An internal chemical pipeline leak prevention and detection joint

Abstract

The present invention relates to a built-in leak-proof and leak-detection joint for chemical pipelines, effectively solving the problems of easy failure, poor applicability, bulky volume, and troublesome installation of pipeline interface air leakage detection devices; the technical solution includes a connecting pipe, two coaxial annular grooves are opened on the outer wall of the connecting pipe, and an annular piston is installed in each annular groove. After the connecting pipe is inserted into the pipeline port, the end of the pipeline abuts against the piston, and a sealed cavity is formed between the piston, the inner wall of the pipeline, and the annular groove. Pushing the piston towards the middle of the connecting pipe creates a negative pressure in the cavity. There is also a negative pressure detection device. When there is air leakage, the negative pressure in the cavity disappears, and the alarm device alarms; the present invention adopts a built-in hidden installation, with a neat appearance without bulges, can remain effective for a long time, is suitable for air leakage detection of low-pressure pipelines, has two-stage sealing, is safe and reliable, and is easy to install.

Description

Technical Field

[0001] The present invention relates to the field of chemical industry safety, and specifically to an in-built leak prevention and detection joint for chemical pipelines. Background Art

[0002] Chemical pipelines are a common way to transport various chemical gases and liquid raw materials, and are inevitably used in various chemical enterprises; for a long transportation distance, several sections of pipelines need to be connected. Flanges are commonly used connection methods for end-to-end connection of pipelines and installation of valves, etc. Sealing rings are used to seal between flanges, and the connection part is a high-incidence area of leakage. Therefore, monitoring the leakage at the connection part is of great significance for the safe transportation of chemical pipelines.

[0003] Currently, the detection methods for pipeline leakage are roughly divided into two categories:

[0004] The first category, such as the invention patent with the application number 201611144227.9, the invention patent with the application number 201711337360.0, etc., monitors the fluctuations of pressure and flow rate inside the pipeline through a pressure sensor inserted into the pipeline or a flow meter connected in series on the pipeline. If the pressure and flow rate decrease significantly, it can be determined that the pipeline leaks. Since a tiny leak has an extremely small impact on the pressure and flow rate inside the pipeline, especially in a large pipeline, its detection sensitivity for tiny leaks is poor, and it is impossible to focus on detecting specific points;

[0005] The second category, such as the invention patent with the application number 202010927311.8, the utility model patent with the application number 202123095162.2, the utility model patent with the application number 201621318281.6, etc., forms a sealed sandwich cavity outside the pipeline by covering the interface with a housing, and detects the pressure inside the sandwich cavity, and issues an alarm signal in the form of vision, audition, electrical signal, etc. for the pressure change inside the cavity caused by the leakage of gas and liquid from the pipeline into the sandwich cavity to prompt the occurrence of leakage; this type of method has the following defects:

[0006] Firstly, the entire detection device is installed behind the pipeline, and it is necessary to ensure the sealing fit with the outer wall of the pipeline. The detection device is in a long-term exposed state, and it is easy to cause sealing failure due to weathering and aging of the sealing ring, rust on the outer wall of the pipeline, peeling and cracking of the paint layer, and damage to the housing of the detection device by being knocked. As a result, when the pipeline leaks, especially when there is a tiny leak, the pressure inside the sandwich cavity cannot rise, resulting in the loss of detection function. Moreover, the detection device forms a bulge outside the pipeline, making the appearance of the pipeline messy and bloated, increasing the volume, and not suitable for installation in a narrow space or on pipelines that are arranged closely side by side;

[0007] Secondly, the pressure increase in the interlayer cavity is used as the monitoring variable. When the conveying pressure in the pipeline is close to normal pressure, even if a leak occurs, the pressure in the interlayer cavity will not increase significantly. Therefore, this type of device is not suitable for leak detection of low-pressure conveying pipeline joints.

[0008] Third, since the seal failure between the detection device and the outer wall of the pipeline will not cause the detection device to alarm, and compared with the accuracy of the inner wall and the end, the accuracy of the outer wall of the pipeline is the lowest, the seal between the detection device and the outer wall of the pipeline cannot be regarded as a reliable secondary seal when the raw material leaks in the pipeline. Therefore, when the detection device issues a leakage alarm, regardless of the time period and production situation, it must be repaired quickly, resulting in extremely passive maintenance and production operations;

[0009] Fourthly, the detection device needs to be installed outside the pipeline after the pipeline connection is completed, which adds extra steps, is cumbersome to operate, and has low efficiency. Summary of the invention

[0010] In order to solve the problems of easy failure, poor applicability, bulky size, and troublesome installation of pipeline interface leakage detection devices, the present invention provides a built-in chemical pipeline leak-proof and leak-detecting joint.

[0011] The technical solution includes a connecting pipe, wherein a first sealing ring is installed on the outer wall of each end of the connecting pipe, and two coaxial annular grooves are opened on the outer wall of the connecting pipe, and the two annular grooves are symmetrical about the midpoint of the connecting pipe. An annular piston is installed in each annular groove, and the piston can slide axially along the connecting pipe in the annular groove. A second sealing ring is installed between the inner wall of the piston and the annular groove, and a third sealing ring is attached to the outer side of the piston. After the connecting pipe is inserted into the pipe port, the end of the pipe abuts against the third sealing ring on the piston, and the piston is pushed toward the middle of the connecting pipe, so that a sealed cavity is formed between the piston, the inner wall of the pipe and the annular groove; the bottom of each annular groove is connected to a An airway is provided at the port of the airway, and the elastic diaphragm closes the airway opening. The elastic diaphragm can be elastically deformed when subjected to force. A conductor sheet is attached to the outside of the elastic diaphragm. Two conductor rings located between the two elastic diaphragms are provided in the side wall of the connecting tube. The two conductor rings are spaced apart up and down. When the elastic diaphragm is not subjected to force and is in a straight state, the conductor sheet contacts the side walls of the two conductor rings at the same time to connect the two conductor rings. When the elastic diaphragm is concavely deformed under the action of negative pressure in the cavity, the conductor sheet separates from the two conductor rings, and the two conductor rings are disconnected. An alarm is provided outside the connecting tube, and the two conductor rings are respectively connected to the two poles of the alarm through wires. When the two conductor rings are connected, the alarm sends an alarm signal.

[0012] The outer wall of the first sealing ring is in a tapered shape with a small outer end and a large inner end, and the inner wall of the pipe port is also processed to have a chamfer that is consistent with the taper of the outer wall of the first sealing ring.

[0013] The inner wall of the second sealing ring is a cone with a smaller outer end and a larger inner end, and the bottom of the annular groove is also a cone with the same taper as the inner wall of the second sealing ring.

[0014] A threaded hole located between the two annular grooves is formed in the side wall of the connecting pipe. A stud is rotated in the threaded hole, and two conductor rings are fixed to the lower end of the stud and extend between the two elastic diaphragms.

[0015] An annular flange is provided in the middle of the outer wall of the connecting pipe. The outer diameter of the piston is equal to the diameter of the flange and equal to the outer diameter of the pipe. After the connecting pipe is inserted into the two sections of the pipe to connect the pipes, the outer walls of the pipes, the outer walls of the pistons, and the outer walls of the flanges are flush, forming a flat surface, and a protective layer is coated on this surface.

[0016] The elastic diaphragm is fixed in an annular frame, and the annular frame is fixed at the air inlet.

[0017] The present invention adopts an internal hidden installation, with a neat appearance without bulges, can remain effective for a long time, is suitable for leakage detection of low-pressure pipes, has two-stage sealing which is safe and reliable, and is simple to install. Description of the Drawings

[0018] Figure 1 It is a front view cross-sectional view of the present invention.

[0019] Figure 2 It is a front view cross-sectional view after the present invention is connected to the pipe.

[0020] Figure 3 It is Figure 2 an enlarged view of position A in

[0021] Figure 4 It is Figure 1 an enlarged view of position B in

[0022] Figure 5 It is Figure 3 an enlarged view of position C in Detailed Embodiment

[0023] In conjunction with the accompanying drawings, the present invention includes a connecting pipe 1, the two ends of the connecting pipe 1 are respectively inserted into the ports of the connecting ends of the two sections of the pipeline to achieve the connection of the two sections of the pipeline, and a first sealing ring 2 is installed on the outer wall of each end of the connecting pipe 1. After the connecting pipe 1 is inserted into the pipeline port, the first sealing ring 2 cooperates with the inner wall of the pipeline and is pressed to achieve sealing. Two coaxial annular grooves 3 are opened on the outer wall of the connecting pipe 1, and the two annular grooves 3 are symmetrical about the midpoint of the connecting pipe 1. An annular piston 4 is installed in each annular groove 3, and the piston 4 can slide axially along the connecting pipe 1 in the annular groove 3. A second sealing ring 5 is installed between the inner wall of the piston 4 and the annular groove 3, and the outer side of the piston 4 is attached with The third sealing ring 6, the outer surface of which is the side of the piston 4 facing the end of the connecting pipe 1, after the connecting pipe 1 is inserted into the pipe port, the end of the pipe abuts against the third sealing ring 6 on the piston 4, and the piston 4 is pushed toward the middle of the connecting pipe 1, and a sealed cavity 7 is formed between the piston 4, the inner wall of the pipe and the annular groove 3. As the piston 4 moves, the cavity 7 increases, and a negative pressure is formed in the cavity 7. When the pipe pushes the piston 4 to the end of the annular groove 3, the pipe is plugged into place. At this time, a two-level seal is formed between the pipe and the connecting pipe 1, the first sealing ring 2 is the first-level seal, and the second sealing ring 5 and the third sealing ring 6 are the second-level seals. If any one-level seal fails, the negative pressure in the cavity 7 will disappear.

[0024] The bottom of each annular groove 3 is connected to an airway 8 opened in the side wall of the connecting tube 1. An elastic diaphragm 9 is installed at the end of the airway 8. The elastic diaphragm 9 closes the airway 8. The elastic diaphragm 9 can be elastically deformed and bulge to one side after being stressed. Under the action of the negative pressure in the cavity 7, the elastic diaphragm 9 bulges into the airway 8. A conductor sheet 10 is attached to the outside of the elastic diaphragm 9. Two conductor rings 11 located between the two elastic diaphragms 9 are arranged in the side wall of the connecting tube 1. The two conductor rings 11 are arranged at intervals up and down. When the elastic diaphragm 9 is not stressed and is in a straight state, the conductor sheet 10 contacts the side walls of the two conductor rings 11 at the same time, and the two conductor rings 11 are connected. When the elastic diaphragm 9 is concavely deformed under the action of the negative pressure in the cavity 7, the conductor sheet 10 and the two conductor rings 11 are in contact with each other. The conductor ring 11 is detached, the two conductor rings 11 are disconnected, an alarm 12 is provided outside the connecting tube 1, and the two conductor rings 11 are respectively connected to the two poles of the alarm 12 through wires. When the two conductor rings 11 are connected, the alarm 12 sends out an alarm signal. The alarm signal can be a buzzer, a light, a remote wireless signal, etc., and the type of alarm 12 can be selected according to needs; when no leakage occurs in the two-stage seal, a negative pressure state is maintained in the cavity 7, the elastic diaphragm 9 is in a concave state, the conductor sheet 10 is detached from the conductor ring 11, and the alarm 12 is in an open circuit state. When any one-stage seal leaks, the negative pressure in the cavity 7 will disappear, the elastic diaphragm 9 returns to a straight state, the conductor sheet 10 contacts the two conductor rings 11 at the same time, and the alarm 12 is connected to send out an alarm signal.

[0025] The outer wall of the first sealing ring 2 is tapered with a smaller outer end and a larger inner end. The outer end refers to the end facing the end of the connecting pipe 1, and the inner end refers to the end facing the middle of the connecting pipe 1. The inner wall of the pipe port is also machined with a chamfer having the same taper as the outer wall of the first sealing ring 2. When the connecting pipe 1 is inserted into the pipe, under the action of the tapered surface, the first sealing ring 2 will be pressed tighter and tighter, improving its sealing performance.

[0026] The inner wall of the second sealing ring 5 is tapered with a smaller outer end and a larger inner end. The outer end refers to the end facing the end of the connecting pipe 1, and the inner end refers to the end facing the middle of the connecting pipe 1. The bottom of the annular groove 3 is also tapered with the same taper as the inner wall of the second sealing ring 5. When the piston 4 is pushed inward, the second sealing ring 5 will be pressed tighter and tighter under the action of the tapered surface, improving its sealing performance. At the same time, the tapered surface exerts a large resistance to the inward movement of the piston 4, increasing the pressure between the pipe end face and the third sealing ring 6, so that the third sealing ring 6 is always in a sealed state during the movement of the piston 4, and thus the cavity 7 is always in a closed state.

[0027] A threaded hole 13 is formed in the side wall of the connecting pipe 1 between the two annular grooves 3. Both air passages 8 communicate with the side wall of the threaded hole 13. An elastic diaphragm 9 is installed at one end where the air passage 8 communicates with the threaded hole 13. A stud 14 is rotated in the threaded hole 13. Two conductor rings 11 are fixed to the lower end of the stud 14 and extend between the two elastic diaphragms 9. Insulating sheets are provided between the two conductor rings 11 and the stud 14, or the stud 14 is made of an insulating material such as hard plastic, so that the two conductor rings 11 cannot be connected through the stud 14.

[0028] A circular flange 15 is provided in the middle of the outer wall of the connecting pipe 1. The outer diameter of the piston 4 is equal to the diameter of the flange 15 which is equal to the outer diameter of the pipe. After the connecting pipe 1 is inserted into the two pipes to connect the pipes, the outer wall of the pipe, the outer wall of the piston 4 and the outer wall of the flange 15 are flush, forming a flat surface. A protective layer 16 is applied to this surface. The protective layer 16 can be a waterproof coating, an anti-rust paint, a sealant, etc., to enclose and protect the piston 4 and the third rubber ring, avoiding corrosion and aging of the rubber ring and rust of the pipe end and the piston 4.

[0029] The elastic diaphragm 9 is fixed in an annular frame 17. The annular frame 17 is fixed at the air passage 8 opening. The material of the annular frame 17 can be rubber, hard plastic, etc., and is integrally formed and cast on the outer edge of the elastic diaphragm 9 to clamp the elastic diaphragm 9 inside. The annular frame 17 can be screwed onto the air passage 8 opening and sealed with glue at the edge, or can be hot melt welded to the air passage 8 opening. The elastic diaphragm 9 can be replaced when damaged.

[0030] The working principle of the present invention is as follows: when making a pipe interface connection, the two ends of the connecting pipe 1 are respectively inserted into the ports of the two pipes to be connected, and then the flange bolts on the flanges of the two pipe ends are installed, and the flange bolts are gradually tightened to pull the two pipes closer to the middle, so that the two ends of the connecting pipe 1 gradually go deeper into the pipe mouth; after the connecting pipe 1 is inserted into the pipe, the first sealing ring 2 contacts the inner wall of the pipe and is gradually squeezed by the conical surface, and when the end of the pipe abuts against the third sealing ring 6 on the outside of the piston 4, it pushes the piston 4 to move the middle of the connecting pipe 1. At this time, the inner wall of the pipe, the annular groove 3 and the piston 4 have formed a closed cavity 7. As the piston 4 moves inward, the cavity 7 increases and forms a negative pressure until the piston 4 moves to the end of the annular groove 3 and abuts against the convex edge 15. During the inward movement of the piston 4, the second sealing ring 5 is squeezed by the conical surface, and the third sealing ring 6 is also pressed tighter and tighter as the resistance of the piston 4 increases. After the piston 4 abuts against the convex edge 15, two circles of flange bolts are tightened to further tighten the third sealing ring 6. At this point, the pipeline connection is completed, and the elastic diaphragm 9 at the mouth of the airway 8 is concave under the action of the negative pressure in the cavity 7, the conductor sheet 10 is separated from the two conductor rings 11, and a protective layer 16 is applied to the outer wall of the pipeline section between the flanges, and then the alarm 12 is connected.

[0031] When there is no leakage in the first-level seal, i.e. the first sealing ring 2, and the second-level seal, i.e. the third sealing ring 6 of the second sealing ring 5, the cavity 7 always maintains a negative pressure state, and the elastic diaphragm 9 also remains in a concave state. The alarm 12 is not turned on and no alarm is given. When a leak occurs at any sealing ring at either end, the negative pressure in the cavity 7 at the leaking end will disappear, and the elastic diaphragm 9 at this end will return to a straight state. Then the conductor sheet 10 at this end will contact the two conductor rings 11 at the same time to connect the two conductor rings 11, and then the alarm 12 will be turned on. The alarm 12 sends an alarm signal to remind the staff to perform maintenance.

[0032] Compared with the prior art, the present invention has the following technical effects:

[0033] First, after the connection is completed, the present invention is inside the pipeline and will not be damaged by weathering, rust, collision, etc., which will cause the detection failure, so that the effectiveness of the leakage detection function can be maintained for a long time. Even if there is a very small leak in the pipeline, the negative pressure in the cavity 7 will eventually disappear, so there will be no monitoring escape of the small leak. Moreover, there is no bulge outside the connected pipeline, the outer pipe is neat, and the volume is not increased, so it can be installed in a small space;

[0034] Second, the present invention automatically forms a negative pressure cavity 7 during the connection process, and uses the disappearance of negative pressure as a monitoring variable. Even if the pressure in the pipeline is close to normal pressure, effective leakage monitoring can still be performed, so it has higher sensitivity and a wider monitoring range;

[0035] Thirdly, the present invention has two-stage sealing. The first sealing ring 2 is the first stage, and the second sealing ring 5 and the third sealing ring 6 are the second stage. The negative pressure cavity 7 is located between the two-stage sealing. If any stage of sealing fails, the negative pressure in the cavity 7 will disappear, that is, the monitored variable changes, and then an alarm signal is sent. However, the separate failure of any stage of sealing will not cause the gas-liquid in the pipeline to leak to the outside. Therefore, there is sufficient time for preparation before maintenance or to choose a suitable time for maintenance, which gains the initiative for maintenance preparation and the choice of maintenance time. Without accidental accidents, the gas-liquid is basically not likely to leak outside the pipeline;

[0036] Fourthly, the present invention integrates the functions of connection and detection, with a high structural integration degree. During the tightening process of the flange bolts, the pressing of each sealing ring and the establishment of the negative pressure cavity 7 are automatically completed. Except for putting the connecting pipe 1 in front of the connecting pipe 1, no other additional operations are required, and the additional workload is basically not increased. The installation is simple and efficient.

Claims

1. An internal leak-proof and leak-detecting joint for chemical pipelines, characterized in that It includes a connecting pipe (1). A first sealing ring (2) is installed on the outer wall at each end of the connecting pipe (1). Two annular grooves (3) coaxial with the connecting pipe (1) are formed on the outer wall of the connecting pipe (1). The two annular grooves (3) are symmetric about the midpoint of the connecting pipe (1). An annular piston (4) is installed in each annular groove (3). The piston (4) can slide axially along the connecting pipe (1) in the annular groove (3). A second sealing ring (5) is installed between the inner wall of the piston (4) and the annular groove (3). A third sealing ring (6) is attached to the outer side surface of the piston (4). After the connecting pipe (1) is inserted into the pipe port, the end of the pipe abuts against the third sealing ring (6) on the piston (4) and pushes the piston (4) towards the middle of the connecting pipe (1). A sealed cavity (7) is formed among the piston (4), the inner wall of the pipe and the annular groove (3). A gas passage (8) opened in the side wall of the connecting pipe (1) communicates with the bottom of each annular groove (3). An elastic diaphragm (9) is installed at the port of the gas passage (8). The elastic diaphragm (9) closes the opening of the gas passage (8). The elastic diaphragm (9) can undergo elastic deformation when stressed. A conductor sheet (10) is attached to the outer side of the elastic diaphragm (9). Two conductor rings (11) are arranged between the two elastic diaphragms (9) in the side wall of the connecting pipe (1). The two conductor rings (11) are arranged at intervals up and down. When the elastic diaphragm (9) is not stressed and in a flat state, the conductor sheet (10) contacts the side walls of the two conductor rings (11) simultaneously to connect the two conductor rings (11). When the elastic diaphragm (9) is concave deformed under the action of negative pressure in the cavity (7), the conductor sheet (10) separates from the two conductor rings (11), and the two conductor rings (11) are open-circuited. An alarm (12) is arranged outside the connecting pipe (1). The two conductor rings (11) are respectively connected to the two poles of the alarm (12) through wires. When the two conductor rings (11) are connected, the alarm (12) emits an alarm signal.

2. The built-in chemical pipeline leak prevention and detection joint according to claim 1, characterized in that, The outer wall of the first sealing ring (2) is a cone with a smaller outer end and a larger inner end. The inner wall of the pipe port is also machined with a chamfer having the same taper as the outer wall of the first sealing ring (2).

3. An internal chemical pipeline leak prevention and detection joint according to claim 1, characterized in that, The inner wall of the second sealing ring (5) is a cone with a smaller outer end and a larger inner end. The bottom of the annular groove (3) is also a cone having the same taper as the inner wall of the second sealing ring (5).

4. The built-in chemical pipeline leak prevention and detection joint according to claim 1, characterized in that, A threaded hole (13) is formed in the side wall of the connecting pipe (1) between the two annular grooves (3). A stud (14) is rotated in the threaded hole (13). The two conductor rings (11) are fixed at the lower end of the stud (14) and extend between the two elastic diaphragms (9).

5. An internal chemical pipeline leak prevention and detection joint according to claim 1, characterized in that, An annular flange (15) is arranged in the middle of the outer wall of the connecting pipe (1). The outer diameter of the piston (4) is equal to the diameter of the flange (15) which is equal to the outer diameter of the pipe. After the connecting pipe (1) is inserted into two sections of pipes to connect the pipes, the outer wall of the pipe, the outer wall of the piston (4) and the outer wall of the flange (15) are flush, forming a flat surface. A protective layer (16) is painted on this surface.

6. The built-in chemical pipeline leak prevention and detection joint according to claim 1, characterized in that, The elastic diaphragm (9) is fixed in an annular frame (17). The annular frame (17) is fixed at the opening of the gas passage (8).

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