Welding method for gapped full-automatic outer root welding of long-distance pipeline

Abstract

The invention provides a welding method for gapped full-automatic external root welding of a long-distance pipeline, which adopts a V-shaped groove and a gapped assembly (2.5-4.5 mm), adopts gapped tungsten electrode argon arc automatic external root welding and is used for circumferential weld welding construction of the long-distance pipeline, automation of external root welding is realized by the tungsten electrode argon arc automatic external root welding, and the welding efficiency is improved. The problem of automatic gap full-automatic outer root welding is solved, the welding quality is stable, the welding efficiency is high, the labor intensity of workers is small, and a new process model is provided for welding construction of long-distance pipeline connectors.

Description

Welding method for fully automated external root welding of long-distance pipelines with gaps Technical Field

[0001] This invention belongs to the technical field of circumferential welds for long-distance pipelines, and particularly relates to a welding method for fully automatic external root welding with gaps in long-distance pipelines. Background Technology

[0002] The existing connection processes for long-distance pipelines mainly consist of combined automatic welding and argon-electric welding. The root welding process mostly uses manual tungsten inert gas welding. However, manual root welding suffers from problems such as low welding efficiency and significant dependence on the welder's skill level.

[0003] In the field of long-distance pipeline welding, the current welding technology uses tungsten inert gas (TIG) automatic welding for external root welding, combined with gas-shielded solid welding wire downward welding for filling and capping using single / double welding torch automatic external welding equipment. However, the welding process is designed for narrow gap assembly, and the fully automatic external root welding technology for gaps is still a research and development gap. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides a welding method for fully automated external root welding of long-distance pipelines with gaps, characterized by comprising the following steps:

[0005] S1) Processing of steel pipe welding bevels: on-site cutting and grinding of bevels, using V-shaped bevels, and the bevel dimensions adopting the common combination of bevels used in automatic welding processes;

[0006] S2) Assembly and welding: After the gap assembly is completed, preheating, root welding, hot welding, fill welding and cover welding are carried out in accordance with the welding process specification, using solid welding wire upward welding process;

[0007] S3) Non-destructive testing: Phased array ultrasonic testing and radiographic testing are performed on the circumferential welds of the welded long-distance pipeline.

[0008] According to the above scheme, the gap mentioned in step S2) is 2.5-4.5mm.

[0009] According to the above scheme, the root welding, hot welding, fill welding and cover welding mentioned in step S2) all require the introduction of protective gas.

[0010] According to the above scheme, the welding process parameters in step S2) are as follows:

[0011] Root pass welding: Welding current: 120-180A; Welding voltage: 8-15V; Welding speed: 5-10cm / min; Shielding gas flow rate: 10-20L / mm;

[0012] Hot welding: Welding current: 140-250A; Welding voltage: 8-15V; Welding speed: 12-15cm / min; Shielding gas flow rate: 10-20L / mm;

[0013] Filler welding: Welding current: 80-180A; Welding voltage: 18-26V; Welding speed: 10-22cm / min; Shielding gas flow rate: 25-35L / mm;

[0014] Cover weld: Welding current: 80-150A; Welding voltage: 18-26V; Welding speed: 12-18cm / min; Shielding gas flow rate: 25-35L / mm.

[0015] According to the above scheme, the protective gas for root welding and hot welding is argon, and the protective gas for filler welding and capping welding is a mixture of argon and carbon dioxide.

[0016] According to the above scheme, the purity of the argon gas is ≥99.99%, and the water content of the argon gas is ≤0.005%, and the purity of the carbon dioxide is ≥99.7%, and the water content of the carbon dioxide is ≤0.005%.

[0017] According to the above scheme, the preheating temperature mentioned in step S2) is 80-150℃.

[0018] According to the above scheme, the time interval between the end of root welding and the start of hot welding in step S2) is ≤15min.

[0019] According to the above scheme, the thickness of each weld metal layer in the root weld, hot weld, and filler weld shall not exceed 3mm.

[0020] According to the above scheme, the interpass temperature of each weld seam in the root weld, hot weld, filler weld and cover weld is 80-150℃.

[0022] The beneficial effects of this invention are: it provides a welding method for fully automated external root welding of long-distance pipelines with gaps.

[0023] The proposed method introduces a gap-type fully automated external root welding process for long-distance pipeline joint welding. This process employs gap-type tungsten inert gas (TIG) automatic welding for the external root, achieving automation compared to combined automatic welding. This results in stable and easily controllable welding quality. Furthermore, it automates the gap-type external root welding process. The use of solid welding wire instead of flux-cored wire for filler welding effectively ensures welding quality. Compared to combined automatic welding, it offers advantages such as stable welding quality and reduced labor intensity for personnel. Attached Figure Description

[0024] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 is a schematic diagram of a steel pipe welding bevel type according to an embodiment of the present invention.

[0026] Figure 2 is a schematic diagram of the number of bevel welding layers in an embodiment of the present invention. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0028] Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of the application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0029] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0030] The features and performance of this application will be further described in detail below with reference to the embodiments.

[0031] This invention provides a welding method for fully automated external root welding of long-distance pipelines with gaps.

[0032] The core technology is the automation of gapped external root welding, with the filler welding employing a single-torch automatic welding machine using gas-shielded solid wire upward welding. The steps of this technology are as follows:

[0033] 1) Processing of steel pipe welding bevels: V-shaped bevels are adopted, and the bevel dimensions adopt the bevels of commonly used combined automatic welding processes (see Appendix 1). Bevel face angle (α): 23.5°±1.5°; blunt edge (P): 1.0±0.5mm; butt gap (b): 2.5~4.5mm; misalignment: 0~2.0mm; reinforcement height: 0~2.0mm. The reinforcement height of the weld should not exceed 2mm, and the continuous length of local areas not exceeding 3mm should not exceed 50mm; the width of the cap weld: the upper edge of the bevel should be widened by 1.0mm~2.0mm on each side.

[0034] 2) Assembly and welding: The assembly gap is 2.5-4.5mm. After assembly, preheating, root welding, hot welding, filling and capping are carried out in accordance with the welding process specification (see Appendix 2 for the number of layers).

[0035] 3) Root pass and hot pass welding shall be protected with 100% Ar gas, while filler and cover passes shall be protected with a mixed gas (80% Ar + 20% CO2); gas purity requirements: CO2 gas purity ≥ 99.7%, Ar gas purity ≥ 99.99%; gas moisture content requirements: CO2 gas moisture content ≤ 0.005%, Ar gas moisture content ≤ 0.005%.

[0036] 4) The thickness of each weld metal layer in the non-cover layer shall not exceed 3mm.

[0037] 5) Preheating and inter-track temperature:

[0038] Preheating temperature: 80-150℃; Interlayer temperature: 80-150℃.

[0039] 6) Welding process parameters:

[0040] Root welding: Welding current (A): 120-180; Welding voltage (V): 8-15; Welding speed (cm / min): 5-10; Shielding gas flow rate (L / mm): 10-20;

[0041] Hot welding: Welding current (A): 140-250; Welding voltage (V): 8-15; Welding speed (cm / min): 12-15; Shielding gas flow rate (L / mm): 10-20;

[0042] Filler parameters: Welding current (A): 80-180; Welding voltage (V): 18-26; Welding speed (cm / min): 10-22; Shielding gas flow rate (L / mm): 25-35;

[0043] Cover pass: Welding current (A): 80-150; Welding voltage (V): 18-26; Welding speed (cm / min): 12-18; Shielding gas flow rate (L / mm): 25-35.

[0044] 7) The time interval between the end of root welding and the start of hot welding: ≤15min.

[0045] 8) Non-destructive testing, using PAUT 100% + RT 100% for non-destructive testing:

[0046] PAUT testing shall be conducted in accordance with the requirements of "Non-destructive Testing of Steel Pipelines for Oil and Gas" (SY / T 4109-2020), with a qualification standard of Level II or above. It shall also meet the requirements of "Technical Specifications for Phased Array Ultrasonic Testing of Oil and Gas Pipeline Engineering" (DEC-OGP-G-NT-004-2020-1).

[0047] RT testing shall be carried out in accordance with the "Non-destructive Testing of Steel Pipelines for Oil and Gas" (SY / T 4109-2020) and the "Technical Regulations for Radiographic Testing of Oil and Gas Pipeline Engineering" (DEC-OGP-G-NT-001-2021-2), and the qualified standard for radiographic testing shall be Level II or above.

[0048] The following is a comparison between this root welding technique (gap-welded tungsten inert gas welding) and the original root welding technique (tungsten inert gas welding - manual):

[0049] Taking a steel pipe with an outer diameter of 1219mm and a wall thickness of 22mm as an example:

[0050] 1) Comparison of welding quality

[0051] The pass rate for intermittent tungsten inert gas (TIG) automatic root welding is 96%-98%; inspection method: 100% PAUT + 100% RT.

[0052] Manual tungsten inert gas welding: pass rate is 90%-92%, inspection method: 100% PAUT + 100% RT;

[0053] The pass rate is higher for tungsten inert gas (TIG) automatic welding with gaps.

[0054] 2) Comparison of welding personnel

[0055] Both processes require two people for the base coat, so there is no change in personnel.

[0056] 3) Comparison of welding equipment

[0057] The cost of automated tungsten inert gas (TIG) welding equipment for external root welding is higher than that of manual TIG welding.

[0058] 4) Comparison of welding efficiency

[0059] The welding time for automatic tungsten inert gas (TIG) welding of the outer root is 30-40 minutes; the welding time for manual TIG welding of the root pass is 60-80 minutes; the welding efficiency of automatic TIG welding is more than 1.5 times that of manual TIG welding.

[0060] Example 1

[0061] This process was applied to pipelines at a certain site, using L555M steel. The first-pass yield rate was 98.5%, meeting the project's welding requirements. The construction steps are as follows:

[0062] 1) The beveling of the welded joint of the steel pipe shall be done by adopting a V-shaped beveling.

[0063] 2) Assembly and welding: The assembly gap is 2.5-4.5mm. After assembly, preheating, root welding, hot welding, filling and capping are carried out in accordance with the welding process specification.

[0064] 3) Root pass and hot pass welding shall be protected with 100% Ar gas, and filler gas shall be protected with a mixed gas (80% Ar + 20% CO2); gas purity requirements: CO2 gas purity ≥ 99.7%, Ar gas purity ≥ 99.99%; gas moisture content requirements: CO2 gas moisture content ≤ 0.005%, Ar gas moisture content ≤ 0.005%;

[0065] 4) The thickness of each weld metal layer in the non-cover layer shall not exceed 3mm;

[0066] 5) Preheating and inter-track temperature

[0067] Preheating temperature: 80-150℃; Interlayer temperature: 80-150℃;

[0068] 6) Welding process parameters

[0069] Root pass welding: Welding current (A): 120-180; Welding voltage (V): 8-15; Welding speed (cm / min): 5-10; Shielding gas flow rate (L / mm): 10-15;

[0070] Hot welding: Welding current (A): 140-250; Welding voltage (V): 8-15; Welding speed (cm / min): 12-15; Shielding gas flow rate (L / mm): 10-15;

[0071] Filler parameters: Welding current (A): 80-180; Welding voltage (V): 18-26; Welding speed (cm / min): 11-22; Shielding gas flow rate (L / mm): 25-35;

[0072] Cover pass: Welding current (A): 80-180; Welding voltage (V): 18-26; Welding speed (cm / min): 12-18; Shielding gas flow rate (L / mm): 25-35;

[0073] 7) The time interval between the end of root welding and the start of hot welding: ≤15min;

[0074] 8) Non-destructive testing, using PAUT 100% + RT 100% for non-destructive testing; PAUT standard: SY / T 4109-2020, DEC-OGP-G-NT-004-2020-1; RT standard: SY / T4109-2020, DEC-OGP-G-NT-001-2021-2, with a pass level of II or above.

[0075] Example 2

[0076] This process was applied on a certain railway line using L555M steel with a pipe diameter of D1219×18.4mm. The first-pass yield rate was 98.3%, meeting the project's welding requirements. The construction steps are as follows:

[0077] 1) The beveling of the welded joint of the steel pipe shall be done by adopting a V-shaped beveling.

[0078] 2) Assembly and welding: The assembly gap is 2.5-4.5mm. After assembly, preheating, root welding, hot welding, filling and capping are carried out in accordance with the welding process specification.

[0079] 3) Root pass and hot pass welding shall be protected with 100% Ar gas, and filler gas shall be protected with a mixed gas (80% Ar + 20% CO2); gas purity requirements: CO2 gas purity ≥ 99.7%, Ar gas purity ≥ 99.99%; gas moisture content requirements: CO2 gas moisture content ≤ 0.005%, Ar gas moisture content ≤ 0.005%;

[0080] 4) The thickness of each weld metal layer in the non-cover layer shall not exceed 3mm;

[0081] 5) Preheating and inter-track temperature

[0082] Preheating temperature: 80-150℃; Interlayer temperature: 80-150℃;

[0083] 6) Welding process parameters

[0084] Root welding: Welding current (A): 130-180; Welding voltage (V): 8-15; Welding speed (cm / min): 6-10; Shielding gas flow rate (L / mm): 15-20;

[0085] Hot welding: Welding current (A): 145-240; Welding voltage (V): 8-15; Welding speed (cm / min): 12-15; Shielding gas flow rate (L / mm): 15-20;

[0086] Filler parameters: Welding current (A): 85-180; Welding voltage (V): 18-26; Welding speed (cm / min): 12-22; Shielding gas flow rate (L / mm): 25-35;

[0087] Cover pass: Welding current (A): 85-180; Welding voltage (V): 18-26; Welding speed (cm / min): 13-18; Shielding gas flow rate (L / mm): 25-35;

[0088] 7) The time interval between the end of root welding and the start of hot welding: ≤15min;

[0089] 8) Non-destructive testing, using PAUT 100% + RT 100% for non-destructive testing; PAUT standard: SY / T 4109-2020, DEC-OGP-G-NT-004-2020-1; RT standard: SY / T4109-2020, DEC-OGP-G-NT-001-2021-2, with a pass level of II or above.

[0090] The embodiments described above are some, but not all, of the embodiments of this application. The detailed description of the embodiments of this application is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

Claims

1. A welding method for fully automated external root welding of long-distance pipelines with gaps, characterized in that, The process includes the following steps: S1) Processing of steel pipe weld bevels: on-site cutting and grinding of the bevels, using V-shaped bevels, and the bevel dimensions adopting the common combination of bevels used in automatic welding processes; S2) Assembly and welding: after gap assembly, preheating, root welding, hot welding, fill welding and cover welding are performed according to the welding process specifications, using solid welding wire upward welding process; S3) Non-destructive testing: phased array ultrasonic testing and radiographic testing are performed on the circumferential welds of the welded long-distance pipeline.

2. The welding method for fully automated external root welding of long-distance pipelines with gaps according to claim 1, characterized in that, The gap mentioned in step S2) is 2.5-4.5mm.

3. The welding method for fully automated external root welding of long-distance pipelines with gaps according to claim 1 or 2, characterized in that, In step S2), the root weld, hot weld, filler weld, and cap weld all require the introduction of a protective gas.

4. The welding method for fully automated external root welding of long-distance pipelines with gaps according to claim 3, characterized in that, The welding process parameters described in step S2) are as follows: Root pass welding: Welding current: 120-180A; Welding voltage: 8-15V; Welding speed: 5-10cm / min; Shielding gas flow rate: 10-20L / mm; Hot pass welding: Welding current: 140-250A; Welding voltage: 8-15V; Welding speed: 12-15cm / min; Shielding gas flow rate: 10-20L / mm; Fill pass welding: Welding current: 80-180A; Welding voltage: 18-26V; Welding speed: 10-22cm / min; Shielding gas flow rate: 25-35L / mm; Cover pass welding: Welding current: 80-150A; Welding voltage: 18-26V; Welding speed: 12-18cm / min; Shielding gas flow rate: 25-35L / mm.

5. The welding method for fully automated external root welding of long-distance pipelines with gaps according to claim 4, characterized in that, Argon is used as the shielding gas for root welding and hot welding, and a mixture of argon and carbon dioxide is used as the shielding gas for filler welding and capping welding.

6. The welding method for fully automated external root welding of long-distance pipelines with gaps according to claim 5, characterized in that, The argon gas has a purity of ≥99.99% and a water content of ≤0.005%, and the carbon dioxide has a purity of ≥99.7% and a water content of ≤0.005%.

7. The welding method for fully automated external root welding of long-distance pipelines with gaps according to claim 1 or 6, characterized in that, The preheating temperature mentioned in step S2) is 80-150℃.

8. The welding method for fully automated external root welding of long-distance pipelines with gaps according to claim 7, characterized in that, The time interval between the end of root welding and the start of hot welding in step S2) is ≤15min.

9. The welding method for fully automated external root welding of long-distance pipelines with gaps according to claim 6, characterized in that, The thickness of each weld metal layer in the root weld, hot weld, and filler weld shall not exceed 3 mm.

10. The welding method for fully automated external root welding of long-distance pipelines with gaps according to claim 6, characterized in that, The interpass temperature of each weld in the root weld, hot weld, filler weld, and cap weld is 80-150℃.

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