Insulation structure and method for cathode protection of low-pressure pipeline

Abstract

The invention relates to the technical field of pipeline connection, and provides an insulation structure and method for low-voltage pipeline cathode protection, the insulation structure comprises an insulation spacer, a pair of fastening flanges, a pair of insulation sleeves and a fastening assembly, the insulation spacer is arranged between a pair of connecting flanges; the fastening flanges are arranged on the portions, on the outer sides of the connecting flanges, of the low-pressure pipeline in a sleeving mode correspondingly. Each fastening flange is of an annular structure formed by splicing at least two split flange units. The pair of insulating sleeves respectively sleeve a pair of low-pressure pipelines to be connected, are positioned between the fastening flange and the connecting flange, and are used for blocking the electrical connection between the connecting flange and the fastening flange; the insulation sleeve is of an annular structure formed by splicing at least two split insulation units. The fastening assembly is used for oppositely connecting the pair of fastening flanges so as to press and fix the insulating sleeve and the connecting flange; installation is simple, long-term stability of insulation performance is ensured, and the problem of insulation failure caused by the fact that a traditional bolt insulation sleeve is prone to damage is effectively solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of pipeline connection, in particular to an insulation structure and method for low-pressure pipeline cathodic protection. BACKGROUND

[0002] When the metal pipeline is buried in the soil, the corrosion problem is inevitable. Due to the existence of soil corrosion, the pipeline is prone to corrosion thinning and corrosion perforation, which greatly affects the safe and reliable operation of the pipeline.

[0003] Cathodic protection is a scientific and effective means to inhibit pipeline corrosion. By applying cathodic protection current to the pipeline, the potential difference on the surface of the pipeline is eliminated to slow down the corrosion. During the construction and installation of pipeline cathodic protection, the protected pipeline and the non-protected pipeline need to be effectively electrically insulated and isolated, effectively blocking the flow of cathodic protection current to other non-protected pipelines, so that the cathodic protection current can only reach the surface of the protected pipeline.

[0004] For example, in the gas industry, the way of insulating between pipelines by cathodic protection is mostly to use insulation joints and insulation flanges. Among them, insulation joints are commonly used for medium-pressure and above pipelines, and insulation flanges are mostly used for low-pressure pipelines. With the increasing number of low-pressure gas accidents in recent years, cathodic protection is gradually installed and used in low-pressure pipelines. When installing cathodic protection on low-pressure gas pipelines, the flange position of the standpipe in front of the user's residential building needs to be insulated, otherwise the cathodic protection current will flow into the building through the standpipe, resulting in the failure of cathodic protection.

[0005] Currently, the flange insulation of the standpipe in front of the building is composed of insulation gaskets between flanges, bolt insulation sleeves (mostly yellow wax pipes), bolt insulation gaskets, nuts, etc. However, since the insulation material is a non-metallic material and the material itself is thin and soft, it is easy to be squeezed and damaged during the tightening process of the bolts, resulting in insulation failure. Moreover, during the operation and maintenance of the pipeline, the flange may be repeatedly twisted and disassembled, and the insulation sleeve and insulation gasket may be damaged during this process, resulting in insulation failure. After the insulation fails, the cathodic protection current of the pipeline flows into other positions, and the cathodic protection cannot effectively protect the corrosion of the pipeline. SUMMARY

[0006] The present application provides an insulation structure and method for low-pressure pipeline cathodic protection to solve the defects of complex installation and maintenance of the existing low-pressure pipeline cathodic protection insulation structure, easy insulation failure, and further leakage of cathodic protection current and corrosion protection failure of the pipeline, and to realize insulation assembly without pipe breaking and improve the reliability of the insulation structure.

[0007] The application provides an insulation structure for low-pressure pipeline cathodic protection, which is arranged between connecting flanges of two low-pressure pipelines to be connected, and comprises the following: an insulation gasket arranged between the pair of connecting flanges; a pair of fastening flanges, which are respectively arranged on the low-pressure pipelines outside the pair of connecting flanges, and are annular structures formed by splicing at least two split flange units; a pair of insulation sleeves, which are respectively arranged on the pair of low-pressure pipelines to be connected and are located between the fastening flanges and the connecting flanges, and are used for blocking the electrical connection between the connecting flanges and the fastening flanges; the insulation sleeves are annular structures formed by splicing at least two split insulation units; a fastening assembly, which is used for connecting the pair of fastening flanges to press and fix the insulation sleeves and the connecting flanges.

[0008] According to the application, the insulation sleeve comprises the following: an axial insulation part, which is arranged on the low-pressure pipeline and is used for isolating the fastening flanges from the low-pressure pipeline; a radial insulation part, which is respectively in contact with the outer side of the connecting flange and the abutting surface of the fastening flange.

[0009] According to the application, the splicing part of the split flange unit is provided with a positioning matching structure.

[0010] According to the application, the positioning matching structure is a step arranged on the matching connecting surfaces of the split flange units, or the positioning matching structure is a boss and a groove arranged on the matching connecting surfaces of the split flange units.

[0011] According to the application, the insulation structure for low-pressure pipeline cathodic protection further comprises the following: a lightning protection member, which is arranged on the low-pressure pipeline outside the connecting flange, and comprises the following: a linear conductor, which is wrapped with a fusible insulation layer, and whose end is connected with a grounding connecting member reserved in the insulation structure, so that when lightning strikes, the insulation layer is damaged due to the thermal effect of lightning current, the linear conductor forms a conductive path with the low-pressure pipeline, and guides the lightning current to flow to the ground.

[0012] According to the application, the insulation structure for low-pressure pipeline cathodic protection further comprises the following: a first anti-skid gasket, which is arranged between the fastening flange and the insulation sleeve.

[0013] According to the insulating structure for cathodic protection of low-pressure pipelines provided by the present invention, the fastening flange is provided with a plurality of bolt holes along the circumferential direction, and the fastening assembly includes: A connecting bolt, adapted to the bolt hole, is used to pass sequentially through the bolt holes of a pair of fastening flanges, and the connecting bolt is connected to the end of the linear conductor; The lock nut is connected to the free end of the connecting bolt.

[0014] According to the insulating structure for cathodic protection of low-pressure pipelines provided by the present invention, a second anti-slip pad is provided between the connecting bolt and the fastening flange.

[0015] In a second aspect, the present invention provides an insulation method applied to the insulation structure for low-pressure pipeline cathodic protection described in the first aspect, comprising: Step S1: Without cutting off the original pipeline, the individual insulation units are spliced ​​together to form a complete insulation sleeve, which is then fitted onto the low-pressure pipeline outside the connecting flange. Step S2: Without cutting off the original pipeline, the individual flange units are spliced ​​into a complete fastening flange, which is then fitted onto the low-pressure pipeline outside the connecting flange, and the insulating sleeve is pressed tightly onto the outside of the connecting flange. Step S3: Use fasteners to connect a pair of fastening flanges between the two low-pressure pipes to be connected, and press and fix the insulating sleeve, connecting flange and insulating gasket.

[0016] The insulation method provided by the present invention further includes: Step S4: Wrap the linear conductor around the low-pressure pipe and connect its end to the connecting bolt, wherein the linear conductor is wrapped with a heat-fusible insulating layer.

[0017] This invention provides an insulating structure for cathodic protection of low-pressure pipelines, disposed between the connecting flanges of two low-pressure pipelines to be connected. The insulating structure includes an insulating gasket, a pair of fastening flanges, a pair of insulating sleeves, and a fastening assembly. The insulating gasket is disposed between the pair of connecting flanges. The pair of fastening flanges are respectively fitted onto the low-pressure pipelines outside the pair of connecting flanges, and the fastening flanges are annular structures formed by splicing at least two separate flange units. The pair of insulating sleeves are respectively fitted onto the pair of low-pressure pipelines to be connected, located between the fastening flanges and the connecting flanges, and are used to block the electrical connection between the connecting flanges and the fastening flanges. The insulating sleeves are annular structures formed by splicing at least two separate insulating units. The fastening assembly is used to connect the pair of fastening flanges relative to each other to press and fix the insulating sleeves and connecting flanges. The insulating sleeves and fastening flanges of this invention are both of a separate splicing structure. This invention allows for assembly without cutting the low-pressure pipeline, making it suitable for maintenance and modification scenarios of low-pressure pipelines in use and avoiding gas outages caused by pipeline breaks. The modular structure facilitates replacement of individual units during later maintenance without requiring overall disassembly, reducing maintenance difficulty and cost. The fastening assembly tightly compresses a pair of fastening flanges, an insulating sleeve, a connecting flange, and an insulating gasket, ensuring both the airtightness and stability of the original connecting flanges and the fixation of the insulating sleeve by the fastening flanges. This prevents displacement or detachment of the insulating sleeve due to vibration and temperature changes during long-term pipeline operation, ensuring long-term stable insulation performance. Furthermore, the insulating sleeve and insulating gasket prevent electrical connection between the connecting flange and the fastening flange, ensuring that the cathodic protection current only acts on the surface of the protected low-pressure pipeline, effectively solving the insulation failure problem caused by the easy breakage of traditional bolt-insulating sleeves. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0019] Figure 1 This is a schematic diagram of an insulation structure for cathodic protection of low-pressure pipelines provided in an embodiment of the present invention.

[0020] Figure 2 This is a top view of the split flange unit provided in an embodiment of the present invention.

[0021] Figure 3 This is a front view of the insulating sleeve provided in an embodiment of the present invention.

[0022] Figure label: 1. Insulating gasket; 2. Connecting flange; 3. Low-pressure pipeline; 4. Fastening flange; 41. Split flange unit; 42. Bolt hole; 5. Insulating sleeve; 51. Axial insulation part; 52. Radial insulation part; 6. Linear conductor; 7. Connecting bolt. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0024] The following is combined Figures 1-3 This invention describes an insulation structure and method for cathodic protection of low-pressure pipelines.

[0025] This invention provides an insulating structure for cathodic protection of low-pressure pipelines, disposed between connecting flanges 2 of two low-pressure pipelines 3 to be connected. The insulating structure includes an insulating gasket 1, a pair of fastening flanges 4, a pair of insulating sleeves 5, and a fastening assembly. The insulating gasket 1 is disposed between the pair of connecting flanges 2. The pair of fastening flanges 4 are respectively fitted onto the low-pressure pipelines 3 outside the pair of connecting flanges 2. The fastening flanges 4 are annular structures formed by splicing at least two separate flange units 41. The pair of insulating sleeves 5 are respectively fitted onto the pair of low-pressure pipelines 3 to be connected and are located between the fastening flanges 4 and the connecting flanges 2, used to block the electrical connection between the connecting flanges 2 and the fastening flanges 4. The insulating sleeves 5 are annular structures formed by splicing at least two separate insulating units. The fastening assembly is used to connect the pair of fastening flanges 4 relative to each other to press and fix the insulating sleeves 5 and the connecting flanges 2.

[0026] During installation, the insulating structure provided by this invention involves first precisely placing the insulating gasket 1 between the mating surfaces of the two connecting flanges 2; then, assembling a pair of insulating sleeves 5 on the low-pressure pipes 3 to be connected, fastening the separate insulating units against the outer wall of the pipe to form a complete ring structure, so that the insulating sleeves 5 are respectively fitted onto the pipe sections outside the two connecting flanges 2, and ensuring that the axial position of the insulating sleeves 5 is between the connecting flanges 2 and the subsequently installed fastening flanges 4; then, assembling a pair of fastening flanges 4 on the outside of the insulating sleeves 5, fastening them to form a ring structure, and then fitting them onto the pipe, ensuring that the fastening flanges 4 and the insulating sleeves 5 are completely fitted; the pair of fastening flanges 4 are connected by fastening components until the fastening flanges 4 tightly press the insulating sleeves 5, connecting flanges 2, and insulating gasket 1 together.

[0027] As can be seen from the above scheme, the insulating sleeve 5 and fastening flange 4 of the present invention adopt a split splicing structure, which can be assembled without cutting the low-pressure pipeline 3. It is suitable for maintenance and modification scenarios of the low-pressure pipeline 3 in use, avoiding gas outage losses caused by pipeline breakage. At the same time, the split structure facilitates the replacement of individual units in later operation and maintenance without the need for overall dismantling, reducing maintenance difficulty and cost. The fastening components press the pair of fastening flanges 4, insulating sleeve 5, connecting flange 2 and insulating gasket 1 together, which not only ensures the airtightness and stability between the original connecting flanges 2, but also fixes the insulating sleeve 5 through the fastening flange 4, preventing the insulating sleeve 5 from shifting or falling off due to vibration and temperature changes during long-term pipeline operation, and ensuring long-term stable insulation performance. The present invention, through the insulating sleeve 5 and insulating gasket 1, blocks the electrical connection between the connecting flange 2 and the fastening flange 4, ensuring that the cathodic protection current only acts on the surface of the protected low-pressure pipeline 3, effectively solving the problem of insulation failure caused by easy breakage of the traditional bolt insulating sleeve 5.

[0028] In this embodiment, the insulating sleeve 5 includes an axial insulating part 51 and a radial insulating part 52. The axial insulating part 51 is sleeved on the low-pressure pipeline 3 to isolate the fastening flange 4 from the low-pressure pipeline 3. The radial insulating part 52 is in contact with the outer side of the connecting flange 2 and the mating surface of the fastening flange 4, respectively.

[0029] like Figure 1 , Figure 3 As shown, the insulating sleeve 5 has a T-shaped structure and can be made of glass fiber reinforced composite material or engineering plastic. By fastening the axial insulating part 51 to the outer wall of the low-pressure pipeline 3, it is ensured that the axial insulating part 51 completely wraps the pipeline section outside the connecting flange 2, forming a ring structure to isolate the direct contact between the fastening flange 4 and the pipeline. At the same time, one end of the radial insulating part 52 is tightly attached to the outer end face of the connecting flange 2, and the other end is attached to the fastening flange 4 that will be installed later. With this configuration, the axial insulating part 51 directly wraps the outer wall of the pipeline, isolating the radial electrical contact between the fastening flange 4 and the pipeline. The radial insulating part 52 fills the axial gap between the connecting flange 2 and the fastening flange 4, blocking the electrical contact between their end faces. Compared with the traditional single insulating structure, this completely eliminates the current leakage blind zone and improves airtightness, achieving effective protection for the low-pressure pipeline 3.

[0030] Preferably, the joint of the split flange unit 41 is provided with a positioning and mating structure.

[0031] In some embodiments, the positioning and mating structure is a mating step provided on the connecting surface of each split flange unit 41. If the fastening flange 4 consists of two split flange units 41, during installation, the first split flange unit 41 is placed against the pipe wall on the outside of the insulating sleeve 5, and another split flange unit 41 is taken, and its concave step on the connecting surface is precisely aligned with the convex step of the first split flange unit 41. They are then fastened together along the circumference of the pipe, so that the step surfaces of the two units are completely fitted together to form a ring structure. If the fastening flange 4 consists of three or more split flange units 41, they are spliced ​​together sequentially along the circumference until a complete ring-shaped fastening flange 4 is formed, and the inner wall of the fastening flange 4 is tightly fitted with the outer wall of the insulating sleeve 5.

[0032] Alternatively, the positioning and mating structure consists of mating bosses and grooves on the connecting surfaces of each split flange unit 41. The first split flange unit 41 is placed against the pipe wall with the boss facing the splicing direction. The second split flange unit 41 is then taken, and its groove is aligned with the boss of the first unit. It is pressed radially along the low-pressure pipe 3 so that the boss is fully embedded in the groove, achieving a concave-convex fit. If multiple units are spliced, they are assembled sequentially along the circumference to ensure that the bosses and grooves of adjacent units are fitted without gaps, and that the inner wall of the fastening flange 4 is tightly fitted with the outer wall of the insulating sleeve 5.

[0033] This configuration, through a structured docking method, avoids problems such as misalignment and circumferential offset when splicing the split flange unit 41, prevents local loosening caused by lack of positioning, and thus prevents local squeezing or wear of the insulating sleeve 5 caused by flange loosening, extending the service life of the insulation structure, and ensuring the positioning accuracy and connection stability of subsequent fastening components.

[0034] In some embodiments, the fastening flange 4 is provided with a plurality of bolt holes 42 along the circumferential direction. The fastening assembly includes a connecting bolt 7 and a lock nut. The connecting bolt 7 is adapted to the bolt holes 42 and is used to pass through a pair of bolt holes 42 of the fastening flange 4 in sequence. The connecting bolt 7 is connected to the end of the linear conductor 6. The lock nut is connected to the free end of the connecting bolt 7.

[0035] like Figure 2As shown, the multiple bolt holes 42 arranged along the circumference of the fastening flange 4 are precisely matched with the connecting bolts 7, which can achieve uniform force distribution around the circumference. During installation, by tightening the connecting bolts 7 symmetrically in stages, the preload of the locking nut can be evenly transmitted to the entire circumference of the fastening flange 4, avoiding uneven force distribution and local warping of the flange caused by traditional single bolt or a few bolt tightening. This ensures that the insulating sleeve 5 and the insulating gasket 1 are evenly compressed, preventing airtight leakage due to local lack of compression and avoiding damage to the insulating sleeve 5 due to local overpressure, thus ensuring the dual stability of insulation performance and structural sealing. The threaded engagement between the locking nut and the free end of the connecting bolt 7 can lock the connecting bolt 7 by applying a stable preload. Anti-loosening washers such as spring washers and locking washers can be used to further improve the anti-loosening effect. In addition, the detachable design of the locking nut also facilitates the later inspection and replacement of the insulating sleeve 5 and the insulating gasket 1.

[0036] Furthermore, the bolt holes 42 are located at the positioning and fitting structure. For example, when the positioning and fitting structure is a mating step on the connecting surface of each split flange unit 41, the bolt holes 42 are located on the step along the axial direction of the low-pressure pipe 3; or, when the positioning and fitting structure is a mating boss and groove on the connecting surface of each split flange unit 41, the bolt holes 42 are located on the boss and groove along the axial direction of the low-pressure pipe 3, so that the connecting bolts 7 pass through the bolt holes 42 to lock the two split flange units 41 after docking, preventing them from separating.

[0037] In this embodiment, a first anti-slip pad is also included, which is disposed between the fastening flange 4 and the insulating sleeve 5. This arrangement, with the first anti-slip pad sandwiched between the fastening flange 4 and the insulating sleeve 5, significantly enhances the friction between the fastening flange 4 and the insulating sleeve 5, preventing slippage and ensuring the long-term effectiveness of the insulation.

[0038] In addition, it can also disperse local pressure. The first anti-slip pad can be made of elastic material such as silicone rubber, which can buffer local pressure through its own deformation, and evenly transmit the pre-tightening force applied by the fastening flange 4 to the surface of the insulating sleeve 5, reducing the risk of damage to the insulating sleeve 5 caused by local stress concentration and extending the service life of the insulating sleeve 5.

[0039] In a further embodiment, a second anti-slip washer is provided between the connecting bolt 7 and the fastening flange 4. By clamping the second anti-slip washer between the connecting bolt 7 or the lock nut and the fastening flange 4, the friction between the bolt and the fastening flange 4 is enhanced, the bolt position is fixed, and the preload is ensured to be stable over a long period of time.

[0040] Optionally, the surface of the anti-slip pad is provided with an anti-slip structure, which may be a raised grid-like texture or a striped texture.

[0041] In other embodiments, the radial insulating portion 52 of the insulating sleeve 5 may be provided with a positioning groove or a positioning protrusion. Correspondingly, the contact surface of the fastening flange 4 is provided with a positioning protrusion or a positioning groove. The fitting gap between the positioning protrusion and the positioning groove is 0.05-0.1mm. Both the positioning protrusion and the positioning groove are annular. Thus, the positioning of the insulating sleeve 5 can also be achieved through the concave-convex fit to prevent its movement; and there is no need to add anti-slip pads.

[0042] In this embodiment, a lightning protection component is also included. The lightning protection component is arranged around the low-pressure pipe 3 outside the connecting flange 2. The lightning protection component includes a linear conductor 6, which is wrapped with a fusible insulating layer. The end of the linear conductor 6 is connected to a reserved grounding connector or fastening assembly. When struck by lightning, the insulating layer is destroyed by the thermal effect of the lightning current, so that the linear conductor 6 and the low-pressure pipe 3 form a conductive path, guiding the lightning current to the ground.

[0043] Optionally, the linear conductor 6 is a metal wire or metal strip made of copper, copper alloy or aluminum alloy, and the insulating coating is made of polyethylene, polypropylene or polyvinyl chloride.

[0044] When a lightning strike occurs, the low-pressure pipeline 3 and the connecting flange 2 are easily induced or directly subjected to huge lightning currents. If no lightning protection components are installed, the current will force its way through the insulating structure, such as the insulating sleeve 5 and the insulating gasket 1. The thermal effect of the current will melt the insulating material, causing insulation failure and leading to cathodic protection current leakage, resulting in the pipeline losing its corrosion protection. This invention uses a linear conductor 6, such as copper wire or copper alloy wire, which has excellent conductivity. Its external fusible insulating layer can isolate the linear conductor 6 from the pipeline under normal conditions, avoiding affecting the cathodic protection insulation effect. When the lightning current arrives, the insulating layer melts rapidly due to the thermal effect, allowing the linear conductor 6 to directly form a conductive path with the pipeline. The lightning current preferentially flows through the linear conductor 6, through the reserved grounding connection or fastening components such as the connecting bolt 7, to the ground, completely bypassing the insulating sleeve 5, insulating gasket 1 and other insulating components, thus preventing the insulating structure from being burned at the source.

[0045] With this configuration, the lightning protection component is surrounded on the pipe outside the connecting flange 2. The circular design of the linear conductor 6 covers the circumference of the pipe, ensuring that the current can be quickly captured and guided away regardless of the direction from which lightning strikes the pipe. The connecting bolt 7 is directly connected to the end of the linear conductor 6, eliminating the need for an additional independent grounding connection. This simplifies the structure of the lightning protection path and eliminates the need for drilling or welding grounding terminals on the fastening flange 4, reducing damage to the structural integrity of the fastening flange 4. At the same time, it ensures that the lightning current can be quickly conducted through the connecting bolt 7 to the fastening flange 4 and the low-pressure pipe 3 below, and then flow to the ground, reducing the risk of the insulation structure being burned by lightning.

[0046] This invention also provides an insulation method applied to the aforementioned insulation structure for cathodic protection of low-pressure pipelines, comprising: Step S1: Without cutting off the original pipeline, the individual insulation units are spliced ​​together to form a complete insulation sleeve 5, which is then fitted onto the low-pressure pipeline 3 outside the connecting flange 2. Step S2: Without cutting off the original pipeline, the individual flange units 41 are spliced ​​into a complete fastening flange 4, which is then fitted onto the low-pressure pipeline 3 outside the connecting flange 2, and the insulating sleeve 5 is pressed tightly onto the outside of the connecting flange 2. Step S3: Use fasteners to connect a pair of fastening flanges 4 between the two low-pressure pipes 3 to be connected, and press and fix the insulating sleeve 5, connecting flange 2 and insulating gasket 1.

[0047] Furthermore, it also includes step S4: winding the linear conductor 6 around the low-pressure pipe 3 and connecting its end to the connecting bolt 7, wherein the linear conductor 6 is wrapped with a heat-fusible insulating layer.

[0048] In some embodiments, between step S1 and step S2, a first anti-slip pad is provided on the surface of the insulating sleeve 5, and the first anti-slip pad contacts the fastening flange 4.

[0049] Compared with existing technologies, the present invention enables insulation assembly to be completed without pipe disconnection, improving the reliability and durability of the insulation structure, taking into account lightning protection function, adapting to different thermal expansion and contraction conditions in different environments, and ultimately ensuring the stable operation of the low-pressure pipeline cathodic protection system, extending the service life of the pipeline and reducing operation and maintenance costs.

[0050] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. An insulating structure for cathodic protection of low-pressure pipelines, characterized in that, The insulation structure, located between the connecting flanges (2) of the two low-pressure pipes (3) to be connected, includes: An insulating gasket (1) is disposed between a pair of the connecting flanges (2); A pair of fastening flanges (4) are respectively fitted on the low-pressure pipeline (3) outside the pair of connecting flanges (2). The fastening flanges (4) are ring structures spliced ​​from at least two split flange units (41). A pair of insulating sleeves (5) are respectively fitted on the pair of low-pressure pipes (3) to be connected and located between the fastening flange (4) and the connecting flange (2) to block the electrical connection between the connecting flange (2) and the fastening flange (4); the insulating sleeve (5) is a ring structure spliced ​​from at least two separate insulating units; Fastening assembly for connecting a pair of said fastening flanges (4) relative to each other to press and fix said insulating sleeve (5) and said connecting flange (2).

2. The insulation structure for cathodic protection of low-pressure pipelines according to claim 1, characterized in that, The insulating sleeve (5) includes: An axial insulating part (51) is sleeved on the low-pressure pipe (3) to isolate the fastening flange (4) from the low-pressure pipe (3). The radial insulating part (52) is in contact with the outer side of the connecting flange (2) and the mating surface of the fastening flange (4), respectively.

3. The insulation structure for cathodic protection of low-pressure pipelines according to claim 1, characterized in that, The split flange unit (41) is provided with a positioning and fitting structure at the splice joint.

4. The insulation structure for cathodic protection of low-pressure pipelines according to claim 3, characterized in that, The positioning and fitting structure is a step that fits on the connecting surface of each of the split flange units (41); or, the positioning and fitting structure is a boss and a groove that fit on the connecting surface of each of the split flange units (41).

5. The insulation structure for cathodic protection of low-pressure pipelines according to claim 1, characterized in that, Also includes: A lightning protection device, which is disposed around the low-pressure pipeline (3) outside the connecting flange (2), the lightning protection device comprising: A linear conductor (6) is wrapped with a fusible insulating layer. The end of the linear conductor (6) is connected to a grounding connector reserved in the insulating structure. When struck by lightning, the insulating layer is damaged by the thermal effect of the lightning current, so that the linear conductor (6) and the low-pressure pipe (3) form a conductive path and guide the lightning current to the ground.

6. The insulation structure for cathodic protection of low-pressure pipelines according to claim 1, characterized in that, Also includes: The first anti-slip pad is disposed between the fastening flange (4) and the insulating sleeve (5).

7. The insulation structure for cathodic protection of low-pressure pipelines according to claim 5, characterized in that, The fastening flange (4) is provided with a plurality of bolt holes (42) along the circumferential direction, and the fastening assembly includes: A connecting bolt (7) is adapted to the bolt hole (42) for sequentially passing through the bolt holes (42) of a pair of fastening flanges (4), and the connecting bolt (7) is connected to the end of the linear conductor (6); The lock nut is connected to the free end of the connecting bolt (7).

8. The insulation structure for cathodic protection of low-pressure pipelines according to claim 7, characterized in that, A second anti-slip pad is provided between the connecting bolt (7) and the fastening flange (4).

9. An insulation method applied to the insulation structure for low-pressure pipeline cathodic protection as described in any one of claims 1-8, characterized in that, include: Step S1: Without cutting off the original pipeline, the individual insulation units are spliced ​​into a complete insulation sleeve (5) and fitted onto the low-pressure pipeline (3) outside the connecting flange (2); Step S2: Without cutting off the original pipeline, the individual flange units (41) are spliced ​​into a complete fastening flange (4), which is then fitted onto the low-pressure pipeline (3) outside the connecting flange (2), and the insulating sleeve (5) is pressed tightly onto the outside of the connecting flange (2). Step S3: Use fasteners to connect a pair of fastening flanges (4) between the two low-pressure pipes (3) to be connected, and press and fix the insulating sleeve (5), connecting flange (2) and insulating gasket (1).

10. The insulation method according to claim 9, characterized in that, Also includes: Step S4: Wrap the linear conductor (6) around the low-pressure pipe (3) and connect its end to the connecting bolt (7), wherein the linear conductor (6) is wrapped with a heat-fusible insulating layer.

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