Method for welding girth of tail water elbow pipe of pumped storage power station

Abstract

The invention discloses a pumped storage power station tail water elbow girth welding method which comprises the following steps: S1, preheating areas on two sides of a weld joint to be welded to 80-95 DEG C; s2, after being dried, the welding rod is placed in a heat preservation cylinder to be stored; s3, backing welding is conducted on a weld joint area, and the interlayer temperature is 185 DEG C; s4, finishing a fusion line of backing welding; and S5, cosmetic welding is conducted, and the interlayer temperature is 175 DEG C. The method has the characteristic that the one-time flaw detection yield of the circular seam of the tail water elbow pipe can be effectively improved.

Description

Technical Field

[0001] The invention relates to a welding method, in particular to a circumferential seam welding method for a tailwater elbow pipe of a pumped storage power station. Background Art

[0002] The total length of the elbow of the tailwater pipe of the pumped storage power station unit is relatively long. In order to facilitate transportation, it is generally necessary to transport it in multiple sections. This requires manual welding rod welding for the circumferential seam welding of the tailwater elbow. However, during manual welding, the circumferential seam of the tailwater elbow has dense pores, unfused and other common welding problems, resulting in a low one-time flaw detection pass rate of the manual welding of the circumferential seam of the tailwater elbow installation, which has quality problems; and the tailwater elbow welding process is an irreversible process. If it is not well controlled, it will not only cause a large amount of welding rework, but also multiple reworks will change the grain structure of the material, affecting the strength of the material. Finally, it is necessary to take measures to plan and re-weld, which affects the one-time pass rate of welding. Therefore, it is urgent to develop a tailwater elbow welding method that can improve the one-time flaw detection pass rate to meet actual construction needs. Summary of the invention

[0003] The object of the present invention is to provide a method for welding the annular seam of a tailwater elbow pipe of a pumped storage power station. The present invention has the characteristic of being able to effectively improve the qualified rate of the annular seam of the tailwater elbow pipe in one flaw detection.

[0004] The technical solution of the present invention is a method for welding the annular seam of a tailwater elbow pipe of a pumped storage power station, comprising the following steps:

[0005] S1. Preheat the areas on both sides of the weld to be welded to 80-95°C;

[0006] S2. After the welding rod is dried, it is placed in a heat preservation tube for storage;

[0007] S3. Perform base welding on the weld area with an interpass temperature of 185°C;

[0008] S4. Repair the fusion line of the base weld;

[0009] S5. Cover welding, interlayer temperature is 175℃.

[0010] In the aforementioned pumped storage power station tailwater elbow annular seam welding method, the welding current during the base welding is 110A, the welding voltage is 380V, the welding speed is 11cm / min, and the line energy is 3.8kj / cm.

[0011] In the aforementioned method for welding the annular seam of the tailwater elbow of a pumped storage power station, the welding thickness during the base welding is 2.5-3.5 mm.

[0012] In the aforementioned pumped storage power station tailwater elbow annular seam welding method, the welding current during cover welding is 115A, the welding voltage is 380V, the welding speed is 10cm / min, and the line energy is 4.3kj / cm.

[0013] In the aforementioned method for welding the annular seam of the tailwater elbow of a pumped storage power station, the welding thickness during the cover welding is 2.5-3.5 mm.

[0014] In the aforementioned method for welding the annular seam of the tailwater elbow pipe of a pumped-storage power station, the insulation cylinder includes a central core heating cylinder, an outer insulation cylinder body is arranged outside the central core heating cylinder, a connecting port is arranged between the central core heating cylinder and the outer insulation cylinder body, and an outlet is arranged at the end of the outer insulation cylinder body; it also includes a flexible welding rod belt for inserting welding rods, a group of evenly distributed welding rod insertion bags are arranged on the flexible welding rod belt, a part of the flexible welding rod belt is placed in a coiled state in the central core heating cylinder, and the remaining part of the flexible welding rod belt is placed in an unfolded state in the outer insulation cylinder, and the end of the flexible welding rod belt is located outside the outlet.

[0015] In the aforementioned method for welding the annular seam of the tailwater elbow of a pumped storage power station, a thermal insulation cover is threadedly connected to the top of the outer thermal insulation cylinder.

[0016] In the aforementioned method for welding the annular seam of the tailwater elbow pipe of a pumped storage power station, a group of electric heating wires distributed in a spiral shape are embedded in the central heating cylinder.

[0017] In the aforementioned method for welding the annular seam of the tailwater elbow of a pumped storage power station, symmetrically distributed sealing strips are provided on both sides of the outlet, the sealing strips are rotatably connected to the outlet wall via a rotating shaft, and a reset torsion spring is provided on the rotating shaft.

[0018] Compared with the prior art, the present invention reasonably optimizes and improves the welding method of the circumferential seam according to the characteristics of the tailwater elbow, preheats the areas on both sides of the weld, and strictly controls the interlayer temperature, thereby effectively reducing the occurrence of welding defects; and dries the welding rod before use, thereby ensuring that the welding rod can exert its best performance. Through the improvement of the above welding method, the first-time qualified rate of the circumferential seam welding quality of the tailwater elbow installation reaches 99.7%, significantly reducing the length of the repair weld. The construction cost is saved on site due to the reduction of repair welds, and the construction efficiency is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a structural schematic diagram of the heat preservation cylinder of the present invention.

[0020] The markings in the attached drawings are: 1-core heating cylinder, 2-external insulation cylinder, 3-connecting port, 4-export, 5-flexible welding strip, 6-sealing strip. DETAILED DESCRIPTION

[0021] The present invention is further described below in conjunction with the accompanying drawings and embodiments, but they are not intended to limit the present invention.

[0022] Embodiment: A method for welding the annular seam of a tailwater elbow pipe of a pumped storage power station comprises the following steps:

[0023] S1. Preheat the areas on both sides of the weld to be welded to 80-95°C;

[0024] S2. After the welding rod is dried, it is placed in a heat preservation tube for storage;

[0025] S3. Perform base welding on the weld area with an interpass temperature of 185°C;

[0026] S4. Repair the fusion line of the base weld;

[0027] S5. Cover welding, interlayer temperature is 175℃.

[0028] The welding current during the base welding is 110A, the welding voltage is 380V, the welding speed is 11cm / min, and the line energy is 3.8kj / cm.

[0029] The welding thickness during base welding is 2.5-3.5mm.

[0030] The welding current during cover welding is 115A, the welding voltage is 380V, the welding speed is 10cm / min, and the line energy is 4.3kj / cm.

[0031] The welding thickness during cover welding is 2.5-3.5mm.

[0032] Composition Figure 1 As shown, the insulation cylinder includes a central heating cylinder 1, an outer insulation cylinder body 2 is arranged outside the central heating cylinder 1, a connecting port 3 is arranged between the central heating cylinder 1 and the outer insulation cylinder body 2, and an outlet 4 is arranged at the end of the outer insulation cylinder body 2; it also includes a flexible welding rod belt 5 for inserting welding rods, and a group of evenly distributed welding rod insertion bags are arranged on the flexible welding rod belt 5. A part of the flexible welding rod belt 5 is placed in the central heating cylinder 1 in a coiled state, and the remaining part of the flexible welding rod belt 5 is placed in the outer insulation cylinder body 2 in an unfolded state, and the end of the flexible welding rod belt 5 is located outside the outlet 4.

[0033] The top of the outer heat-insulating cylinder 2 is connected with a heat-insulating cover via threads.

[0034] The central heating cylinder 1 is embedded with a group of electric heating wires distributed in a spiral shape.

[0035] Symmetrically distributed sealing strips 6 are provided on both sides of the outlet 4. The sealing strips 6 are rotatably connected to the wall surface of the outlet 4 via a rotating shaft, and a return torsion spring is provided on the rotating shaft.

[0036] The welding method adopted is SMAW.

[0037] By strictly limiting the welding current, welding voltage, welding speed and wire energy during base welding and cover welding, the mechanical properties of the tailwater elbow can be effectively guaranteed.

[0038] During the welding process, arc discharge can easily cause cracks in the base material, so gradual back-off and arc-starting plates should be used at the beginning of welding.

[0039] The present invention makes reasonable optimization and improvement to the heat preservation cylinder, which not only facilitates the storage and taking of welding rods, but also has a good heat preservation effect. Moreover, the structure of the central heating cylinder, the outer heat preservation cylinder and the flexible welding rod belt can ensure that the welding rod will not affect other welding rods when it is taken.

[0040] Moreover, a sealing strip with a torsion spring reset is arranged at the outlet, which can further improve the sealing and heat insulation effect, ensuring that one welding rod is pulled out at a time, and the remaining welding rods are all located in the outer insulation cylinder and the core heating cylinder.

[0041] How to use the insulation cylinder: insert the dried welding rods into the corresponding welding rod insertion bags of the flexible welding rod belt in turn, then roll up part of the flexible welding rod belt according to the inner diameter of the core heating cylinder and place it in the core heating cylinder, and pass the remaining part of the flexible welding rod belt through the connecting port, unfold and arrange it in the outer insulation cylinder, and the end of the flexible welding rod belt is exposed outside the outlet for subsequent pulling. When the welding rod is needed, the operator only needs to pull the flexible welding rod belt outward to expose one welding rod. The sealing strip has a certain damping effect, which can not only play an effective sealing and heat preservation role, but also prevent the flexible welding rod belt from falling out when it is not subject to external force.

Claims

1. A method for welding the annular seam of tailwater elbow pipe of a pumped storage power station, characterized in that: The following steps are involved: S1. Preheat the areas on both sides of the weld to be welded to 80-95°C; S2. After the welding rod is dried, it is placed in a heat preservation tube for storage; S3. Perform base welding on the weld area with an interpass temperature of 185°C; S4. Repair the fusion line of the base weld; S5. Cover welding, interlayer temperature is 175℃.

2. The method for welding the annular seam of the tailwater elbow of a pumped storage power station according to claim 1, characterized in that: The welding current during the base welding is 110A, the welding voltage is 380V, the welding speed is 11cm / min, and the line energy is 3.8kj / cm.

3. The method for welding annular seam of tailwater elbow of pumped storage power station according to claim 1, characterized in that: The welding thickness during base welding is 2.5-3.5mm.

4. The method for welding annular seam of tailwater elbow of pumped storage power station according to claim 1, characterized in that: The welding current during cover welding is 115A, the welding voltage is 380V, the welding speed is 10cm / min, and the line energy is 4.3kj / cm.

5. The method for welding the annular seam of the tailwater elbow of a pumped storage power station according to claim 1, characterized in that: The welding thickness during cover welding is 2.5-3.5mm.

6. The method for welding annular seam of tailwater elbow of pumped storage power station according to claim 1, characterized in that: The heat preservation cylinder comprises a central heating cylinder (1), an outer heat preservation cylinder body (2) is arranged outside the central heating cylinder (1), a communication port (3) is arranged between the central heating cylinder (1) and the outer heat preservation cylinder body (2), and an outlet (4) is arranged at the end of the outer heat preservation cylinder body (2); and further comprises a flexible welding rod belt (5) for inserting welding rods, a group of evenly distributed welding rod insertion pockets are arranged on the flexible welding rod belt (5), a part of the flexible welding rod belt (5) is placed in the central heating cylinder (1) in a coiled state, and the remaining part of the flexible welding rod belt (5) is placed in the outer heat preservation cylinder body (2) in an unfolded state, and the end of the flexible welding rod belt (5) is located outside the outlet (4).

7. The method for welding annular seam of tailwater elbow of pumped storage power station according to claim 6, characterized in that: The top of the outer heat-insulating cylinder (2) is connected to a heat-insulating cover via threads.

8. The method for welding annular seam of tailwater elbow of pumped storage power station according to claim 6, characterized in that: The central core heating cylinder (1) is embedded with a group of electric heating wires distributed in a spiral shape.

9. The method for welding the annular seam of the tailwater elbow of a pumped storage power station according to claim 6, characterized in that: Symmetrically distributed sealing strips (6) are provided on both sides of the outlet (4); the sealing strips (6) are rotatably connected to the wall surface of the outlet (4) via a rotating shaft, and a return torsion spring is provided on the rotating shaft.

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