Ambient liquid phase piped delivery for cold tube holders

Abstract

The utility model discloses a normal temperature liquid phase pipeline conveying device for cold -insulated pipe support, including pipeline system and cold -insulated pipe support, pipeline system includes the flowmeter, pressure transmitter, interpolation type temperature sensor, first surface temperature sensor and second surface temperature sensor who set up between two emergency cut -out valve and connect gradually, flowmeter and pressure transmitter are equipped with the bypass pipe of connecting to torch or storage tank through three -way pipe, bypass pipe is equipped with the manual control valve group and bypass automatic release control valve of parallel structure, manual control valve group includes first manual ball valve, safety valve and second manual ball valve who connect gradually, bypass automatic release control valve controls according to the pressure value of pressure transmitter and opens and closes, the utility model solves the limitation of traditional cold -insulated pipe support for low temperature working condition, in such as local rupture, pipeline pressure loss special working condition adaptability.

Description

Technical Field

[0001] This utility model relates to the field of cold-insulating pipe support technology for low-temperature working conditions, and particularly to a normal-temperature liquid phase pipeline conveying device for cold-insulating pipe supports. Background Technology

[0002] In existing technologies, insulated pipe supports suitable for low-temperature conditions consist primarily of an insulation layer and a metal support body (including pipe clamps and support assemblies). Their working principle involves wrapping the pipe with insulation materials such as insulating cotton or felt to block the transfer of cold energy to the steel structure. Ultimately, the components work together to provide both support and insulation for the pipe. However, these insulated pipe supports have significant limitations in adaptability to special operating conditions. Especially in scenarios such as localized ruptures or pipe depressurization, the insulation layer is prone to failure, and the metal support is susceptible to functional malfunctions, making the problems even more pronounced.

[0003] Meanwhile, the main components of existing cryogenic pipeline systems are emergency shut-off valves and flow meters. This system also faces the problem of insufficient adaptability to special operating conditions: in scenarios such as localized ruptures or pipeline depressurization, when the shut-off valve is closed, a monitoring blind spot forms in the middle section of the pipeline. The lack of safety detection devices for effective real-time monitoring, anomaly warning, and risk prevention poses a significant potential hazard to the safe and stable operation of the pipeline system.

[0004] For cold insulation layers, high-density polyurethane and polyisocyanurate are commonly used as the main materials. To meet the cold insulation requirements in long-term low-temperature environments, the insulation layer thickness is typically 50-150mm. Its structure is ring-shaped or semi-circular, tightly wrapped between the pipe wall and the pipe clamp, and adhered to the pipe wall using a special adhesive or mechanical clamping method, forming the first line of defense against cold air. However, this fixed thickness design has drawbacks; it cannot adapt to special operating conditions of "normal temperature and occasional low temperature," the insulation layer thickness is large, material is redundant, and investment is increased.

[0005] On the metal pipe support body, pipe clamps are generally made of carbon steel or stainless steel, and the pipe is fastened to the insulation layer with M10-M16 bolts. The bolt spacing is usually 150-200mm to ensure uniform distribution of clamping force on the pipe. The support, as the core of the connection, is welded from a base plate, vertical plate, and stiffening plate, and is mostly made of Q235 ordinary carbon steel. It is rigidly connected to the pipe rack structure by welding or expansion bolts, forming a continuous metal conduction path from the pipe to the pipe rack, providing a direct channel for low-temperature conduction. However, the pipe rack structure usually uses steel that is not resistant to low temperatures. Once the metal pipe support conducts low temperatures to the pipe rack, it is very easy to cause brittle fracture of the steel in the pipe rack, seriously threatening the stability and safety of the pipe rack structure.

[0006] Regarding the deployment of safety monitoring devices, the safety relief devices and temperature and pressure monitoring devices at both ends of the export pipeline are typically located downstream of the shut-off valve. When the shut-off valve is closed, a monitoring blind spot is formed in the middle section of the pipeline, lacking effective monitoring methods. This situation poses a significant potential risk to the safe operation of the pipeline system and may lead to serious accidents such as pipeline rupture and explosion under extreme operating conditions.

[0007] In the field of pipeline engineering, for pipelines that operate at normal temperatures under normal conditions and only experience low temperatures during accidents or special circumstances, there is currently a technical challenge in the selection and application of insulated pipe supports. Existing commercially available insulated pipe supports have relatively thick insulation layers, resulting in high costs. From a practical standpoint, the core issue for this type of pipeline is preventing the low temperatures under special operating conditions from being conducted through the metal pipe supports to the pipe rack structure supporting the pipeline.

[0008] Because utility tunnel structures typically use steel that is not resistant to low temperatures, once low temperatures are conducted, the steel is very prone to brittle fracture, which seriously threatens the stability and safety of the utility tunnel structure.

[0009] The existing pipeline system mainly consists of three parts: emergency shut-off valves, flow meters, and emergency shut-off valves. A drawback is that when the emergency shut-off valve is closed, the intermediate pipe section is in a monitoring blind spot, lacking effective monitoring methods. In this situation, if the medium inside the pipe experiences overheating or overpressure, the system cannot issue timely warning signals or effectively relieve pressure. This undoubtedly poses a significant hidden danger to the safe operation of the pipeline system, potentially leading to serious accidents such as pipeline rupture and explosions in extreme circumstances.

[0010] Traditional cold-insulated pipe supports typically consist of PIR insulation, clamp-type pipe supports, and steel structures to support and secure the pipes. A drawback is that if low temperatures are conducted through the metal pipe supports to the pipe rack structure supporting the pipes, the steel in the pipe rack structure is highly susceptible to brittle fracture, seriously threatening the stability and safety of the pipe rack structure.

[0011] Furthermore, due to the long distances and complex environments of long-distance pipelines, it is difficult to monitor leaks in real time and effectively. Once a leak occurs, it is difficult to detect it promptly and take appropriate measures, potentially leading to a series of safety and environmental problems caused by the leakage of the medium.

[0012] Therefore, how to solve the limitations of traditional cold-insulated pipe supports in adaptability to special conditions such as local rupture and pipeline depressurization when used in low-temperature conditions has become a technical problem that urgently needs to be solved by those skilled in the art. Utility Model Content

[0013] In view of the above-mentioned defects of the prior art, the present invention provides a room temperature liquid phase pipeline conveying device for cold insulation pipe supports. The purpose is to solve the limitations of traditional cold insulation pipe supports in adaptability to special working conditions such as local rupture and pipeline depressurization when used in low temperature conditions.

[0014] To achieve the above objectives, this utility model discloses a room temperature liquid phase pipeline conveying device for a cold insulation pipe support, including a pipeline system and a cold insulation pipe support;

[0015] The piping system includes a flow meter, an additional pressure transmitter, an interpolated temperature sensor, a first surface temperature sensor, and a second surface temperature sensor, which are sequentially connected between two emergency shut-off valves.

[0016] The flow meter and the pressure transmitter are provided with bypass pipes that are connected to the flare or storage tank via a tee pipe.

[0017] The bypass pipe is equipped with a manual control valve group and an automatic bypass discharge control valve in parallel structure.

[0018] The manual control valve group includes a first manual ball valve, a safety valve, and a second manual ball valve connected in sequence.

[0019] The bypass automatic relief control valve controls its opening, closing, and alarm based on the pressure value of the increased pressure transmitter.

[0020] Preferably, the interpolated temperature sensor, the first surface temperature sensor, and the second surface temperature sensor are spaced 100m apart, and an alarm interlock TIA is provided.

[0021] Preferably, the cold insulation pipe support includes a tubular polytetrafluoroethylene cold insulation pad layer disposed outside the pipe and a clamp-type pipe support;

[0022] The clamp-type pipe support is installed on the steel structure through a shock-absorbing structure.

[0023] More preferably, the shock-absorbing structure includes a shock-absorbing spring and a plate-shaped polytetrafluoroethylene cold insulation pad disposed between the shock-absorbing spring and the steel structure.

[0024] Preferably, both the first surface temperature sensor and the second surface temperature sensor are fixed to the corresponding pipes via surface temperature sensor connectors;

[0025] Each of the aforementioned surface temperature sensor connectors includes a metal bend that matches the outer wall of the corresponding pipe, an internally threaded pipe cap fixed to the convex side of the corresponding metal bend, a double-ended externally threaded pipe disposed on the corresponding internally threaded pipe cap, and a first surface temperature sensor or a second surface temperature sensor disposed at the other end of the corresponding double-ended externally threaded pipe.

[0026] More preferably, the length direction of each of the double-ended externally threaded tubes forms an angle of 5°±1° with the horizontal plane.

[0027] More preferably, each of the double-ended externally threaded tubes is connected to the corresponding first surface temperature sensor or the corresponding second surface temperature sensor via an internally threaded sleeve.

[0028] The beneficial effects of this utility model are:

[0029] This utility model optimizes the pipe support by replacing the original insulation material (PIR, "polyisocyanurate foam", also commonly referred to as "PIR foam") with polytetrafluoroethylene (PTFE) material for insulation. At the same time, a spring damping structure and a PTFE pad are added to the original steel structure for vibration reduction and secondary insulation. The damping structure can effectively solve the vibration during liquid transportation, and has the advantages of effective insulation, protection of the stability and safety of the pipe gallery structure, saving project investment, and convenient construction.

[0030] This utility model uses a three-level pressure protection method, adding a pressure transmitter, a bypass automatic relief control valve, a first manual ball valve, a second manual ball valve, a safety valve, and a relief valve between the original emergency shut-off valve to flare or storage tank.

[0031] This utility model's pipeline system pioneers a three-level pressure protection system, featuring high-pressure alarm (first-level pressure protection), automatic bypass relief from the safety valve (second-level pressure protection), and overpressure relief from the safety valve (third-level pressure protection). This three-level protection ensures pipeline safety, effectively monitors pipeline leaks, and can promptly issue early warning signals and effectively relieve pressure in cases of excessive temperature or pressure in the pipeline medium, thus ensuring that the pipeline does not exceed the pressure limit and guaranteeing the safe operation of the pipeline system.

[0032] This utility model uses temperature and pressure linkage monitoring to add a pressure transmitter, an internal temperature sensor, a first surface temperature sensor, a second surface temperature sensor, and a bypass automatic relief control valve between the original emergency shut-off valve. The pressure transmitter is equipped with PISA (representing pressure indication switch alarm, meaning the device has a pressure indication function and can trigger a switch action and issue an alarm signal when the pressure reaches a specific value). It can control the bypass automatic relief control valve to release the medium and reduce the pressure when there is overpressure.

[0033] This utility model incorporates an interpolated temperature sensor, a first surface temperature sensor, and a second surface temperature sensor, all equipped with a TIA (Temperature Indication Alarm, with pressure indication and alarm functions). By deploying multiple temperature monitoring units, it achieves coordinated control of temperature and pressure parameters. Simultaneously, flow monitoring data is incorporated as an auxiliary basis for judgment. Furthermore, combined with safety shut-off valves configured at the boundary, a complete intelligent safety monitoring system is constructed. The system possesses advantages such as temperature and pressure linkage monitoring, effective detection of pipeline leaks, and timely alarms for abnormal temperatures, forming a multi-dimensional safety protection mechanism and providing a solid guarantee for the stable and safe operation of the pipeline system.

[0034] This utility model improves the original pipeline system and pipe support device through system integration and innovation. It configures the system from multiple aspects such as pipe support, pressure protection, temperature, and flow monitoring, so that all parts can work together to ensure that when a local rupture or pipeline pressure loss causes a drop in pipeline temperature, an alarm is triggered immediately. It has the advantages of effective cold insulation, protection of the pipe gallery structure, three-level pressure protection, temperature and pressure linkage monitoring, timely alarm, and automatic discharge. The entire system can effectively solve the problem of the difficulty in safe, stable, and effective operation of the normal temperature liquid phase pipeline transportation process under the condition of sudden drop in low temperature, and creates an efficient, safe, and economical pipeline operation system.

[0035] The following will further explain the concept, specific structure and technical effects of this utility model in conjunction with the accompanying drawings, so as to fully understand the purpose, features and effects of this utility model. Attached Figure Description

[0036] Figure 1 This diagram illustrates the structure of a pipeline system in the prior art.

[0037] Figure 2 A schematic diagram of the structure of a cold insulation pipe support in the prior art is shown.

[0038] Figure 3 This diagram shows a schematic representation of the piping system in one embodiment of the present invention.

[0039] Figure 4 The diagram shows a structural schematic of a cold insulation pipe support in one embodiment of the present invention.

[0040] Figure 5 This diagram illustrates the installation structure of a first surface temperature sensor or a second surface temperature sensor according to one embodiment of the present invention. Detailed Implementation

[0041] Example: Figures 3 to 5 As shown, a normal temperature liquid phase pipeline conveying device for use with cold insulation pipe support includes a pipeline system and a cold insulation pipe support;

[0042] The piping system includes a flow meter, an additional pressure transmitter 1, an internal temperature sensor 2, a first surface temperature sensor 3, and a second surface temperature sensor 4, which are sequentially connected between two emergency shut-off valves 10.

[0043] The flow meter and pressure transmitter 1 are provided with a bypass pipe that is connected to the flare or storage tank 9 via a tee pipe;

[0044] The bypass pipe is equipped with a manual control valve group and an automatic bypass discharge control valve 5 in parallel structure;

[0045] The manual control valve assembly includes a first manual ball valve 6, a safety valve 8, and a second manual ball valve 7 connected in sequence.

[0046] The bypass automatic relief control valve 5 controls the opening and closing of the valve and the alarm based on the pressure value of the increased pressure transmitter 1.

[0047] When the pressure value of the pressure transmitter is 0.9 to 0.92 times the design pressure, the system alarms to remind the operator of the abnormal pressure; when the pressure value is 0.95 times the design pressure, the two shut-off valves 10 are interlocked and closed.

[0048] The pipeline system in this utility model is a three-level pressure protection system;

[0049] The first-level pressure protection is a high-pressure alarm;

[0050] The secondary pressure protection is an automatic pressure relief bypass of the safety valve;

[0051] The three-stage pressure protection is for overpressure relief via the safety valve.

[0052] This invention ensures the safe operation of pipelines with this property through a three-stage protection system for both ultra-low and high pressure.

[0053] In practical applications, when the operating pressure of the liquid phase pipeline exceeds the limit, pressure transmitter 1 will first perform first-level pressure protection, namely high-pressure alarm. When the high-pressure alarm occurs, the pipeline operation should be adjusted or the source of overpressure should be checked.

[0054] When the pipeline pressure exceeds the set interlock value, the pipeline system transmits a signal to the bypass automatic relief control valve 5 through the pressure transmitter 1, which opens the bypass automatic relief control valve 5 of the interlock safety valve 8 to release pressure and reduce the pipeline pressure. When the pressure drops below the set value, the bypass automatic relief control valve 8 will automatically close.

[0055] If the bypass automatic relief control valve 5 fails, and the pressure exceeds the set pressure allowable value of the safety valve 8, the safety valve 8 will automatically open and release part of the medium in the pipeline, thereby reducing the pipeline pressure. When the pressure drops below the set value, the safety valve 8 will automatically close.

[0056] This invention, through the aforementioned automatic pressure relief mechanism, can quickly respond to overpressure situations without human intervention, effectively protecting the safety of pipelines and equipment.

[0057] If the pipeline pressure is low, below the set pressure, the bypass automatic relief control valve 5 and safety valve 8 will not open.

[0058] Furthermore, because the liquid phase pipeline is prone to sudden temperature drop and becomes a low-temperature medium when the operating pressure is lost, the protection measures for this situation are also divided into three levels.

[0059] The first level of protection consists of: intercalation temperature sensor 2, first surface temperature sensor 3, and second surface temperature sensor 4.

[0060] The second level of protection is: low pressure alarm. When the pipeline pressure is too low, the pressure transmitter 1 system will alarm.

[0061] The third level of protection is as follows: when the pressure gauge approaches the saturated vapor pressure of the medium, the emergency shut-off valves 10 on both sides are interlocked to prevent further leakage of the medium.

[0062] During this three-level failure protection process, the flow meter's monitoring data can also help the pipeline system determine the true state of the pipeline.

[0063] When performing maintenance on the pipeline system, the maintenance personnel can close the first manual ball valve 6 and the second manual ball valve 7, and perform maintenance on the safety valve 8 without shutting down the entire operating pipeline, thus shortening the gas outage time.

[0064] This utility model, through the adoption of tiered venting measures and coordinated pipeline design, and through innovative means such as pipe support optimization, three-level pressure protection, temperature and pressure linkage monitoring, and system integration, achieves high-pressure alarm, automatic bypass venting of safety valves, overpressure venting of safety valves, pipeline support and insulation, saving total project investment, and comprehensively ensuring pipeline safety.

[0065] This invention can solve the problems of traditional cold-insulating pipe supports and pipeline systems in low-temperature working conditions, such as local rupture, pipeline depressurization, and the easy occurrence of brittle fracture of steel in pipe racks. The middle pipe section of the shut-off valve is in a monitoring blind spot and lacks effective monitoring means. The system cannot issue early warning signals in time, nor can it carry out effective pressure relief, which seriously threatens the stability and safety of pipe racks and pipeline systems.

[0066] This utility model optimizes the pipe support by upgrading the original cold insulation material pipe support to a pipe support with a polytetrafluoroethylene pad and a shock-absorbing structure.

[0067] This utility model achieves three-level pressure protection, pioneering a three-level pressure protection system that covers high-pressure alarm, automatic bypass relief of safety valve, and overpressure relief of safety valve, providing comprehensive protection for pipeline safety.

[0068] This invention enables temperature and pressure linkage monitoring. It achieves linkage control of temperature and pressure through multi-point temperature monitoring, supplemented by flow monitoring data for judgment, and combined with safety shut-off valves in the boundary area to construct an intelligent safety monitoring system.

[0069] This utility model features a comprehensive system configuration encompassing pipe supports, pressure protection, temperature monitoring, and flow monitoring. All components work together to create an efficient, safe, and economical pipeline operation system.

[0070] In some embodiments, the interpolated temperature sensor 2, the first surface temperature sensor 3, and the second surface temperature sensor 4 are spaced 100m apart, and an alarm interlock TIA is provided.

[0071] In practical applications, when the readings of the interpolated temperature sensor 2, the first surface temperature sensor 3, and the second surface temperature sensor 4 show a step-down trend, the alarm interlock TIA will issue an alarm based on a specific algorithm.

[0072] In some embodiments, the cold insulation pipe support includes a tubular polytetrafluoroethylene cold insulation pad 14 disposed outside the pipe 13 and a clamp-type pipe support 15;

[0073] The clamp-type pipe support 15 is installed on the steel structure 16 through a shock-absorbing structure.

[0074] In practical applications, the cold-insulating pipe support is used to support and fix the pipe 13. This cold-insulating pipe support optimizes the original cold-insulating material pipe support into a tubular polytetrafluoroethylene cold-insulating pad 14 and a shock-absorbing structure. The shock-absorbing structure can effectively solve the vibration during liquid transportation. Therefore, the cold-insulating pipe support has the advantages of effective cold insulation, protection of the stability and safety of the pipe gallery structure, saving project investment and convenient construction.

[0075] In some embodiments, the damping structure includes a damping spring 17 and a plate-shaped polytetrafluoroethylene (PTFE) cold insulation pad 18 disposed between the damping spring 17 and the steel structure 16.

[0076] In practical applications, a plate-shaped polytetrafluoroethylene (PTFE) cold insulation pad 18 is added at the contact point between the shock-absorbing spring 17 connected to the clamp-type pipe support 15 and the steel structure 16 of the pipe gallery, and the plate-shaped PTFE cold insulation pad 18 is used to separate the metal parts.

[0077] In some embodiments, both the first surface temperature sensor 3 and the second surface temperature sensor 4 are fixed to the corresponding pipes via surface temperature sensor connectors;

[0078] Each surface temperature sensor connector includes a metal bend 19 that matches the outer wall of the corresponding pipe 13, an internally threaded pipe cap 20 fixed to the convex side of the corresponding metal bend 19, a double-ended externally threaded pipe 21 disposed on the corresponding internally threaded pipe cap 20, and a first surface temperature sensor 3 or a second surface temperature sensor 4 disposed at the other end of the corresponding double-ended externally threaded pipe 21.

[0079] In some embodiments, the length direction of each double-ended externally threaded tube 21 forms an angle of 5°±1° with the horizontal plane.

[0080] In some embodiments, each double-ended externally threaded tube 21 is connected to the corresponding first surface temperature sensor 3 or the corresponding second surface temperature sensor 4 via an internally threaded sleeve 22.

[0081] When installing the first surface temperature sensor 3 or the second surface temperature sensor 4, first install the metal bend 19 on the pipe 13, then install the internal threaded pipe cap 20 on the metal bend 19 and tilt it at an angle of 5° to the horizontal plane, then install the double-ended external threaded pipe 21 on the internal threaded pipe cap 20, and connect the other end of the double-ended external threaded pipe 21 to the internal threaded sleeve 22, and finally install the first surface temperature sensor 3 or the second surface temperature sensor 4 on the internal threaded sleeve 22.

[0082] The first surface temperature sensor 3 or the second surface temperature sensor 4 can monitor the pipe temperature changes in real time. When the pipe surface temperature is low or high above the set value, it is considered an abnormal temperature. The surface thermometer will trigger an alarm through the interlocking device TI. Multiple temperature monitoring units are deployed in the pipe 13 to achieve linkage control of temperature and pressure parameters. At the same time, flow monitoring data is introduced as an auxiliary judgment basis. Maintenance personnel can accurately determine the pipe area with low temperature based on the location of the surface thermometer, which is more convenient for maintenance work and provides a solid guarantee for the stable and safe operation of the pipeline system.

[0083] The preferred embodiments of this utility model have been described in detail above. It should be understood that those skilled in the art can make numerous modifications and variations based on the concept of this utility model without creative effort. Therefore, all technical solutions that can be obtained by those skilled in the art based on the concept of this utility model through logical analysis, reasoning, or limited experimentation on the basis of existing technology should be within the scope of protection defined by the claims.

Claims

1. A room-temperature liquid phase pipeline conveying device for use with cold-insulating pipe supports; characterized in that, Including piping systems and insulation pipe supports; The piping system includes a flow meter, an additional pressure transmitter (1), an internal temperature sensor (2), a first surface temperature sensor (3), and a second surface temperature sensor (4) connected in sequence between two emergency shut-off valves (10). The flow meter and the pressure transmitter (1) are provided with a bypass pipe that is connected to the flare or storage tank (9) via a three-way pipe; The bypass pipe is equipped with a manual control valve group and a bypass automatic discharge control valve (5) in parallel structure. The manual control valve group includes a first manual ball valve (6), a safety valve (8), and a second manual ball valve (7) connected in sequence. The bypass automatic relief control valve (5) controls the valve opening and closing and alarm according to the pressure value of the increased pressure transmitter (1).

2. The ambient temperature liquid phase pipeline conveying device for cold-insulating pipe support according to claim 1, characterized in that, The interpolated temperature sensor (2), the first surface temperature sensor (3) and the second surface temperature sensor (4) are spaced 100m apart and are equipped with an alarm interlock TIA.

3. The ambient temperature liquid phase pipeline conveying device for cold-insulating pipe support according to claim 1, characterized in that, The cold insulation pipe support includes a tubular polytetrafluoroethylene cold insulation pad (14) and a clamp-type pipe support (15) disposed outside the pipe (13). The clamp-type pipe support (15) is installed on the steel structure (16) through a shock-absorbing structure.

4. The ambient temperature liquid phase pipeline conveying device for cold-insulating pipe support according to claim 3, characterized in that, The shock-absorbing structure includes a shock-absorbing spring (17) and a plate-shaped polytetrafluoroethylene cold insulation pad (18) disposed between the shock-absorbing spring (17) and the steel structure (16).

5. The ambient temperature liquid phase pipeline conveying device for cold-insulating pipe support according to claim 1, characterized in that, The first surface temperature sensor (3) and the second surface temperature sensor (4) are both fixed to the corresponding pipes via surface temperature sensor connectors; Each of the surface temperature sensor connectors includes a metal bend (19) that matches the outer wall of the corresponding pipe (13), an internally threaded cap (20) fixed to the convex side of the corresponding metal bend (19), a double-ended externally threaded pipe (21) disposed on the corresponding internally threaded cap (20), and the first surface temperature sensor (3) or the second surface temperature sensor (4) disposed at the other end of the corresponding double-ended externally threaded pipe (21).

6. The ambient temperature liquid phase pipeline conveying device for cold-insulating pipe support according to claim 5, characterized in that, Each of the aforementioned double-ended externally threaded tubes (21) has a length direction that forms an angle of 5°±1° with the horizontal plane.

7. The ambient temperature liquid phase pipeline conveying device for cold-insulating pipe support according to claim 5, characterized in that, Each of the double-ended external threaded tubes (21) is connected to the corresponding first surface temperature sensor (3) or the corresponding second surface temperature sensor (4) via an internal threaded sleeve (22).

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