of the Invention
[0004] At least in order to solve the technical problems mentioned in the background technology, the present invention aims to provide a high-grade steel pipeline welding process based on ultra-small angle butt welding.
[0005] The present invention adopts the following technical solutions.
[0006] A high-grade steel pipeline welding process based on ultra-small angle butt welding, comprising the following steps: Step 1: Prepare the pipe workpiece to be welded and process a groove at the end of the pipe workpiece. The wall thickness of the pipe workpiece is not less than 13 mm. The groove adopts a U-shaped groove, a Y-shaped groove, or a V-shaped groove. A shallow groove with a depth and width of no more than 3 mm is provided in the upper part of the groove. Step 2: Butt the pipe workpieces with processed welding grooves and then perform spot welding; Step 3, performing bottom welding; Step 4: Perform filler welding and cap welding.
[0007] Preferably, when the wall thickness of the pipe workpiece is 12-18 mm, the groove adopts a Y-shaped groove or a V-shaped groove, and the angle between the two slope surfaces is 30-65°.
[0008] Preferably, when the wall thickness of the pipe workpiece is not less than 18 mm, the groove adopts a U-shaped groove, the angle between the middle parts of the two slopes is 60-78°, and the angle between the upper part of any slope and the vertical surface is 0-15°.
[0009] Preferably, the shallow grooves are annular grooves arranged in an annular manner or radially arranged linear grooves, and the spacing between adjacent shallow grooves is 0.5 to 0.6 times the diameter of the welding rod used.
[0010] Furthermore, in the process of implementing filling welding in the shallow groove height range, for the weld path of the direct fusion shallow groove, the single-layer welding thickness is controlled to 0.6-0.8 times the standard welding thickness corresponding to the welding rod; for the weld path of the unfused shallow groove, the single-layer welding thickness is controlled to the standard welding thickness corresponding to the welding rod; wherein, the standard welding thickness corresponding to the welding rod refers to the filling layer thickness obtained by welding with the welding rod under the set standard welding process parameters.
[0011] Preferably, during the filling welding process in the shallow groove height range, after 2-3 layers of single-layer welds that directly fuse the shallow groove are stacked continuously, the area where the shallow groove is not fused is welded.
[0012] Preferably, the gap at the root of the groove is controlled to be 1-3 mm.
[0013] Beneficial effect: The solution of the present invention can not only significantly reduce the increase in welding difficulty caused by the increase in wall thickness of high-grade steel pipes, but also greatly reduce the welding cost and welding difficulty of large-wall-thick high-grade steel pipes, and improve the welding efficiency of large-wall-thick high-grade steel pipes. BRIEF DESCRIPTION OF THE DRAWINGS
[0014] Figure 1 Schematic diagram of the V-shaped groove of the weld in the existing scheme; Figure 2 Schematic diagram of the V-shaped groove of the weld in Example 1; Figure 3 Schematic diagram of the weld in Example 1; Figure 4 Schematic diagram of the U-shaped groove of the weld in Example 2; Figure 5 Schematic diagram of the weld in Example 2. DETAILED DESCRIPTION
[0015] The following is a clear and complete description of the technical solutions of the present invention in conjunction with the accompanying drawings. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention. Example 1
[0016] A high-grade steel pipe welding process based on ultra-small angle butt welding is used to weld the butt weld of an X80 steel grade pipe with a specification of DN200*12.8mm. The steps include: Step 1: Prepare the pipe workpiece 1 to be welded and process the groove at the end of the pipe workpiece 1. The wall thickness of the pipe workpiece 1 is 12.8 mm. The groove adopts a V-shaped groove, and a shallow groove 3 (with a V-shaped cross section) with a depth and width of no more than 2 mm is set in the middle and upper part of the groove (the middle and upper parts defined based on the height direction of the slope, the same below). Figure 1 As shown; in this embodiment, the angle between the two slopes 2 is 30°, and the shallow grooves 3 are annularly arranged ring grooves (the ring grooves are machined half an hour before welding. If the ring grooves are machined before leaving the factory, it is necessary to apply an anti-corrosion layer or a protective film on the slope 2 of the pipe workpiece 1). The spacing between adjacent shallow grooves 3 (the spacing in the present invention refers to the distance between the edges of adjacent shallow grooves 3) is 0.5 times the diameter of the welding rod (φ4mm) used (i.e., 2-2.4mm, taking into account the error range), and the gap at the root of the groove is controlled to be 2mm; Step 2: butt-join the pipe workpiece 1 with the groove processed, and then perform spot welding; Step 3, performing bottom welding; Step 4: Use CHE657GX welding rod produced by Atlantic Company to perform filler welding and cap welding. Figure 2 As shown, During the filling welding process in the height range of the shallow groove 3, for the weld path of the direct fusion shallow groove 3, the single-layer weld thickness is controlled to be 0.8 times the standard weld thickness of the electrode (that is, the thickness of the single-layer molten pool 4 directly fused with the slope surface 2 is 0.8 times the standard weld thickness of the electrode); for the weld path of the unfused shallow groove 3, the single-layer weld thickness is controlled to be the standard weld thickness of the electrode (that is, the thickness of the single-layer molten pool 5 not fused with the slope surface 2 is the standard weld thickness of the electrode); each time 2-3 layers of single-layer welds of the direct fusion shallow groove 3 are stacked continuously, the area of the unfused shallow groove 3 (that is, the area between the single-layer molten pools 4 on both sides) is welded; The standard welding thickness of the electrode refers to the thickness of the filler layer obtained by welding with the electrode under the set standard welding process parameters. The set standard welding process parameters include welding current 160A, voltage 24V, welding speed 28cm / min, preheating temperature 180℃, and hydrogen removal treatment at 200℃ / 2h. In this scheme, welding is carried out according to standard welding process parameters to obtain a weld with an unfused shallow groove 3, and the thickness of the filling layer obtained by welding with a φ4mm welding rod is 2~2.5mm; when welding the weld with a directly fused shallow groove 3, the welding speed is adjusted to 31cm / min based on the standard welding process parameters, and the corresponding thickness of the single-layer molten pool 4 directly fused with the slope surface 2 is 1.6~2mm (the thickness range is mainly due to the weld texture and the shallow groove 3).
[0017] Comparative Example 1, a high-grade steel pipeline welding process based on ultra-small angle butt jointing is different from Example 1 in that: the shallow groove 3 is omitted, and during the filling welding process, the single-layer welding thickness is always controlled to the standard welding thickness corresponding to the welding rod.
[0018] Comparative Example 2, a high-grade steel pipeline welding process based on ultra-small angle butt welding, differs from Example 1 in that the included angle between the two slope surfaces 2 is 45° (this included angle of 45° is the lower limit specified by technical standards in this field), the gap at the root of the groove is controlled to 4 mm, and the shallow groove 3 is omitted. During the filling welding process, the single-layer weld thickness is always controlled to the standard welding thickness corresponding to the welding rod. Example 2
[0019] A high-grade steel pipe welding process based on ultra-small angle butt welding is used to weld the butt weld of an X80 steel grade pipe with a specification of DN300*21.44mm. The steps include: Step 1: Prepare the pipe workpiece 1 to be welded and process the groove at the end of the pipe workpiece 1. The wall thickness of the pipe workpiece 1 is 21.44 mm. The groove adopts a U-shaped groove and a shallow groove 3 (V-shaped cross section) with a depth and width of no more than 3 mm is set in the upper part of the groove. Figure 3 As shown; in this embodiment, the angle a between the lower middle portions of the two slope surfaces 2 is 60° (i.e., the angle a corresponding to h=8mm is 60°), the angle between the upper portion of any slope surface 2 and the vertical surface is 0° (i.e., the upper portion of the slope surface 2 is a vertical surface, β=0°), the shallow grooves 3 are annularly arranged ring grooves (machined ring grooves), the spacing between adjacent shallow grooves 3 is 0.5 times the diameter of the welding rod (φ4mm) used (i.e., 2-2.4mm, taking into account the error range), and the gap at the root of the groove is controlled to be 2mm; Step 2: butt-join the pipe workpiece 1 with the groove processed, and then perform spot welding; Step 3, performing bottom welding; Step 4: Use CHE657GX welding rod produced by Atlantic Company to perform filler welding and cap welding. Figure 4 As shown, During the filling welding process in the height range of the shallow groove 3, for the weld path of the direct fusion shallow groove 3, the single-layer weld thickness is controlled to 0.6 times the standard weld thickness of the welding rod (that is, the thickness of the single-layer molten pool 4 directly fused with the slope surface 2 is 0.6 times the standard weld thickness of the welding rod); for the weld path of the unfused shallow groove 3, the single-layer weld thickness is controlled to the standard weld thickness of the welding rod (that is, the thickness of the single-layer molten pool 5 not fused with the slope surface 2 is the standard weld thickness of the welding rod); after each single-layer weld of the direct fusion shallow groove 3 is stacked continuously for 2-3 layers, the area of the unfused shallow groove 3 is welded; Among them, the standard welding thickness corresponding to the welding rod refers to the thickness of the filling layer obtained by welding with the welding rod under the set standard welding process parameters. The set standard welding process parameters are (welding current 170A, voltage 27V, welding speed 30cm / min, preheating temperature 180℃, hydrogen removal treatment 200℃ / 2h); in this scheme, welding is carried out according to the standard welding process parameters to obtain the weld of the unfused shallow groove 3, and the thickness of the filling layer obtained by welding with a φ4mm welding rod is 2.2~2.6mm; when welding the weld of the directly fused shallow groove 3, the welding speed is adjusted to 35cm / min on the basis of the standard welding process parameters, and the corresponding thickness of the single-layer molten pool 4 directly fused with the slope 2 is 1.32~1.56mm.
[0020] Comparative Example 3 is a high-grade steel pipeline welding process based on ultra-small angle butt welding. The difference between it and Example 2 is that the shallow groove 3 is omitted, and during the filling welding process, the single-layer welding thickness is always controlled to the standard welding thickness corresponding to the welding rod.
[0021] Comparative Example 4, a high-grade steel pipe welding process based on ultra-small angle butt joint, is different from Example 2 in that the angle β between the two slopes 2 is 8° (combined with Figure 5 As shown, this angle β=8° is the lower limit value specified by the technical standards in this field), and the shallow groove 3 is omitted. During the filling welding process, the single-layer welding thickness is always controlled to be the standard welding thickness corresponding to the welding rod.
[0022] The schemes in the examples and comparative examples were used, and the same senior welding technician with ten years of experience performed welding under the same working environment. The results were as follows: using the scheme in Example 1, the time required to complete one weld was 1 hour, and the resulting weld passed the RT test, and the amount of welding rods used was 21; using the scheme in comparative example 1, the time required to complete one weld was 1.1 hours, but the resulting weld had four incomplete fusion defects and multiple porosity defects after RT testing, and the amount of welding rods used was 20; using the scheme in comparative example 2, the time required to complete one weld was 1.5 hours, and the resulting weld passed the RT test, and the amount of welding rods used was 25; Using the solution in Example 2, the time required to complete a weld was 3.5 hours, and the resulting weld passed the RT test, with 49 welding rods used. Using the solution in Comparative Example 3, the time required to complete a weld was 3.8 hours, but the resulting weld had eight incomplete fusion defects and multiple porosity defects after RT testing, with 47 welding rods used. Using the solution in Comparative Example 4, the time required to complete a weld was 4.1 hours, and the resulting weld passed the RT test, with 58 welding rods used. It should be noted that in Comparative Examples 2 and 3, special attention should be paid to the arc starting angle of the welding rod corresponding to the weld of the direct fusion shallow groove 3, otherwise slag inclusion is very likely to occur. Compared with the solutions of Comparative Examples 2 and 4, the solutions of Examples 1 and 2 can significantly reduce the amount of welding rods and the welding time (higher welding efficiency) while ensuring the quality of the weld. The corresponding welding costs (material costs and labor time costs) are greatly reduced, which can significantly reduce the welding cost and difficulty of large-wall thick high-grade steel pipes and improve the welding efficiency of large-wall thick high-grade steel pipes.
[0023] In the present invention, the key points include: a shallow groove with a depth and width of no more than 3 mm is provided in the upper middle part of the groove. Under specific welding process parameters, this shallow groove is more conducive to the smooth combination of the electrode molten droplet and the base material (compared to the plain wall slope), thereby significantly reducing the welding difficulty. In the weld area of the direct fusion shallow groove 3, the shallow groove is combined with multi-layer and multi-pass welding of a specific thickness to ensure welding quality and avoid welding defects caused by smaller groove angles and spacing.
Claims
1. A high-grade steel pipe welding process based on ultra-small angle butt welding, characterized in that the steps include: Step 1: Prepare the pipe workpiece to be welded and process a groove at the end of the pipe workpiece. The wall thickness of the pipe workpiece is not less than 12 mm. The groove adopts a U-shaped groove, a Y-shaped groove, or a V-shaped groove. A shallow groove with a depth and width of no more than 3 mm is provided in the upper part of the groove. Step 2: Butt the pipe workpieces with processed welding grooves and then perform spot welding; Step 3, performing bottom welding; Step 4: Perform filler welding and cap welding.
2. The high-grade steel pipeline welding process according to claim 1, characterized in that: When the wall thickness of the pipe workpiece is 13~18mm, the groove adopts a Y-shaped groove or a V-shaped groove, and the angle between the two slopes is 30~65°.
3. The high-grade steel pipeline welding process according to claim 1, characterized in that: When the wall thickness of the pipe workpiece is not less than 18mm, the groove adopts a U-shaped groove, the angle between the middle of the two slope surfaces is 60~78°, and the angle between the upper part of any slope surface and the vertical surface is 0~15°.
4. The high-grade steel pipeline welding process according to any one of claims 1 to 3, characterized in that: The shallow grooves are arranged in an annular manner or in a radially arranged linear manner, and the spacing between adjacent shallow grooves is 0.5 to 0.6 times the diameter of the welding rod used.
5. The high-grade steel pipeline welding process according to claim 4, characterized in that: In the process of implementing filling welding in the shallow groove height range, for the weld path of direct fusion shallow groove, the single-layer welding thickness is controlled to 0.6-0.8 times the standard welding thickness corresponding to the welding rod; for the weld path of unfused shallow groove, the single-layer welding thickness is controlled to the standard welding thickness corresponding to the welding rod; among which, the standard welding thickness corresponding to the welding rod refers to the filling layer thickness obtained by welding with the welding rod under the set standard welding process parameters.
6. The high-grade steel pipeline welding process according to claim 5, characterized in that: During the filling welding process in the shallow groove height range, after the single-layer welds that directly fuse the shallow groove are stacked continuously for 2-3 layers, the area where the shallow groove is not fused is welded.
7. The high-grade steel pipeline welding process according to claim 6, characterized in that: The gap at the root of the groove is controlled to be 1-3mm.