Circular seam groove structure suitable for end socket and thick-wall tube plate and welding process

Abstract

The invention discloses a circular seam groove structure suitable for an end socket and a thick-wall tube plate, a groove comprises a U-shaped groove part, a V-shaped groove part, a root gap and a plurality of gaskets, and the gaskets are adhered to the back surface of a welding seam. The invention further discloses a welding process which comprises the following steps: S1, groove processing: processing the grooves in the thick-wall tube plate and the end socket, and cleaning groove surfaces and groove peripheral areas; s2, assembling is conducted, specifically, the thick-wall tube plate and the end socket are assembled firstly, the positions and angles of the thick-wall tube plate and the end socket are adjusted, the maximum unfitness of butt joint is controlled to be within 2.5 mm, and the root gap of a welding seam is controlled to be 6-7 mm; then, the gaskets are assembled, the multiple gaskets are sequentially pasted along the welding seam, and it is ensured that the center line of each gasket coincides with the center line of the groove; s3, welding is conducted, specifically, an annular flame heater is used for preheating to 150-200 DEG C before welding, and then weld joint welding is completed; and S4, detecting, namely polishing the weld joint until the weld joint meets the flaw detection requirement, and performing flaw detection. The device can improve the working environment of workers, improve the welding quality stability and improve the welding efficiency.

Description

Technical Field

[0001] The present invention belongs to the technical field of welding, and particularly relates to a circumferential groove structure and welding process applicable to the circumferential joint of a head and a thick-wall tube sheet. Background Art

[0002] In the production and manufacturing of pressure vessels, the welding quality and efficiency of the circumferential joint between a thick-wall tube sheet and a head play a decisive role in the overall performance and safety of the product. When the wall thickness of the tube sheet and the head exceeds 90 mm, many insurmountable obstacles are exposed in the traditional internal wall root clearing welding method.

[0003] From the perspective of the operating environment, workers need to enter a confined space for root clearing and welding operations, with extremely high labor intensity. The high-temperature environment not only seriously threatens the health of workers, but also reduces the operation efficiency. Workers are prone to fatigue and heat stroke, and long-term exposure to this environment may also cause chronic diseases.

[0004] In the welding process, the control accuracy of the preheating temperature has a significant impact on the welding quality. Once the preheating temperature is lower than the standard value, cold cracks are extremely likely to occur, which not only reduces the weld strength, but also poses a safety hazard in the subsequent use of the equipment.

[0005] The conventional welding process is to first carry out manual welding for backing with a thickness of 10 - 15 mm on the inner wall, and then carry out submerged arc welding. The operation of manual welding for backing in a narrow space is difficult, with extremely high requirements for the skills and experience of welders, consuming a large amount of time and manpower. After the submerged arc welding is completed, the inner wall needs to be root cleared, which additionally increases the workload, and the welding quality is affected by human factors and multiple processes, and its stability is difficult to guarantee. Summary of the Invention

[0006] In order to solve the above problems, the present invention provides a circumferential groove structure and welding process applicable to the circumferential joint of a head and a thick-wall tube sheet, which can improve the working environment of workers, enhance the stability of welding quality, and improve welding efficiency.

[0007] The embodiments of the present invention are achieved through the following technical solutions:

[0008] A circumferential groove structure applicable to the circumferential joint of a head and a thick-wall tube sheet, the groove includes a U-shaped groove part, a V-shaped groove part, a root gap, and several gaskets. The upper end of the V-shaped groove part is connected to the lower end of the U-shaped groove part, the lower end of the V-shaped groove part is connected to the root gap, and the gasket is pasted on the back of the weld.

[0009] In an embodiment of the present invention, the gasket is a ceramic gasket.

[0010] In an embodiment of the present invention, the ceramic gasket is provided with a groove, and both sides of the groove are provided with bonding areas for bonding with the workpiece. When the ceramic gasket is bonded to the workpiece, the groove is located at the root of the weld.

[0011] A circumferential welding process applicable to the circumferential seam welding of a head and a thick-walled tube sheet, comprising the following steps:

[0012] S1. Groove machining: Machine the groove as described in claim 3 on the thick-walled tube sheet and the head, and clean the groove surface and the area around the groove;

[0013] S2. Assembly: First, assemble the thick-walled tube sheet and the head, adjust the position and angle of the thick-walled tube sheet and the head so that the maximum misalignment is controlled within 2.5 mm, and control the root gap of the weld between 6 - 7 mm; then assemble the backing. Paste several backings as described in claim 3 along the weld in sequence, ensuring that the center line of each backing coincides with the center line of the groove;

[0014] S3. Welding: Preheat to 150 - 200 °C with a ring-shaped flame heater before welding, and then complete the weld;

[0015] S4. Inspection: After grinding the weld to meet the flaw detection requirements, perform flaw detection.

[0016] In an embodiment of the present invention, when cleaning the groove surface and the area around the groove in step S1, use a grinding wheel to clean the rust, oil stain, oxide and other impurities in the range of more than 10 mm on the outer and inner walls of the circumferential seam of the head and the tube sheet at the groove edge and around, so that it shows a metallic luster.

[0017] In an embodiment of the present invention, in step S2, the method to ensure that the center line of the backing coincides with the center line of the groove is: When pasting the ceramic backing, when observing from the outside of the workpiece that the center line of the backing coincides with the center line of the groove, perform the pasting operation from the inside of the workpiece.

[0018] In an embodiment of the present invention, when welding in step S3, first perform backing welding by arc welding. Swing evenly during welding until the weld height reaches about 5 mm from the bottommost weld, and remove the backing on the back of the weld after welding.

[0019] In an embodiment of the present invention, in step S3, after the backing welding is completed, perform filling welding by single-wire submerged arc automatic welding until the weld height reaches about 10 mm from the bottommost weld.

[0020] In an embodiment of the present invention, in step S3, after the filling welding is completed, perform double-wire submerged arc welding until it is close to 10 mm from the top of the weld.

[0021] In an embodiment of the present invention, in step S3, after the double-wire submerged arc welding is completed, perform single-wire submerged arc welding until completion.

[0022] The technical solution of the present invention has at least the following advantages and beneficial effects:

[0023] The present invention adopts a composite groove combining a U-shaped groove and a V-shaped groove, and at the same time pastes a backing on the back of the groove weld, which changes the situation that traditional welders need to enter a confined space for root cleaning and welding operations, reduces the labor intensity of workers, eliminates the threat of high-temperature environment to the health of workers, reduces the risks of worker fatigue and heatstroke, reduces the probability of chronic diseases, improves the operation efficiency, enhances the stability of welding quality, and improves the welding efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention, and therefore should not be regarded as limiting the scope. For those of ordinary skill in the art, without creative efforts, other related drawings can also be obtained based on these drawings.

[0025] Figure 1 It is a schematic diagram of the circumferential weld groove structure of the head and the thick-walled tube sheet in the present invention and omitting the backing.

[0026] Figure 2 It is a schematic diagram of the circumferential weld groove structure of the head and the thick-walled tube sheet in the present invention and including the backing.

[0027] Figure 3 It is a schematic diagram of the circumferential weld of the head and the thick-walled tube sheet in the present invention.

[0028] Reference numerals: 1 - thick-walled tube sheet, 2 - head, 31 - U-shaped groove part, 32 - V-shaped groove part, 33 - root gap, 34 - backing. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0029] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. Usually, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0030] Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed present invention, but merely represents the selected embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention.

[0031] It should be noted that: similar reference numerals and letters represent similar items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings.

[0032] In the description of the present invention, it should be noted that if terms such as "inner" and "outer" are used to indicate the orientation or positional relationship, which is based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the product of the present invention is usually placed during use, it is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation to the present invention.

[0033] In the description of the present invention, it should also be noted that unless otherwise clearly specified and defined, if terms such as "set", "installed", "configured", "connected" are understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected, or indirectly connected through an intermediate medium, and can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0034] Embodiment

[0035] Please refer to Figures 1-3 , this embodiment provides a circumferential weld groove structure suitable for the head and the thick wall tube sheet. The groove structure includes a U-shaped groove portion 31, a V-shaped groove portion 32, a root gap 33 and a plurality of pads 34. The depth of the U-shaped groove portion 31 is about 80 mm and the angle is 1.5°. The angle of the V-shaped groove portion 32 is 45°. The upper end of the V-shaped groove portion 32 is connected to the lower end of the U-shaped groove portion 31, and the lower end of the V-shaped groove portion 32 is connected to the root gap 33. The root gap 33 is controlled within 6 - 7 mm. The pad 34 is pasted on the back of the weld. The pad 34 is made of a material that is resistant to high temperature and does not react with the weld pool. For example, in this embodiment, the pad 34 is a ceramic pad 34, and the ceramic pad 34 is provided with a groove. Both sides of the groove are provided with bonding areas for pasting with the workpiece, and the bonding areas are coated with an adhesive. When the ceramic pad 34 is pasted with the workpiece, the groove is located at the root of the weld. In this embodiment, the groove width of the groove of the ceramic pad 34 is 12 mm and the depth is 1.2 mm. The deposited metal of the backing weld is easier to spread with a groove width of 12 mm compared with other groove widths, which is more convenient for the welder to weld. The width of the surface weld pool after welding is also wider, and the back of the weld is well formed without grinding and repair welding. It should be noted that Figure 2 There are dotted lines drawn in the groove structure. These dotted lines do not represent any physical structure, but are only auxiliary lines for dividing the U-shaped groove portion 31, the V-shaped groove portion 32 and the root gap 33.

[0036] Based on the above groove structure, this embodiment also provides a circumferential weld process suitable for the head 2 and the thick wall tube sheet 1, including the following steps:

[0037] S1. Groove machining: Machine the grooves on the thick-walled tube sheet 1 and the head 2 as described above, clean the groove surface and the area around the groove. Moreover, when cleaning the groove surface and the area around the groove, use a grinding wheel to polish and clean the groove edges and the area more than 10 mm around the outer and inner walls of the circumferential weld between the head 2 and the tube sheet, removing rust, oil, oxides and other impurities to make it show metallic luster.

[0038] S2. Assembly: First, assemble the thick-walled tube sheet 1 and the head 2, adjust the positions and angles of the thick-walled tube sheet 1 and the head 2 so that the maximum misalignment is controlled within 2.5 mm, and control the root gap of the weld 33 to be between 6 - 7 mm; then assemble the gasket 34. Paste several gaskets 34 as described above along the weld in sequence, ensuring that the center line of each gasket 34 coincides with the center line of the groove. The method to ensure that the center line of the gasket 34 coincides with the center line of the groove is: when pasting the ceramic gasket 34, when observing from the outside of the workpiece that the center line of the gasket 34 coincides with the center line of the groove, perform the pasting operation from the inside of the workpiece. When pasting the ceramic gasket 34, it can be pasted manually or assisted by equipment. In this embodiment, manual pasting is adopted, that is, when pasting the ceramic gasket 34, when one operator observes from the outside of the workpiece that the center line of the gasket 34 coincides with the center line of the groove, another operator performs the pasting operation from the inside of the workpiece.

[0039] S3. Welding: Preheat to 150 - 200 °C with a ring - shaped flame heater before welding, and then complete the weld; The welding process is divided into four steps. Specifically, first, perform backing welding by arc welding. Use J607NiRφ5.0 electrode for arc welding backing, with a current of 180 - 200 A and a voltage of 25 - 30 V. Swing evenly during welding until the weld height reaches about 5 mm from the bottom - most weld, and remove the backing 34 on the back of the weld after welding. Secondly, after the backing welding is completed, preheat again to 150 - 200 °C, and perform filling welding by single - wire submerged arc automatic welding. Select H10Mn2NiMAφ4.0 welding wire, with a welding current of 640 - 650 A and a welding voltage of 32 - 34 V. The welding flux is SJ101. Strike an arc at the bottom of the groove, control the welding speed and inter - pass overlap. Clean the welding slag and spatter on the weld surface after each layer is welded, check the appearance quality of the weld, and repair defects in time until the weld height reaches about 10 mm from the bottom - most weld. Then, after the filling welding is completed, perform double - wire submerged arc welding. Select H10Mn2NiMAφ4.0 welding wire and SJ101 welding flux. The DC gun welding current of 640 - 660 A controls the weld penetration, and the AC gun welding current of 550 - 570 A affects the weld width and surface formation; The DC gun arc voltage is 30 - 35 V, and the AC gun arc voltage is 33 - 38 V, which is adjusted according to the welding current and welding speed to ensure stable arc and good weld formation; The welding speed is 70 - 75 m / min to ensure welding stability and quality; The distance between the two guns is 20 - 25 mm, and the angle between the two guns is 55 - 65°. Switch to the double - wire submerged arc welding mode. After adjusting the position, distance, and angle of the guns, strike arcs simultaneously, observe the weld fusion and surface formation, clean and check the weld quality after each layer is welded until it is about 10 mm from the top of the weld. Finally, after the double - wire submerged arc welding is completed, perform single - wire submerged arc welding, with a welding current of 580 - 600 A, an arc voltage of 33 - 35 V, and a welding speed of 72 - 76 cm / min. Start welding from 10 mm from the top of the weld. After welding is completed, stop wire feeding and the welding power supply, and clean the welding slag and spatter on the weld surface. The present invention uses the coordinated application of multiple welding methods at different stages, taking into account different requirements for accuracy, speed, penetration, width, etc. in each welding stage.

[0040] S4. Detection: After grinding the weld to meet the flaw detection requirements, perform 100% magnetic particle flaw detection, 100% penetrant flaw detection, 100% ultrasonic flaw detection, and 100% radiographic flaw detection on the welded joint.

[0041] The present invention adopts a composite groove combining a U-shaped groove and a V-shaped groove, and at the same time pastes a backing 34 on the back of the groove weld, effectively solving the problem of the circumferential weld between the head 2 and the thick wall tube sheet 1, achieving single-sided welding with double-sided forming, and meeting the requirement of full penetration of the weld; moreover, it changes the situation that traditional welders need to enter a confined space for root cleaning and welding operations, reduces the labor intensity of workers, eliminates the threat of high-temperature environment to the health of workers, reduces the risks of worker fatigue and heat stroke, reduces the probability of chronic diseases, improves the operation efficiency at the same time, enhances the stability of welding quality, and improves the welding efficiency.

[0042] Adopting the welding process of the present invention can avoid the problems of difficult operation and low efficiency of manual welding for backing in a narrow space in the conventional welding process, reduce the excessive dependence on the skills and experience of welders, and save a large amount of time and manpower; at the same time, it avoids the additional workload of root cleaning on the inner wall after submerged arc welding, reduces the influence of human factors and multiple processes on welding quality, and greatly improves welding quality and efficiency.

[0043] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A circumferential groove structure suitable for a head and a thick-walled tube sheet, characterized in that: The groove includes a U-shaped groove part, a V-shaped groove part, a root gap and a plurality of gaskets, the upper end of the V-shaped groove part is connected to the lower end of the U-shaped groove part, the lower end of the V-shaped groove part is connected to the root gap, and the gasket is pasted on the back of the weld.

2. The annular groove structure suitable for a head and a thick-walled tube sheet according to claim 1, characterized in that: The liner is a ceramic liner.

3. The annular groove structure suitable for a head and a thick-walled tube sheet according to claim 3, characterized in that: The ceramic liner is provided with a groove, and bonding areas for bonding with the workpiece are provided on both sides of the groove. When the ceramic liner is bonded to the workpiece, the groove is located at the root of the weld.

4. A circumferential seam welding process suitable for head and thick-walled tube sheet, characterized by the following steps: S1. Groove processing: Process the groove as described in claim 3 on the thick-walled tube sheet and the head, and clean the groove surface and the surrounding area of ​​the groove; S2. Assembly: first assemble the thick-walled tube sheet and the head, adjust the position and angle of the thick-walled tube sheet and the head, so that the maximum misalignment is controlled within 2.5mm, and the gap at the root of the weld is controlled between 6-7mm; then assemble the gasket, and paste the gaskets as described in claim 3 along the weld in sequence, ensuring that the center line of each gasket coincides with the center line of the groove; S3. Welding: Preheat to 150-200℃ with a ring flame heater before welding, and then complete the weld; S4. Inspection: After the weld is polished to meet the NDT requirements, conduct NDT inspection.

5. A circumferential seam welding process applicable to a head and a thick-walled tube sheet according to claim 4, characterized in that: When cleaning the groove surface and the surrounding area of ​​the groove in step S1, the groove edge of the outer wall and inner wall of the head and the tube sheet annular seam and the surrounding rust, oil, oxides and other impurities within a range of more than 10 mm are cleaned with a grinding wheel to make them metallic.

6. A circumferential seam welding process applicable to a head and a thick-walled tube sheet according to claim 4, characterized in that: In step S2, the method for ensuring that the center line of the liner coincides with the center line of the groove is: when pasting the ceramic liner, when the center line of the liner coincides with the center line of the groove when viewed from the outside of the workpiece, the pasting operation is performed from the inside of the workpiece.

7. A circumferential seam welding process applicable to a head and a thick-walled tube sheet according to claim 4, characterized in that: When welding in step S3, firstly, the base welding is performed by arc welding, and the welding is swung evenly until the weld height reaches about 5 mm from the bottom weld. After welding, the backing on the back of the weld is removed.

8. A circumferential seam welding process applicable to a head and a thick-walled tube sheet according to claim 7, characterized in that: In step S3, after the base welding is completed, single-wire submerged arc automatic welding is used for filling welding until the weld height reaches about 10 mm from the bottom weld.

9. A circumferential seam welding process applicable to a head and a thick-walled tube sheet according to claim 8, characterized in that: In step S3, after the filling welding is completed, double-wire submerged arc welding is used until it is close to 10 mm from the top of the weld.

10. A circumferential seam welding process applicable to a head and a thick-walled tube sheet according to claim 9, characterized in that: In step S3, after the double-wire submerged arc welding is completed, single-wire submerged arc welding is used to complete the welding.

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