TIG (Tungsten Inert Gas) automatic welding narrow-gap welding method for oil and gas pipeline and application thereof

Abstract

The invention belongs to the technical field of welding, and particularly relates to an oil and gas pipeline TIG automatic welding narrow gap welding method and application thereof. The method at least comprises root welding, wherein an ER80S-G solid welding wire is adopted for root welding; root welding is conducted through TIG welding; and a narrow-gap groove is adopted for root welding. According to the technical scheme, the welding efficiency can be greatly improved to meet the requirement for large-scale pipeline construction, high-quality welding seams are guaranteed to enhance the safety and reliability of the pipeline, the welding material cost is saved through the narrow-gap groove form, the labor intensity of welders is relieved, high-performance steel such as X80 pipeline steel is well matched, and high-quality safe operation of the pipeline is guaranteed.

Description

Technical Field

[0001] The invention belongs to the technical field of welding, and in particular relates to a TIG automatic welding narrow gap welding method for oil and gas pipelines and an application thereof. Background Art

[0002] With the rapid development of modern industry, the demand for pipeline construction is increasing day by day, especially in the energy fields such as oil and natural gas, as well as the chemical industry, the demand for large-diameter and thick-walled pipelines is more urgent. However, traditional welding technology has gradually revealed many limitations in the face of these demands.

[0003] Traditional TIG welding has problems such as shallow penetration, slow deposition speed and low productivity, which makes it difficult to meet the high-efficiency requirements of large-scale pipeline construction. When welding thick-walled pipelines, ordinary TIG welding requires beveling and multi-layer welding. Its electrode current carrying capacity is limited, and the arc power is restricted, resulting in shallow weld penetration and low welding speed, which cannot adapt to the rhythm of modern industrial production.

[0004] At the same time, the traditional groove form is relatively wide, which not only consumes a large amount of welding materials and increases costs, but also requires welders to perform long-term, high-intensity operations, which is extremely labor-intensive.

[0005] In addition, traditional welding processes are prone to defects such as porosity and slag inclusions in welds due to human and environmental factors, which restricts the quality and efficiency of pipeline welding. Summary of the invention

[0006] In order to solve the deficiencies of the prior art, the present invention provides a TIG automatic welding narrow gap welding method for oil and gas pipelines and its application. The technical solution of the present invention can greatly improve the welding efficiency to meet the needs of large-scale pipeline construction, ensure high-quality welds to enhance pipeline safety and reliability, save welding material costs through narrow gap grooves, reduce welder labor intensity, and is well adapted to high-performance steels such as X80 pipeline steel to ensure high-quality and safe operation of pipelines.

[0007] The technical solution provided by the present invention is as follows:

[0008] A TIG automatic welding narrow gap welding method for oil and gas pipelines, comprising at least root welding, wherein:

[0009] Use ER80S-G solid welding wire for root welding;

[0010] Root welding is performed using TIG welding;

[0011] Use narrow gap groove for root welding.

[0012] The above technical solution is based on the X80 pipeline all-position narrow gap welding method of telescopic hot wire TIG welding, which combines the advantages of telescopic hot wire technology and narrow gap groove form. The hot wire technology improves the melting speed and deposition efficiency of the welding wire, greatly improving the welding production efficiency; the narrow gap groove form significantly saves the use of welding materials, reduces costs and labor intensity. At the same time, it can better control the welding process, reduce the generation of defects, and form a pipeline girth weld with better quality and lower defect rate, which effectively guarantees the quality and safety performance of the pipeline.

[0013] Specifically, the wire feeding method is telescopic wire feeding, and the frequency is 0-21 Hz.

[0014] The groove form of the pipeline ring weld is a U-shaped gapless groove. The selection of welding materials comprehensively considers the chemical composition, mechanical properties, welding joint form, low temperature resistance and crack resistance requirements of the parent material (X80). The outer root welding uses a lower-grade ER80S-G solid welding wire with a wire diameter of 1.0mm.

[0015]

[0016] The vibration frequency range of the telescopic wire feeding is 0-21Hz, and the continuous output torque can reach 8Nm. At the vibration frequency of 0-10Hz, almost no oscillation phenomenon is observed in the molten pool. When the wire feeding vibration frequency is greater than 10Hz, the molten pool will show obvious oscillation phenomenon. When the frequency is set at 16-20Hz, the oscillation phenomenon causes physical stirring of the metal in the welding molten pool, refines the grains, and forms a finer weld texture, which can effectively improve the fusion of the weld metal with the parent materials on both sides. This process has strict requirements on the groove parameters and welding parameters, and has strict requirements on groove processing and assembly. The tolerance for blunt edge thickness and joint gap is low, and a U-shaped groove with 0 gap is required.

[0017] Specifically, in TIG welding:

[0018] Polarity is DCEN;

[0019] The welding direction is upward, downward or continuous upward and downward;

[0020] The current is 180-220A;

[0021] Voltage is 6.0-10V;

[0022] Wire feeding speed is 1.0-2.2m / min;

[0023] The welding speed is 13-20cm / min;

[0024] The protective gas flow rate is 15-30L / min;

[0025] The width of the groove pair is 8-12mm;

[0026] The deposition rate is 0.5-1kg / h.

[0027] like Figure 2 The figure shows the relationship between the welding gun height and voltage at different wire feeding speeds. The horizontal axis unit is s and the vertical axis unit is V. It can be seen that the welding gun height is linearly related to the voltage, so the voltage can be used to calibrate the arc length. The system uses high-speed bus communication to directly read the welding voltage and welding current data from the welding power supply, and a linear relationship curve is proposed. In combination with the welding power supply voltage and current transmission protocol, a data reading and processing program is written. During the non-side stop time, the one-way mean of the welding voltage is compared with the set value. If it is greater than the set value, the arc length is longer, and if it is less than the set value, the arc length is shorter. The calculation result is sent to the servo node via the bus to adjust the arc length.

[0028] The arc length fixed-length control technology is used to realize automatic arc starting of pipeline full-position TIG automatic welding. During welding, the tungsten electrode automatically moves down to contact the pipeline annular seam and then rises to the set arc starting height, accurately controlling the arc starting. In the welding process, the arc length is stably controlled through real-time dynamic tracking of signals to maintain the consistency of the arc length and further improve the welding quality.

[0029] The specific parameters of the process of the present invention and the comparison with the traditional TIG root welding process parameters are shown in the following table.

[0030]

[0031]

[0032] Specifically, the narrow gap groove has a groove angle of 4 to 6 degrees, a groove width of 8 to 12 mm after assembly, an arc chamfer of R2.4 to 3.2 mm, and a blunt edge height of 1.2 to 2 mm.

[0033] Specifically, the gap width between the pipes is ≤0.5 mm.

[0034] Furthermore, it also includes filling welding and cap welding.

[0035] Specifically, in filling welding:

[0036] The welding method is GMAW-G;

[0037] Polarity is DCEP;

[0038] The welding direction is upward, downward or continuous upward and downward;

[0039] The current is 180-240A;

[0040] Voltage is 19.0-23.0V;

[0041] Wire feeding speed is 8000-11000mm / min;

[0042] The welding speed is 35-50cm / min;

[0043] The protective gas flow rate is 25-30L / min.

[0044] Specifically, in cover welding:

[0045] The welding method is GMAW-G;

[0046] Polarity is DCEP;

[0047] The welding direction is upward, downward or continuous upward and downward;

[0048] The current is 140-160A;

[0049] Voltage is 19.0-23.0V;

[0050] Wire feeding speed is 5000-7000mm / min;

[0051] The welding speed is 35-50cm / min;

[0052] The protective gas flow rate is 25-30L / min.

[0053] The present invention also provides an application of the TIG automatic welding narrow gap welding method for oil and gas pipelines to perform circumferential welding on X80 pipelines.

[0054] Specifically, the pipe thickness is ≤30.8mm.

[0055] Especially for the welding of high-performance steel such as X80, its high strength and good toughness can be fully utilized to ensure the stable operation of the pipeline under complex working conditions.

[0056] Beneficial effects of the present invention:

[0057] The oil and gas pipeline TIG automatic welding narrow gap welding method provided by the present invention meets the requirements of the weld joint group and the weld performance index: it meets the relevant requirements of "DEC-OGP-G-WD-002-2020-1 Oil and Gas Pipeline Engineering Line Welding Technical Regulations". Compared with the traditional TIG welding process, it has the following advantages:

[0058] 1. Adapt to narrow gap groove welding, single-side groove angle 4 to 6 degrees, single groove width 4 to 6 mm. Compared with traditional TIG welding, it can adapt to smaller gap groove welding, reduce the amount of welding wire filling, and improve welding efficiency.

[0059] 2. Faster deposition speed, about twice that of traditional TIG welding.

[0060] 3. Faster welding speed. Compared with traditional TIG automatic welding, the welding speed of the process of the present invention is more than 1.5 times.

[0061] 4. The first-time welding qualification rate is over 98%, and the welding efficiency is more than twice that of manual argon arc welding.

[0062] The welding process of the present invention has low heat input, narrow heat-affected zone width, excellent welding joint performance, and can achieve high-quality narrow-gap pipeline all-position welding. BRIEF DESCRIPTION OF THE DRAWINGS

[0063] Figure 1 This is a comparison chart of groove sizes.

[0064] Figure 2 This is a graph showing the relationship between welding gun height and voltage at different wire feeding speeds.

[0065] Figure 3 It is a schematic diagram of weld seam welding. DETAILED DESCRIPTION

[0066] The principles and features of the present invention are described below. The examples given are only used to explain the present invention and are not used to limit the scope of the present invention.

[0067] Unless otherwise specified, the test methods used in the embodiments of the present invention are all conventional methods; the materials, reagents, etc. used are reagents and materials that can be obtained from commercial channels unless otherwise specified. Specific implementation method:

[0069] like Figure 1 The figure shows a comparison of groove dimensions, which is a typical comparison of the groove dimensions of the conventional groove and the groove dimensions of the groove of the invention after two pipes are assembled. The pipe assembly method is internal aligner assembly.

[0070] Traditional TIG welding refers to manual TIG welding and semi-automatic TIG welding.

[0071] The process of the present invention adopts a narrow gap U-shaped groove, the groove angle is 4 to 6 degrees, the groove width after assembly is 8 to 12 mm, the arc chamfer is R2.4 mm, and the blunt edge height is 1.2 to 2 mm.

[0072] The invention requires zero-gap assembly for the pipe assembly quality, and the actual assembly gap width should be ≤0.1mm.

[0073] The welding current polarity of the process of the present invention is direct current positive connection, and an upward welding method is adopted. The current is 180-200A, the voltage is 8.0-9.5V, the wire feeding speed is 2-2.2m / min, the welding speed is 16-18cm / min, the shielding gas is pure argon, and the flow rate is 18-25L / min.

[0074] The TIG welding process of the present invention is only used for root welding of the pipeline girth weld. The telescopic vibration frequency of the welding wire is 16-20 Hz.

[0075] The TIG welding process of the present invention performs preheating treatment on the welding wire loading current, and the hot wire current is controlled at 70-80A. By preheating the molten pool with the hot wire, the fault tolerance of the joint gap and the amount of misalignment can be effectively improved, the probability of undercut and unmelted defects can be reduced, the penetration can be increased, the back penetration forming is more stable, and a better weld appearance can be obtained.

[0076] like Figure 3 As shown, it is a schematic diagram of weld seam welding. It can be seen that the telescopic hot wire TIG welding involved in the present invention is a root welding process. For pipeline girth weld welding, it needs to be implemented with filling and capping welding processes. The specific filling and capping welding processes are shown in the following table.

[0077]

[0078]

[0079] The protective gas used for filling and covering is a mixed gas, and the volume percentage is CO2 / Ar=60~80 / 40~20. The device used is a full-position automatic welding machine.

[0080] Example 1

[0081] The pipe diameter is 1219mm and the wall thickness is 22mm. The narrow gap groove is U-shaped, the groove angle is 4 degrees, the groove width after assembly is 9.7mm, the arc chamfer is R2.4mm, and the blunt edge height is 18mm.

[0082] The polarity of the connection current is DC positive connection, and the upward welding method is adopted. The current is 190A, the voltage is 8.75V, the wire feeding speed is 2.1m / min, the welding speed is 17cm / min, the shielding gas is pure argon, and the flow rate is 21.5L / min.

[0083] Root welding of pipeline girth weld is performed. The telescopic vibration frequency of the welding wire is 18Hz.

[0084] In filling welding: the welding method is GMAW-G; the polarity is DCEP; the welding direction is downward; the current is 210A; the voltage is 21V; the wire feeding speed is 95000mm / min; the welding speed is 42.5cm / min; and the shielding gas flow rate is 27.5L / min.

[0085] In the cap welding: the welding method is GMAW-G; the polarity is DCEP; the welding direction is downward; the current is 150A; the voltage is 21V; the wire feeding speed is 6000mm / min; the welding speed is 37.5cm / min; and the shielding gas flow rate is 27.5L / min.

[0086] The protective gas used for filling and covering is a mixed gas with a volume percentage of CO2 / Ar=70 / 30. The device used is a full-position automatic welding machine.

[0087] Effect Example 1

[0088] By setting the test pipe to an inclination angle of 29.3° and adopting the working parameters of Example 1 to simulate the technical characteristics of ramp welding in special scenarios such as mountainous areas, the weld forming quality and efficiency of the welding process of the present invention are no different from those of flat ground welding.

[0089] Effect Example 2

[0090] The test pipeline obtained in Example 1 was tested and met the relevant requirements of "DEC-OGP-G-WD-002-2020-1 Technical Regulations for Welding of Oil and Gas Pipeline Engineering Lines".

[0091] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A TIG automatic narrow gap welding method for oil and gas pipelines, at least including root welding, characterized in that: Use ER80S-G solid welding wire for root welding; Root welding is performed using TIG welding; Use narrow gap groove for root welding.

2. The oil and gas pipeline TIG automatic welding narrow gap welding method according to claim 1 is characterized in that: The wire feeding method is telescopic wire feeding, and the frequency is 0-21Hz.

3. The oil and gas pipeline TIG automatic welding narrow gap welding method according to claim 1 is characterized in that: TIG welding: Polarity is DCEN; The welding direction is upward, downward or continuous upward and downward; The current is 180-220A; Voltage is 6.0-10V; Wire feeding speed is 1.0-2.2m / min; The welding speed is 13-20cm / min; The protective gas flow rate is 15-30L / min; The groove width is 8-12mm; The deposition rate is 0.5-1kg / h.

4. The oil and gas pipeline TIG automatic welding narrow gap welding method according to claim 1 is characterized in that: The narrow gap groove has a groove angle of 4 to 6 degrees, a groove width of 8 to 12 mm after assembly, an arc chamfer of R2.4 to 3.2 mm, and a blunt edge height of 1.2 to 2 mm.

5. The oil and gas pipeline TIG automatic welding narrow gap welding method according to claim 1 is characterized in that: The gap width between pipes is ≤0.5mm.

6. The oil and gas pipeline TIG automatic welding narrow gap welding method according to claim 1, characterized in that: Also includes filler welds and cap welds.

7. The oil and gas pipeline TIG automatic welding narrow gap welding method according to claim 6 is characterized in that: Filling welding: The welding method is GMAW-G; Polarity is DCEP; The welding direction is upward, downward or continuous upward and downward; The current is 180-240A; Voltage is 19.0-23.0V; Wire feeding speed is 8000-11000mm / min; The welding speed is 35-50cm / min; The protective gas flow rate is 25-30L / min.

8. The oil and gas pipeline TIG automatic welding narrow gap welding method according to claim 6 is characterized in that: Cover welding: The welding method is GMAW-G; Polarity is DCEP; The welding direction is upward, downward or continuous upward and downward; The current is 140-160A; Voltage is 19.0-23.0V; Wire feeding speed is 5000-7000mm / min; The welding speed is 35-50cm / min; The protective gas flow rate is 25-30L / min.

9. An application of the method according to any one of claims 1 to 8, characterized in that: Girth welding of X80 pipe.

10. The use according to claim 9, characterized in that: Pipe thickness ≤30.8mm.

Images