Welding method and system for improved chromium-molybdenum steel cylinder section

Abstract

The invention provides a welding method and system for an improved chromium-molybdenum steel cylinder section, and the welding method for the improved chromium-molybdenum steel cylinder section comprises the following steps: machining a first novel welding groove in a first to-be-welded surface of a pre-assembled and welded cylinder section, and machining a second novel welding groove in a second to-be-welded surface of a service cylinder body; the first novel welding groove in the pre-installed and welded barrel section is in butt joint with the second novel welding groove in the service barrel; according to the first novel welding groove and the second novel welding groove which are in butt joint, the pre-installed and welded barrel section and the service barrel body are welded together; the invention further discloses a welding system for the improved chromium-molybdenum steel cylinder section, the welding system comprises a pre-installed and welded cylinder section and a service cylinder body, and the pre-installed and welded cylinder section and the service cylinder body are welded together through the welding method for the improved chromium-molybdenum steel cylinder section. According to the method, the labor intensity and the welding difficulty during welding of the pre-installed and welded barrel section and the service barrel are greatly reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of large steel cylinder welding, and in particular to a welding method and system for an improved chromium-molybdenum steel cylinder section. Background Art

[0002] During the maintenance process of horizontal pressure vessels and boilers in service in coal chemical enterprises, they often need to be repaired to replace cylinder sections, which requires the entire equipment to be dismantled and transported to the manufacturer for repair. The repair construction period is very long, resulting in a long shutdown time of the production line in the coal chemical enterprise during the repair period.

[0003] Therefore, most coal chemical enterprises prefer to replace cylinder segments and carry out repairs on site. During the process of replacing cylinder segments and repairs, both ends or one end of the original equipment need to maintain a fixed position and full-position welding is required.

[0004] Pressure vessels or boiler bodies made of improved chromium-molybdenum steel such as 12Cr2Mo1VR are mostly used to replace equipment made of ordinary chromium-molybdenum steel and serve in high temperature and high pressure environments. The thickness of the improved chromium-molybdenum steel is generally more than 100mm.

[0005] There are the following welding difficulties for the improved chromium-molybdenum steel large-wall thickness full-position cylinder section welding:

[0006] 1. There is quality uncertainty in welding with improved chrome-molybdenum steel electrodes in all positions;

[0007] 2. The welding base material needs to be preheated to above 205°C, resulting in a harsh welding environment and difficult welding operation in the overhead welding position;

[0008] 3. In the welding process of improved chromium-molybdenum steel, if the back of the groove is cleaned by carbon arc air planer, it is necessary to preheat to above 177°C, then grind and weld, which has low production efficiency.

[0009] Therefore, a welding method for improved chromium-molybdenum steel cylinder section is urgently needed. Summary of the invention

[0010] According to the technical problem raised above, a welding method and system for an improved chromium-molybdenum steel cylinder section are provided.

[0011] The technical means adopted by the present invention are as follows:

[0012] In a first aspect, a welding method for an improved chromium-molybdenum steel cylinder section comprises the following steps:

[0013] S1: processing a first new type of welding groove that can reduce the welding difficulty on the first to-be-welded surface of the pre-assembled cylinder segment, and processing a second new type of welding groove that can reduce the welding difficulty on the second to-be-welded surface of the in-service cylinder, wherein the blunt edge of the first new type of welding groove is consistent in shape with the blunt edge of the second new type of welding groove;

[0014] S2: Butt the first new type welding groove on the pre-welded cylinder section with the second new type welding groove on the service cylinder;

[0015] S3: The pre-assembled cylinder section is welded together with the service cylinder according to the first new type welding groove and the second new type welding groove after butt joint.

[0016] Furthermore, the vertex of the blunt edge of the first new type of welding groove and the vertex of the inner ring of the first surface to be welded are located on the same horizontal plane, and the bottom point of the blunt edge of the first new type of welding groove and the bottom point of the outer ring of the first surface to be welded are located on the same horizontal plane; the vertex of the blunt edge of the second new type of welding groove and the vertex of the inner ring of the second surface to be welded are located on the same horizontal plane, and the bottom point of the blunt edge of the second new type of welding groove and the bottom point of the outer ring of the second surface to be welded are located on the same horizontal plane.

[0017] Furthermore, the step S1 includes the following steps:

[0018] S1A: constructing a blunt edge of a first new type of welding groove on the first surface to be welded, and processing the first new type of welding groove on the first surface to be welded according to the blunt edge of the first new type of welding groove;

[0019] S1B: constructing a blunt edge of a second new type of welding groove on the second surface to be welded, and processing a second new type of welding groove on the second surface to be welded according to the blunt edge of the second new type of welding groove.

[0020] Furthermore, the blunt edge of the first novel welding groove is a circular structure, and the step S1A comprises the following steps:

[0021] S1A1: connecting the vertex of the inner ring of the first surface to be welded and the bottom point of the outer ring of the first surface to be welded to obtain the diameter of the blunt side of the first new welding groove;

[0022] S1A2: constructing a blunt edge of the first new type of welding groove on the first surface to be welded according to the diameter of the blunt edge of the first new type of welding groove;

[0023] S1A3: Processing the inner groove of the first new type of welding groove on the portion of the first surface to be welded located inside the blunt edge of the first new type of welding groove, and processing the outer groove of the first new type of welding groove on the portion of the first surface to be welded located outside the blunt edge of the first new type of welding groove.

[0024] Furthermore, the blunt edge of the second novel welding groove is a circular structure, and the step S1B comprises the following steps:

[0025] S1B1: connecting the vertex of the inner ring of the second surface to be welded and the bottom point of the outer ring of the second surface to be welded to obtain the diameter of the blunt side of the second new welding groove;

[0026] S1B2: constructing a second new type of welding groove blunt edge on the second surface to be welded according to the diameter of the second new type of welding groove blunt edge;

[0027] S1B3: Processing the inner groove of the second new type of welding groove on the portion of the second surface to be welded located inside the blunt edge of the second new type of welding groove, and processing the outer groove of the second new type of welding groove on the portion of the second surface to be welded located outside the blunt edge of the second new type of welding groove.

[0028] Furthermore, the step S3 includes the following steps:

[0029] S31: preheating the first new type welding groove and the second new type welding groove after butt-jointing to a specified welding temperature;

[0030] S32: welding the blunt edge of the first new type welding groove and the blunt edge of the second new type welding groove together;

[0031] S33: welding the inner groove of the first new type welding groove to the inner groove of the second new type welding groove, and welding the outer groove of the first new type welding groove to the outer groove of the second new type welding groove. At this point, the pre-assembled welded cylinder section is welded to the service cylinder.

[0032] Furthermore, the method further comprises step S4, wherein step S4 comprises the following steps:

[0033] S41: Perform intermediate stress relief heat treatment on the pre-welded cylinder section and the service cylinder after welding;

[0034] S42: Heat treatment is performed on the pre-assembled welded cylinder section and the service cylinder after the intermediate stress relief heat treatment.

[0035] In a second aspect, a welding system for an improved chromium-molybdenum steel cylinder section comprises a horizontally arranged pre-assembled welded cylinder section and a service cylinder body, wherein the pre-assembled welded cylinder section is provided with a first surface to be welded having an annular structure and being perpendicular to the horizontal plane, and the service cylinder body is provided with a second surface to be welded having an annular structure and being perpendicular to the horizontal plane, wherein the first surface to be welded and the second surface to be welded have the same shape, and the pre-assembled welded cylinder section and the service cylinder body are welded together using any one of the welding methods for the improved chromium-molybdenum steel cylinder section described in the first aspect.

[0036] Compared with the prior art, the present invention has the following advantages:

[0037] 1. In the present invention, the blunt edge of the first new welding groove is consistent with the blunt edge of the second new welding groove. Since the apex of the blunt edge of the first welding groove and the apex of the inner ring of the first surface to be welded are located on the same horizontal plane, and the apex of the blunt edge of the second welding groove and the apex of the inner ring of the second surface to be welded are located on the same horizontal plane, after the first welding groove and the second welding groove are butt-jointed together, the upper half circumference of the pre-assembled welding cylinder section and the upper half circumference of the service cylinder can be welded outside the pre-assembled welding cylinder section and the service cylinder, and it is not necessary to perform overhead welding; Similarly, since the bottom point of the blunt edge of the first new welding groove and the bottom point of the outer ring of the first surface to be welded are located on the same horizontal plane, and the bottom point of the blunt edge of the second new welding groove and the bottom point of the outer ring of the second surface to be welded are located on the same horizontal plane, after the first new welding groove and the second new welding groove are butt-jointed together, the lower half circumference of the pre-assembled barrel section and the lower half circumference of the serving barrel can be welded inside the pre-assembled barrel section and the serving barrel, and there is no need to perform overhead welding, which greatly reduces the labor intensity and welding difficulty when welding the pre-assembled barrel section and the serving barrel.

[0038] 2. In the present invention, the blunt edge of the first new type welding groove is first welded to the blunt edge of the second new type welding groove, and then the inner groove of the first new type welding groove is welded to the inner groove of the second new type welding groove, and the outer groove of the first new type welding groove is welded to the outer groove of the second new type welding groove to ensure the strength of the welding between the pre-assembled cylinder section and the service cylinder.

[0039] 3. In the present invention, the pre-welded cylinder section and the service cylinder body are first subjected to intermediate stress relief heat treatment after welding to improve the strength, toughness and durability of the weld and improve the corrosion resistance of the weld; then the pre-welded cylinder section and the service cylinder body after the intermediate stress relief heat treatment are subjected to heat treatment to eliminate the stress at the weld. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0041] Figure 1 It is an overall flow chart of a welding method for an improved chromium-molybdenum steel cylinder section in the present invention;

[0042] Figure 2 Schematic diagram of processing the inner groove of the first new welding groove in Example 1 of the present invention;

[0043] Figure 3Schematic diagram of processing the outer groove of the first new type welding groove in Example 1 of the present invention;

[0044] Figure 4 It is a front view of the first novel welding groove and the pre-assembled welded barrel section in Example 1 of the present invention;

[0045] Figure 5 for Figure 4 EE cross-sectional view;

[0046] Figure 6 for Figure 4 FF cross-sectional view;

[0047] Figure 7 Schematic diagram of processing the inner groove of the second new welding groove in Example 1 of the present invention;

[0048] Figure 8 Schematic diagram of processing the outer groove of the second new type welding groove in Example 1 of the present invention;

[0049] Fig. 9 It is a front view of the second new welding groove and the service cylinder in Example 1 of the present invention;

[0050] Fig.10 for Fig. 9 E1-E1 sectional view;

[0051] Fig.11 for Fig. 9 F1-F1 cross-sectional view;

[0052] Fig.12 It is a schematic diagram of the change in groove depth in the circumferential eight-direction cross section and the welding sequence of the first new type welding groove and the second new type welding groove after butt jointing. DETAILED DESCRIPTION

[0053] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0054] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0055] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0056] Unless otherwise specifically stated, the relative arrangement of the parts and steps described in these embodiments, the numerical expressions and numerical values ​​do not limit the scope of the present invention. At the same time, it should be clear that, for ease of description, the sizes of the various parts shown in the drawings are not drawn according to the actual proportional relationship. The technology, methods and equipment known to ordinary technicians in the relevant field may not be discussed in detail, but in appropriate cases, the technology, methods and equipment should be regarded as part of the authorization specification. In all examples shown and discussed here, any specific value should be interpreted as merely exemplary, rather than as a limitation. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar numbers and letters represent similar items in the following drawings, so once an item is defined in one drawing, it does not need to be further discussed in subsequent drawings.

[0057] In the description of the present invention, it is necessary to understand that the directions or positional relationships indicated by directional words such as "front, back, up, down, left, right", "lateral, vertical, perpendicular, horizontal" and "top, bottom" are usually based on the directions or positional relationships shown in the drawings. They are only for the convenience of describing the present invention and simplifying the description. Unless otherwise specified, these directional words do not indicate or imply that the device or element referred to must have a specific direction or be constructed and operated in a specific direction. Therefore, they cannot be understood as limiting the scope of protection of the present invention: the directional words "inside and outside" refer to the inside and outside relative to the contours of each component itself.

[0058] For ease of description, spatially relative terms such as "above", "above", "on the upper surface of", "above", etc. may be used here to describe the spatial positional relationship between a device or feature and other devices or features as shown in the figure. It should be understood that spatially relative terms are intended to include different orientations of the device in use or operation in addition to the orientation described in the figure. For example, if the device in the accompanying drawings is inverted, the device described as "above other devices or structures" or "above other devices or structures" will be positioned as "below other devices or structures" or "below their position devices or structures". Thus, the exemplary term "above" can include both "above" and "below". The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatially relative descriptions used here are interpreted accordingly.

[0059] In addition, it should be noted that the use of terms such as "first" and "second" to limit components is only for the convenience of distinguishing the corresponding components. If not otherwise stated, the above terms have no special meaning and therefore cannot be understood as limiting the scope of protection of the present invention.

[0060] Embodiment 1:

[0061] like Figure 1 As shown, a welding method for an improved chromium-molybdenum steel cylinder section comprises the following steps:

[0062] S1: processing a first new type of welding groove that can reduce the welding difficulty on the first to-be-welded surface of the pre-assembled cylinder segment, and processing a second new type of welding groove that can reduce the welding difficulty on the second to-be-welded surface of the in-service cylinder, wherein the blunt edge of the first new type of welding groove is consistent in shape with the blunt edge of the second new type of welding groove;

[0063] S2: Butt the first new type welding groove on the pre-welded cylinder section with the second new type welding groove on the service cylinder;

[0064] S3: The pre-assembled cylinder section is welded together with the service cylinder according to the first new type welding groove and the second new type welding groove after butt joint.

[0065] Specifically, the form of the first new type of welding groove can be processed into X-shape or U-shape according to the plate thickness of the pre-assembled cylinder section, and the form of the second new type of welding groove can be processed into X-shape or U-shape according to the plate thickness of the service cylinder. The form of the first new type of welding groove is consistent with the form of the second new type of welding groove, and the width of the blunt edge of the first new type of welding groove and the width of the blunt edge of the second new type of welding groove are both 0mm.

[0066] In this embodiment, the vertex of the blunt edge of the first new type of welding groove and the vertex of the inner ring of the first surface to be welded are located on the same horizontal plane, and the bottom point of the blunt edge of the first new type of welding groove and the bottom point of the outer ring of the first surface to be welded are located on the same horizontal plane; the vertex of the blunt edge of the second new type of welding groove and the vertex of the inner ring of the second surface to be welded are located on the same horizontal plane, and the bottom point of the blunt edge of the second new type of welding groove and the bottom point of the outer ring of the second surface to be welded are located on the same horizontal plane.

[0067] In this embodiment, step S1 includes the following steps:

[0068] S1A: constructing a blunt edge of a first new type of welding groove on the first surface to be welded, and processing the first new type of welding groove on the first surface to be welded according to the blunt edge of the first new type of welding groove;

[0069] S1B: constructing a blunt edge of a second new type of welding groove on the second surface to be welded, and processing a second new type of welding groove on the second surface to be welded according to the blunt edge of the second new type of welding groove.

[0070] In this embodiment, the blunt edge of the first novel welding groove is a circular structure, and the step S1A includes the following steps:

[0071] S1A1: connecting the vertex of the inner ring of the first surface to be welded and the bottom point of the outer ring of the first surface to be welded to obtain the diameter of the blunt side of the first new welding groove;

[0072] S1A2: constructing a blunt edge of the first new type of welding groove on the first surface to be welded according to the diameter of the blunt edge of the first new type of welding groove;

[0073] S1A3: Processing the inner groove of the first new type of welding groove on the portion of the first surface to be welded located inside the blunt edge of the first new type of welding groove, and processing the outer groove of the first new type of welding groove on the portion of the first surface to be welded located outside the blunt edge of the first new type of welding groove.

[0074] Specifically, Figures 2 to 3 As shown, line segment BD is the diameter of the blunt edge of the first new welding groove, point O is the center of the blunt edge of the first new welding groove, line segment BC is the diameter of the inner ring of the first surface to be welded, and line segment AD is the diameter of the outer ring of the first surface to be welded; the inner groove of the first new welding groove is processed from point D to the inside of the blunt edge of the first new welding groove using the machine tool in the manufacturing plant with line segment OD as the radius. Similarly, the outer groove of the first new welding groove is processed from point D to the outside of the blunt edge of the first new welding groove using the machine tool in the manufacturing plant with line segment OA as the radius.

[0075] In addition, if Figures 4 to 6As shown, the inner R of the first new type of welding groove is processed at the junction of the inner groove of the first new type of welding groove and the blunt edge of the first new type of welding groove, and the outer R of the first new type of welding groove is processed at the junction of the outer groove of the first new type of welding groove and the blunt edge of the first new type of welding groove.

[0076] In this embodiment, the blunt edge of the second novel welding groove is a circular structure, and the step S1B includes the following steps:

[0077] S1B1: connecting the vertex of the inner ring of the second surface to be welded and the bottom point of the outer ring of the second surface to be welded to obtain the diameter of the blunt side of the second new welding groove;

[0078] S1B2: constructing a second new type of welding groove blunt edge on the second surface to be welded according to the diameter of the second new type of welding groove blunt edge;

[0079] S1B3: Processing the inner groove of the second new type of welding groove on the portion of the second surface to be welded located inside the blunt edge of the second new type of welding groove, and processing the outer groove of the second new type of welding groove on the portion of the second surface to be welded located outside the blunt edge of the second new type of welding groove.

[0080] Specifically, Figures 7 and 8 As shown, line segment B1D1 is the diameter of the blunt edge of the second new welding groove, point O1 is the center of the blunt edge of the second new welding groove, line segment B1C1 is the diameter of the inner ring of the second surface to be welded, and line segment A1D1 is the diameter of the outer ring of the second surface to be welded; the inner groove of the second new welding groove is processed by an online groove processing machine starting from point D1 with line segment O1D1 as the radius toward the inside of the blunt edge of the second new welding groove. Similarly, the outer groove of the second new welding groove is processed by an online groove processing machine starting from point D1 with line segment O1A1 as the radius toward the outside of the blunt edge of the second new welding groove.

[0081] In addition, if Figures 9 to 11 As shown, the inner R of the second new type of welding groove is processed at the junction of the inner groove of the second new type of welding groove and the blunt edge of the second new type of welding groove, and the outer R of the second new type of welding groove is processed at the junction of the outer groove of the second new type of welding groove and the blunt edge of the second new type of welding groove.

[0082] In this embodiment, Fig.12 As shown, step S3 includes the following steps:

[0083] S31: preheating the first new type welding groove and the second new type welding groove after butt-jointing to a specified welding temperature, wherein the welding temperature is 205° C.;

[0084] S32: Use Ф2.0 welding wire GTAW (gas tungsten arc welding) to weld the blunt edge of the first new welding groove with the blunt edge of the second new welding groove. Fig.12 The meaning of ① in the sentence;

[0085] S33: First, use SMAW (manual arc welding) with a Ф3.2 / Ф4.0 / Ф5.0 electrode to weld the outer groove of the first new welding groove with the outer groove of the second new welding groove. Fig.12 The meaning of ② in the figure is: then use SMAW (manual arc welding) with a Ф3.2 / Ф4.0 / Ф5.0 electrode to weld the inner groove of the first new type of welding groove with the inner groove of the second new type of welding groove, which is Fig.12 The meaning of ③ in the figure; so far, the pre-assembled welded cylinder section is welded to the service cylinder body, and the welding strength between the pre-assembled welded cylinder section and the service cylinder body is relatively high.

[0086] In this embodiment, after the first new type of welding groove is butted together with the second new type of welding groove, the upper half circumference of the pre-assembled cylinder section and the upper half circumference of the serving cylinder can be welded outside the pre-assembled cylinder section and the serving cylinder, without the need for overhead welding; similarly, after the first new type of welding groove is butt-jointed with the second new type of welding groove, the lower half circumference of the pre-assembled cylinder section and the serving cylinder can be welded inside the pre-assembled cylinder section and the serving cylinder, also without the need for overhead welding, which greatly reduces the labor intensity and welding difficulty when welding the pre-assembled cylinder section and the serving cylinder.

[0087] In this embodiment, step S4 is also included, and step S4 includes the following steps:

[0088] S41: performing intermediate stress relief heat treatment on the pre-welded cylinder section and the service cylinder after welding, which can improve the strength, toughness and durability of the welded joint, and improve the corrosion resistance of the welded joint. The intermediate stress relief heat treatment is a conventional technical means in this field and will not be described in detail here;

[0089] S42: Heat treatment is performed on the pre-assembled welded cylinder section and the service cylinder after the intermediate stress relief heat treatment to eliminate stress at the welding point. The heat treatment is a conventional technical means in this field and will not be described in detail here.

[0090] Embodiment 2:

[0091] like Figures 1 to 12As shown, a welding system for an improved chromium-molybdenum steel cylinder section comprises a horizontally arranged pre-assembled welded cylinder section and a service cylinder body, the pre-assembled welded cylinder section is provided with a first surface to be welded which is an annular structure and perpendicular to the horizontal plane, the service cylinder body is provided with a second surface to be welded which is an annular structure and perpendicular to the horizontal plane, the first surface to be welded and the second surface to be welded are consistent in shape, the pre-assembled welded cylinder section and the service cylinder body are welded together using the welding method for the improved chromium-molybdenum steel cylinder section described in any one of Example 1.

[0092] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A welding method for an improved chromium-molybdenum steel cylinder section, characterized in that: The following steps are involved: S1: processing a first new type of welding groove that can reduce the welding difficulty on the first to-be-welded surface of the pre-assembled cylinder segment, and processing a second new type of welding groove that can reduce the welding difficulty on the second to-be-welded surface of the in-service cylinder, wherein the blunt edge of the first new type of welding groove is consistent in shape with the blunt edge of the second new type of welding groove; S2: Butt the first new type welding groove on the pre-welded cylinder section with the second new type welding groove on the service cylinder; S3: The pre-assembled cylinder section is welded together with the service cylinder according to the first new type welding groove and the second new type welding groove after butt connection.

2. A welding method for improved chromium-molybdenum steel cylinder section according to claim 1, characterized in that: The apex of the blunt side of the first new welding groove and the apex of the inner ring of the first surface to be welded are located on the same horizontal plane, and the bottom point of the blunt side of the first new welding groove and the bottom point of the outer ring of the first surface to be welded are located on the same horizontal plane; The apex of the blunt edge of the second new welding groove and the apex of the inner ring of the second surface to be welded are located on the same horizontal plane, and the bottom point of the blunt edge of the second new welding groove and the bottom point of the outer ring of the second surface to be welded are located on the same horizontal plane.

3. A welding method for improved chromium-molybdenum steel cylinder section according to claim 2, characterized in that: The step S1 comprises the following steps: S1A: constructing a blunt edge of a first new type of welding groove on the first surface to be welded, and processing the first new type of welding groove on the first surface to be welded according to the blunt edge of the first new type of welding groove; S1B: constructing a blunt edge of a second new type of welding groove on the second surface to be welded, and processing a second new type of welding groove on the second surface to be welded according to the blunt edge of the second new type of welding groove.

4. A welding method for improved chromium-molybdenum steel cylinder section according to claim 3, characterized in that: The blunt edge of the first novel welding groove is a circular structure, and the step S1A comprises the following steps: S1A1: connecting the vertex of the inner ring of the first surface to be welded and the bottom point of the outer ring of the first surface to be welded to obtain the diameter of the blunt side of the first new welding groove; S1A2: constructing a blunt edge of the first new type of welding groove on the first surface to be welded according to the diameter of the blunt edge of the first new type of welding groove; S1A3: Processing the inner groove of the first new type of welding groove on the portion of the first surface to be welded located inside the blunt edge of the first new type of welding groove, and processing the outer groove of the first new type of welding groove on the portion of the first surface to be welded located outside the blunt edge of the first new type of welding groove.

5. A welding method for improved chromium-molybdenum steel cylinder section according to claim 3, characterized in that: The blunt edge of the second novel welding groove is a circular structure, and the step S1B comprises the following steps: S1B1: connecting the vertex of the inner ring of the second surface to be welded and the bottom point of the outer ring of the second surface to be welded to obtain the diameter of the blunt side of the second new welding groove; S1B2: constructing a second new type of welding groove blunt edge on the second surface to be welded according to the diameter of the second new type of welding groove blunt edge; S1B3: Processing the inner groove of the second new type of welding groove on the portion of the second surface to be welded located inside the blunt edge of the second new type of welding groove, and processing the outer groove of the second new type of welding groove on the portion of the second surface to be welded located outside the blunt edge of the second new type of welding groove.

6. A welding method for an improved chromium-molybdenum steel cylinder section according to any one of claims 4 to 5, characterized in that: The step S3 comprises the following steps: S31: preheating the first new type welding groove and the second new type welding groove after butt-jointing to a specified welding temperature; S32: welding the blunt edge of the first new type welding groove and the blunt edge of the second new type welding groove together; S33: welding the inner groove of the first new type welding groove to the inner groove of the second new type welding groove, and welding the outer groove of the first new type welding groove to the outer groove of the second new type welding groove. At this point, the pre-assembled welded cylinder section is welded to the service cylinder.

7. A welding method for improved chromium-molybdenum steel cylinder section according to claim 1, characterized in that: The step S4 further comprises: S41: Perform intermediate stress relief heat treatment on the pre-welded cylinder section and the service cylinder after welding; S42: Heat treatment is performed on the pre-assembled welded cylinder section and the service cylinder after the intermediate stress relief heat treatment.

8. A welding system for an improved chromium-molybdenum steel cylinder section, comprising a pre-assembled welded cylinder section and a service cylinder body arranged horizontally, wherein the pre-assembled welded cylinder section is provided with a first surface to be welded having an annular structure and being perpendicular to the horizontal plane, and the service cylinder body is provided with a second surface to be welded having an annular structure and being perpendicular to the horizontal plane, wherein the first surface to be welded and the second surface to be welded have the same shape, and characterized in that: The pre-welded cylinder section and the service cylinder are welded together using the welding method for improved chromium-molybdenum steel cylinder sections as described in any one of claims 1 to 7.

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