Plug bush type high-pressure glass fiber reinforced plastic maintenance pipe fitting

Abstract

The utility model discloses a plug bush type high-pressure glass fiber reinforced plastic maintenance pipe fitting and relates to the field of pipeline leakage repair. The plug bush type high-pressure glass fiber reinforced plastic maintenance pipe fitting comprises a glass fiber reinforced plastic sleeve and a glass fiber reinforced plastic inner pipe, the inner wall of one end of the glass fiber reinforced plastic sleeve and the middle of the glass fiber reinforced plastic sleeve are provided with sleeve pipe threads and a sleeve reducing section which are connected with a glass fiber reinforced plastic pipe respectively, and the inner diameter of the sleeve reducing section is gradually reduced along with approaching to the sleeve pipe threads. At least one pressure relief hole penetrating through the glass fiber reinforced plastic sleeve is formed in the sleeve reducing section, a sleeve threaded section and a sleeve smooth section are arranged at the ends, away from and close to the sleeve pipe threads, of the sleeve reducing section correspondingly, and inner pipe threads connected with the glass fiber reinforced plastic pipe are arranged on the inner wall of the end, extending out of the glass fiber reinforced plastic sleeve, of the glass fiber reinforced plastic inner pipe; the end, inserted into the glass fiber reinforced plastic sleeve, of the glass fiber reinforced plastic inner pipe is sequentially provided with an inner pipe threaded section in threaded connection with the sleeve threaded section, an inner pipe reducing section in sealing fit with the sleeve reducing section and an inner pipe smooth section in sliding fit with the sleeve smooth section. The plug bush type high-pressure glass fiber reinforced plastic maintenance pipe fitting has the advantages of being convenient to assemble and disassemble, good in sealing performance and high in stability.

Description

Technical Field

[0001] This application relates to the field of pipeline leak repair, and more specifically, to a plug-in type high-pressure fiberglass repair pipe fitting. Background Technology

[0002] High-pressure water injection in oil fields often involves reinjecting produced water, which has a high chloride ion concentration, making it highly corrosive. When using steel pipes, corrosion and perforation are common, often occurring within 3-5 years. Currently, with advancements in new materials, fiberglass pipes are widely replacing steel pipes. Fiberglass is corrosion-resistant, with a service life often reaching 20-30 years. However, fiberglass is easily damaged by external forces. Fiberglass pipelines laid in ditches, roadsides, and farmland are particularly vulnerable to damage from rotary tillers and excavators. The current repair method for damaged fiberglass pipes involves cutting off the damaged section, creating tapered joints at the cut ends of the good pipe, attaching on-site threads, connecting the threads to steel fittings to form a steel adapter, and finally connecting the two steel adapters with a steel pipe to complete the repair. Essentially, a section of steel pipe is used to replace the damaged fiberglass pipe.

[0003] The drawback of existing fiberglass pipe repair methods is that the repaired steel pipes are prone to corrosion and perforation. Since water injection pipelines are typically tens to hundreds of meters long, there are multiple damaged repair points along the entire pipeline. These damaged sections of steel pipe only have a service life of 3-5 years, failing to achieve the original purpose of using non-metallic pipelines to prevent corrosion and perforation. Perforation of high-pressure water injection pipelines can cause major environmental accidents and huge economic losses. To prevent perforation of these repaired sections, the steel pipes are usually replaced with new ones every two years, with each replacement costing several million yuan. Utility Model Content

[0004] The purpose of this application is to provide a plug-in type high-pressure fiberglass maintenance pipe fitting, which has the advantages of convenient installation and removal, good sealing performance and strong stability.

[0005] This application is implemented as follows:

[0006] This application provides a plug-in type high-pressure fiberglass repair pipe fitting, which includes a fiberglass sleeve and a fiberglass inner tube that can be inserted into the fiberglass sleeve at one end. The inner wall of one end of the fiberglass sleeve is provided with a sleeve thread for connecting to the fiberglass pipe. The middle part of the fiberglass sleeve is provided with a sleeve diameter reducing section. The inner diameter of the sleeve diameter reducing section gradually decreases as it approaches the sleeve thread. The sleeve diameter reducing section is provided with at least one pressure relief hole penetrating the inner and outer walls of the fiberglass sleeve. The ends of the sleeve diameter reducing section away from and close to the sleeve thread are respectively provided with a sleeve threaded section and a sleeve smooth section. The inner wall of the fiberglass inner tube extending out of the fiberglass sleeve is provided with an inner tube thread for connecting to the fiberglass pipe. The end of the fiberglass inner tube inserted into the fiberglass sleeve is provided with an inner tube threaded section that is threadedly connected to the sleeve threaded section, an inner tube diameter reducing section that is sealed and fitted with the sleeve diameter reducing section, and an inner tube smooth section that is slidably fitted with the sleeve smooth section.

[0007] In some alternative embodiments, the outer wall of the smooth section of the inner tube is provided with at least one first sealing groove, and a first sealing ring is provided in the first sealing groove.

[0008] In some alternative embodiments, the inner wall of the smooth section of the casing is provided with at least one second sealing groove, and the second sealing groove is provided with a second sealing ring that seals with the outer wall of the smooth section of the inner tube.

[0009] In some alternative embodiments, the inner wall of the fiberglass sleeve away from the sleeve thread is provided with at least one third sealing groove, and the third sealing groove is provided with a third sealing ring for sealing and engaging with the outer wall of the fiberglass inner tube.

[0010] In some alternative implementations, screws corresponding to the pressure relief holes are also included, which can be inserted to close the pressure relief holes by sealing them with a sealant layer.

[0011] In some alternative implementations, a resin adhesive layer connects the sleeve threaded section and the inner tube threaded section.

[0012] In some alternative embodiments, a connecting sleeve is also included, one end of which is configured to be threaded onto the fiberglass sleeve at the end away from the sleeve thread, and the other end of the connecting sleeve has a fourth sealing groove on its inner wall, and the fourth sealing groove has a fourth sealing ring on its inner wall for pressing against the outer wall of the fiberglass inner tube.

[0013] In some alternative implementations, an elastic rubber sleeve for the diameter-changing section is also included, located between the casing diameter-changing section and the inner tube diameter-changing section.

[0014] The beneficial effects of this application are as follows: The plug-in type high-pressure fiberglass repair pipe fitting provided by this application includes a fiberglass sleeve and a fiberglass inner tube that can be inserted into the fiberglass sleeve at one end. The inner wall of one end of the fiberglass sleeve is provided with a sleeve thread for connecting the fiberglass pipe. The middle part of the fiberglass sleeve is provided with a sleeve diameter reducing section. The inner diameter of the sleeve diameter reducing section gradually decreases as it approaches the sleeve thread. The sleeve diameter reducing section is provided with at least one pressure relief hole that penetrates the inner and outer walls of the fiberglass sleeve. The ends of the sleeve diameter reducing section away from and close to the sleeve thread are respectively provided with a sleeve thread section and a sleeve smooth section. The inner wall of the fiberglass inner tube extending out of the fiberglass sleeve is provided with an inner tube thread for connecting the fiberglass pipe. The end of the fiberglass inner tube inserted into the fiberglass sleeve is provided with an inner tube thread section that is threadedly connected to the sleeve thread section, an inner tube diameter reducing section that is sealed and fitted with the sleeve diameter reducing section, and an inner tube smooth section that is slidably fitted with the sleeve smooth section. The plug-in type high-pressure fiberglass maintenance pipe fitting provided in this application has the advantages of convenient installation and removal, good sealing performance and strong stability, which can avoid corrosion and perforation of maintenance pipelines and reduce the workload of pipeline maintenance. Attached Figure Description

[0015] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying any creative work.

[0016] Figure 1 A schematic diagram of the fiberglass sleeve and fiberglass inner tube in a plug-in type high-pressure fiberglass maintenance pipe fitting provided in an embodiment of this application;

[0017] Figure 2 For along Figure 1 Sectional view of section line AA in the middle;

[0018] Figure 3 For along Figure 1 Sectional view of the BB section line;

[0019] Figure 4 This is a schematic diagram of the structure of the fiberglass sleeve in a plug-in type high-pressure fiberglass maintenance pipe fitting provided in another embodiment of this application;

[0020] Figure 5 This is a schematic diagram of the structure of the fiberglass sleeve in a plug-in type high-pressure fiberglass maintenance pipe fitting provided in another embodiment of this application;

[0021] Figure 6 This is a schematic diagram of the structure of the fiberglass sleeve in a plug-in type high-pressure fiberglass maintenance pipe fitting provided in another embodiment of this application;

[0022] Figure 7 This is a schematic diagram of the fiberglass inner tube in a plug-in type high-pressure fiberglass repair pipe fitting provided in another embodiment of this application.

[0023] In the diagram: 100, FRP sleeve; 110, sleeve thread; 120, sleeve reducing section; 130, pressure relief hole; 140, sleeve threaded section; 150, sleeve smooth section; 160, second sealing groove; 170, second sealing ring; 180, third sealing groove; 190, third sealing ring; 200, FRP inner tube; 210, inner tube thread; 220, inner tube threaded section; 230, inner tube reducing section; 240, inner tube smooth section; 250, first sealing groove; 260, first sealing ring; 270, screw; 300, connecting sleeve; 310, fourth sealing groove; 320, fourth sealing ring; 330, reducing section elastic sleeve. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0025] Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of the application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0026] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, it does not need to be further defined or explained in subsequent drawings.

[0027] In the description of this application, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of this application is in use. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this application. In addition, the terms "first," "second," and "third," etc., are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0028] Furthermore, terms such as "horizontal," "vertical," and "sag" do not imply that components must be absolutely horizontal or suspended, but rather that they can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal relative to "vertical," and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0029] In the description of this application, it should also be noted that, unless otherwise expressly specified and limited, the terms "set up," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0030] In this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature being directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature being directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0031] The features and performance of the plug-in type high-pressure fiberglass maintenance pipe fitting of this application are further described in detail below with reference to the embodiments.

[0032] like Figure 1 , Figure 2 and Figure 3 As shown, this application embodiment provides a plug-in type high-pressure fiberglass repair pipe fitting for repairing damaged parts of fiberglass pipes. It includes a fiberglass sleeve 100, a fiberglass inner tube 200 with one end insertable into the fiberglass sleeve 100, and a screw 270.

[0033] The fiberglass sleeve 100 has a sleeve thread 110 on the inner wall of one end for connecting to the fiberglass pipe. The fiberglass sleeve 100 has a sleeve diameter reducing section 120 in the middle. The inner diameter of the sleeve diameter reducing section 120 gradually decreases as it approaches the sleeve thread 110. The sleeve diameter reducing section 120 has a pressure relief hole 130 that penetrates the inner and outer walls of the fiberglass sleeve 100. A screw 270 is used to insert into the pressure relief hole 130. The screw 270 is used to seal the pressure relief hole 130 with the sealing layer between the screw 270 and the pressure relief hole 130. The end of the sleeve diameter reducing section 120 away from the sleeve thread 110 has a sleeve thread section 140. The end of the sleeve diameter reducing section 120 near the sleeve thread 110 has a sleeve smooth section 150.

[0034] The inner wall of the fiberglass inner tube 200 extending out of the fiberglass sleeve 100 is provided with an inner tube thread 210 for connecting the fiberglass tube. The outer wall of the end of the fiberglass inner tube 200 inserted into the fiberglass sleeve 100 is provided with an inner tube thread section 220 connected to the sleeve thread section 140 by threads, an inner tube reducing section 230 that is sealed to the sleeve reducing section 120, and an inner tube smooth section 240 that is slidably engaged with the sleeve smooth section 150 along the direction away from the inner tube thread 210. The outer diameter of the inner tube reducing section 230 gradually decreases as it moves away from the inner tube thread 210. The outer wall of the inner tube smooth section 240 is provided with three first sealing grooves 250 arranged axially at intervals. Each first sealing groove 250 is provided with an O-ring 260. Only one first sealing ring 260 is shown in the figure. A resin adhesive layer is connected between the sleeve thread section 140 and the inner tube thread section 220.

[0035] The working principle of the plug-in type high-pressure fiberglass repair pipe fitting provided in this application embodiment is as follows: When the damaged part of the fiberglass pipe is found, the damaged part of the fiberglass pipe is cut off, and tapered sections are made on the outer wall of the fiberglass pipe at both ends of the cut-off part, and field threads are glued on to correspond to the sleeve pipe thread 110 and the inner pipe thread 210 for connection. Subsequently, resin adhesive is applied to the inner pipe thread section 220 on the outer wall of the fiberglass inner pipe 200, and the fiberglass inner pipe 200 is fitted with an inner pipe. When one end of the threaded section 220, the inner tube reducing section 230, and the inner tube smooth section 240 is inserted into the end of the fiberglass sleeve 100 away from the inner tube thread 210, and the inner tube smooth section 240 extends into the sleeve smooth section 150 after passing through the sleeve reducing section 120 in the fiberglass sleeve 100, the fiberglass inner tube 200 is rotated so that the inner tube threaded section 220 on the outer wall of the fiberglass inner tube 200 is threadedly connected to the sleeve threaded section 140 on the inner wall of the fiberglass sleeve 100, until the fiberglass... The smooth section 240 of the inner tube at one end of the steel inner tube 200 extends completely into the smooth section 150 of the sleeve, and the inner tube reducing section 230 of the outer wall of the fiberglass inner tube 200 abuts and seals against the reducing section 120 of the inner wall of the fiberglass sleeve 100. Then, the connected fiberglass inner tube 200 and fiberglass sleeve 100 are placed at the damaged part of the fiberglass pipe, and the sleeve thread 110 at one end of the fiberglass sleeve 100 is threaded to the damaged end of the fiberglass pipe. Then, the connection is reversed. Rotate the fiberglass inner tube 200 so that it moves away from the fiberglass sleeve 100 and is threadedly connected to the other end of the fiberglass pipe at the damaged point. Finally, use a syringe to inject sealant into the pressure relief hole 130. Then, insert the screw 270 into the pressure relief hole 130 and wait for the sealant to solidify and form a sealant layer. The screw 270 and the sealant layer between the screw 270 and the pressure relief hole 130 will seal the pressure relief hole 130, thus completing the repair of the damaged fiberglass pipe.

[0036] The plug-in type high-pressure fiberglass repair pipe fitting provided in this application embodiment uses a fiberglass inner tube 200 and a fiberglass sleeve 100 to cooperate, so that one end of the fiberglass inner tube 200 is inserted and threaded to the middle of the fiberglass sleeve 100. Then, the fiberglass inner tube 200 and the fiberglass sleeve 100 are respectively threaded to the two ends of the damaged part of the fiberglass pipe. The fiberglass inner tube 200, which can extend and retract relative to the fiberglass sleeve 100, can conveniently and quickly connect the two ends of the damaged part of the fiberglass pipe. The inner tube diameter-changing section 230 of the fiberglass inner tube 200 cooperates with the sleeve diameter-changing section 120 of the outer wall of the fiberglass sleeve 100 to play a positioning role. The inner tube smooth section 240 of the fiberglass inner tube 200 slides and cooperates with the sleeve smooth section 150 of the inner wall of the fiberglass sleeve 100, and the sealing between the two is achieved by the first sealing groove 250 and the first sealing ring 260 provided on the outer wall of the inner tube smooth section 240.

[0037] The reducing section 120 of the sleeve is provided with a pressure relief hole 130 that penetrates the inner and outer walls of the fiberglass sleeve 100. This hole can prevent the fiberglass inner tube 200 from being compressed and damaged by pressure build-up in the tank space between the first sealing ring 260 and the sleeve thread 110 during the expansion and contraction process. After the connection is completed, the pressure relief hole 130 is sealed with a screw 270 and a sealing layer between the screw 270 and the pressure relief hole 130 to ensure the sealing of the pipeline.

[0038] In other alternative embodiments, such as Figure 4 As shown, the inner wall of the smooth section 150 of the fiberglass sleeve 100 is provided with a second sealing groove 160, and a second sealing ring 170 is provided in the second sealing groove 160 to seal against the outer wall of the smooth section 240 of the inner tube. By providing a second sealing ring 170 that seals against the outer wall of the smooth section 240 of the inner tube within the second sealing groove 160 on the inner wall of the smooth section 150, the sealing performance when the fiberglass inner tube 200 and the fiberglass sleeve 100 are connected can be further improved. In other optional embodiments, the number of the second sealing groove 160 and the second sealing ring 170 can be two, three, or more.

[0039] In other alternative embodiments, such as Figure 5 As shown, a third sealing groove 180 is provided on the inner wall of the end of the fiberglass sleeve 100 away from the sleeve thread 110. A third sealing ring 190 is provided within the third sealing groove 180 for sealing with the outer wall of the fiberglass inner tube 200. By providing a third sealing ring 190 within the third sealing groove 180 on the inner wall of the fiberglass sleeve 100 away from the sleeve thread 110, the sealing performance when the fiberglass inner tube 200 and the fiberglass sleeve 100 are connected can be further improved. In other optional embodiments, the number of third sealing grooves 180 and third sealing rings 190 can be two, three, or more.

[0040] In other alternative embodiments, such as Figure 6 As shown, it also includes a connecting sleeve 300. The inner wall of one end of the connecting sleeve 300 is threadedly connected to the outer wall of the fiberglass sleeve 100 away from the sleeve thread 110. The inner wall of the other end of the connecting sleeve 300 is provided with a fourth sealing groove 310. The fourth sealing groove 310 is provided with a fourth sealing ring 320 whose inner wall is used to press against the outer wall of the fiberglass inner tube 200. By threading the connecting sleeve 300 onto the outer wall of the fiberglass sleeve 100 away from the sleeve thread 110 and providing the fourth sealing groove 310 on the inner wall of the connecting sleeve 300, and the fourth sealing ring 320 whose inner wall is used to press against the outer wall of the fiberglass inner tube 200, the sealing performance between the outer wall of the fiberglass inner tube 200 and the connecting sleeve 300 can be further improved.

[0041] In other alternative embodiments, such as Figure 7 As shown, it also includes a variable diameter section elastic sleeve 330 disposed between the sleeve variable diameter section 120 and the inner tube variable diameter section 230. The variable diameter section elastic sleeve 330 is a hollow frustum shape, and both its inner and outer diameters gradually decrease as it moves away from the inner tube thread 210. When one end of the fiberglass inner tube 200, which has the inner tube thread section 220, the inner tube variable diameter section 230, and the inner tube smooth section 240, is inserted into the end of the fiberglass sleeve 100 away from the inner tube thread 210, the variable diameter section elastic sleeve 330 is fitted onto the inner tube variable diameter section. On the outer wall of 230, the smooth section 240 of the inner tube at one end of the fiberglass inner tube 200 extends completely into the smooth section 150 of the sleeve, and the inner tube diameter-changing section 230 of the outer wall of the fiberglass inner tube 200 and the sleeve diameter-changing section 120 of the inner wall of the fiberglass sleeve 100 press against the inner and outer walls of the diameter-changing section elastic rubber sleeve 330 to cause deformation. When the fiberglass inner tube 200 moves in the opposite direction to connect with the damaged fiberglass tube, the diameter-changing section elastic rubber sleeve 330 improves the sealing performance of the inner tube diameter-changing section 230 and the sleeve diameter-changing section 120.

[0042] The embodiments described above are some, but not all, of the embodiments of this application. The detailed description of the embodiments of this application is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

Claims

1. A plug-in type high-pressure fiberglass repair pipe fitting, characterized in that, It includes a fiberglass sleeve and a fiberglass inner tube that can be inserted into the fiberglass sleeve at one end. The inner wall of one end of the fiberglass sleeve is provided with a sleeve thread for connecting to the fiberglass tube. The middle part of the fiberglass sleeve is provided with a sleeve diameter reducing section. The inner diameter of the sleeve diameter reducing section gradually decreases as it approaches the sleeve thread. The sleeve diameter reducing section is provided with at least one pressure relief hole penetrating the inner and outer walls of the fiberglass sleeve. The ends of the sleeve diameter reducing section away from and close to the sleeve thread are respectively provided with a sleeve threaded section and a sleeve smooth section. The inner wall of the fiberglass inner tube extending out of the fiberglass sleeve is provided with an inner tube thread for connecting to the fiberglass tube. The end of the fiberglass inner tube inserted into the fiberglass sleeve is provided with an inner tube threaded section that is threadedly connected to the sleeve threaded section, an inner tube diameter reducing section that is sealed to the sleeve diameter reducing section, and an inner tube smooth section that is slidably engaged with the sleeve smooth section.

2. The plug-in type high-pressure fiberglass maintenance pipe fitting according to claim 1, characterized in that, The outer wall of the smooth section of the inner tube is provided with at least one first sealing groove, and a first sealing ring is provided in the first sealing groove.

3. The plug-in type high-pressure fiberglass maintenance pipe fitting according to claim 1, characterized in that, The inner wall of the smooth section of the sleeve is provided with at least one second sealing groove, and the second sealing groove is provided with a second sealing ring that seals with the outer wall of the smooth section of the inner tube.

4. The plug-in type high-pressure fiberglass maintenance pipe fitting according to claim 1, characterized in that, The inner wall of the fiberglass sleeve away from the sleeve thread is provided with at least one third sealing groove, and the third sealing groove is provided with a third sealing ring for sealing and cooperating with the outer wall of the fiberglass inner tube.

5. The plug-in type high-pressure fiberglass maintenance pipe fitting according to claim 1, characterized in that, It also includes screws that correspond one-to-one with the pressure relief holes, which can be inserted into the pressure relief holes to seal them through a sealant layer.

6. The plug-in type high-pressure fiberglass maintenance pipe fitting according to claim 1, characterized in that, A resin adhesive layer connects the sleeve thread section and the inner tube thread section.

7. The plug-in type high-pressure fiberglass maintenance pipe fitting according to claim 1, characterized in that, It also includes a connecting sleeve, one end of which is configured to be threaded onto the fiberglass sleeve away from the sleeve pipe thread end, and the other end of the connecting sleeve has a fourth sealing groove on its inner wall, and the fourth sealing groove has a fourth sealing ring with an inner wall for pressing against the outer wall of the fiberglass inner tube.

8. The plug-in type high-pressure fiberglass maintenance pipe fitting according to claim 1, characterized in that, It also includes a variable diameter section elastic rubber sleeve disposed between the sleeve variable diameter section and the inner tube variable diameter section.

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