Chemical pipeline and lining thermal fixing process thereof

Abstract

The invention relates to the technical field of chemical pipelines, in particular to a chemical pipeline and a lining thermal fixing process thereof.The chemical pipeline comprises an outer pipe, flange plates and a lining pipe lined on the inner circumferential wall of the outer pipe, the two ends of the lining pipe are turned outwards to form turned edges, the turned edges are fixed to the end faces of the flange plates, and a buffering piece is arranged on the inner circumferential wall of the outer pipe and is spiral; the buffering piece is of a hollow tubular structure and comprises a first arc-shaped part and a second arc-shaped part which are oppositely arranged, the first end of the first arc-shaped part is fixedly connected with the first end of the second arc-shaped part, the second end of the first arc-shaped part and the second end of the second arc-shaped part are arranged in an overlapped mode, and the overlapped position abuts against the inner circumferential wall of the outer pipe; bolts are fixed to the two ends of the buffer part, and two or more through insertion holes are formed in the circumferential face, covered by the flange plate, of the outer pipe. The adaptive capacity of the chemical pipeline to cold and hot fluid can be improved, and the service life of the whole chemical pipeline is prolonged.

Description

Technical Field

[0001] The invention relates to the technical field of chemical pipelines, in particular to a chemical pipeline and a thermal fixing process for its lining. Background Art

[0002] Plastic-lined pipe is a common chemical pipeline. It is also called steel-lined plastic composite pipe. It is based on ordinary carbon steel pipe and lined with thermoplastic plastic with excellent chemical properties. The inner layer of the plastic-lined pipe is made of plastic material, which has good corrosion resistance and can effectively prevent corrosive media from corroding metal pipes and extend the service life of the pipe. This kind of pipe is an ideal choice for conveying media such as acid, alkali, salt, and corrosive gases; and because the surface of the plastic inner layer is smooth and the fluid resistance is small, it is beneficial to reduce energy loss when conveying fluids and improve conveying efficiency.

[0003] The Chinese patent document with announcement number CN206846118U discloses a plastic-lined pipe, comprising a metal outer pipe and a plastic inner pipe, wherein the plastic inner pipe is arranged inside the metal outer pipe, and an adhesive layer is arranged between the plastic inner pipe and the metal outer pipe, and the plastic inner pipe is bonded to the inner wall of the metal outer pipe through the adhesive layer; the length of the plastic inner pipe is less than the length of the metal outer pipe, and the two ends of the metal outer pipe are respectively fixed with limit blocks, and the limit blocks abut against the end face of the plastic inner pipe. The plastic inner pipe of the plastic-lined pipe of the utility model is bonded to the inner wall of the metal outer pipe through an adhesive layer; the two ends of the metal outer pipe are respectively fixed with limit blocks, and the limit blocks abut against the end face of the plastic inner pipe; although this technical solution ensures the stability of the overall structure of the plastic-lined pipe; however, the plastic-lined pipe still has the following shortcomings when in use:

[0004] As we all know, different materials have different thermal expansion coefficients, and the fluid temperatures transported by plastic-lined pipes are often different. They can transport both high-temperature and low-temperature fluids. However, regardless of whether they are transporting high-temperature or low-temperature fluids, due to the different thermal expansion coefficients of metals and plastics, the two will expand to different degrees when transporting fluids, which can easily lead to damage to the plastic-lined pipe, especially the inner plastic pipe of the plastic-lined pipe, which cannot be buffered during expansion or contraction, is prone to cracking and damage, and has a short service life. Summary of the invention

[0005] The object of the present invention is to provide a chemical pipeline and a thermal fixing process for its lining to solve the problems raised in the above-mentioned background technology.

[0006] To achieve the above object, the present invention provides the following technical solution: a chemical pipeline, comprising an outer pipe and a flange, and an inner liner pipe lined on the inner circumferential wall of the outer pipe, the two ends of the inner liner pipe are turned outward to form flanges, the flanges are fixed on the end surface of the flange, and the inner circumferential wall of the outer pipe is provided with a buffer, and the buffer is spiral;

[0007] The buffer is a hollow tubular structure, which includes a first arc-shaped portion and a second arc-shaped portion arranged opposite to each other, a first end of the first arc-shaped portion and a first end of the second arc-shaped portion are fixedly connected, a second end of the first arc-shaped portion and a second end of the second arc-shaped portion are overlapped, and the overlapped position is pressed against the inner circumferential wall of the outer tube;

[0008] Pins are fixed at both ends of the buffer, and a through hole is opened on the circumference of the outer tube covered by the flange. There are two or more holes. When the pins are inserted into different holes, the overlapping positions of the buffer exert different pressures on the inner wall of the outer tube.

[0009] Preferably, the buffer component further includes a connecting portion, two ends of the connecting portion are respectively fixedly connected to the first end of the first arc-shaped portion and the first end of the second arc-shaped portion, and a middle portion of the connecting portion is recessed toward the inside of the buffer component.

[0010] Preferably, a warning member is provided at the bottom of the outer tube, and the warning member comprises a fixed tube, a piston provided inside the fixed tube with a sliding seal, a plug rod fixed at the bottom of the piston and provided coaxially with the fixed tube, and a second warning sticker;

[0011] One end of the fixed tube is fixedly and sealedly connected to the outer tube, and a joint formed at the overlapping position between the second end of the first arc-shaped portion and the second end of the second arc-shaped portion is connected to the one end of the fixed tube;

[0012] When the pressure in the buffer changes, the piston slides along the inner wall of the fixed tube, so that the second warning sticker is converted from a hidden state to an exposed state.

[0013] Preferably, the warning member further comprises a connecting sleeve and a bottom cover, and the connecting sleeve comprises a first sleeve and a second sleeve that are coaxial and fixedly connected;

[0014] The outer diameter of the first sleeve is larger than the outer diameter of the second sleeve, the first sleeve is threadedly sleeved on the bottom of the fixed pipe, the inner diameter of the second sleeve is larger than the diameter of the plug rod, and the plug rod passes through the second sleeve;

[0015] The second warning sticker is sleeved and fixed on the outer periphery of the second sleeve;

[0016] The bottom cover is connected to the bottom end of the plug rod, and the bottom cover is sleeved on the outside of the second warning sticker;

[0017] When the pressure in the buffer changes, the piston and the plug rod move downward to drive the bottom cover downward, so that the second warning sticker is converted from a hidden state stored inside the bottom cover to an exposed state exposed to the external environment.

[0018] Preferably, the outer diameter of the bottom cover is equal to the outer diameter of the first sleeve.

[0019] Preferably, a second rubber ring is provided between the bottom end of the fixing tube and the top end of the second sleeve.

[0020] Preferably, a retaining ring is sleeved and fixed on the outer circumferential surface of the fixed tube, and a first rubber ring is arranged between the top end of the first sleeve and the retaining ring.

[0021] Preferably, the bottom cover comprises two half cover bodies, and the half cover bodies are hinged to the bottom end of the plug rod through hinges;

[0022] A first warning sticker is fixed on the inner surface of the half cover;

[0023] A half iron ring is embedded and installed on the top of the half cover;

[0024] An annular magnet is embedded and installed at the bottom end of the first sleeve;

[0025] The half iron ring is magnetically connected to the ring magnet.

[0026] The chemical pipeline lining heat fixing process is based on the above-mentioned chemical pipeline and includes the following steps:

[0027] S1, reducing the diameter of the liner pipe through a reducing die;

[0028] S2, putting the prefabricated buffer into the outer tube, and inserting the pin into the socket at a suitable position, so that the buffer is pressed against the inner wall of the outer tube;

[0029] S3, sending the reduced diameter inner liner pipe into the outer pipe;

[0030] S4. Send the outer tube with the inner liner tube of reduced diameter placed inside into the furnace for heating, so that the inner liner tube expands to fully fit the inner wall of the outer tube.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] 1. The present invention provides a spiral buffer on the inner wall of the outer tube, and the buffer is wrapped inside the inner liner tube. When the inner liner tube expands due to heat, the inner liner tube will generate an extrusion force on the buffer along the length direction, the circumference direction and the diameter direction of the tube. Since the second end of the first arc portion and the second end of the second arc portion are overlapped, the second end of the first arc portion and the second end of the second arc portion can be relatively displaced. Therefore, under the expansion and extrusion of the inner liner tube, the buffer will buffer the expansion of the inner liner tube along the length direction, the circumference direction and the diameter direction by shrinking the diameter, thereby improving the adaptability of the chemical pipeline to hot and cold fluids and extending the service life of the entire chemical pipeline.

[0033] 2. In the present invention, when the pressure in the buffer changes, the piston slides along the inner wall of the fixed tube, so that the second warning sticker is converted from a hidden state to an exposed state. For example, when the liner tube leaks, since the buffer is spiral and spreads over the entire circumference of the liner tube, the fluid leaked from the liner tube will enter the buffer through the seam, and then enter the fixed tube through the seam, so that the pressure generated by the fluid pushes the piston and the plug rod to move downward, so that the second warning sticker is converted from a hidden state to an exposed state. At this time, the staff can judge whether the liner tube of the corresponding chemical pipeline is damaged by observing whether the second warning sticker is in an exposed state. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It is a structural schematic diagram of the present invention;

[0035] Figure 2 It is a schematic diagram of the structure of the outer tube, flange and buffer member of the present invention;

[0036] Figure 3 It is a schematic diagram of the cross-sectional structure of the buffer member of the present invention;

[0037] Figure 4 It is a schematic diagram of the local structure of the present invention;

[0038] Figure 5 For the present invention Figure 4 The enlarged structural diagram at B in the middle;

[0039] Figure 6 It is a schematic diagram of the position structure of the jack of the present invention;

[0040] Figure 7 For the present invention Figure 4 The enlarged structural diagram at C in the middle;

[0041] Figure 8 For the present invention Figure 2 Schematic diagram of the structure at A in the middle;

[0042] Fig. 9 It is a structural schematic diagram of the warning member of the present invention;

[0043] Fig.10 It is a schematic diagram of the cross-sectional three-dimensional structure of the warning member of the present invention;

[0044] Fig.11 It is a schematic cross-sectional structure diagram of the warning member of the present invention;

[0045] Fig.12 It is a schematic diagram of the force on a certain position of the buffer component of the present invention after the inner liner pipe expands.

[0046] In the figure: 1, outer tube; 11, socket; 2, flange; 3, liner tube; 31, flange; 4, buffer; 41, first arc-shaped portion; 42, second arc-shaped portion; 43, connecting portion; 44, latch; 45, joint; 5, warning member; 51, fixing tube; 511, retaining ring; 52, piston; 53, plug rod; 54, connecting sleeve; 541, first sleeve; 542, second sleeve; 543, annular magnet; 55, bottom cover; 551, half cover body; 552, half iron ring; 553, hinge; 554, first warning sticker; 56, second warning sticker; 57, first rubber ring; 58, second rubber ring. DETAILED DESCRIPTION

[0047] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions 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. 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.

[0048] See also Figure 1-Figure 12 , the present invention provides a technical solution:

[0049] The chemical pipeline includes an outer tube 1 and a flange 2 and an inner lining tube 3 lined on the inner wall of the outer tube 1. Both ends of the inner lining tube 3 are turned outward to form flanges 31, and the flanges 31 are fixed on the end surface of the flange 2. The above are all existing technologies and will not be repeated here.

[0050] The technical solutions of the present invention which are different from the prior art are described in detail below.

[0051] The inner wall of the outer tube 1 is provided with a buffer 4, which is spiral-shaped. In some embodiments, the buffer 4 can be made of metal (such as stainless steel). The material requirement of the buffer 4 is that its high temperature resistance should be higher than that of the inner liner 3, so that the buffer 4 can be prevented from maintaining its shape during the heat fixing process of the chemical pipeline and prevented from being deformed by heat during the heat fixing process. The cross-sectional shape of the buffer 4 is not specifically limited in the present technical solution; for example, Figure 3As shown, in this embodiment, the buffer 4 is a hollow tubular structure, which includes a first arc portion 41 and a second arc portion 42 arranged opposite to each other, and the first end of the first arc portion 41 and the first end of the second arc portion 42 are fixedly connected. As can be seen from the figure, the first end of the first arc portion 41 and the first end of the second arc portion 42 are both lower ends, and the second end of the first arc portion 41 and the second end of the second arc portion 42 are overlapped. As can be seen from the figure, the second end of the first arc portion 41 and the second end of the second arc portion 42 are both upper ends, and the overlapping position is pressed against the inner circumferential wall of the outer tube 1; pins 44 are fixed at both ends of the buffer 4, and a through hole is provided on the circumferential surface of the outer tube 1 covered by the flange 2. The plug hole 11 is connected to each other, and there are two or more plug holes 11. When the pin 44 is inserted into different plug holes 11, the overlapping positions of the buffer member 4 exert different pressures on the inner wall of the outer tube 1. When the pin 44 is inserted into one of the plug holes 11, the pin 44 should be completely received in the plug hole 11 so as not to affect the welding between the flange 2 and the outer tube 1. At the same time, the purpose of opening the plug hole 11 on the circumference of the outer tube 1 covered by the flange 2 is to utilize the welding connection between the flange 2 and the outer tube 1 to achieve sealing of the plug hole 11, so as to prevent pollutants in the external environment from entering between the outer tube 1 and the inner liner tube 3 through the plug hole 11.

[0052] The diameter of the buffer member 4 in the above solution should be between one half and one third of the wall thickness of the liner pipe 3 .

[0053] The basic working principle of the above technical solution is: since a spiral buffer 4 is provided on the inner wall of the outer tube 1, and the buffer 4 is wrapped inside the inner liner 3, when the inner liner 3 expands due to heat, the force at any position of the buffer 4 is as follows: Fig.12 As shown by the four arrows in the figure, the liner tube 3 will generate an extrusion force on the buffer component 4 along the length direction, the circumference direction and the diameter direction of the tube. Since the second end of the first arc portion 41 and the second end of the second arc portion 42 are overlapped, the second end of the first arc portion 41 and the second end of the second arc portion 42 can be relatively displaced. Therefore, under the expansion and extrusion of the liner tube 3, the buffer component 4 will buffer the expansion of the liner tube 3 along the length direction, the circumference direction and the diameter direction by shrinking the diameter, thereby improving the adaptability of the chemical pipeline to cold and hot fluids and extending the service life of the entire chemical pipeline. In addition, since the second end of the first arc-shaped portion 41 and the second end of the second arc-shaped portion 42 are overlapped, the pin 44 can be inserted into different insertion holes 11 to change the pressure of the overlapping position of the buffer 4 on the inner wall of the outer tube 1. Since the pin 44 is inserted into different insertion holes 11, the buffer 4 will produce different degrees of twisting, so the gap size of the seam 45 at the overlapping position of the buffer 4 can also be changed, which is more conducive to the fluid entering or flowing out of the buffer 4 when leakage occurs.

[0054] Furthermore, the buffer 4 also includes a connecting portion 43, the two ends of which are fixedly connected to the first end of the first arc-shaped portion 41 and the first end of the second arc-shaped portion 42 respectively, and the middle portion of the connecting portion 43 is recessed toward the interior of the buffer 4, so that the cross-sectional shape of the connecting portion 43 is roughly an inverted V shape. The advantage of such a setting is that the deformation ability of the buffer 4 after being compressed can be enhanced.

[0055] In order to improve the self-checking capability of the chemical pipeline after the inner liner pipe 3 is damaged, the present invention provides the following technical solutions:

[0056] The outer tube 1 is provided with a warning member 5 at the bottom thereof. Specifically, the warning member 5 comprises a fixed tube 51, a piston 52 which is slidingly and sealingly arranged inside the fixed tube 51, a plug rod 53 which is fixed at the bottom of the piston 52 and coaxially arranged with the fixed tube 51, and a second warning sticker 56; one end of the fixed tube 51 is fixedly and sealedly connected with the outer tube 1, and the fixed tube 51 can be integrally formed with the outer tube 1; the second warning sticker 56 can be a reflective sticker; the second end of the first arc-shaped portion 41 and the second end of the second arc-shaped portion 42 are connected with one end of the fixed tube 51 by forming a seam 45 at the overlapping position; when the pressure in the buffer 4 changes, the piston 52 slides along the inner wall of the fixed tube 51 The second warning sticker 56 is moved to change from a hidden state to an exposed state. For example, when the inner liner tube 3 leaks, since the buffer 4 is spiral and spreads throughout the outer circumference of the inner liner tube 3, the fluid leaked from the inner liner tube 3 will enter the interior of the buffer 4 through the seam 45, and then enter the interior of the fixed tube 51 through the seam 45, so that the pressure generated by the fluid pushes the piston 52 and the plug rod 53 to move downward, so that the second warning sticker 56 is changed from a hidden state to an exposed state. At this time, the staff can judge whether the inner liner tube 3 of the corresponding chemical pipeline is damaged by observing whether the second warning sticker 56 is in an exposed state.

[0057] The structure of the warning member 5 is further described below.

[0058] The warning member 5 also includes a connecting sleeve 54 and a bottom cover 55. The bottom cover 55 can be made of an opaque material such as stainless steel. The connecting sleeve 54 includes a first sleeve 541 and a second sleeve 542 that are coaxial and fixedly connected. In some embodiments, the first sleeve 541 and the second sleeve 542 can be integrally formed, and the material of the first sleeve 541 and the second sleeve 542 can be consistent with that of the outer tube 1; wherein the outer diameter of the first sleeve 541 is greater than the outer diameter of the second sleeve 542, and the first sleeve 541 is threadedly sleeved on the fixed At the bottom of the tube 51, the inner diameter of the second sleeve 542 is larger than the diameter of the plug rod 53, and the plug rod 53 passes through the second sleeve 542; the second warning sticker 56 is sleeved and fixed on the outer periphery of the second sleeve 542; the bottom cover 55 is connected to the bottom end of the plug rod 53, and the bottom cover 55 is sleeved on the outside of the second warning sticker 56; when the pressure in the buffer 4 changes, the piston 52 and the plug rod 53 move downward, driving the bottom cover 55 to move downward, so that the second warning sticker 56 is converted from a hidden state stored inside the bottom cover 55 to an exposed state exposed to the external environment.

[0059] The basic working principle of the above scheme is: in the process of using the pressure generated by the fluid to push the piston 52 and the plug rod 53 downward, the bottom cover 55 will also gradually move downward, and the second warning sticker 56 wrapped by the bottom cover 55 will gradually be exposed to the external environment.

[0060] To improve the overall aesthetics, in some embodiments, the outer diameter of the bottom cover 55 is equal to the outer diameter of the first sleeve 541. Another function of this arrangement is to facilitate the staff to inspect and maintain the warning member 5. For example, by holding the bottom cover 55 tightly, the piston 52 can be driven to rotate to prevent the piston 52 from being stuck to the inner wall of the fixed tube 51 due to the piston 52 not moving for a long time.

[0061] A second rubber ring 58 is provided between the bottom end of the fixed tube 51 and the top end of the second sleeve 542; a retaining ring 511 is sleeved and fixed on the outer circumference of the fixed tube 51, and a first rubber ring 57 is provided between the top end of the first sleeve 541 and the retaining ring 511. The first rubber ring 57 and the second rubber ring 58 can both generate a certain elasticity when squeezed, so as to maintain a tight connection between the connecting sleeve 54 and the fixed tube 51 to prevent loosening.

[0062] The bottom cover 55 includes two half cover bodies 551, and the half cover bodies 551 are hinged to the bottom end of the plug rod 53 through hinges 553; a first warning sticker 554 is fixed to the inner surface of the half cover body 551; a half iron ring 552 is embedded in the top of the half cover body 551; a ring magnet 543 is embedded in the bottom end of the first sleeve 541; the half iron ring 552 is magnetically connected to the ring magnet 543.

[0063] The basic working principle of the bottom cover 55 is as follows: when the bottom cover 55 moves down to a certain height under the push of the plug rod 53, the magnetic attraction force of the annular magnet 543 on the half iron ring 552 disappears, and the half cover body 551 will rotate around the pivot of the hinge 553 under the action of gravity and open, thereby exposing the first warning sticker 554 to the external environment, which makes it easier for the staff to judge the status of the inner liner tube 3; further, the magnetic attraction force between the annular magnet 543 and the half iron ring 552 can also play a role in maintaining the position of the piston 52, preventing the piston 52 from automatically sliding down due to factors such as gravity.

[0064] The chemical pipeline lining heat fixing process is based on the above-mentioned chemical pipeline and includes the following steps:

[0065] S1, reducing the diameter of the inner liner pipe 3 through a reducing die;

[0066] S2, placing the prefabricated buffer 4 into the outer tube 1, and inserting the latch 44 into the insertion hole 11 at a suitable position, so that the buffer 4 is pressed against the inner wall of the outer tube 1;

[0067] S3, sending the reduced diameter inner liner pipe 3 into the outer pipe 1;

[0068] S4, placing the outer tube 1 with the inner liner tube 3 after the diameter reduction placed inside into the furnace for heating, so that the inner liner tube 3 expands to be fully close to the inner wall of the outer tube 1.

[0069] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A chemical pipeline, comprising an outer pipe and a flange, and an inner liner pipe lined on the inner circumferential wall of the outer pipe, wherein both ends of the inner liner pipe are turned outward to form flanges, and the flanges are fixed on the end surface of the flange, characterized in that: The inner circumferential wall of the outer tube is provided with a buffer member, which is in a spiral shape; The buffer is a hollow tubular structure, which includes a first arc-shaped portion and a second arc-shaped portion arranged opposite to each other, a first end of the first arc-shaped portion and a first end of the second arc-shaped portion are fixedly connected, a second end of the first arc-shaped portion and a second end of the second arc-shaped portion are overlapped, and the overlapped position is pressed against the inner circumferential wall of the outer tube; Pins are fixed at both ends of the buffer, and a through hole is opened on the circumference of the outer tube covered by the flange. There are two or more holes. When the pins are inserted into different holes, the overlapping positions of the buffer exert different pressures on the inner wall of the outer tube.

2. The chemical pipeline according to claim 1, characterized in that: The buffer also includes a connecting portion, two ends of which are fixedly connected to the first end of the first arc-shaped portion and the first end of the second arc-shaped portion respectively, and the middle portion of the connecting portion is recessed toward the inside of the buffer.

3. The chemical pipeline according to claim 1, characterized in that: A warning piece is arranged at the bottom of the outer tube, and the warning piece comprises a fixed tube, a piston which is slidingly sealed and arranged inside the fixed tube, a plug rod which is fixed at the bottom of the piston and arranged coaxially with the fixed tube, and a second warning sticker; One end of the fixed tube is fixedly and sealedly connected to the outer tube, and a joint formed at the overlapping position between the second end of the first arc-shaped portion and the second end of the second arc-shaped portion is connected to the one end of the fixed tube; When the pressure in the buffer changes, the piston slides along the inner wall of the fixed tube, so that the second warning sticker is converted from a hidden state to an exposed state.

4. The chemical pipeline according to claim 3, characterized in that: The warning member also includes a connecting sleeve and a bottom cover, and the connecting sleeve includes a first sleeve and a second sleeve that are coaxial and fixedly connected; The outer diameter of the first sleeve is larger than the outer diameter of the second sleeve, the first sleeve is threadedly sleeved on the bottom of the fixed pipe, the inner diameter of the second sleeve is larger than the diameter of the plug rod, and the plug rod passes through the second sleeve; The second warning sticker is sleeved and fixed on the outer periphery of the second sleeve; The bottom cover is connected to the bottom end of the plug rod, and the bottom cover is sleeved on the outside of the second warning sticker; When the pressure in the buffer changes, the piston and the plug rod move downward to drive the bottom cover downward, so that the second warning sticker is converted from a hidden state stored inside the bottom cover to an exposed state exposed to the external environment.

5. The chemical pipeline according to claim 4, characterized in that: The outer diameter of the bottom cover is equal to the outer diameter of the first sleeve.

6. The chemical pipeline according to claim 4, characterized in that: A second rubber ring is arranged between the bottom end of the fixing tube and the top end of the second sleeve tube.

7. The chemical pipeline according to claim 4, characterized in that: A retaining ring is sleeved and fixed on the outer peripheral surface of the fixed tube, and a first rubber ring is arranged between the top end of the first sleeve and the retaining ring.

8. The chemical pipeline according to claim 4, characterized in that: The bottom cover comprises two half cover bodies, and the half cover bodies are hinged to the bottom end of the plug rod through hinges; A first warning sticker is fixed on the inner surface of the half cover; A half iron ring is embedded and installed on the top of the half cover; An annular magnet is embedded and installed at the bottom end of the first sleeve; The half iron ring is magnetically connected to the ring magnet.

9. Chemical pipeline lining thermal fixing process, characterized in that: The chemical pipeline lining thermal fixing process is based on the chemical pipeline according to any one of claims 1 to 8 above, and comprises the following steps: S1, reducing the diameter of the liner pipe through a reducing die; S2, putting the prefabricated buffer into the outer tube, and inserting the pin into the socket at a suitable position, so that the buffer is pressed against the inner wall of the outer tube; S3, sending the reduced diameter inner liner pipe into the outer pipe; S4. Send the outer tube with the inner liner tube of reduced diameter placed inside into the furnace for heating, so that the inner liner tube expands to fully fit the inner wall of the outer tube.

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