Small-diameter pipe manual argon tungsten-arc welding method based on ultimate obstacles

Abstract

The invention relates to a manual tungsten electrode argon arc welding method for a small-diameter pipe under extreme obstacles, which is particularly suitable for extreme obstacle welding in a narrow space. According to the method, a welding area is divided into an obstacle area and a barrier-free area in the circumferential direction, different types of grooves are welded in the different areas, the obstacle area is welded through assembly gaps, obstacles do not need to be cut, the influence of surrounding pipelines on welding operation is relieved, and the welding efficiency is improved under the condition that the skill level of team personnel is not changed. The obstacle welding operation problem can be effectively solved, and then the construction efficiency is improved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of welding technology, and particularly relates to a manual tungsten argon arc welding method for small-diameter pipes under limit obstacles. BACKGROUND

[0002] In the construction of oil refining and chemical projects, due to the dense pipelines on site, and the influence of the precast depth, equipment form and space position, there are inevitably more or less narrow areas in the installation stage, and there are other pipelines beside the pipeline joints to be welded, which leads to different degrees of welding obstacles and cannot be moved, seriously affecting the welder's vision and welding operation process, causing great distress to the construction, and making it difficult to reliably guarantee the welding quality and project progress. In addition, due to the close distance between the welding joint and the obstacle, the swing of the welding gun and the feeding of the welding wire are limited during manual tungsten argon arc welding, and the vision is blocked, and the welding process cannot be observed; when the operation space is slightly larger, small-size welding guns and mirror welding can be used for welding, but the operation is extremely difficult, and only experienced high-level welders can complete it, and ordinary welders cannot handle it.

[0003] When encountering limit obstacles (the distance between carbon steel pipe obstacles is 4mm-50mm, the distance between stainless steel and other materials requiring back argon protection for backing welding is 10mm-50mm; or there are obstacles on two sides and three sides, and the distance between carbon steel pipes is 4mm-100mm, and the distance between stainless steel and other materials requiring back argon protection for backing welding is 10mm-100mm), small-size welding guns and mirror welding cannot be completed, and the commonly used method in construction is: first cut the pipeline beside, and then restore the cut pipeline to its original state after welding; or cut other welding passes of the same line, move the obstacle pass to the unlimited area, and then complete the cutting of the welding seam after welding. Although the above two measures avoid welding at the obstacle position, they increase the number of welds and increase the construction cost, causing waste of manpower and material resources. At the same time, the pipelines of oil refining and chemical plants are mostly high-temperature and high-pressure pipelines, and the welding quality of the pipelines needs to be detected by using a ray detector, and the welding quality of the obstacle pipe becomes a difficult point in construction.

[0004] Therefore, the welding operation process of the obstacle pipe needs to be studied to overcome the space constraints on the construction site, so as to better improve the welding quality and efficiency, especially when welding furnace pipes, boiler water walls and other important welds, the importance of the welding operation process of the obstacle pipe is more prominent. SUMMARY

[0005] The present application aims to provide a manual tungsten argon arc welding method for small-diameter pipes under limit obstacles, so as to overcome the above technical defects.

[0006] To solve the above technical problems, the application provides a manual tungsten electrode argon arc welding method for small-diameter pipes under extreme obstacles, characterized by comprising the following steps: determining that the welding joint of the target pipe to be welded is in an extreme obstacle scenario; dividing the obstacle region and the non-obstacle region at the welding joint; positioning the weld in the non-obstacle region; sealing the gap at the welding joint and filling inert gas into the target pipe to be welded; inserting the tungsten electrode from the gap in the non-obstacle region to weld the inner groove of the obstacle region to achieve single-sided welding and double-sided forming; welding the outer groove of the non-obstacle region.

[0007] According to the manual tungsten electrode argon arc welding method for small-diameter pipes under extreme obstacles, the extreme obstacle scenario includes that the target pipe to be welded faces a single-sided obstacle, and the target pipe to be welded is a material that does not require back argon protection, and the obstacle distance between the target pipe to be welded and the single-sided obstacle is 4-50 mm.

[0008] According to the manual tungsten electrode argon arc welding method for small-diameter pipes under extreme obstacles, the extreme obstacle scenario includes that the target pipe to be welded faces a single-sided obstacle, and the target pipe to be welded is a material that requires back argon protection, and the obstacle distance between the target pipe to be welded and the single-sided obstacle that requires back argon protection during backing welding is 10-50 mm.

[0009] According to the manual tungsten electrode argon arc welding method for small-diameter pipes under extreme obstacles, the extreme obstacle scenario includes that the target pipe to be welded faces two-sided obstacles or three-sided obstacles, and the target pipe to be welded is a material that does not require back argon protection, and the obstacle distance between the target pipe to be welded and the two-sided obstacles or three-sided obstacles is 4-100 mm.

[0010] According to the manual tungsten electrode argon arc welding method for small-diameter pipes under extreme obstacles, the extreme obstacle scenario includes that the target pipe to be welded faces two-sided obstacles or three-sided obstacles, and the target pipe to be welded is a material that requires back argon protection, and the obstacle distance between the target pipe to be welded and the two-sided obstacles or three-sided obstacles that requires back argon protection during backing welding is 10-100 mm.

[0011] According to the manual tungsten electrode argon arc welding method for small-diameter pipes under extreme obstacles, the obstacle region is divided, and the tungsten electrode is inserted from the gap in the non-obstacle region to weld the inner groove of the obstacle region, which specifically comprises the following steps: dividing the obstacle region into at least two continuous sub-regions along the circumference and sequentially numbering them; selecting the first obstacle sub-region for operation, first backing welding the outer groove of the welding joint, and then covering welding the inner groove of the welding joint. Move to the second obstacle sub-area for operation. First, perform root pass welding on the inner bevel of the outer pipe wall of the weld joint, and then perform cover pass welding on the inner bevel of the inner pipe wall of the weld joint. Continue moving to other obstacle sub-areas and repeating the work until the welding of the obstacle area is completed.

[0012] Based on the manual tungsten inert gas (TIG) welding method for small-diameter pipes under extreme barrier conditions, the barrier-free zone is defined, and the outer bevel of the barrier-free zone is welded, specifically including: The barrier-free area is divided into two consecutive sub-areas along the circumference and numbered sequentially. Select the first unobstructed sub-area for operation and perform root pass welding on the outer bevel of the inner pipe wall of the weld joint; Move to the second unobstructed sub-area to perform the root pass weld on the outer bevel of the inner pipe wall of the weld joint; Select the first unobstructed sub-area for operation, and weld on the outer bevel cover of the outer pipe wall of the weld joint; Move to the second unobstructed sub-area to work on the outer bevel cap of the outer pipe wall of the weld joint.

[0013] According to the manual tungsten inert gas welding method for small-diameter pipes under extreme barriers, when welding the inner bevel of the barrier area, high-temperature resistant tape is wrapped around the root of the tungsten electrode to avoid short circuits caused by contact with the bevel. When welding the outer bevel of an unobstructed area, replace it with a regular tungsten electrode without high-temperature resistant tape wrapping.

[0014] According to the manual tungsten inert gas (TIG) welding method for small-diameter pipes under extreme barriers, when the target pipe to be welded is made of a material that requires back argon purging protection, an argon gas protective shield is set at the weld seam to prevent oxidation and slag formation on the outer surface during internal welding.

[0015] According to the manual tungsten inert gas welding method for small-diameter tubes under extreme barriers, the argon gas protective cover includes a half-sectioned copper tube with half-section along the axial centerline, and a metal filter screen is installed in the inner cavity of the half-sectioned copper tube. When using an argon gas shield, the argon gas shield is detachably and tightly fixed to the outer wall of the target pipe to be welded to form a structure with a ventilation channel and openings at both ends. One end of the ventilation channel is blocked, and argon gas is introduced into the ventilation channel from the other end.

[0016] The manual tungsten inert gas (TIG) welding method for small-diameter pipes under extreme obstacles proposed in this embodiment is particularly suitable for welding under extreme obstacles in confined spaces. This method divides the welding area circumferentially into obstacle and unobstructed areas, and welds different types of bevels in different areas. Welding in the obstacle area is carried out using the assembly gap, eliminating the need to cut obstacles and removing the influence of surrounding pipelines on the welding operation. With the skill level of the team members remaining unchanged, this method effectively solves the difficulties of obstacle welding operations, thereby improving construction efficiency.

[0017] To make the above description of the present invention more apparent and understandable, preferred embodiments are described below in detail with reference to the accompanying drawings. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the target pipe to be welded.

[0019] Figure 2 The target pipe to be welded ( Figure 1 A sectional view (AA direction).

[0020] Figure 3 This is a plan view of the inner and outer bevels of the target pipe to be welded.

[0021] Figure 4 This is a schematic diagram showing the positions of obstacles and the target pipe to be welded.

[0022] Figure 5 This is a diagram showing the welding sequence at the welded joint.

[0023] Figure 6 This is a schematic diagram of an argon gas protective shield.

[0024] Explanation of reference numerals in the attached figures: 10. The target pipe to be welded; 11. Obstacle Area; 11-1. First Obstacle Sub-area; 11-2. Second Obstacle Sub-area; 11-3. Inner Slope; 12. Accessible area; 12-1. First accessible sub-area; 12-2. Second accessible sub-area; 12-3. External ramp; 13. The transition area between the inner and outer bevels; 14. Assembly gap; 15. Argon gas protective cover; 15-1. Metal filter screen; 15-2. Argon gas inlet. Detailed Implementation

[0025] The following specific embodiments illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification.

[0026] It should be noted that, in this invention, the top, bottom, left, and right in the figure are considered to be the top, bottom, left, and right of the manual tungsten inert gas welding method for small-diameter pipes under extreme barriers described in this specification.

[0027] Exemplary embodiments of the present invention will now be described with reference to the accompanying drawings. However, the present invention may be embodied in many different forms and is not limited to the embodiments described herein. These embodiments are provided to fully and completely disclose the invention and to fully convey its scope to those skilled in the art. The terminology used in the exemplary embodiments illustrated in the drawings is not intended to limit the invention. In the drawings, the same units / elements are referred to by the same reference numerals.

[0028] Unless otherwise stated, the terms used herein (including technical terms) have their common meaning as understood by one of ordinary skill in the art. Furthermore, it is understood that terms defined in commonly used dictionaries should be understood to have a meaning consistent with the context of their relevant field, and not to be interpreted as having an idealized or overly formal meaning.

[0029] Small-diameter pipes refer to pipes with a diameter of ≤100mm.

[0030] This embodiment relates to a manual tungsten inert gas (TIG) welding method for small-diameter pipes under extreme barrier conditions, including: (1) Determine that the welding joint of the target pipe 10 to be welded is in a limit obstacle scenario.

[0031] An extreme obstacle scenario refers to a situation where the target pipe 10 to be welded is in a confined space, where the oscillation of the welding torch and the feeding of the welding wire are both restricted. The obstacle creating the confined space may be an obstacle pipe, a wall, a plate, etc. In this embodiment, when one side of the target pipe 10 to be welded is close to an obstacle (e.g., a wall), it is defined as a single-sided obstacle scenario; when two sides of the target pipe 10 to be welded are close to an obstacle (e.g., a corner), it is defined as a two-sided obstacle scenario; when three sides of the target pipe 10 to be welded are close to an obstacle (e.g., a corner), it is defined as a three-sided obstacle scenario. Figure 4 When the three obstacle tubes shown can be replaced with a wall, this embodiment defines it as a three-sided obstacle scene.

[0032] The structure of the target pipe 10 to be welded can be found in [reference]. Figure 1 and Figure 2 .

[0033] The following will explain welding under different extreme obstacle scenarios.

[0034] The extreme obstacle scenario includes: the target pipe 10 to be welded faces a single-sided obstacle, and the target pipe 10 to be welded is made of a material that does not require argon purging protection on the back. At the same time, the distance between the target pipe 10 to be welded and the single-sided obstacle is 4mm to 50mm.

[0035] The extreme obstacle scenario includes: the target pipe 10 to be welded faces a single-sided obstacle, and the target pipe 10 to be welded is made of a material that requires argon purging protection on the back. At the same time, the distance between the target pipe 10 to be welded and the single-sided obstacle that requires argon purging protection on the back during the initial welding is 10mm to 50mm.

[0036] Extreme obstacle scenarios include: the target pipe 10 to be welded faces two or three obstacles, and the target pipe 10 to be welded is made of a material that does not require argon purging protection on the back. At the same time, the distance between the target pipe 10 to be welded and the two or three obstacles is 4mm to 100mm.

[0037] Extreme obstacle scenarios include: the target pipe 10 to be welded faces two or three obstacles, and the target pipe 10 to be welded is made of a material that requires argon purging protection on the back. At the same time, the distance between the target pipe 10 to be welded and the two or three obstacles that require argon purging protection on the back during the initial welding is 10mm to 100mm.

[0038] The above four categories illustrate the specific extreme obstacle scenarios in which the manual tungsten inert gas welding method for small-diameter pipes under extreme obstacle conditions provided in this embodiment is applied. Among them, materials that do not require back argon purging protection can be carbon steel, low-carbon steel, low-alloy steel, etc., while materials that require back argon purging protection can be stainless steel, nickel-based alloys, etc.

[0039] In practical applications, the above extreme obstacle scenarios mainly involve welds on furnace tubes of welding heating furnaces and welded seams of boiler water-cooled walls.

[0040] (2) Position welding in the unobstructed area 12.

[0041] (3) Seal the gap at the weld joint and fill the target pipe 10 to be welded with inert gas.

[0042] Before welding, the inside of the pipeline must be purged with argon gas for protection. The gaps in the weld seam are sealed with tape. Welding operations can begin when the argon gas concentration inside the pipe reaches 99% or higher.

[0043] In some embodiments, the inert gas is preferably argon, but helium, nitrogen, etc. may also be used.

[0044] (4) At the welded joint, divide the obstacle area 11 and the unobstructed area 12.

[0045] Obstacle area 11 refers to the section of the pipe wall 10 to be welded that is close to an obstacle. This area is narrow and unfavorable for welding operations. Obstacle-free area 12 refers to the remaining area of ​​the weld joint, for example... Figure 5 As shown.

[0046] Before starting welding, the bevel type is determined to be an integral V-shaped bevel. The unobstructed area 12 is welded with an outer bevel, and the obstructed area 11 is welded with an inner bevel. The bevel angle is 30°±5°, the tungsten electrode diameter is 2.5~3mm, and the blunt edge is 0~0.5mm.

[0047] like Figure 2 As shown, the pairing gap is 3-5mm. Specifically, the gap on the obstructed side is 3-3.5mm, and the gap on the unobstructed side is 3.5-5mm, to ensure that the tungsten electrode has sufficient swing space.

[0048] (5) Take a tungsten electrode and insert it into the gap of the unobstructed area 12 to weld the inner bevel 11-3 of the obstructed area 11 to achieve single-sided welding and double-sided forming.

[0049] Please continue reading. Figure 5 The obstacle region 11 is divided circumferentially into at least two consecutive sub-regions, which are then numbered sequentially. Typically, it is divided into two sub-regions. Figure 5 The lower left side of the diagram shows the first obstacle sub-region 11-1, and the upper left side shows the second obstacle sub-region 11-2.

[0050] The welding sequence for obstacle area 11 is as follows: Select the first obstacle sub-region 11-1 for operation. First, perform a root pass weld on the inner bevel 11-3 of the outer pipe wall of the weld joint, i.e., region S1; then perform a cover pass weld on the inner bevel 11-3 of the inner pipe wall of the weld joint, i.e., region S2; move to the second obstacle sub-region 11-2 for operation. First, perform a root pass weld on the inner bevel 11-3 of the outer pipe wall of the weld joint, i.e., region S3; then perform a cover pass weld on the inner bevel 11-3 of the inner pipe wall of the weld joint, i.e., region S4.

[0051] Continue moving to other obstacle sub-areas and repeating the operation until the welding of obstacle area 11 is completed.

[0052] In summary, the tungsten electrode is inserted through the gap in the unobstructed area 12, and the inner bevel 11-3 of the obstruction area 11 is welded first. The welding wire can be fed in from the gap or from the outside of the pipe (the root of the inner bevel) to achieve single-sided welding and double-sided forming. The number of filling and capping welding layers is increased according to the pipe wall thickness until the root, filling and capping welds of the inner bevel of the obstruction area 11 are completed.

[0053] (6) For the outer bevel 12-3 of the unobstructed welding area 12, please refer to the following: Figure 5 Specifically, this includes dividing the barrier-free area 12 into two consecutive sub-regions along the circumference, and numbering them sequentially. Typically, this is done by dividing it into two sub-regions. Figure 5 The lower right side of the image shows the first accessible sub-region 12-1, and the upper right side shows the second accessible sub-region 12-2.

[0054] The welding sequence for barrier-free area 12 is as follows: Select the first unobstructed sub-area 12-1 for operation, and perform a root pass weld on the outer bevel 12-3 of the inner pipe wall of the weld joint, i.e., area S5; move to the second unobstructed sub-area 12-2 for operation, and perform a root pass weld on the outer bevel 12-3 of the inner pipe wall of the weld joint, i.e., area S6; select the first unobstructed sub-area 12-1 for operation, and perform a cover pass weld on the outer bevel 12-3 of the outer pipe wall of the weld joint, i.e., area S7; move to the second unobstructed sub-area 12-2 for operation, and perform a cover pass weld on the outer bevel 12-3 of the outer pipe wall of the weld joint, i.e., area S8.

[0055] That is, after the inner bevel 11-3 is completely welded, replace it with an ordinary tungsten rod without high-temperature resistant tape wrapping, shorten the tungsten electrode length to 8-10mm, and perform root pass, fill and cover pass welding of the outer bevel 11-3 until the weld is completely completed.

[0056] See the adjacent area between barrier area 11 and barrier-free area 12 Figure 3 The transition area 13 between the inner and outer bevels is shown.

[0057] The above welding method uses manual tungsten inert gas (GTAW) welding, employing an inverter DC power supply, argon as the shielding gas, and a high-frequency or high-voltage arc welding torch.

[0058] When welding the inner bevel 11-3 in the obstacle area 11, it is necessary to wrap the root of the tungsten electrode with high-temperature resistant tape to avoid short circuit due to contact with the bevel. Moreover, the extension length of the tungsten electrode exceeds the diameter of the target pipe 10 to be welded by about 5mm.

[0059] In some embodiments, if the target pipe 10 to be welded faces three obstacles, the parameters of the target pipe 10 to be welded are DN89mm×6mm carbon steel small-diameter pipe, with a pairing gap of 5mm, a blunt edge of 0.5mm, and a φ3.0 tungsten electrode. The tungsten electrode extends 95mm beyond the nozzle. The root of the tungsten electrode is wrapped with high-temperature resistant tape to avoid contact with the bevel surface and short circuit. Before welding, the target pipe 10 to be welded needs to be sealed and purged with argon on the back. When the argon content on the back of the weld bead reaches 99% or more, the welding process parameters are adjusted to appropriate and welding begins. The tungsten electrode is inserted from the gap in the unobstructed area 12. The inner bevel 11-3 of the obstacle area 11 is welded first. The welding wire is fed in from the gap to achieve single-sided welding and double-sided forming. After one section of the base is welded, another section is filled and capped. The number of welding layers is determined according to the thickness of the base material until the obstacle area 11 is welded.

[0060] After the inner bevel 11-3 is completely welded, when welding the outer bevel 12-3 of the barrier-free area 12, replace it with a regular tungsten electrode without high-temperature resistant tape wrapping. The tungsten electrode length is 8-10mm. Perform root pass, fill pass, and cover pass welding on the outer bevel 12-3 of the barrier-free area 12 until the entire weld is completed.

[0061] The manual tungsten inert gas (TIG) welding method for small-diameter pipes under extreme obstacles avoids the processes of cutting the weld joint and re-welding under obstacles. It requires only average welding skills and avoids high-difficulty welding operations such as welding in confined spaces and mirror welding. It can effectively solve the problem of obstacle welding operation without changing the skill level of the team members, eliminate the influence of surrounding pipelines on the welding operation, and reduce additional work procedures.

[0062] When the target pipe 10 to be welded is made of a material that requires argon purging protection on the back, an argon gas protective cover 15 is installed at the weld seam to prevent oxidation and slag formation on the outer surface during internal welding. Materials that require argon purging protection on the back can be stainless steel, high-alloy heat-resistant steel, nickel-based alloys, and other materials that are prone to oxidation on the back.

[0063] Specifically, please refer to Figure 6 The argon gas protective cover 15 includes a half-sectioned copper tube split along the axial centerline. A metal filter 15-1 is installed inside the half-sectioned copper tube. The metal filter 15-1 can filter and rectify the argon gas. When using the argon gas protective cover 15, it is detachably and tightly fixed to the outer wall of the target pipe 10 to be welded to form a structure with a ventilation channel and openings at both ends. One end of the ventilation channel is blocked, and argon gas is introduced into the ventilation channel from the other end, or in other words, an argon gas pipe is introduced. See [link to relevant documentation]. Figure 6 Argon gas inlet 15-2 is shown.

[0064] In some embodiments, aluminum foil can be used to adhere the argon gas protective cover 15 to the outside of the target pipe 10 to be welded, and the curvature of the semi-cut copper pipe is consistent with the curvature of the outside of the target pipe 10 to be welded.

[0065] Those skilled in the art will understand that the above embodiments are specific examples of implementing the present invention, and in practical applications, various changes in form and detail may be made without departing from the spirit and scope of the present invention.

Claims

1. A manual tungsten inert gas (TIG) welding method for small-diameter pipes under extreme barrier conditions, characterized in that, include: The welding joint of the target pipe (10) to be welded is determined to be in a limit obstacle scenario; At the welded joint, an obstacle area (11) and an unobstructed area (12) are defined. Position welding is performed in the unobstructed area (12); Seal the gap at the weld joint and fill the target pipe (10) to be welded with inert gas; A tungsten electrode is inserted into the gap of the unobstructed area (12) and the inner bevel (11-3) of the obstructed area (11) is welded to achieve single-sided welding and double-sided forming. Weld the outer bevel (12-3) of the barrier-free area (12).

2. The method for manual tungsten inert gas welding of small-diameter pipes under extreme barriers according to claim 1, characterized in that, The extreme obstacle scenario includes: the target pipe to be welded (10) faces a single-sided obstacle, and the target pipe to be welded (10) is made of a material that does not require argon back filling protection. At the same time, the obstacle distance between the target pipe to be welded (10) and the single-sided obstacle is 4mm to 50mm.

3. The method for manual tungsten inert gas welding of small-diameter pipes under extreme barriers according to claim 1, characterized in that, The extreme obstacle scenario includes: the target pipe to be welded (10) faces a single-sided obstacle, and the target pipe to be welded (10) is made of a material that requires argon back filling protection. At the same time, the distance between the target pipe to be welded (10) and the single-sided obstacle that requires argon back filling protection during the initial welding is 10mm to 50mm.

4. The manual tungsten inert gas (TIG) welding method for small-diameter pipes under extreme barriers according to claim 1, characterized in that, The extreme obstacle scenario includes: the target pipe to be welded (10) faces two or three obstacles, and the target pipe to be welded (10) is made of a material that does not require argon back protection. At the same time, the distance between the target pipe to be welded (10) and the two or three obstacles is 4mm to 100mm.

5. The method for manual tungsten inert gas welding of small-diameter pipes under extreme barriers according to claim 1, characterized in that, The extreme obstacle scenario includes: the target pipe to be welded (10) faces two or three obstacles, and the target pipe to be welded (10) is made of a material that requires argon backing protection. At the same time, the distance between the target pipe to be welded (10) and the two or three obstacles that require argon backing protection during the initial welding is 10mm to 100mm.

6. The method for manual tungsten inert gas welding of small-diameter pipes under extreme barriers according to claim 1, characterized in that, The obstacle area (11) is divided, and a tungsten electrode is inserted into the gap of the obstacle-free area (12) to weld the inner bevel (11-3) of the obstacle area (11), specifically including: The obstacle region (11) is divided into at least two consecutive sub-regions along the circumference and numbered sequentially. Select the first obstacle sub-area (11-1) for operation. First, perform root pass welding on the inner bevel (11-3) of the outer pipe wall of the weld joint, and then perform cover pass welding on the inner bevel (11-3) of the inner pipe wall of the weld joint. Move to the second obstacle sub-area (11-2) for operation. First, perform root pass welding on the inner bevel (11-3) of the outer pipe wall of the welded joint, and then perform cover pass welding on the inner bevel (11-3) of the inner pipe wall of the welded joint. Continue moving to other obstacle sub-areas and repeating the operation until the welding of the obstacle area (11) is completed.

7. The manual tungsten inert gas welding method for small-diameter pipes under extreme barriers according to claim 6, characterized in that, The barrier-free area (12) is defined, and the outer bevel (12-3) of the barrier-free area (12) is welded, specifically including: The barrier-free area (12) is divided into two continuous sub-regions along the circumference and numbered sequentially. Select the first unobstructed sub-area (12-1) for operation, and perform root pass welding on the outer bevel of the inner pipe wall (12-3) of the weld joint; Move to the second unobstructed sub-area (12-2) to perform the root pass weld on the outer bevel of the inner pipe wall of the weld joint (12-3); Select the first unobstructed sub-area (12-1) for operation, and perform cap welding on the outer bevel (12-3) of the outer pipe wall of the weld joint; Move to the second unobstructed sub-area (12-2) for operation, and perform cap welding on the outer bevel (12-3) of the outer pipe wall of the weld joint.

8. The method for manual tungsten inert gas welding of small-diameter pipes under extreme barriers according to claim 1, characterized in that, When welding the inner bevel (11-3) of the obstacle area (11), wrap the tungsten electrode root with high-temperature resistant tape to avoid short circuit due to contact with the bevel; When welding the outer bevel (12-3) of the barrier-free area (12), replace it with an ordinary tungsten electrode without high-temperature resistant adhesive tape.

9. The manual tungsten inert gas welding method for small-diameter pipes under extreme barriers according to claim 3 or 5, characterized in that, When the target pipe (10) to be welded is made of a material that requires argon back purging protection, an argon protective cover is set at the weld seam to prevent oxidation and slag formation on the outer surface during internal welding.

10. The method for manual tungsten inert gas welding of small-diameter pipes under extreme barriers according to claim 9, characterized in that, The argon gas protective cover includes a half-sectioned copper tube that is half-sectioned along the axial centerline, and a metal filter screen is installed in the inner cavity of the half-sectioned copper tube. When using the argon gas protective cover, the argon gas protective cover is detachably attached to the outer wall of the target pipe (10) to be welded to form a structure with a ventilation channel and openings at both ends. One end opening of the ventilation channel is blocked, and argon gas is introduced into the ventilation channel from the other end opening.

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