Welding method and process for an asymmetric J-groove between a thin-walled pipe and a plate

Abstract

The present invention relates to the technical field of tube and plate welding, and particularly to a welding method for an asymmetric J-groove of a thin-walled tube and a plate. The welding method for the asymmetric J-groove of the thin-walled tube and the plate specifically comprises the following steps: S1: Assembly spot welding and root welding: Spot welding is carried out in the direction of 6H → 3H → 9H → 12H, and then root welding is alternately carried out in the direction of 6H → 3H / 9H → 12H; S2: Filling the lower half: The area of 6H ± 4.5H is filled. Each pass is welded alternately left and right in the directions of 6H → 3H → 1.5H and 6H → 9H → 10.5H. Weld 3-4 layers. When welding each layer, first weld the area of the groove close to the head side, and then weld the area close to the sleeve side to reduce the heat input on the sleeve; S3: Filling the upper half: The area of 12H ± 1.5H is filled. Each pass is welded alternately left and right in the directions of 10.5H → 12H and 1.5H → 12H. Weld 3-4 layers. When welding each layer, first weld the area of the groove close to the head side, and then weld the area close to the sleeve side to reduce the heat input on the sleeve. The present invention has the advantages of effectively controlling the welding deformation direction and deformation amount.

Description

Technical Field

[0001] The present invention relates to the technical field of tube-to-plate welding, and particularly to a welding method and process for an asymmetric J-groove of a thin-walled tube and a plate. Background Technique

[0002] As one of the main equipment in the primary loop of a nuclear power plant, the function of the pressurizer is to maintain the pressure in the primary loop at a constant pressure during the operation of the power plant. The electric heater element of the lower head assembly is a key component for the pressurizer to achieve the pressure regulation function of the primary loop. When the nuclear power plant operates normally, the heating and regulating function of the electric heater assembly can be maximally exerted to reduce the operation of other safety systems (such as spray, charging and discharging systems). The electric heater element consists of two parts, an electric heater sleeve and an electric heater. The connection method with the lower head is as follows: first, the electric heater sleeve is welded to the lower head using a J-groove weld, and then the electric heater passes through the heater sleeve and enters the inside of the pressurizer. The electric heater sleeve / electric heater is distributed in 4 circles on the lower head (as Figure 1 shown), and each circle has a different number of electric heater elements, totaling more than 100 pieces, and is assembled with the lower head in a vertical state.

[0003] Lower head: with a thickness of 120 mm, made of low-alloy high-strength steel 18MND5, and an austenitic stainless steel (309L + 308L) with a thickness of about 20 mm is surfacing welded on the inner surface as a corrosion-resistant layer.

[0004] Heater sleeve: made of stainless steel Z2CND18.12(N), with a thickness of 6.3 mm and an inner diameter of 23.6 mm.

[0005] According to the calculation based on the outer diameter size of the electric heater and the inner diameter size of the sleeve, when the electric heater penetrates into the inner wall of the electric heater sleeve, the theoretical gap between them is only 0.7 mm. The design requirement is that after the sleeve is welded to the head, the electric heater can safely pass through the sleeve and enter the inside of the pressurizer without jamming problems and without damaging the base material. Therefore, a through-rod inspection needs to be carried out after the electric heater sleeve is welded. The outer diameter of the through-rod is set to 22.55 mm, which requires that the shrinkage deformation amount in any quadrant after the electric heater sleeve is welded to the lower head shall not be greater than 0.425 mm.

[0006] The connection method between the electric heater sleeve and the lower head is welding with an asymmetric J-groove weld (for the specific groove type and weld size, see Figure 2), the casing is made of austenitic stainless steel. Stainless steel has the characteristics of low thermal conductivity, strong thermal sensitivity, and large expansion coefficient, making it extremely prone to welding deformation. Moreover, the wall thickness of the casing is only 6.3 mm, with poor rigidity. At the same time, the welding filling amount is large, and heat accumulation will further exacerbate the welding shrinkage. The above situation determines that the welding of this weld will extremely easily produce large welding deformation. At the same time, the diameter of the weld between the casing and the head is small, the groove is asymmetric, and the welding difficulty is high. Since this weld is the main pressure-bearing weld, the design requires that the root pass and every third weld pass are qualified by PT inspection, and the weld quality requirements are high. Therefore, while ensuring the quality of the J-shaped weld between the casing and the lower head, controlling the welding deformation and ensuring the smooth passage of the electric heater are the top priorities in the manufacture of the pressurizer product.

[0007] When welding the electric heater casing and the lower head, since the head is hemispherical and the casing is vertically welded, there is a height difference between the upper and lower sides of the groove, and the groove of the weld is larger at the top and smaller at the bottom (see Figure 2 ). As the distance from the casing to the axis of the head increases, the height difference also increases, and the welding amount at the lower part and the higher part differs more and more. The asymmetric welding amount will exacerbate the severity of the welding deformation. According to the existing technology, although certain measures have been taken in terms of welding process and operation to control the welding deformation as much as possible, the asymmetric shrinkage between the higher and lower parts of the weld still causes the pipe orifice to produce a deformation amount exceeding the design requirements (≤0.425 mm). It is mainly manifested as the overall deformation of the casing towards the direction near 12 o'clock with a larger welding amount, resulting in jamming of the passing rod near the 6 o'clock position. Each pressurizer product has 108 electric heaters, and about 95% of the electric heaters cannot pass through the casing during the general assembly. The schematic diagram of the passing rod jamming caused by the welding deformation of the existing technology is shown in Figure 2 [[ID=?]]as shown.

[0008] The disadvantage of the existing technology is that only certain measures have been implemented from the perspective of controlling the overall welding deformation, which has reduced the welding deformation shrinkage amount to a certain extent and ensured the weld quality. However, the control measures taken still cannot control the welding deformation amount within the design requirements (i.e., ≤0.425 mm), and the problem of the single-direction deformation of the asymmetric J-shaped groove weld has not been solved, resulting in passing rod jamming and unable to meet the design requirements.

[0009] Therefore, in view of the deficiencies of the existing technology, a welding method for an asymmetric J-shaped groove between a thin-walled pipe and a plate is provided. Summary of the Invention

[0010] In order to overcome the deficiencies of the existing technology, the present invention provides a welding method and process for an asymmetric J-shaped groove between a thin-walled pipe and a plate, aiming to solve the problems of the overall single-direction deformation of the casing after welding and the large deformation amount.

[0011] In order to achieve the above object, the present invention adopts the following technical solutions:

[0012] A welding method for an asymmetric J-shaped groove between a thin-walled pipe and a plate, comprising the following steps:

[0013] S1: Assembly spot welding and backing welding: Perform spot welding in the direction of 6H → 3H → 9H → 12H, and then alternately perform backing welding in the direction of 6H → 3H / 9H → 12H;

[0014] S2: Fill the lower half: Fill the area of 6H ± 4.5H, and alternately weld left and right in the directions of 6H → 3H → 1.5H and 6H → 9H → 10.5H for each pass. Weld 3 - 4 layers. When welding each layer, first weld the area of the groove close to the head side, and then weld the area close to the casing side;

[0015] S3: Fill the upper half: Fill the area of 12H ± 1.5H, and alternately weld left and right in the directions of 10.5H → 12H and 1.5H → 12H for each pass. Weld 3 - 4 layers. When welding each layer, first weld the area of the groove close to the head side, and then weld the area close to the casing side.

[0016] As a further improvement of the technical solution of the present invention, in step S1: Weld one layer for the entire circle of backing welding, and perform penetrant inspection on the backing weld.

[0017] As a further improvement of the technical solution of the present invention, in step S1: Perform backing welding by alternately welding left and right in the directions of 6H → 3H → 12H and 6H → 9H → 12H.

[0018] As a further improvement of the technical solution of the present invention, in step S2: After welding is completed, grind the lap joint and perform liquid penetrant inspection.

[0019] As a further improvement of the technical solution of the present invention, in step S3: After welding is completed, grind the lap joint and perform liquid penetrant inspection.

[0020] A welding process for an asymmetric J-shaped groove between a thin-walled pipe and a plate, applicable to the welding method for an asymmetric J-shaped groove between a thin-walled pipe and a plate as described above, and the welding is carried out by manual tungsten inert gas welding.

[0021] As a further improvement of the technical solution of the present invention, it includes controlling welding parameters: the wire diameter is 1.2 - 1.6 mm, the welding current is 120 - 130 A, and the welding speed is 8 cm / min - 10 cm / min.

[0022] As a further improvement of the technical solution of the present invention, it also includes controlling the interpass temperature: Set a water cooling device to control the interpass temperature between 45°C - 55°C. Set a water cooling device to assist in cooling, and it can be cooled to the above temperature about 15 seconds after each pass of welding is completed, improving the welding efficiency.

[0023] As a further improvement of the technical solution of the present invention, the water cooling device is detachably connected to the heater sleeve;

[0024] The water cooling device includes a water supply device, a water spray head, an inclined sleeve, a water through head, a water supply pipe, a tensioning member and a connecting head;

[0025] The inclined sleeve is located above the heater sleeve. The water spray head penetrates through the inclined sleeve and extends into the heater sleeve. The water through head is connected to the water spray head. The water supply pipe communicates the water through head with the connecting head. The other end of the connecting head is connected to the water supply device. The tensioning member abuts against the heater sleeve. The connecting head abuts against the tensioning member through a nut. The connecting head is communicated with the water supply device.

[0026] As a further improvement of the technical solution of the present invention, the water spray head is provided with a plurality of through holes, and the plurality of through holes communicate the inside of the water spray head with the inner wall of the heater sleeve.

[0027] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0028] In the welding method of the thin-walled tube and plate asymmetric J-groove of the present invention, on the premise of symmetric welding on the left and right sides, the asymmetric pass arrangement for welding on the upper and lower sides can effectively control the welding deformation direction, that is, only the lower half is welded first, and the whole sleeve is fixed in the normal position through the strength of the lower half weld to offset the effect of the welding stress during the subsequent filling of the upper half, avoiding the overall deformation of the sleeve, solving the problem of the overall deformation of the sleeve in a single direction after welding, and controlling the deformation shrinkage amount of the weld in any direction within 0.425 mm, thus solving the problem of through-rod jamming and enabling all the electric heaters 21 of the product to finally pass smoothly. The welding method of the thin-walled tube and plate asymmetric J-groove of the present invention has the characteristics of effectively controlling the welding deformation direction and deformation amount. Description of the Drawings

[0029] The following further details the technology of the present invention in conjunction with the drawings and specific embodiments:

[0030] Figure 1 is a schematic structural diagram of the thin-walled tube and plate of the present invention;

[0031] Figure 2 is a schematic diagram of the deformation and through-rod blockage after welding of the thin-walled tube and plate asymmetric J-groove in the prior art;

[0032] Figure 3 is a schematic diagram of the backing welding of the welding method of the thin-walled tube and plate asymmetric J-groove of the present invention;

[0033] Figure 4 is a top view of the spot welding and backing welding sequence of the welding method of the thin-walled tube and plate asymmetric J-groove of the present invention;

[0034] Figure 5 It is a schematic diagram of the lower part filling of the welding method for the asymmetric J-groove between the thin-walled pipe and the plate of the present invention;

[0035] Figure 6 It is a top view of the filling sequence of the lower part of the welding method for the asymmetric J-groove between the thin-walled pipe and the plate of the present invention;

[0036] Figure 7 It is a graph of the filling deformation trend of the lower part of the welding method for the asymmetric J-groove between the thin-walled pipe and the plate of the present invention;

[0037] Figure 8 It is a schematic diagram of the upper part filling of the welding method for the asymmetric J-groove between the thin-walled pipe and the plate of the present invention;

[0038] Figure 9 It is a top view of the filling sequence of the upper part of the welding method for the asymmetric J-groove between the thin-walled pipe and the plate of the present invention;

[0039] Figure 10 It is a graph of the filling deformation trend of the upper part of the welding method for the asymmetric J-groove between the thin-walled pipe and the plate of the present invention;

[0040] Figure 11 It is a schematic diagram of the structure of the water cooling device in the welding method for the asymmetric J-groove between the thin-walled pipe and the plate of the present invention.

[0041] In the figure:

[0042] 1. Lower head;

[0043] 2. Heater sleeve; 21. Electric heater;

[0044] 3. Weld seam;

[0045] 4. Water cooling device; 41. Sprinkler head; 42. Through hole; 43. Inclined sleeve; 44. Water passing head; 45. Water supply pipe; 46. Tension member; 47. Connector;

[0046] 5. Through rod. Specific embodiments

[0047] The concept, specific structure and technical effects of the present invention will be clearly and completely described below in combination with the embodiments and the drawings, so as to fully understand the purpose, scheme and effects of the present invention. It should be noted that, without conflict, the embodiments in the present application and the features in the embodiments can be combined with each other. The same reference numerals used in the drawings indicate the same or similar parts everywhere.

[0048] It should be noted that, unless otherwise specified, when a feature is referred to as "fixed" or "connected" to another feature, it can be directly fixed or connected to the other feature, or indirectly fixed or connected to the other feature. In addition, the descriptions such as up, down, left, and right used in the present invention are only relative to the mutual positional relationship of the components of the present invention in the drawings.

[0049] Referring to Figures 1 to 11 , a welding method for an asymmetric J-groove of a thin-walled tube and a plate, comprising the following steps:

[0050] S1: Assembly spot welding and backing welding: Spot weld 4 places in the direction of 6H → 3H → 9H → 12H, and then alternately carry out backing welding left and right in the direction of 6H → 3H / 9H → 12H, that is, alternately weld in the directions of 6H → 3H → 12H and 6H → 9H → 12H;

[0051] S2: Filling the lower half: Fill the area of 6H ± 4.5H, and alternately weld left and right in the direction from bottom to top for each pass, that is, alternately weld in the directions of 6H → 3H → 1.5H and 6H → 9H → 10.5H, and weld 3 - 4 layers; When welding each layer, first weld the area of the groove close to the head side, and then weld the area close to the sleeve side to reduce the heat input on the sleeve;

[0052] S3: Filling the upper half: Fill the area of 12H ± 1.5H, and alternately weld left and right in the direction from bottom to top for each pass, that is, alternately weld in the directions of 10.5H → 12H and 1.5H → 12H, and weld 3 - 4 layers; When welding each layer, first weld the area of the groove close to the head side, and then weld the area close to the sleeve side to reduce the heat input on the sleeve.

[0053] Among them, on the premise of symmetric welding on the left and right sides, adopting an asymmetric pass arrangement for welding on the upper and lower sides can effectively control the direction of welding deformation, that is, first only weld the lower half, and fix the whole sleeve in the normal position through the strength of the weld 3 in the lower half to offset the action of the welding stress during the subsequent filling of the upper half, avoid the overall deformation of the sleeve, and on the basis of ensuring the quality of the asymmetric J-groove weld 3 between the heater sleeve 2 and the lower head 1, further reduce the overall welding deformation amount of the weld 3, solve the problem of the overall deformation of the sleeve in a single direction after welding, and control the deformation shrinkage amount of the weld 3 in any direction within 0.425 mm, thereby solving the problem of the jamming of the through rod 5 and enabling all the electric heaters 21 of the product to finally pass smoothly. The welding method for the asymmetric J-groove of the thin-walled tube and the plate has the characteristics of effectively controlling the direction and amount of welding deformation.

[0054] In one embodiment, referring to Figures 3 - 4As shown, in step S1: Weld a full circle for the backing layer, and perform visual inspection and liquid penetration inspection on the root pass of the weld seam 3. If only a part of the root pass is welded, when performing PT inspection, the PT liquid will enter the gap between the casing and the head, and it cannot be cleaned. In addition, during subsequent welding, impurities such as slag will also enter the gap between the casing and the head, making it difficult to clean, which will not guarantee the quality of the weld seam 3.

[0055] In one embodiment, referring to Figures 5 - 7 As shown, in step S2: Fill the 6H±4.5H area. Weld alternately left and right in the directions of 6H→3H→1.5H and 6H→9H→10.5H for each pass, and weld 3 - 4 layers; when welding each layer, first weld the area of the groove near the head side, and then weld the area near the casing side to reduce the heat input on the casing. After welding is completed, grind the lap joint and perform liquid penetration inspection.

[0056] In one embodiment, referring to Figures 8 to 10 , in step S3: Fill the 12H±1.5H area. Weld alternately left and right in the directions of 10.5H→12H and 1.5H→12H for each pass, and weld 3 - 4 layers; when welding each layer, first weld the area of the groove near the head side, and then weld the area near the casing side to reduce the heat input on the casing. After welding is completed, grind the lap joint and perform liquid penetration inspection.

[0057] In one embodiment, for the control of the filling amount of the lower half: It is proved through multiple tests that welding about 3 / 4 of a circle and welding 3 - 4 layers can better play the role of controlling deformation. If the welding amount is less than 3 / 4 of a circle or the number of layers is insufficient, the welding fixation effect is not enough to withstand the stress during the welding of the upper half, and the casing will still deflect in the 12 o'clock direction as a whole after the upper half is welded. If the welding exceeds 3 / 4 of a circle, due to structural limitations, it is difficult to grind the arc starting and ending areas of the lower half clean, and defects are likely to occur during the subsequent welding of the upper half, which is not conducive to the control of the quality of the weld seam 3.

[0058] A welding process for the asymmetric J-groove of a thin-walled pipe and a plate, which is applicable to the above-mentioned welding method for the asymmetric J-groove of a thin-walled pipe and a plate, is a welding method with a relatively small heat input, and manual tungsten inert gas welding is used for welding.

[0059] In one embodiment, the welding process includes controlling welding parameters to reduce the heat input during welding: the wire diameter is selected to be 1.2 - 1.6 mm, and the welding current is 120 - 130 A. When the welding current exceeds this range, the heat input is relatively large, and it is impossible to precisely control the welding deformation. Moreover, the base material of the lower head 1 is relatively thick. When the current is less than this range, it affects the formation of the weld 3 and cannot guarantee the quality of the weld 3. On this basis of the current, the welding speed is controlled to be 8 cm / min - 10 cm / min. When the welding speed is less than this range, the heat input is relatively large, which is not conducive to welding deformation control. When it exceeds this range, the formation of the weld 3 is poor and cannot guarantee the quality of the weld 3.

[0060] In one embodiment, the welding process further includes controlling the interpass temperature: the smaller the interpass temperature, the more conducive it is to controlling welding deformation. However, this means that a relatively long waiting time is required after each pass of welding, reducing the product manufacturing efficiency. After multiple simulation tests, by setting the water cooling device 4, the interpass temperature is controlled between 45°C - 55°C, and the post-weld deformation can meet the design requirements.

[0061] In one embodiment, referring to Figure 11 As shown, the water cooling device 4 is detachably connected to the heater sleeve 2. Water cooling during the welding process can quickly remove the heat generated during welding, reduce the residual stress, and increase the cooling rate during welding. This can not only obtain an ideal welded joint with fine metal grains, uniform structure, and small welding residual stress in the weld 3, but also reduce the residence time of the welded joint at high temperature and reduce welding deformation. For this reason, we have developed a dedicated water cooling device 4. At the same time, wet towels are used to wipe and cool the head side. After implementing this measure, the actual product can be cooled to about 50°C in about 15 seconds after each pass of welding, which is not only conducive to the control of welding deformation but also greatly improves the production efficiency.

[0062] In one embodiment, the water cooling device 4 includes a water supply device, a spray head 41, an inclined sleeve 43, a water passing head 44, a water supply pipe 45, a tensioning member 46, and a connecting head 47; the inclined sleeve 43 is located above the heater sleeve 2, the spray head 41 passes through the inclined sleeve 43 and extends into the heater sleeve 2, the water passing head 44 is connected to the spray head 41, the water supply pipe 45 connects the water passing head 44 and the connecting head 47, the other end of the connecting head 47 is connected to the water supply device, the tensioning member 46 abuts against the heater sleeve 2, the connecting head 47 abuts against the tensioning member 46 through a nut, and the connecting head 47 is in communication with the water supply device. When the water cooling device 4 cools down, the water supply device supplies cooling water from bottom to top through the connecting head 47 and the water supply pipe 45 into the spray head 41, and the heater sleeve 2 is cooled through the spray head 41.

[0063] In one embodiment, the water spray head 41 is provided with a plurality of through holes 42. The plurality of through holes 42 communicate the interior of the water spray head 41 with the inner wall of the heater sleeve 2, and the cooling water cools the inner wall of the heater sleeve 2 through the through holes 42.

[0064] In one embodiment, for the control of the welding sequence, the control of the welding parameters, and the design of the water-cooling tooling, none of them can be missing. Under the synergistic effect of these three aspects, the weld 3 between the heater sleeve 2 and the lower head 1 solves the problem of the weld 3 deforming in a single direction while ensuring the welding quality, and controls the deformation shrinkage in any direction within 0.425 mm. As a result, all 108 electric heaters 21 of the product finally pass smoothly, achieving the product design requirements.

[0065] For other contents of the welding method and process of the asymmetric J-shaped groove between the thin-walled tube and the plate of the present invention, reference can be made to the prior art and will not be elaborated here.

[0066] The above are only preferred embodiments of the present invention, and do not impose any form of limitation on the present invention. Therefore, any modification, equivalent change, and modification made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention still fall within the scope of the technical solution of the present invention.

[0067] In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one of such features. In the description of the present invention, the meaning of "a plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0068] In the present invention, unless otherwise clearly specified and limited, the terms "install", "connect", "connection", "fix", etc. should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or integrated; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the internal communication of two components or the interaction relationship between two components, unless otherwise clearly limited. 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 circumstances.

Claims

1. A welding method for an asymmetric J-groove between a thin-walled pipe and a plate, characterized in that, It includes the following steps: S1: Assembly spot welding and backing welding: Spot welding is carried out in the direction of 6H→3H→9H→12H, and then the backing is welded alternately left and right in the directions of 6H→3H→12H and 6H→9H→12H; S2: Filling the lower part: Fill the area of 6H±4.5H. Each pass is welded alternately left and right in the directions of 6H→3H→1.5H and 6H→9H→10.5H, and welded for 3 - 4 layers. When welding each layer, first weld the area of the groove near the head side, and then weld the area near the sleeve side; S3: Filling the upper part: Fill the area of 12H±1.5H. Each pass is welded alternately left and right in the directions of 10.5H→12H and 1.5H→12H, and welded for 3 - 4 layers. When welding each layer, first weld the area of the groove near the head side, and then weld the area near the sleeve side.

2. The welding method of an asymmetric J-groove between a thin-walled tube and a plate according to claim 1, characterized in that, In step S1: Weld one layer of the full - circle backing, and perform penetrant inspection on the backing weld.

3. A welding method for an asymmetric J-groove of a thin-walled tube and a plate according to claim 1, characterized in that, In step S2: After welding, grind the lap joint and perform liquid penetrant inspection.

4. A welding method for an asymmetric J-groove of a thin-walled tube and a plate according to claim 1, characterized in that, In step S3: After welding, grind the lap joint and perform liquid penetrant inspection.

5. A welding process for an asymmetric J-groove between a thin-walled tube and a plate, applicable to the welding method for the asymmetric J-groove between a thin-walled tube and a plate described in any one of claims 1-4, characterized in that, Manual tungsten inert gas arc welding is used for welding.

6. The welding process of an asymmetric J-groove between a thin-walled tube and a plate according to claim 5, characterized in that, It includes controlling welding parameters: The wire diameter is 1.2 - 1.6mm, the welding current is 120 - 130A, and the welding speed is 8cm / min - 10cm / min.

7. The welding process of an asymmetric J-groove between a thin-walled tube and a plate according to claim 6, characterized in that It also includes controlling the inter - pass temperature: Control the inter - pass temperature between 45℃ - 55℃, set up a water - cooling device to assist in cooling, and it can be cooled to the above temperature about 15 seconds after each pass of welding, improving the welding efficiency.

8. A welding process for an asymmetric J-groove of a thin-walled tube and a plate according to claim 7, characterized in that, The water - cooling device is detachably connected to the heater sleeve; The water - cooling device includes a water supply device, a spray head, an inclined sleeve, a water - passing head, a water supply pipe, a tensioning member and a connecting head; The inclined sleeve is located above the heater sleeve. The spray head passes through the inclined sleeve and extends into the heater sleeve. The water - passing head is connected to the spray head. The water supply pipe connects the water - passing head and the connecting head. The other end of the connecting head is connected to the water supply device. The tensioning member abuts against the heater sleeve. The connecting head abuts against the tensioning member through a nut, and the connecting head is communicated with the water supply device.

9. The welding process for an asymmetric J-groove of a thin-walled tube and a plate according to claim 8, characterized in that, The spray head is provided with a number of through - holes, and the number of the through - holes communicates the inside of the spray head with the inner wall of the heater sleeve.

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