Pipeline connecting pipe fitting

Abstract

The invention relates to the technical field of pipeline connecting structures, in particular to a pipeline connecting pipe fitting which comprises a first straight pipe section body, a bearing section body and at least one second straight pipe section body which are integrally cast, and the bearing section body is provided with a turning part which is bent or inclined from the axial direction of the pipe fitting to the radial direction. A corrosion buffer piece extending in the direction away from the bearing section body is integrally arranged in the middle of the outer wall of the turning part, a fixing through hole is formed in the corrosion buffer piece, and the fixing through hole is formed in the end, away from the bearing section body, of the corrosion buffer piece, so that a corrosion buffer area is formed between the fixing through hole and the outer wall of the turning part; the inner walls and the outer walls of the first straight pipe section body, the bearing section body and the second straight pipe section body are all covered with corrosion-resistant layers. The connecting pipe fitting has the beneficial effects that the corrosion buffer sheet is arranged outside the connecting pipe fitting, and even if an easily-corroded point of the connecting pipe fitting is corroded in the long-term use process, generated corrosion products cannot fall off and be mixed into a conveyed water body, so that water pollution is avoided.

Description

Technical Field

[0001] The invention relates to the technical field of pipeline connection structures, and in particular to a pipeline connection pipe fitting. Background Art

[0002] Cast iron pipe fittings are widely used in municipal water supply, drainage, gas transmission and other fields. In order to improve their service life and aesthetics, it is usually necessary to spray the inner and outer surfaces of cast iron pipe fittings to form a protective coating. The spraying process can effectively isolate the pipe fittings from direct contact with the external environment, prevent erosion by corrosive media, and thus extend the service life of the pipe fittings.

[0003] However, during the spraying process, cast iron pipe fittings usually need to be fixed by a hanging device to facilitate the spraying operation. The contact area between the hanging device and the pipe fitting often results in the coating not being fully covered, forming local unsprayed areas. These unsprayed areas are exposed to the external environment and are easily corroded by corrosive media, forming process corrosion points. Over time, these corrosion points will gradually expand, affecting the overall performance and durability of the pipe fittings. Therefore, how to effectively reduce or eliminate the process corrosion points at the contact point between the hanging device and the pipe fitting without affecting the spraying efficiency has become a problem that needs to be solved urgently in the current technical field. Summary of the invention

[0004] Therefore, in view of the above-mentioned problem, the present invention provides a pipeline connecting pipe fitting.

[0005] The present invention is achieved through the following technical solutions.

[0006] A pipeline connecting pipe fitting comprises a first straight pipe section body, a receiving section body and at least one second straight pipe section body which are integrally cast. The first straight pipe section body, the receiving section body and the second straight pipe section body are interconnected to form a fluid flow channel which can guide the fluid to enter from the inside of the first straight pipe section body and then flow out through the second straight pipe section body and change the flow direction of the fluid. A connecting structure is provided on the outer wall of the open end of the first straight pipe section body and the second straight pipe section body. The receiving section body is provided with at least one turning portion which is bent or inclined from the axial direction of the pipe fitting to the radial direction. A corrosion buffer sheet extending in a direction away from the receiving section body is integrally provided in the middle part of the outer wall of the turning portion. A fixed through hole is provided on the corrosion buffer sheet. The fixed through hole is provided on the side of the corrosion buffer sheet away from the receiving section body so that a corrosion buffer zone is formed between the fixed through hole and the outer wall of the turning portion. The inner and outer walls of the first straight pipe section body, the receiving section body and the second straight pipe section body are all covered with a corrosion-resistant layer.

[0007] As a further improvement of the present invention, the corrosion-resistant layer forms a sealed cavity with only one opening, the first straight pipe section body, the receiving section body and the second straight pipe section body are in the sealed cavity, and the shape and position of the opening of the sealed cavity correspond to the shape and position of the contact surface between the corrosion buffer plate and the outer wall of the turning part.

[0008] As a further improvement of the present invention, the corrosion-resistant layer forms a sealed cavity with only one opening, the first straight pipe section body, the receiving section body, the second straight pipe section body and the corrosion buffer plate are all in the sealed cavity, the fixed through hole has an inner contact point, and the shape and position of the opening of the sealed cavity correspond to the shape and position of the inner contact point of the fixed through hole.

[0009] As a further improvement of the present invention, the corrosion buffer plate includes a connecting plate integrally connected to the outer wall of the turning part and a positioning plate integrally connected to the connecting plate, the connecting plate and the positioning plate both have notches, and the notches of the two form the fixed through hole, and the inner contact point of the fixed through hole is on the notch of the positioning plate.

[0010] As a further improvement of the present invention, the contact surface between the connecting piece and the outer wall of the turning portion is in the shape of a long strip, and the long strip extends along the axial direction of the turning portion.

[0011] As a further improvement of the present invention, the inner contact point of the fixing through hole is located on the side of the notch of the positioning piece away from the receiving section body.

[0012] As a further improvement of the present invention, the inner contact point of the fixing through hole is provided with a supplementary corrosion-resistant layer.

[0013] As a further improvement of the present invention, the corrosion-resistant layer and the supplementary corrosion-resistant layer are both epoxy plastic corrosion-resistant layers.

[0014] As a further improvement of the present invention, the first straight pipe section body, the receiving section body and at least one second straight pipe section body are all made of ductile iron.

[0015] As a further improvement of the present invention, an avoidance zone is provided between the corrosion buffer plate and the connection structure.

[0016] Beneficial effects of the present invention: 1. In the present application, the corrosion buffer sheet is arranged on the outside of the connecting pipe fitting. Even if the corrosion-prone points of the connecting pipe fitting are corroded during long-term use, the corrosion products (such as rust) produced therein will not fall off and mix into the transported water body, so as to avoid water pollution.

[0017] 2. When spraying the connecting pipe fittings, the hook can be passed through the fixed through hole and then spraying is performed. At this time, there is no direct contact point between the hanging device (hook) and the main body of the connecting pipe fitting (the first straight pipe section main body, the receiving section main body and the second straight pipe section main body), which effectively reduces the contact point between the hanging device and the connecting pipe fitting, thereby reducing the corrosion points of the connecting pipe fittings in this application. In addition, since the connecting pipe fittings are installed by hooking them, the operation is simple and the phenomenon of the connecting pipe fittings falling due to not being in a horizontal state can be avoided.

[0018] 3. During the transportation of the connecting pipes, the ropes can be controlled to pass through the fixed through holes, and multiple connecting pipes can be transported in strings, which reduces the loading and unloading time of a single pipe and improves the transportation efficiency. Moreover, since the connecting pipes are transported in strings through the fixed through holes, the connecting pipes can be prevented from rolling, colliding or falling off during transportation, thereby preventing the corrosion-resistant layer from being worn.

[0019] 4. During the installation of the connecting pipe fittings, the fasteners can be first controlled to pass through the fixed through holes to fix the connecting pipe fittings on the installation device, and then other pipe fittings can be controlled to connect to the connecting pipe fittings of this embodiment, that is, other pipe fittings are installed based on the connecting pipe fittings. This can ensure that the connection positions of other pipe fittings are accurate, reduce connection errors, and at the same time make the installation of other pipe fittings more orderly to improve installation efficiency.

[0020] 5. When the hanging device (hook), rope and fastener pass through the fixed through hole respectively, since the fixed through hole is opened on the side of the corrosion buffer plate away from the receiving section body, that is, there is a certain distance between the fixed through hole and the outer wall of the turning part, the hanging device (hook), rope and fastener can be prevented from touching the corrosion-resistant layer to a certain extent, thereby preventing the corrosion-resistant layer from being worn.

[0021] 6. Even if corrosion occurs, the buffer sheet should be corroded first, and then the body of the connecting pipe should be corroded, which can delay the corrosion time of the connecting pipe to a certain extent. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings to help understand the purpose and advantages of the present invention, wherein: Figure 1 It is a schematic diagram of the hook structure in the background technology of the invention patent; Figure 2 It is a schematic diagram of the structure of the hanging pipe fitting in the background technology of the invention patent; Figure 3 This is a schematic diagram of the structure when the connecting pipe fitting in the embodiment of the invention patent is in a straight pipe shape; Figure 4 This is a schematic diagram of the structure when the connecting pipe fitting in the embodiment of the invention patent is in a curved pipe shape; Figure 5This is a schematic diagram of the structure when the connecting pipe fitting in the embodiment of the invention patent is a three-way connection; Figure 6 It is a structural schematic diagram of the embodiment of the invention patent when the connecting pipe is hooked by a hook in a curved pipe shape; Figure 7 For invention patents Figure 6 A partial enlarged view of the middle part; Figure 8 This is a schematic diagram of the corrosion buffer plate structure in the invention patent.

[0023] Numbers in the figure: first straight pipe section body 1, receiving section body 2, second straight pipe section body 3, connecting structure 4, turning part 5, corrosion buffer plate 6, fixed through hole 7, inner contact point 8, connecting plate 601, positioning plate 602, suspension device 10, end 11, contact point 12. DETAILED DESCRIPTION

[0024] The present invention is further described in detail below based on the accompanying drawings and implementation examples.

[0025] The directional terms such as up, down, left, right, front, back, front, back, top, bottom, etc. mentioned or may be mentioned in this specification are defined relative to the structures shown in the drawings. The words "inside" and "outside" refer to the direction toward or away from the geometric center of a specific component, respectively. They are relative concepts, and therefore may change accordingly according to different locations and different usage conditions. Therefore, these or other directional terms should not be interpreted as restrictive terms.

[0026] refer to Figures 1 to 8 , the embodiments of the present invention disclose: A pipeline connecting pipe fitting comprises a first straight pipe section body 1, a receiving section body 2 and at least one second straight pipe section body 3 which are integrally cast. The first straight pipe section body 1, the receiving section body 2 and the at least one second straight pipe section body 3 are all made of ductile iron. The ductile iron material has low manufacturing cost, is lighter in weight than traditional cast iron, and has excellent corrosion resistance.

[0027] The first straight pipe section body 1, the receiving section body 2 and the second straight pipe section body 3 are interconnected to form a fluid flow channel that can guide the fluid to enter from the inside of the first straight pipe section body 1 and then flow out through the second straight pipe section body 3 and change the flow direction of the fluid. The outer walls of the opening ends of the first straight pipe section body 1 and the second straight pipe section body 3 are provided with a connecting structure 4. Figure 3 , Figure 4 , Figure 5 As shown, the second straight pipe section body 3 can be 1, 2 or 3, that is, formed into a two-way, three-way or four-way pipe fitting; please also refer to Figure 1 , Figure 2As shown, in this embodiment, the suspension device 10 used in the spraying process is in the shape of a hook, and its end 11 is inserted into the interior of the connecting pipe, and the end has only two contact points 12 that contact the connecting pipe, thereby effectively reducing the number of contact points.

[0028] However, during the spraying process, before spraying, the connecting pipe fittings need to be hung on the hooks, and then the pipe fittings need to be adjusted so that the pipe fittings can be in a horizontal state to prevent the pipe fittings from falling off; after spraying, the pipe fittings need to be adjusted, and the two contact points need to be sprayed again; at the same time, the contact points and the rest of the inner wall of the connecting pipe fittings are sprayed multiple times, and it is difficult to ensure the uniformity of the coating around the contact points during spraying, resulting in a thin or missing coating in the local area, which in turn causes the contact points to easily become the starting point of corrosion. The corrosive medium invades through these weak points and gradually expands to other parts of the pipe fittings, affecting the integrity of the overall structure; and the rust products (such as rust) produced by the internal corrosion of the pipe fittings will fall off and mix into the transported water body, causing water pollution and affecting the safety of water supply. In particular, for pipe fittings used for drinking water transportation, internal corrosion will directly threaten public health; based on this, in this embodiment, the receiving section body 2 is provided with at least one turning portion 5 that is bent or inclined from the axial direction of the pipe fitting to the radial direction, and a corrosion buffer sheet 6 is integrally provided at the center of the outer wall of the turning portion 5 and in the direction away from the receiving section body 2.

[0029] Specific, for example Figure 3 In the connecting pipe shown in the figure, the pipe is in a straight pipe shape, and the turning portion 5 is inclined from the pipe axial direction to the radial direction at a certain angle (15°-30°), that is, the receiving section body 2 is a trumpet-shaped pipe body with a larger bottom and a smaller top, and the corrosion buffer sheet 6 is arranged on the turning portion 5; Figure 4 In the connecting pipe shown in the figure, the turning portion 5 is bent from the axial direction of the pipe to the radial direction. Specifically, the connecting pipe is in the shape of a curved pipe (the receiving section body 2 is the curved pipe section body). At this time, the receiving section body 2 is composed of an inner semi-cylindrical tube and an outer semi-cylindrical tube that are both bent in the axial direction of the pipe. The length of the inner semi-cylindrical tube in the axial direction of the pipe is less than the length of the outer semi-cylindrical tube, and the turning portion 5 is the inner semi-cylindrical tube. The corrosion buffer sheet 6 is arranged on the outer wall of the inner semi-cylindrical tube. Figure 5 As shown, the connecting pipe fitting has a T-shaped three-way pipe structure, that is, two second straight pipe section bodies 3 are provided, the first straight pipe section body 1 and the receiving section body 2 are arranged between the two straight pipe sections, and accordingly, the connecting pipe fitting is provided with two turning parts 5 bent axially to radially from the receiving section body 2, and the corrosion buffer plate 6 is arranged on one of the turning parts 5; similar to the three-way pipe, the connecting pipe fitting can also be provided with a four-way pipe structure, that is, three second straight pipe section bodies 3 are provided, and the turning part 5 is arranged on the turning part 5 of the receiving section body 2.

[0030] Based on the above structure, a fixed through hole 7 is provided on the corrosion buffer sheet 6, and the fixed through hole 7 is provided on the side of the corrosion buffer sheet 6 away from the receiving section body 2, so that a corrosion buffer zone 9 is formed between the fixed through hole 7 and the outer wall of the turning portion 5, and the inner and outer walls of the first straight pipe section body 1, the receiving section body 2 and the second straight pipe section body 3 are all covered with a corrosion-resistant layer (epoxy plastic corrosion-resistant layer); in this embodiment, since the contact point between the suspension device and the connecting pipe fitting is arranged outside the connecting pipe fitting, even if the corrosion-prone point of the connecting pipe fitting is corroded during long-term use, the corrosion products (such as rust) produced therefrom will not fall off and Mixed into the transported water to avoid water pollution; in addition, when spraying the connecting pipe, the hook can be passed through the fixed through hole 7, and then spraying is carried out. At this time, there is no direct contact point between the hanging device (hook) and the main body of the connecting pipe (the first straight pipe section main body 1, the receiving section main body 2 and the second straight pipe section main body 3), which further effectively reduces the direct contact point between the hanging device and the connecting pipe, thereby reducing the corrosion points of the connecting pipe in this application, and because the corrosion buffer sheet 6 is installed by hooking the corrosion buffer sheet 6, the operation is simple, and the phenomenon of the connecting pipe falling due to not being in a horizontal state can be avoided; in addition, the connecting pipe is transported During the process, the rope can be controlled to pass through the fixed through hole 7, and the multiple connecting pipes can be controlled to be transported in a string, which reduces the loading and unloading time of a single pipe and improves the transportation efficiency. In addition, since the connecting pipes are transported in a string through the fixed through hole 7, the connecting pipes can be prevented from rolling, colliding or falling off during transportation, thereby preventing the corrosion-resistant layer from being worn. At the same time, during the installation of the connecting pipes, the fasteners can be controlled to pass through the fixed through hole 7 first to fix the connecting pipes on the installation device, and then other pipes can be controlled to connect with the connecting pipes of this embodiment, that is, the connecting pipes are used as a reference, and then other pipes are installed, which can ensure that the connection positions of other pipes are accurate. It reduces connection errors and makes the installation of other pipes more orderly to improve installation efficiency. At the same time, when the hanging device (hook), rope and fastener pass through the fixed through hole 7 respectively, since the fixed through hole 7 is opened on the side of the corrosion buffer plate 6 away from the receiving section body 2, and a corrosion buffer zone 9 is formed between the fixed through hole 7 and the outer wall of the turning part 5, when the hanging device (hook), rope and fastener pass through the fixed through hole 7, there is still a certain distance (1-3CM) from the outer wall of the turning part 5, thereby avoiding the hanging device (hook), rope and fastener from touching the corrosion-resistant layer, thereby preventing the corrosion-resistant layer from being worn.

[0031] It is worth mentioning that when the connecting pipe is Figure 4In the curved pipe shape shown in the figure, since the corrosion buffer sheet 6 is arranged at the center of the outer wall of the turning portion 5, during the installation, after the connecting pipe fitting is inserted into the fastener and hung during the installation process, the connecting pipe fitting is affected by gravity, which can make the opening ends of the first straight pipe section body 1 and the second straight pipe section body 3 of the connecting pipe fitting tilt upward, further facilitating the connection and installation of other hanging parts; and the corrosion buffer sheet 6 is arranged on the inner semi-cylindrical tube and is integrally arranged extending away from the direction of the curved pipe section body. Compared with the corrosion buffer sheet 6 being directly arranged on the side walls on the front and rear sides of the curved pipe section body, it can avoid the staff from touching the corrosion buffer sheet 6 during the installation process to a certain extent.

[0032] In addition, in the present embodiment, even if corrosion occurs during long-term use, the corrosion buffer sheet 6 should be corroded first, and then the body of the connecting pipe fitting should be corroded, which can delay the corrosion time of the connecting pipe fitting to a certain extent. Based on the above, the corrosion-resistant layer forms a sealed cavity with only one opening, and the first straight pipe section body 1, the receiving section body 2 and the second straight pipe section body 3 are in the sealed cavity. The shape and position of the opening of the sealed cavity correspond to the shape and position of the contact surface between the corrosion buffer sheet 6 and the outer wall of the turning portion 5, that is, the corrosion-resistant layer does not wrap the corrosion buffer sheet 6. During the long-term use of the connecting pipe fitting, the corrosion buffer sheet 6 is usually the starting point of corrosion. The corrosion buffer sheet 6 must be corroded first, and the corrosion site can spread from the opening of the sealed cavity to the first straight pipe section body 1 and the receiving section body. 2 and the second straight pipe section body 3, that is, the first straight pipe section body 1, the receiving section body 2 and at least one second straight pipe section body 3 have a certain buffer time before being corroded; and in this embodiment, the corrosion buffer sheet 6 (especially the corrosion buffer zone 9) can be made of pure metal or alloy that is more resistant to environmental corrosion than ductile iron, such as aluminum alloy, and is connected to the turning portion 5 by welding to further slow down the corrosion rate; or the corrosion buffer sheet 6 is also made of ductile iron material, and can be integrally formed with the receiving section body 2 during production. Under certain circumstances, the corrosion buffer sheet 6 in this embodiment can also be controlled to be connected to an external power supply to apply a cathode current to the corrosion buffer sheet 6 (to achieve an electrical anti-corrosion effect), thereby reducing the corrosion rate of the corrosion buffer sheet 6, and then slowing down the corrosion rate of the connecting pipe as a whole.

[0033] Taking production and maintenance costs into consideration, as a further improvement, the corrosion-resistant layer forms a sealed cavity with only one opening, the first straight pipe section body 1, the receiving section body 2, the second straight pipe section body 3 and the corrosion buffer sheet 6 are all in the sealed cavity, the fixed through hole 7 has an inner contact point 8, and the shape and position of the opening of the sealed cavity correspond to the shape and position of the inner contact point 8 of the fixed through hole 7; that is, the corrosion buffer sheet 6 described in this embodiment is also made of ductile iron material, and can be integrally formed with the receiving section body 2 during production. During the spraying process, the contact point between the suspension device and the fixed through hole 7 is the contact point of this embodiment. The inner contact point 8 in the example is usually the starting point of corrosion during long-term use. The corrosion point first diffuses at the inner wall of the fixed through hole 7. Since a corrosion buffer zone 9 is formed between the fixed through hole 7 and the outer wall of the turning portion 5, the corrosion point first diffuses at the inner wall of the fixed through hole 7, and then diffuses along the corrosion buffer zone 9, and finally diffuses and extends toward the receiving section body 2 and the first straight pipe section body 1 (or the second straight pipe section body), thereby extending the corrosion time of the corrosion buffer sheet 6, indirectly delaying the corrosion time of the main body of the connecting pipe fitting, and improving the service life of the connecting pipe fitting.

[0034] Based on the above (when the connecting pipe is Figure 4 When it is in the curved tube shape shown in the figure), the corrosion buffer plate 6 includes a connecting plate 601 integrally connected to the outer wall of the turning part 5 and a positioning plate 602 integrally connected to the connecting plate 601, the connecting plate 601 and the positioning plate 602 both have notches, and the notches of the two form the fixed through hole 7, and the inner contact point 8 of the fixed through hole 7 is on the notch of the positioning plate 602, the inner contact point 8 of the fixed through hole 7 is located on the side of the notch of the positioning plate 602 away from the receiving section body 2, that is, the position of the inner contact point 8 of the fixed through hole 7 is located on the side of the fixed through hole 7 farther from the outer wall of the turning part 5, that is, the distance between the corrosion point and the outer wall of the turning part 5 is extended, and the corrosion time from the corrosion buffer plate 6 to the outer wall of the turning part 5 is also extended, so as to improve the service life of the connecting pipe fittings.

[0035] Specifically in this embodiment, the contact surface between the connecting piece 601 and the outer wall of the turning portion 5 is in the shape of a long strip, and the long strip extends along the axial direction of the turning portion 5 .

[0036] An avoidance interval is provided between the corrosion buffer sheet 6 and the connection structure 4 , so as to prevent the ends of other pipe fittings from touching or rubbing against the surface of the corrosion buffer sheet 6 when the connection structure 4 is connected to other pipe fittings.

[0037] In addition, in another embodiment, due to the presence of the inner contact point 8, the shape and position of the opening of the sealing cavity correspond to the shape and position of the inner contact point 8 of the fixed through hole 7, and the inner contact point 8 of the fixed through hole 7 is provided with a supplementary corrosion-resistant layer (epoxy plastic corrosion-resistant layer); after the spraying is completed, the spraying device is controlled to spray at the inner contact point 8. Although it is difficult to ensure the uniformity of the coating around the inner contact point 8 through the second spraying, resulting in a thinner or missing coating in some local areas, compared with the inner contact point 8 without coating, the provision of a supplementary corrosion-resistant layer can further prolong the corrosion time from the corrosion buffer plate 6 to the outer wall of the turning part 5.

[0038] Spraying process of this connecting pipe fitting: a. Surface treatment: Take a pipe blank, which includes a first straight pipe section body 1, a receiving section body 2, and at least one second straight pipe section body 3 that are integrally cast, and a corrosion buffer sheet 6 is formed on the receiving section body 2 by welding or integral casting, and the pipe blank is surface treated to remove oil stains, oxide layers, stains, etc.; b. Preheating: transport the pipe blank to the heating furnace and preheat it at 145℃-155℃ for 35 minutes; c. Hanging spraying: Take out the pipe blank, control the hooking part of the hanging device (hook) to pass through the fixed through hole 7 of the corrosion buffer sheet 6, so that the pipe blank is hung on the hanging device, and when the pipe blank is in a static state under the action of gravity, spray epoxy plastic powder on the outer surface and inner wall of the pipe blank through the electrostatic spraying equipment; d. Curing: Take out the pipe blank, convey it to a curing furnace, and cure it at 210° C.-230° C. for 40 minutes. At this time, the epoxy plastic powder is cured into a corrosion-resistant layer, and the connecting pipe of this embodiment is obtained.

[0039] In another embodiment, in step c, after the outer surface and inner wall of the pipe blank are sprayed with epoxy plastic powder by electrostatic spraying equipment, step c1 is further provided, wherein the pipe blank is removed and the contact point (inner contact point 8) between the hanging device and the fixed through hole 7 is supplementarily sprayed by electrostatic spraying equipment. At this time, in step d, the epoxy plastic powder there is solidified into a supplementary corrosion-resistant layer.

[0040] Finally, it should be noted that the above implementation cases 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 implementation cases, those skilled in the art should understand that they can still modify the technical solutions recorded in the aforementioned implementation cases, or make equivalent replacements for some of the technical features therein. 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 implementation cases of the present invention.

Claims

1. A pipe connecting pipe fitting, comprising a first straight pipe section body (1), a receiving section body (2) and at least one second straight pipe section body (3) which are integrally cast, wherein the first straight pipe section body (1), the receiving section body (2) and the second straight pipe section body (3) are interconnected to form a fluid flow channel which can guide a fluid to enter from the inside of the first straight pipe section body (1) and then flow out through the second straight pipe section body (3) and change the flow direction of the fluid, and a connecting structure (4) is provided on the outer wall of the opening end of the first straight pipe section body (1) and the second straight pipe section body (3), characterized in that: The receiving section body (2) is provided with at least one turning portion (5) bent or inclined from the axial direction of the pipe fitting to the radial direction, and a corrosion buffer sheet (6) extending in a direction away from the receiving section body (2) is integrally provided in the middle of the outer wall of the turning portion (5), and a fixing through hole (7) is provided on the corrosion buffer sheet (6), and the fixing through hole (7) is provided on the side of the corrosion buffer sheet (6) away from the receiving section body (2), so that a corrosion buffer zone (9) is formed between the fixing through hole (7) and the outer wall of the turning portion (5), and the inner walls and outer walls of the first straight pipe section body (1), the receiving section body (2) and the second straight pipe section body (3) are all covered with a corrosion-resistant layer.

2. A pipe connecting fitting according to claim 1, characterized in that: The corrosion-resistant layer forms a sealed cavity with only one opening, the first straight pipe section body (1), the receiving section body (2) and the second straight pipe section body (3) are located in the sealed cavity, and the shape and position of the opening of the sealed cavity correspond to the shape and position of the contact surface between the corrosion buffer sheet (6) and the outer wall of the turning portion (5).

3. The pipeline connecting pipe fitting according to claim 1, characterized in that: The corrosion-resistant layer forms a sealed cavity with only one opening; the first straight pipe section body (1), the receiving section body (2), the second straight pipe section body (3) and the corrosion buffer sheet (6) are all located in the sealed cavity; the fixed through hole (7) has an inner contact point (8); the shape and position of the opening of the sealed cavity correspond to the shape and position of the inner contact point (8) of the fixed through hole (7).

4. A pipe connecting fitting according to claim 3, characterized in that: The corrosion buffer plate (6) comprises a connecting plate (601) integrally connected to the outer wall of the turning portion (5) and a positioning plate (602) integrally connected to the connecting plate (601), the connecting plate (601) and the positioning plate (602) both having notches, and the notches of the two form the fixing through hole (7), and the inner contact point (8) of the fixing through hole (7) is located on the notch of the positioning plate (602).

5. A pipe connection fitting according to claim 4, characterized in that: The contact surface between the connecting piece (601) and the outer wall of the turning portion (5) is in the shape of a long strip, and the long strip extends along the axial direction of the turning portion (5).

6. A pipe connection fitting according to claim 4, characterized in that: The inner contact point (8) of the fixing through hole (7) is located on the side of the notch of the positioning sheet (602) away from the receiving section body (2).

7. A pipe connecting fitting according to claim 6, characterized in that: The inner contact point (8) of the fixing through hole (7) is provided with a supplementary corrosion-resistant layer.

8. The pipeline connecting pipe fitting according to claim 7, characterized in that: The corrosion-resistant layer and the supplementary corrosion-resistant layer are both epoxy plastic corrosion-resistant layers.

9. The pipeline connecting pipe fitting according to claim 1, characterized in that: The first straight pipe section body (1), the receiving section body (2) and at least one second straight pipe section body (3) are all made of ductile iron.

10. The pipeline connecting pipe fitting according to claim 1, characterized in that: An avoidance zone is provided between the corrosion buffer sheet (6) and the connection structure (4).

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