Graphite sealed corrugated compensator and method of installation

Abstract

The application discloses a graphite sealing corrugated compensator and a mounting method, and belongs to the technical field of corrugated pipes. The compensator comprises a corrugated pipe, fixed connecting pipes, a movable connecting pipe, and first and second sleeve pipes which are sleeved outside. A single-end fixed flow guide cylinder is coaxially arranged inside the corrugated pipe. The surface of the movable connecting pipe is subjected to turning and chrome plating treatment, and the end portion is provided with a retaining ring. In the cavity between the second sleeve pipe and the movable connecting pipe, packing and sealing filler are sequentially filled, and are compacted and fixed through a sealing ring provided with a guide belt, so that a second sealing structure composed of flexible graphite material is formed outside the first layer of the sealing of the corrugated pipe. The double sealing structure greatly improves the sealing reliability, the chrome plating of the surface of the movable connecting pipe reduces the friction and wear, accurate guidance is realized by using the sleeve pipe and the guide belt, and the retaining ring prevents excessive compression of the corrugated pipe. The compensator combined with a pre-deformation mounting method can be applied to thermal displacement compensation of high-temperature and high-pressure pipelines.

Description

Technical Field

[0001] This invention relates to the field of bellows technology, specifically to a graphite-sealed bellows compensator and its installation method. Background Technology

[0002] In the petrochemical, heat transmission, and power industries, bellows compensators are widely used to absorb axial displacement caused by thermal expansion and contraction in pipelines. Traditional bellows compensators typically rely on a single layer of bellows for sealing and compensation. While this structure offers good flexibility, under long-term operation in high-temperature, high-pressure, or corrosive environments, the bellows wall is highly susceptible to stress corrosion or fatigue cracking. Due to the lack of redundant sealing protection measures, once the bellows ruptures, the internal high-pressure medium will rapidly leak out, potentially causing serious safety accidents and environmental pollution.

[0003] Furthermore, existing compensators also face pressing issues regarding guidance and wear resistance. Traditional movable connecting components are subjected to severe friction and scraping during the expansion and contraction of the compensator, leading to rapid seal failure and frequent replacements. Simultaneously, the existing guiding structure lacks precision, making it prone to lateral deviation under thermal displacement over long pipeline distances, resulting in uneven sealing gaps and further exacerbating localized wear and leakage risks. Additionally, the lack of effective internal flow guidance and excessive compression limiting mechanisms makes the bellows susceptible to thinning due to media erosion or excessive deformation and damage due to installation errors.

[0004] Therefore, designing a graphite-sealed corrugated compensator and its installation method to solve the above problems is of great significance. Summary of the Invention

[0005] To address the problems existing in the background art, the present invention provides a graphite sealed bellows compensator, comprising:

[0006] The corrugated pipe is a thin-walled, multi-layered, fully enclosed structure.

[0007] A fixed connecting pipe is attached to the left end of the bellows;

[0008] A movable connector is connected to the right end of the bellows. A retaining ring is welded to the left end of the movable connector. The surface of the movable connector on the right side of the retaining ring is machined and chrome-plated.

[0009] A flow guide tube is coaxially installed inside the bellows. One end of the flow guide tube is welded and fixed to the left inner wall of the bellows, and the other end extends suspended to the right side of the bellows without contacting the right inner wall of the bellows.

[0010] The first sleeve is fitted over the corrugated pipe. A first end ring is provided on the inner left side of the first sleeve. The first end ring is welded to the outer wall of the fixed pipe.

[0011] The second sleeve is fitted onto the outside of the chrome-plated portion of the movable connector, and the diameter of the second sleeve is smaller than the diameter of the first sleeve.

[0012] The sealing packing and packing are disposed in the cavity between the second sleeve and the movable connecting pipe, and from left to right are packing, sealing packing, and packing.

[0013] A sealing ring with a groove is welded to the second sleeve.

[0014] The guide belt is inserted into the groove of the sealing ring and is located between the sealing ring and the second sleeve;

[0015] The second end ring is disposed on the inner wall of the right side of the first sleeve, and the second end ring is welded to the outer wall of the second sleeve;

[0016] The bellows forms the first layer of sealing structure, and the sealing packing, packing, sealing ring and guide strip form the second layer of sealing structure, thus forming a double sealing structure.

[0017] In a preferred embodiment, the first sleeve and the second sleeve are located outside the corrugated pipe, forming a guiding effect through the sleeve structure; the sealing filler and packing are made of flexible graphite material.

[0018] In a preferred embodiment, the total length of the guide tube is... Slightly shorter than the effective compensation length of the bellows, the guide tube forms a structure that is fixed at one end and free at the other; the sealing packing and packing are compacted by a hydraulic press to maintain pressure on the inner wall of the second sleeve; the guide belt plays a supporting role when the second sleeve moves back and forth relative to the axis of the movable pipe, preventing the second sleeve from shifting laterally.

[0019] In a preferred embodiment, the left end of the second sleeve forms a blocking structure against the retaining ring. When the movable connecting pipe moves to the left relative to the first and second sleeves, causing the bellows to compress and deform, the limit position of the retaining ring moving to the right is the position of the left end of the second sleeve. A radial gap is provided between the second sleeve and the movable connecting pipe. When the pipe diameter hour, When the pipe diameter hour, .

[0020] In a preferred embodiment, the guide belt is installed in a uniformly distributed manner. The compensator uses a three-point 120° evenly distributed design for... The compensator is evenly distributed at four points at 90°, and the circumferential angle deviation of the guide belt is controlled within... Within; the width of the guide strip Satisfying the relation ;in, The guide strip width is in mm. The outer diameter of the movable nozzle is in mm.

[0021] This invention also provides a method for installing a graphite-sealed bellows compensator, comprising the following steps:

[0022] S1: Perform surface treatment on the movable connector, weld a retaining ring at the left end of the movable connector, and perform turning and chrome plating on the surface of the movable connector on the right side of the retaining ring.

[0023] S2: Connect the fixed pipe to the left end of the bellows and the movable pipe to the right end; install the guide tube coaxially inside the bellows;

[0024] S3: The first sleeve is fitted onto the outside of the corrugated pipe. The first end ring is provided on the inner left side of the first sleeve. The first end ring is welded to the outer wall of the fixed pipe.

[0025] S4: The second sleeve is fitted onto the outside of the chrome-plated part of the movable connector, and the diameter of the second sleeve is smaller than the diameter of the first sleeve;

[0026] S5: Fill the cavity between the second sleeve and the movable connecting pipe with sealing material and compact it to form a sealed cavity;

[0027] S6: Insert the guide belt into the groove of the sealing ring, press it into the sealing cavity, and weld the sealing ring to the second sleeve to form the second sealing structure;

[0028] S7: A second end ring is provided on the inner wall of the right side of the first sleeve, and the second end ring is welded to the outer wall of the second sleeve so that the left end of the second sleeve forms a blocking structure against the retaining ring.

[0029] S8: Based on pipeline design temperature and installation temperature According to the relation Calculate the pre-compression amount ;in, This is the pre-compression amount, in mm; The coefficient of linear expansion of the pipeline is expressed in mm / (m·℃), and is taken as 0.012 for steel pipes. The length of the compensation pipe section is in meters (m). The design operating temperature is expressed in °C. The ambient temperature at which the installation is performed is expressed in °C. The pre-deformation coefficient is set to 0.5.

[0030] Temporary tie rods are installed between the flanges at both ends of the compensator; the bellows (2) is pre-compressed by adjusting the nuts on the temporary tie rods. The distance; the compensator is welded and fixed in the pre-compression state, and the temporary tie rod is removed after welding is completed.

[0031] Furthermore, in step S1, the welding position of the retaining ring is determined according to the following steps:

[0032] First, mark the welding position on the left end of the movable connector. The welding position satisfies the following relationship: ;in, This is the distance from the left end face of the retaining ring to the left end of the movable connector, in mm. This refers to the length of the second sleeve, in mm. This represents the maximum compression compensation of the bellows, in mm. To allow for a safety margin, the value should be within the range of 5-10mm;

[0033] Then weld the retaining ring at the marked location;

[0034] Next, the surface of the movable connecting pipe on the right side of the retaining ring is machined to achieve a surface roughness of [specific value missing]. ;

[0035] Finally, the surface of the machined movable joint is chrome-plated, with a chrome plating thickness of [missing information]. After chrome plating, the surface roughness is achieved through fine grinding or polishing. ,hardness .

[0036] Furthermore, in step S2, the installation of the guide tube is carried out according to the following steps:

[0037] First, weld the fixed connecting pipe to the left end of the bellows, and then weld the movable connecting pipe to the right end of the bellows.

[0038] Then, based on the natural length of the bellows... and maximum compression compensation According to the relation Calculate the length of the guide tube ;in, This refers to the length of the guide tube, in mm. The natural length of the bellows is expressed in mm. This represents the maximum compression compensation of the bellows, in mm; coefficient. Selected based on work pressure, when pressure When the pressure is 0.85, the value is taken as 0.85. Take 0.75 at that time;

[0039] Then according to the calculated length Prepare a guide tube by coaxially installing the guide tube inside the bellows. Weld one end of the guide tube to the left inner wall of the bellows, and let the other end extend to the right side of the bellows without contacting the right inner wall of the bellows, forming a structure that is fixed at one end and free at the other.

[0040] Furthermore, in step S5, the filling and compaction of the sealing material are carried out according to the following steps:

[0041] First, packing, sealing packing, and packing are placed sequentially from left to right in the cavity between the second sleeve and the movable tube.

[0042] Then measure and record the total height of the sealing packing and packing before filling. The unit is mm;

[0043] Next, a hydraulic press is used to compact the sealing packing and packing, controlling the compression rate during the compaction process. The compression ratio According to the relation Calculate; where, Compression ratio, in percentages (%) This represents the total height before filling, in mm. This is the total height after compaction, in mm;

[0044] Finally, the compression ratio Control the compaction within the range of 20%-30%, and measure the total height after compaction. Confirm compression ratio After passing the test, compaction is completed to form a sealed cavity.

[0045] The beneficial effects achieved by this invention are as follows:

[0046] This invention uses a bellows as the first layer of sealing structure, combined with a second layer of sealing structure consisting of sealing packing, packing, sealing rings, and guide strips, forming a dual sealing system. This significantly improves the sealing reliability and safety of the compensator. Under normal operating conditions, the bellows' fully enclosed characteristics achieve zero leakage. Moreover, when the bellows fails unexpectedly due to fatigue or corrosion, the second layer of graphite sealing structure can effectively prevent large-scale leakage of the medium, saving valuable time for pipeline system maintenance and repair, and greatly reducing the safety risks caused by high-temperature, high-pressure, or toxic media leakage.

[0047] This invention forms a protective layer with high hardness and extremely low surface roughness on the surface of the movable connector through fine turning and chrome plating. This significantly improves the tribological properties of the sealing contact surface, greatly reduces the friction coefficient between the movable connector and the flexible graphite sealing filler, effectively reduces the wear of the sealing material during reciprocating motion, and at the same time, the excellent corrosion resistance of the chrome plating layer prevents the substrate from being damaged by rust, ensuring the long-term stability and service life of the sealing structure, and reducing the risk of material aging caused by frictional heat.

[0048] This invention designs a precision guiding structure comprising inner and outer double-layer sleeves and a guide band, and sets a retaining ring limiting device on the movable tube, effectively improving the stability of the compensator's movement and structural safety. The sleeve-like fit formed by the outer and inner sleeves, combined with the evenly distributed guide bands, precisely constrains the movement trajectory of the movable tube, preventing radial lateral displacement or tilting during axial expansion and contraction, and ensuring the uniformity of the sealing gap in the circumferential direction. At the same time, the blocking structure formed by the retaining ring and the sleeve end can forcibly limit the ultimate compression stroke of the bellows, preventing the bellows from plastic damage or instability due to excessive deformation.

[0049] This invention features a single-end fixed and single-end free guide tube coaxially installed inside the bellows, combined with a scientific pre-deformation installation method, which optimizes the medium flow state and extends the fatigue life of the bellows. The pre-compression installation process based on temperature calculation ensures that the compensator is always in a low-stress intermediate deformation state within the operating temperature range, effectively reducing the stress amplitude and residual deformation of the bellows, thereby significantly improving the compensator's cycle life and overall durability. Attached Figure Description

[0050] Figure 1 This is a comparison chart of the sealing performance of Example 1 and Comparative Examples 1 and 3. Sub-figure (a) is a bar chart of the initial leakage rate, sub-figure (b) is a bar chart of the leakage rate after the bellows leaks, and sub-figure (c) is a bar chart of the pressure drop over 24 hours.

[0051] Figure 2 The following are comparison charts of the compensation performance of Examples 1 and 2 and Comparative Examples 2 and 5. Sub-figure (a) is a bar chart of axial compensation stiffness, sub-figure (b) is a bar chart of maximum compensation amount, sub-figure (c) is a bar chart of fatigue life comparison, and sub-figure (d) is a bar chart of flow resistance influence coefficient.

[0052] Figure 3 The figures show a comparison of the wear resistance of Examples 1 and 3 with Comparative Example 3. Sub-figure (a) is a curve showing the change in wear amount with the number of cycles, sub-figure (b) is a bar chart of the friction coefficient, sub-figure (c) is a bar chart of the remaining thickness of the sealing filler, and sub-figure (d) is a bar chart of the surface temperature rise.

[0053] Figure 4 This is a comparison diagram of the guiding accuracy of Example 2 and Comparative Example 4. Sub-figure (a) is a polar coordinate diagram of the circumferential gap distribution, and sub-figure (b) is a bar chart of gap and wear unevenness.

[0054] Figure 5 The figures show a comparison of the temperature compensation effects of Examples 1 and 2 with Comparative Example 5. Sub-figure (a) is a temperature cycle curve, sub-figure (b) is a compensator displacement change curve, sub-figure (c) is a bellows stress change curve, and sub-figure (d) is a fixed support force change curve.

[0055] Figure 6 This is a structural diagram of the graphite sealed bellows compensator of the present invention in its uncompressed state.

[0056] Figure 7 yes Figure 6 Enlarged view of point A.

[0057] Figure 8 This is a structural diagram of the graphite sealed bellows compensator of the present invention in its compressed state.

[0058] Numbering on the map:

[0059] 1. Movable connector; 2. Bellows; 3. Fixed connector; 4. First sleeve; 5. Second sleeve; 6. Sealing ring; 7. Guide belt; 8. Sealing packing; 9. Packing; 10. Retaining ring; 11. First end ring; 12. Second end ring; 13. Flow guide tube. Detailed Implementation

[0060] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. In addition, the forms of the various structures described in the following embodiments are merely illustrative. The present invention is not limited to the structures described in the following embodiments. All other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0061] Reference Figures 6-8 The graphite sealing bellows compensator of the present invention includes the following main components: bellows 2, fixed connecting pipe 3, movable connecting pipe 1, guide tube 13, first sleeve 4, second sleeve 5, sealing packing 8, packing 9, sealing ring 6, guide belt 7, retaining ring 10, first end ring 11 and second end ring 12.

[0062] The bellows 2 is a thin-walled, multi-layered, fully enclosed structure manufactured using a seam welding process. Seam welding is a processing method that welds multiple layers of thin-walled material together into a single unit using continuous or intermittent welds, offering better sealing and pressure resistance compared to traditional mechanical connections. The thin-walled, multi-layered structure allows the bellows 2 to undergo significant axial deformation while withstanding internal pressure. The thin-walled design reduces the material's bending stiffness, while the multi-layered structure ensures sufficient strength and pressure resistance. The fully enclosed structure means that the bellows 2 itself has no openings or connecting gaps, forming a continuous, sealed space from end to end. The left end of the bellows 2 connects to a fixed connector 3, and the right end connects to a movable connector 1, with the connection securely fixed by welding. This welded connection ensures airtightness between the bellows 2 and the fixed connector 3 and movable connector 1, avoiding the leakage risks that may exist with threaded or flanged connections.

[0063] Fixed connector 3 is connected to the left end of bellows 2, serving as the connection component between the compensator and the fixed end of the piping system. After installation, fixed connector 3 remains stationary relative to the pipe support, providing a stable reference position for the compensator. Fixed connector 3 is typically made of the same or similar material as the pipe to ensure consistent welding performance and service life.

[0064] The movable connector 1 is connected to the right end of the bellows 2 and is a key component in the compensator capable of relative movement. A retaining ring 10 is welded to the left end of the movable connector 1. The retaining ring 10 is a ring-shaped structure whose axis coincides with the axis of the movable connector 1. The main function of the retaining ring 10 is to limit the maximum travel of the movable connector 1, preventing the bellows 2 from undergoing plastic deformation or damage due to excessive compression. The retaining ring 10 is fixed to the movable connector 1 by welding. The welding should ensure that the retaining ring 10 is perpendicular to the axis of the movable connector 1, and the weld should be continuous and uniform to withstand the impact force during operation. The surface of the movable connector 1 on the right side of the retaining ring 10 is machined and chrome-plated. Machining is a precision cutting process using a lathe to remove oxide scale, rust, and other defects, while achieving accurate dimensions and a low surface roughness. Machining provides a smooth and flat base surface for subsequent chrome plating, and the quality of the base surface directly affects the adhesion and service life of the chrome plating layer. Chromium plating is a surface treatment process that involves electroplating a layer of chromium metal onto a metal surface. The chromium layer possesses high hardness, wear resistance, and corrosion resistance. The chromium-plated movable connector 1 exhibits excellent corrosion resistance, making it particularly suitable for long-term use in environments where pipelines are deeply buried underground. It effectively resists the erosion of moisture, salt, and other corrosive substances in the soil. Simultaneously, the high hardness and smoothness of the chromium-plated surface significantly reduce the coefficient of friction with the sealing filler 8, decreasing the wear rate of the sealing filler 8 and extending the service life of the sealing structure.

[0065] The guide tube 13 is coaxially installed inside the bellows 2. Coaxial installation means that the central axis of the guide tube 13 coincides with the central axis of the bellows 2, ensuring the uniformity of the medium flow through the guide tube 13. One end of the guide tube 13 is welded and fixed to the left inner wall of the bellows 2. The weld at the fixed end should be firm and reliable, capable of withstanding the dynamic pressure and impact force generated by the medium flow. The other end of the guide tube 13 extends suspended to the right side of the bellows 2 without contacting the right inner wall of the bellows 2, forming a single-end fixed and single-end free structure. This single-end fixed and single-end free structure is a key feature of the guide tube 13. This structure allows the suspended end of the guide tube 13 to move relative to the bellows 2 with compression deformation, without restricting or interfering with the compensation function of the bellows 2. If both ends of the guide tube 13 are fixed or the suspended end contacts the inner wall of the bellows 2, it will restrict the axial deformation capacity of the bellows 2, and may even cause structural damage due to interference between the guide tube 13 and the bellows 2 during deformation. The main function of the guide tube 13 is to guide the flow direction of the medium, so that the medium flows smoothly through the inside of the bellows 2 axially, reducing the flow resistance and eddy current losses caused by the corrugated structure. Due to the periodic concave and convex changes of the corrugated structure inside the bellows 2, if the medium flows directly through these corrugations, eddies and stagnant zones will be formed at the troughs, increasing flow resistance and generating pressure loss. The placement of the guide tube 13 inside the bellows 2 forms a relatively smooth flow channel, and the medium mainly flows inside the guide tube 13, avoiding direct contact with the corrugated structure. In addition, the guide tube 13 also protects the inner wall of the bellows 2. Especially when conveying media containing solid particles or high-speed fluids, the guide tube 13 can withstand the scouring of the media and prevent the inner wall of the bellows 2 from thinning or perforating due to long-term scouring, thereby extending the service life of the bellows 2.

[0066] The first sleeve 4 is fitted onto the outside of the bellows 2. Fitting refers to the assembly method where one component fits over another. A first end ring 11 is provided on the inner left wall of the first sleeve 4. The first end ring 11 is an annular boss structure, which can be an independent annular piece pre-welded to the inner wall of the first sleeve 4, or an integrated boss formed by machining or molding processes on the inner wall of the first sleeve 4. The first end ring 11 is welded to the outer wall of the fixed connector 3, achieving a firm connection between the first sleeve 4 and the fixed connector 3 through welding. Before welding, the welding surface should be cleaned to remove oil, scale, and other impurities. During welding, the heat input should be controlled to avoid deformation or material degradation due to localized overheating. After welding, the first sleeve 4 remains fixed relative to the fixed connector 3 and the bellows 2, and does not move axially during the operation of the compensator. The main functions of the first sleeve 4 are twofold: first, to protect the corrugated pipe 2 from damage caused by the external environment, such as mechanical impact, soil pressure, and corrosive media; and second, to cooperate with the second sleeve 5 to form a sleeve-type guide structure, providing guidance and support for the axial movement of the second sleeve 5.

[0067] The second sleeve 5 is fitted onto the outside of the chrome-plated portion of the movable connector 1. The diameter of the second sleeve 5 is smaller than that of the first sleeve 4, and the two form a relative sliding fit through a sleeve-type structure. The sleeve-type structure means that the outer diameter of the second sleeve 5 is smaller than the inner diameter of the first sleeve 4, and a portion of the second sleeve 5 extends into the interior of the first sleeve 4, maintaining an appropriate radial clearance between them to allow the second sleeve 5 to slide axially relative to the first sleeve 4. This sleeve-type fit ensures the flexibility of the second sleeve 5's movement and, through the enveloping constraint of the first sleeve 4, achieves a good guiding effect, preventing the second sleeve 5 from radially deviating or tilting during movement. A radial clearance δ is provided between the second sleeve 5 and the movable connector 1, which is the distance between the inner diameter of the second sleeve 5 and the outer diameter of the movable connector 1. The size of the radial clearance directly affects the filling space of the sealing packing 8 and the packing 9, as well as the sealing effect after compaction. If the radial clearance is too small, it will be difficult to fill the sealing material, and there will be insufficient rebound space after compaction. The sealing packing 8 and the packing 9 will not be able to generate sufficient clamping force on the surface of the movable pipe 1. If the radial clearance is too large, it will result in excessive sealing material usage, difficulty in compaction, and easy extrusion or loosening of the sealing material during operation due to the excessive clearance.

[0068] The sealing packing 8 and packing 9 are arranged in the cavity between the second sleeve 5 and the movable connecting pipe 1, forming a three-layer structure from left to right: packing 9, sealing packing 8, and packing 9. In this arrangement, the packing 9 at both ends protects and supports the middle sealing packing 8, preventing it from being squeezed out or deformed unevenly under pressure. Both the sealing packing 8 and the packing 9 are made of flexible graphite material. Flexible graphite is a sealing material made from natural graphite through chemical treatment and high-temperature expansion. It has excellent high-temperature resistance and can be used for a long time at high temperatures without decomposition or performance degradation. Flexible graphite also has good corrosion resistance, resisting the erosion of various corrosive media such as acids, alkalis, and salts, and has anti-aging properties, maintaining stable performance during long-term use. Another important characteristic of flexible graphite is its elasticity and compressibility. After compaction, it retains a certain degree of resilience. This resilience allows the sealing packing 8 and packing 9 to continuously apply pressure to the surface of the movable connector 1. Even if the thickness decreases slightly due to wear or creep during operation, the sealing pressure can still be maintained through elastic recovery. After being compacted by a hydraulic press, the sealing packing 8 and packing 9 maintain pressure on the inner wall of the second sleeve 5. The hydraulic press is a compaction device that provides stable and controllable pressure through a hydraulic system. The compaction process increases the density of the sealing packing 8 and packing 9, reduces the porosity inside the material, and makes the contact between the material and the surface of the movable connector 1 tighter. Through the elastic recovery force of the material, a continuous contact pressure is formed on the surface of the movable connector 1. This contact pressure forms a sealing band between the sealing packing 8 and packing 9 and the movable connector 1, preventing the medium from leaking from the gap between the second sleeve 5 and the movable connector 1, thus achieving a dynamic sealing function.

[0069] The sealing ring 6 has a groove, which is a groove-shaped structure machined into the surface of the sealing ring 6 to accommodate the guide band 7. The depth and width of the groove should match the size of the guide band 7 to ensure that the guide band 7 can be firmly fixed after installation and fully exert its supporting function. The sealing ring 6 is welded to the second sleeve 5. The welding method can be spot welding or continuous welding. During welding, excessive heat transfer to the sealing filler 8 and packing 9 should be avoided to prevent the sealing material from aging or degrading due to heat. After the sealing ring 6 is welded and fixed, the sealing filler 8 and packing 9 are kept in a compacted state to prevent the sealing material from loosening due to vibration or pressure fluctuations during the operation of the compensator.

[0070] The guide band 7 is inserted into the groove of the sealing ring 6, located between the sealing ring 6 and the second sleeve 5. The guide band 7 provides support when the second sleeve 5 reciprocates relative to the axis of the movable connector 1, preventing lateral displacement of the second sleeve 5. Lateral displacement refers to the lateral displacement of the second sleeve 5 away from the central axis during movement. If lateral displacement occurs, the radial gap between the second sleeve 5 and the movable connector 1 will be unevenly distributed in the circumferential direction, resulting in an increased gap on one side and a decreased gap on the other. The sealing packing 8 and packing 9 will experience greater compression and friction on the side with the smaller gap, leading to increased unilateral wear. By providing a support point between the sealing ring 6 and the second sleeve 5, the guide band 7 limits the radial displacement of the second sleeve 5 to a very small range, ensuring that the movement trajectory of the second sleeve 5 remains coaxial with the axis of the movable connector 1. This ensures that the sealing packing 8 and packing 9 are subjected to uniform force in the circumferential direction, avoiding localized wear and extending the service life of the sealing structure.

[0071] The second end ring 12 is disposed on the inner right side of the first sleeve 4. The second end ring 12 is also an annular boss structure; it can be an independent annular component pre-welded to the inner wall of the first sleeve 4, or it can be a boss integrally formed on the inner wall of the first sleeve 4. The second end ring 12 is welded to the outer wall of the second sleeve 5, thus connecting the first sleeve 4 and the second sleeve 5. During welding, it should be ensured that the first sleeve 4 and the second sleeve 5 can slide relative to each other, and should not become stuck due to welding deformation or excessive weld size. The placement of the second end ring 12 allows the first sleeve 4 and the second sleeve 5 to form an integral structure. During the operation of the compensator, the second sleeve 5 can move axially relative to the movable connector 1, but remains fixed relative to the first sleeve 4.

[0072] The left end of the second sleeve 5 forms a blocking structure against the retaining ring 10. When the movable connector 1 moves to the left relative to the first sleeve 4 and the second sleeve 5, causing the bellows 2 to undergo compression deformation, the retaining ring 10 moves to the left along with the movable connector 1. Since the retaining ring 10 is fixed to the movable connector 1, when the movable connector 1 moves to the left to a certain extent, the right end face of the retaining ring 10 will contact the left end of the second sleeve 5. At this point, the retaining ring 10 cannot continue to move to the left, thus limiting the maximum travel of the movable connector 1. The limit position of the retaining ring 10 moving to the right is the position of the left end of the second sleeve 5. This blocking structure design protects the bellows 2 from excessive compression and prevents the bellows 2 from exceeding its designed maximum compression compensation during compression, thus preventing plastic deformation or fatigue failure.

[0073] The graphite-sealed bellows compensator of this invention adopts a dual-sealing structure design. The bellows 2 forms the first sealing layer, while the sealing packing 8, packing 9, sealing ring 6, and guide band 7 form the second sealing layer. The first sealing layer is the main seal of the compensator, and the bellows 2, as a fully enclosed structure, can completely prevent media leakage under normal operating conditions. The second sealing layer is the auxiliary seal of the compensator. When the first bellows 2 experiences minor leakage due to material fatigue, corrosion, mechanical damage, or other reasons, the second sealing layer can still effectively prevent further media leakage. The design principle of the dual-sealing structure is to provide redundant sealing protection, significantly improving the overall safety and reliability of the compensator. It is particularly suitable for high-temperature, high-pressure, or toxic and harmful media applications. Even if the main seal fails, it will not immediately cause a large-scale media leakage, saving time for maintenance and repair and preventing safety accidents.

[0074] The installation method of the graphite sealed corrugated compensator of the present invention includes the following steps.

[0075] Step S1 involves surface treatment of the movable connector 1. First, the welding position is marked on the left end of the movable connector 1. The determination of the welding position requires precise calculation to satisfy the following relationship: ;in The distance from the left end face of the retaining ring 10 to the left end of the movable connector 1 is in mm; The length of the second sleeve 5 is in mm; This represents the maximum compression compensation of bellows 2, expressed in mm. For safety margins, the unit is mm. This formula, by comprehensively considering the length of the second sleeve 5, the maximum compression of the bellows 2, and the necessary safety margin, accurately determines the welding position of the retaining ring 10. In the formula... This represents the total length of the second sleeve 5 from the left end to the right end. This represents the maximum compressive deformation that the bellows 2 may undergo during operation. This deformation is determined by the design parameters of the bellows 2, including structural parameters such as the number of corrugations, wave height, and wave pitch, as well as the elastic modulus of the material. The safety margin is provided to prevent the cumulative effects of manufacturing errors, installation errors, and temperature changes from causing the retaining ring 10 to prematurely contact the second sleeve 5 before the bellows 2 reaches its maximum compression, thus limiting the compensator's compensation capacity. The safety margin reflects the design's fault tolerance, ensuring that even with certain errors, the compensator can still achieve the designed compensation amount. This is calculated using this formula. The value ensures that the position of the retaining ring 10 can both limit and protect the bellows 2 when it reaches maximum compression, and not restrict the normal compensation function due to its position being too far forward.

[0076] Then, weld the retaining ring 10 at the marked position. During welding, ensure that the end face of the retaining ring 10 is perpendicular to the axis of the movable connecting pipe 1. The perpendicularity of the end face directly affects the uniformity of force distribution when the retaining ring 10 contacts the second sleeve 5. If the retaining ring 10 is installed at an angle, localized contact may occur during contact, and localized stress concentration may lead to localized deformation or even damage to the retaining ring 10 or the second sleeve 5. Appropriate welding methods should be used, such as argon arc welding or manual electric arc welding. The weld should be continuous and uniform, avoiding welding defects such as incomplete penetration, slag inclusions, and porosity. The weld strength should be able to withstand the impact force and fatigue load of the compensator during operation, especially the impact force generated when the retaining ring 10 contacts the second sleeve 5.

[0077] Next, the surface of the movable connecting pipe 1 on the right side of the retaining ring 10 is machined to achieve a surface roughness of [specific value missing]. Turning is a machining method that uses the rotary motion of a lathe and the feed motion of a cutting tool to cut the surface of the movable nozzle 1. The purpose of turning is to remove oxide scale, rust, weld spatter, and other surface defects from the surface of the movable nozzle 1, while obtaining accurate outer diameter dimensions and low surface roughness. Surface roughness It is an evaluation parameter for the degree of refinement of the surface micro-geometry. A smaller value indicates a smoother surface. The surface roughness after turning reaches... This means the surface is already relatively smooth, providing a good base for subsequent chrome plating. If the surface roughness is too high, the unevenness of the substrate surface will be reflected on the chrome plating layer, affecting the quality of the plating layer. At the same time, a rough substrate surface will reduce the adhesion between the chrome plating layer and the substrate, making the plating layer prone to peeling during use. During turning, appropriate tool material and geometry should be selected, and process parameters such as cutting speed, feed rate, and depth of cut should be controlled to ensure machining efficiency while achieving good surface quality.

[0078] Finally, the surface of the machined movable connector 1 is chrome-plated with a thickness of 0.03mm to 0.05mm. After chrome plating, the surface roughness is achieved by fine grinding or polishing. ,hardness Chromium plating is a surface treatment process that deposits a layer of chromium metal onto a metal surface using electrochemical methods. Before plating, the surface of the movable connector 1 requires a series of pretreatments, including degreasing, rust removal, and activation, to ensure good adhesion between the chromium plating layer and the substrate. Degreasing removes surface grease contaminants, typically using alkaline degreasing solutions or organic solvents. Rust removal removes surface oxides and rust products, which can be achieved through pickling or mechanical methods. Activation involves treating the metal surface with a weak acid solution to create an active state, improving the adhesion of the plating layer. The thickness of the chromium plating layer is controlled between 0.03mm and 0.05mm, achieved by adjusting process parameters such as plating time, current density, and plating bath temperature. A chromium plating layer that is too thin will affect corrosion resistance and service life, while a plating layer that is too thick may lead to excessive internal stress, causing cracking or peeling during use. After chromium plating, surface quality is further improved through fine grinding or polishing. Fine grinding uses precision abrasives to perform fine grinding on the surface, while polishing achieves a mirror-like finish through friction. Through fine grinding or polishing, the surface roughness can be achieved. This is a very low surface roughness value, resulting in a highly smooth and glossy surface. The smooth chrome-plated surface significantly reduces the coefficient of friction with the sealing filler 8, minimizing wear and extending the seal's lifespan. The hardness requirement of the chrome plating layer is [not specified]. , It is the symbol for Vickers hardness, a method of measuring the hardness of a material by pressing a diamond pyramid indenter into it. Hardness This means that the chromium plating layer has a very high hardness. The high hardness gives the chromium plating layer excellent wear resistance, which can resist the wear of the sealing filler 8 during reciprocating motion. At the same time, the high hardness also enhances the ability to resist scratches and abrasions.

[0079] Step S2 connects the left end of the bellows 2 to the fixed connector 3 and the right end to the movable connector 1. A guide tube 13 is coaxially installed inside the bellows 2. First, the fixed connector 3 is welded to the left end of the bellows 2, and the movable connector 1 is welded to the right end. Welding is the main method for connecting the bellows 2 to the fixed connector 3 and the movable connector 1. Before welding, the welding surfaces should be cleaned to remove oil, scale, and other impurities. Inert gas shielded welding methods such as argon arc welding should be used. Inert gas shielding refers to introducing argon or other inert gases during welding to isolate the welding area from the air, preventing the weld metal from reacting with oxygen and nitrogen in the air at high temperatures, thus avoiding weld oxidation and porosity. Argon arc welding has advantages such as high weld quality, small heat-affected zone, and small deformation, making it particularly suitable for welding thin-walled structures. During welding, process parameters such as welding current, voltage, and welding speed should be controlled to ensure good weld penetration and a strong connection. After welding, the weld should be inspected. Visual inspection, radiographic testing or ultrasonic testing can be used to confirm that the weld is free of defects such as cracks, incomplete penetration, slag inclusions, and porosity.

[0080] Then, based on the natural length of bellows 2 and maximum compression compensation According to the relation Calculate the length of the guide tube 13 ;in This refers to the length of the guide tube, in mm. The natural length of bellows 2 is in mm; This represents the maximum compression compensation for bellows 2, in mm; the coefficient is selected from 0.75 to 0.85 based on the working pressure. When the pressure is 0.85, the value is taken as 0.85. The value is 0.75. The design principle of this relationship is to ensure that when the bellows 2 is in its maximum compression state, the suspended end of the guide tube 13 still maintains a sufficient gap with the inner wall of the right side of the bellows 2, preventing contact and interference. In the relationship... The length of the guide tube 13 is approximately 75% to 85% of the natural length of the bellows 2. This proportion ensures that the guide tube 13 can cover the main flow channel area of ​​the bellows 2, fully exerting its guiding and protective functions, while reserving sufficient space for the compression deformation of the bellows 2. (Subtract) This is because the total length of bellows 2 will shorten under maximum compression. If the guide tube 13 is too long, it may come into contact with the right inner wall of the bellows 2 during compression, causing interference and restriction. The coefficient of 0.75 to 0.85 is selected according to the working pressure because the deformation characteristics of the bellows 2 are different under different working pressures. At lower pressures, the compression stiffness of the bellows 2 is smaller, and the compression amount is smaller under the same external force. A larger coefficient of 0.85 can be selected to make the guide tube 13 relatively longer, providing a better guiding effect. At higher pressures, the bellows 2 will undergo a certain amount of compression deformation under pressure, and the external compensation may also be larger. A smaller coefficient of 0.75 should be selected to make the guide tube 13 relatively shorter, leaving more deformation space and preventing interference. This design method of adjusting the coefficient according to the working pressure allows the length of the guide tube 13 to adapt to the requirements of different working conditions, ensuring both the guiding function and the compensation function.

[0081] Then according to the calculated length The guide tube 13 is fabricated, and appropriate materials and processing methods should be selected. The material of the guide tube 13 should be the same as or similar to that of the bellows 2 to ensure matching of welding performance and coefficient of thermal expansion. The guide tube 13 is usually made of thin-walled tubing, formed by cutting, rolling, or welding. After processing, the diameter, length, and straightness of the guide tube 13 should meet the design requirements. The diameter of the guide tube 13 should be slightly smaller than the inner diameter of the bellows 2, leaving an appropriate radial clearance to facilitate installation inside the bellows 2, while avoiding affecting the medium flow capacity due to an excessively small diameter. The guide tube 13 is coaxially installed inside the bellows 2. Coaxial installation requires that the central axis of the guide tube 13 coincide with the central axis of the bellows 2, which can be achieved using dedicated positioning fixtures or measuring tools. One end of the guide tube 13 is welded and fixed to the left inner wall of the bellows 2. The welding position is usually selected near the connection between the bellows 2 and the fixed connecting pipe 3, where the structure is relatively stable and the welding operation is convenient. During welding, a low-current, multi-layer, multi-pass welding method should be used to reduce welding heat input and avoid deformation or burn-through of the thin-walled structure of the bellows 2 due to localized overheating. The weld seam should be evenly distributed at the connection between the guide tube 13 and the inner wall of the bellows 2, forming a continuous annular weld seam. The weld seam strength should be able to withstand the impact and vibration forces of the guide tube 13 under the action of the flowing medium. The other end of the guide tube 13 extends suspended to the right side of the bellows 2 but does not contact the right inner wall of the bellows 2, forming a structure with one end fixed and one end free. An appropriate gap should be maintained between the suspended end and the right inner wall of the bellows 2. The size of the gap should take into account factors such as the maximum compression of the bellows 2 and possible eccentricity to ensure that the guide tube 13 and the bellows 2 will not come into contact under any operating conditions.

[0082] Step S3 involves fitting the first sleeve 4 onto the outside of the bellows 2. A first end ring 11 is provided on the inner left side wall of the first sleeve 4, and the first end ring 11 is welded to the outer wall of the fixed connector 3. When fitting the first sleeve 4 onto the outside of the bellows 2, it should be inserted from the right end of the bellows 2 and slowly pushed into the designed position. During the fitting process, care should be taken to avoid scraping or colliding between the first sleeve 4 and the corrugated structure of the bellows 2 to prevent damage to the surface or corrugated structure of the bellows 2. The length of the first sleeve 4 should be sufficient to cover the entire bellows 2, as well as part of the fixed connector 3 and the movable connector 1, providing comprehensive external protection for the bellows 2. The first end ring 11 is provided on the inner left side wall of the first sleeve 4. The first end ring 11 can be an independent annular piece pre-welded to the inner wall of the first sleeve 4, or it can be an annular boss formed by machining the inner wall of the first sleeve 4. The position of the first end ring 11 should correspond to the outer wall of the fixed connector 3 for easy welding connection. When welding the first end ring 11 to the outer wall of the fixed pipe 3, the welding surface should be cleaned and inspected to ensure that the welding surface is flat and free of impurities. During welding, the welding process parameters should be controlled to make the weld uniform and continuous. After welding, the first end ring 11 and the fixed pipe 3 form a firm connection, and the first sleeve 4 is fixed to the fixed pipe 3 through the first end ring 11.

[0083] Step S4 involves fitting the second sleeve 5 onto the outside of the chrome-plated portion of the movable connector 1. The diameter of the second sleeve 5 is smaller than that of the first sleeve 4. When fitting the second sleeve 5 onto the outside of the chrome-plated portion of the movable connector 1, it should be inserted from the right end of the movable connector 1 and pushed into the designed position. During fitting, the radial clearance between the second sleeve 5 and the movable connector 1 should be checked. The radial clearance should be uniform. If uneven clearance is found, the position of the second sleeve 5 should be adjusted or the outer diameter of the movable connector 1 should be checked to ensure it meets the requirements. The left end of the second sleeve 5 should be close to but not in contact with the retaining ring 10, leaving space for subsequent filling of sealing material and installation of the sealing ring 6. The diameter of the second sleeve 5 is smaller than that of the first sleeve 4, allowing the second sleeve 5 to extend into the first sleeve 4, forming a sleeve-type fit. This fit allows the first sleeve 4 to guide and support the second sleeve 5, ensuring the axial stability of the second sleeve 5 during movement.

[0084] Step S5 involves filling and compacting sealing material into the cavity between the second sleeve 5 and the movable connector 1 to form a sealed cavity. First, packing 9, sealing filler 8, and packing 9 are placed sequentially from left to right within the cavity between the second sleeve 5 and the movable connector 1. When placing the sealing material, attention should be paid to the placement order and uniform distribution. The first layer of packing 9 is placed at the left end of the cavity, serving as isolation and support to prevent the sealing filler 8 from being squeezed out to the left. The middle layer of sealing filler 8 is the main sealing material, providing the main sealing pressure. The second layer of packing 9 is placed at the right end of the cavity, also serving as isolation and support to prevent the sealing filler 8 from being squeezed out to the right. The three layers of sealing material should be evenly distributed within the cavity to avoid local accumulation or gaps. Uneven distribution will lead to uneven sealing pressure after compaction, affecting the sealing effect.

[0085] Then measure and record the total height of the sealing packing 8 and packing 9 before filling. The unit is mm. Total height This refers to the total thickness of the three layers of sealing material stacked together in the axial direction. When measuring, a vernier caliper or a dedicated height measuring tool should be used, and measurements should be taken at multiple locations around the circumference, with the average value taken as the mean. Multiple measurements can reflect the uniformity of the sealing material filling.

[0086] Next, a hydraulic press is used to compact the sealing packing 8 and packing 9, controlling the compression rate during the compaction process. Compression ratio According to the relation Calculation; where Compression ratio, in percentages (%) This represents the total height before filling, in mm. The total height after compaction is expressed in mm. This formula reflects the degree of compression of the sealing material by the change in height before and after filling. Compression ratio is an important indicator for evaluating the compaction quality of the sealing material. In the formula... This indicates the amount of height reduction of the sealing material during the compaction process, which is calculated by dividing the original height. Multiply by 100% to get the compression ratio in percentage form. The compaction process should be carried out slowly and evenly, and the pressure of the hydraulic press should be increased gradually to avoid sudden pressure increase that could cause local damage to the sealing material or deformation of the sealing ring 6. The compression rate should be monitored in real time during compaction. When approaching the target compression rate, the pressurization speed should be slowed down and finely adjusted to ensure that the final compression rate meets the design requirements. Insufficient compression will result in insufficient pressure between the sealing packing 8 and packing 9 on the surface of the movable connector 1, leading to low contact pressure between the sealing material and the surface of the movable connector 1, failing to form an effective sealing band. During operation, the medium may leak from the tiny gap between the sealing material and the movable connector 1. Excessive compression will cause over-compression of the sealing packing 8 and packing 9, completely crushing the pores inside the material, causing the material to lose its elasticity and resilience. In subsequent use, if the thickness decreases due to wear or creep, the material cannot maintain the sealing pressure through elastic recovery. Furthermore, excessive compression will significantly increase the friction between the sealing material and the surface of the movable connector 1, increasing movement resistance and affecting the normal operation of the compensator.

[0087] Finally, the compression ratio Control the compaction within the range of 20% to 30%, and measure the total height after compaction. Confirm compression ratio After passing the compaction test, a sealed cavity is formed. A compression ratio controlled within the range of 20% to 30% is the optimal range proven in practice. Within this range, the sealing packing 8 and packing 9 maintain sufficient elastic recovery force to generate a continuous and stable sealing pressure on the surface of the movable nozzle 1, without losing elasticity or generating excessive frictional resistance due to over-compression, thus achieving a good balance between sealing performance and motion performance. After compaction, the sealing packing 8 and packing 9 within the sealed cavity form a stable sealing structure, preparing for the subsequent installation and welding of the sealing ring 6.

[0088] Step S6 involves inserting the guide band 7 into the groove of the sealing ring 6, pressing it into the sealing cavity, and welding the sealing ring 6 to the second sleeve 5 to form the second sealing structure. First, the guide band 7 is inserted into the groove of the sealing ring 6. The size of the guide band 7 should match the depth and width of the groove. During insertion, ensure that the guide band 7 is correctly positioned within the groove and does not tilt or fall off. The guide band 7 is installed using a uniformly distributed method. The compensator uses a three-point 120° evenly distributed design for... The compensator is evenly distributed at four points at 90°, and the circumferential angle deviation of the guide belt 7 is controlled within... Within. Uniformly distributed installation refers to the guide bands 7 being distributed at equal angular intervals along the circumference. Three-point 120° uniform distribution means installing one guide band 7 every 120° along the circumference, for a total of three guide bands 7, dividing the circumference into three equal parts. Four-point 90° uniform distribution means installing one guide band 7 every 90° along the circumference, for a total of four guide bands 7, dividing the circumference into four equal parts. For compensators with smaller pipe diameters, a three-point uniform distribution is used because the circumference is shorter, and three guide bands 7 can provide sufficient support to ensure the stability of the second sleeve 5. For compensators with larger pipe diameters, a four-point uniform distribution is used because the circumference is longer, requiring more support points to effectively prevent radial offset and tilting of the second sleeve 5. The circumferential angular deviation is controlled within... The angle within this range is to ensure the uniform distribution of the guide band 7. If the angle deviation is too large, the second sleeve 5 will lack support in some directions, and radial displacement may occur during movement, affecting the sealing effect. The width of the guide band 7... Satisfying the relation ;in The guide strip width is in mm. The outer diameter of the movable connector 1 is in mm. This formula establishes a proportional relationship between the guide band width and the outer diameter of the movable connector. The guide band width is approximately 15% to 20% of the outer diameter of the movable connector. This ratio ensures that the guide band has sufficient width to provide support without increasing excessive frictional resistance due to excessive width. If the guide band width is too small, it will result in insufficient support area, excessive pressure per unit area, and the guide band will be prone to wear or deformation, failing to effectively prevent lateral displacement of the second sleeve 5. If the guide band width is too large, it will increase the contact area between the guide band and the second sleeve 5, increasing frictional resistance and affecting the axial movement flexibility of the second sleeve 5.

[0089] Then, the sealing ring 6, equipped with the guide band 7, is pressed into the sealing cavity. During pressing, it should be ensured that the sealing ring 6 is aligned with the inner wall of the second sleeve 5, and the end face of the sealing ring 6 is in close contact with the surface of the compacted sealing material. A dedicated pressing tool or hydraulic device can be used to apply uniform axial pressure during the pressing process, gradually pressing the sealing ring 6 into place. After being pressed in place, the sealing ring 6 holds the sealing packing 8 and packing 9 in a compacted state, preventing the sealing material from loosening due to elastic recovery.

[0090] Next, the sealing ring 6 is welded to the second sleeve 5. Welding methods can include spot welding or continuous welding. Spot welding involves evenly distributing several weld points along the circumference at the contact point between the sealing ring 6 and the second sleeve 5, with each weld point forming a local connection. Multiple weld points together secure the sealing ring 6 to the second sleeve 5. Continuous welding forms a continuous annular weld along the contact point between the sealing ring 6 and the second sleeve 5. Continuous welding offers superior strength and sealing performance compared to spot welding, but it requires a larger heat input. During welding, the welding current and speed should be controlled to prevent excessive heat transfer to the sealing filler 8 and packing 9, thus preventing the sealing material from aging, carbonizing, or experiencing performance degradation due to heat. Although flexible graphite materials have good high-temperature resistance, prolonged or excessively high-temperature heating can still cause changes in the internal structure of the material or decomposition of the binder, affecting sealing performance. After welding, the weld should be inspected to ensure it is continuous and uniform, free of cracks, porosity, and other defects. The weld strength should be able to withstand the elastic recovery force of the sealing material and the vibration and impact of the compensator during operation. After welding, the sealing ring 6, guide strip 7, sealing filler 8 and packing 9 together form the second sealing structure, forming a complete auxiliary sealing system.

[0091] Step S7: A second end ring 12 is installed on the inner right side of the first sleeve 4. The second end ring 12 is welded to the outer wall of the second sleeve 5, so that the left end of the second sleeve 5 forms a blocking structure against the retaining ring 10. The second end ring 12 is installed on the inner right side of the first sleeve 4, and its position should correspond to the position on the outer wall of the second sleeve 5 for easy welding connection. The second end ring 12 can be an independent annular piece pre-welded to the inner wall of the first sleeve 4, or it can be an annular boss formed by machining the inner wall of the first sleeve 4. When welding the second end ring 12 to the outer wall of the second sleeve 5, it should be ensured that the welding does not affect the relative sliding performance between the first sleeve 4 and the second sleeve 5. Welding should be performed at the contact point between the outer wall of the second sleeve 5 and the second end ring 12, and the weld should be continuous and uniform to form a reliable connection. Welding deformation should be controlled during welding to avoid reducing the gap between the first sleeve 4 and the second sleeve 5 or even causing jamming due to welding deformation, which would affect the working performance of the compensator. After welding, the second end ring 12 connects the first sleeve 4 and the second sleeve 5 into a whole. The second sleeve 5 remains fixed relative to the first sleeve 4, but the second sleeve 5 can move axially relative to the movable connector 1. Through this connection, the left end of the second sleeve 5 forms a blocking structure against the retaining ring 10. When the movable connector 1 moves to the left, the retaining ring 10 moves to the left accordingly. When the retaining ring 10 moves to contact the left end of the second sleeve 5, the retaining ring 10 cannot continue to move to the left, thereby limiting the maximum travel of the movable connector 1 and protecting the bellows 2 from excessive compression.

[0092] After completing step S7 above, a pre-deformation application step is also included. First, based on the pipeline design temperature... and installation temperature According to the relation Calculate the pre-compression amount ;in This is the pre-compression amount, in mm; The coefficient of linear expansion of the pipeline is expressed in mm / (m·℃). The length of the compensation pipe section is in meters (m). The design operating temperature is expressed in °C. The ambient temperature at which the installation is performed is expressed in °C. This represents the pre-deformation coefficient. This formula is the fundamental formula for pipeline thermal compensation calculations, used to determine the thermal elongation of the pipeline during temperature changes and the amount of pre-deformation that the compensator should apply. In the formula... The linear expansion coefficient of a pipe is an inherent property of the material, representing the elongation per unit length when the material temperature increases by 1℃. Different materials have different linear expansion coefficients. The linear expansion coefficient of steel pipe is approximately 0.012 mm / (m·℃), while that of stainless steel is approximately 0.017 mm / (m·℃). The compensation pipe section length refers to the pipe length between two fixed supports compensated by the compensator. The longer the compensation pipe section length, the greater the total elongation caused by temperature changes, and the stronger the compensation capacity required. This indicates the temperature change of a pipeline from its installation temperature to its operating temperature. This temperature change is the fundamental cause of the thermal expansion of the pipeline. Indicates the pipe temperature from Rise to The theoretical elongation during the process, which needs to be absorbed by the compensator. The pre-deformation coefficient represents the proportion of the pre-applied deformation to the theoretical elongation. It is usually taken as 0.5, which means that half of the elongation is pre-applied as pre-compression, so that the compensator is in a compressed state when cold-installed and gradually releases the pre-compression and deforms in the tensile direction when hot-running. This keeps the compensator in the middle position throughout the temperature change range, so that it can compensate in both the compression and tensile directions, thus improving the adaptability and safety of the compensator.

[0093] Then, temporary tie rods are installed between the flanges at both ends of the compensator. These temporary tie rods are detachable tensioning devices, typically consisting of screws, nuts, and connectors. The two ends of the temporary tie rods are connected to the flanges at both ends of the compensator. Adjusting the nuts changes the distance between the flanges, achieving pre-compression or pre-tensioning of the compensator. The number and distribution of temporary tie rods should be determined based on the size and stiffness of the compensator. Smaller compensators may use two temporary tie rods, while larger compensators may use four or more. The temporary tie rods should be evenly distributed around the flange circumference to ensure uniform stress distribution.

[0094] Next, the bellows 2 is pre-compressed by adjusting the nut on the temporary tie rod. The distance between the flanges and the compensator should be adjusted. A torque wrench or other measuring tools should be used during adjustment to ensure accurate pre-compression. The adjustment of each temporary tie rod should be synchronized to maintain the parallelism of the flange planes and avoid uneven adjustment that could cause the compensator to be misaligned or deformed. During pre-compression, the compression of bellows 2 should be monitored in real time. This can be determined by measuring the change in distance between the flanges at both ends of the compensator or the change in the length of bellows 2. After pre-compression, bellows 2 is in a compressed state, and the movable connector 1 shifts to the left relative to the fixed connector 3, shortening the total length of the compensator. The distance.

[0095] Finally, the compensator is welded and fixed in the pre-compressed state, mainly at the connection between the flanges at both ends of the compensator and the pipeline. During welding, the pre-compressed state should be maintained, and the temporary tie rods should remain taut to ensure that the compression of bellows 2 does not change during welding. Appropriate welding methods and process parameters should be used to ensure weld quality. After welding, the weld should be inspected to confirm it is free of defects. After welding, the temporary tie rods are removed. At this point, the compensator remains in a pre-compressed state because both ends are welded and fixed, and bellows 2 cannot freely spring back; the pre-deformation is locked within the compensator. The application of pre-deformation ensures that as the pipeline heats up from the installation temperature to the operating temperature, the thermal expansion is first used to release the pre-compression, and the compensator gradually returns to its natural length from the compressed state. Then, as the temperature continues to rise, the compensator deforms in the tensile direction. Throughout the process, the deformation of the compensator and the stress on the pipeline support are relatively uniform, avoiding the situation where the compensator is in a position of extreme compression when cold or in a position of extreme tension when hot. This reduces the stress level of bellows 2, extends its fatigue life, and improves the reliability and safety of the compensator.

[0096] The graphite-sealed corrugated compensator installed using the above method has precise fit between its components, firm connection, reliable sealing, accurate guidance, and stable compensation performance, which can meet the compensation needs of high-temperature and high-pressure media such as steam pipelines and hot water pipelines.

[0097] The detailed working process of the graphite-sealed corrugated compensator of the present invention during actual use is as follows. After the compensator is installed and put into operation, the working medium is introduced into the pipeline. The medium enters the compensator from the fixed connector 3, flows through the inside of the guide cylinder 13, and then flows out from the movable connector 1 or flows in the reverse direction. Under normal operation, the pipeline is at the designed operating temperature. If pre-deformation is applied during installation, the bellows 2 will be in a state close to its natural length, neither in the ultimate compression position nor the ultimate tension position, thus reserving sufficient compensation space for pipe length changes caused by subsequent temperature fluctuations or other reasons.

[0098] When the pipeline expands due to increased temperature, the length of the compensating pipe section increases. Since the fixed supports at both ends of the pipeline restrict overall movement, the elongation must be absorbed by the compensator. At this time, the fixed connector 3 connected to the pipeline remains stationary, while the movable connector 1 connected to the other end of the pipeline moves with the pipeline. If the pipeline elongates, the movable connector 1 moves to the right, stretching the bellows 2. The corrugated structure of the bellows 2 allows for tensile deformation in the axial direction, resulting in shallower troughs, increased distance between crests, and an increased overall length of the bellows 2, thus absorbing the pipeline elongation. Simultaneously with the stretching of the bellows 2, the movable connector 1 can move relative to the first sleeve 4 and the second sleeve 5. The second sleeve 5 slides to the right along the chrome-plated surface of the movable connector 1. The sealing filler 8 and packing 9, while maintaining pressure on the surface of the movable connector 1, allow relative movement, achieving a dynamic seal. The guide belt 7 plays a guiding role in this process, ensuring that the movement trajectory of the second sleeve 5 remains coaxial with the axis of the movable connector 1, preventing the second sleeve 5 from radially deviating or tilting, and ensuring that the sealing packing 8 and packing 9 are subjected to uniform force in the circumferential direction, thus avoiding localized aggravation of wear.

[0099] When the pipeline contracts due to temperature drop, the length of the compensating pipe section decreases, the movable connector 1 moves to the left, and the bellows 2 is compressed. The corrugated structure of the bellows 2 allows it to undergo compressive deformation in the axial direction, the troughs of the corrugations deepen, the distance between the crests decreases, and the overall length of the bellows 2 decreases, thus absorbing the shortening of the pipeline. Simultaneously with the compression of the bellows 2, the second sleeve 5 slides to the left along the chrome-plated surface of the movable connector 1. The sealing packing 8 and packing 9 continue to maintain their sealing function, and the guide band 7 continues to provide guidance. When the movable connector 1 moves to a certain extent to the left, the retaining ring 10 welded to the movable connector 1 contacts the left end of the second sleeve 5. At this point, the retaining ring 10 cannot move further to the left, limiting the maximum travel of the movable connector 1 and protecting the bellows 2 from excessive compression that could lead to plastic deformation or fatigue failure.

[0100] When the pipeline changes position due to foundation settlement, support displacement or other reasons, the compensator can also compensate through the deformation of the bellows 2, absorb the displacement of the pipeline, reduce the stress of the pipeline system, and protect the safety of the pipeline and equipment.

[0101] Throughout the operation, bellows 2, acting as the first layer of sealing, completely prevents media leakage under normal conditions, ensuring the sealing of the pipeline system. If bellows 2 develops microcracks or leaks due to material fatigue, corrosion, mechanical damage, or other reasons after long-term use, the leaked media will enter the space between bellows 2 and the first sleeve 4, but will not immediately leak into the external environment. At this time, the second layer of sealing structure, composed of sealing packing 8, packing 9, sealing ring 6, and guide band 7, comes into play. The pressure maintained by sealing packing 8 and packing 9 on the surface of movable connector 1 forms a sealing band, preventing the media from continuing to leak through the gap between the second sleeve 5 and movable connector 1, thus achieving an auxiliary sealing function. The design of the double sealing structure ensures that even if the main seal fails, the compensator can still maintain a seal, avoiding large-scale media leakage that could cause safety accidents or environmental pollution, saving time for maintenance and repair, and significantly improving the safety and reliability of the compensator.

[0102] During operation, the compensator should be inspected and maintained regularly. Inspections include checking the appearance of the bellows (2) for defects such as cracks, dents, and corrosion; checking for leaks at the seals, which can be determined by observing for media seepage or pressure drops; verifying that the compensator's compensation amount is within the normal range, as excessive compensation may indicate an abnormality in the pipeline system; and checking that the fixed and guide supports are functioning properly, as support failure can cause the compensator to bear additional loads. If any abnormalities are found in the compensator, it should be repaired or replaced promptly to ensure the safe and reliable operation of the pipeline system.

[0103] Example 1: Application of DN150 steam pipeline compensator; This example is applied to a steam transmission pipeline system of a chemical plant. The nominal diameter of the pipeline is DN=150mm, the design operating temperature is T2=350℃, the design pressure is P=1.6MPa, the length of the compensating pipe section is L=25m, and the installation ambient temperature is T1=20℃.

[0104] In this embodiment, the bellows 2 is made of 304 stainless steel, with an effective compensation length of 200mm and a maximum compression compensation of Δmax=80mm; the movable connector 1 has an outer diameter of D=159mm, a chrome plating thickness of 0.04mm, a surface roughness of Ra=0.6μm, and a hardness of HV=850; the second sleeve 5 has a length of L3=180mm and a radial clearance of δ=1.0mm with the movable connector 1; the guide tube 13 has a length of L1=145mm; the guide band 7 is evenly distributed at three points at 120° and has a width of B=28mm; the total height of the sealing filler 8 and packing 9 before filling is H0=50mm.

[0105] The implementation steps of Example 1 are as follows:

[0106] S1: Surface treatment of the movable connector. S11: Calculate the welding position of the retaining ring according to the formula L2=L3+Δmax+d1, where L3=180mm, Δmax=80mm, d1=8mm, resulting in L2=268mm. Mark the welding position at 268mm on the left end of the movable connector 1. S12: Weld the retaining ring 10 at the marked position using argon arc welding with a welding current of 120A. S13: Turn the surface of the movable connector on the right side of the retaining ring with a cutting depth of 0.5mm and a feed rate of 0.08mm / r to achieve a surface roughness of Ra=1.4μm. S14: Chrome plating treatment, chrome plating time 45min, current density 30A / dm², chrome plating layer thickness 0.04mm, and surface roughness Ra=0 after fine grinding. 6μm, hardness HV=850; S2: Installation of bellows and guide tube; S21: Weld fixed pipe 3 to the left end of bellows 2 and movable pipe 1 to the right end, the welding method is argon arc welding; S22: Calculate the length of the guide tube according to the formula L1=L0×0.85-Δmax, where L0=270mm, Δmax=80mm, the coefficient is taken as 0.85 (because the pressure 1.6MPa>1.0MPa, it should be taken as 0.75, here it is corrected to 0.75), so L1=270×0.75-80=122.5mm, the actual prepared L1=145mm; S23: Install the guide tube 13 coaxially inside the bellows 2, one end is welded and fixed to the inner wall of the left side of the bellows, and the other end is suspended; S3: Installation of the first sleeve, S4: Install the first sleeve 4 outside the bellows 2, and weld the first end ring 11 to the outer wall of the fixed connector 3; S4: Install the second sleeve, install the second sleeve 5 outside the chrome-plated part of the movable connector 1, and measure the radial clearance δ=1.0mm; S5: Fill and compact the sealing material S51: Insert the packing 9, sealing filler 8, and packing 9 sequentially from left to right in the cavity between the second sleeve 5 and the movable connector 1; S52: Measure the total height H0 before filling = 50mm; S53: Compact with a hydraulic press, compaction pressure 8MPa, and the total height H1 after compaction = 38mm; S54: Calculate the compression ratio η=(50-38) / 50×100%=24%, which meets the 20%-30% requirement; S6: Install the guide belt and sealing ring, and install the guide belt and sealing ring. Insert the 7 (width B=0.176×159=28mm) into the groove of the sealing ring 6, with three points evenly distributed at 120°, with an angle deviation of ±1.5°. After pressing it into the sealing cavity, spot weld the sealing ring 6 to the second sleeve 5; S7: Install the second end ring. Set the second end ring 12 on the inner wall of the right side of the first sleeve 4 and weld it to the outer wall of the second sleeve 5; S8: Apply pre-deformation. S81: Calculate the pre-compression amount Δ0=α×L×(T2-T1)×k=0.012×25×(350-20)×0.5=49.5mm; S82: Add 4 temporary tie rods, evenly distributed at 90° circumference; S83: Adjust the nut to pre-compress the bellows by 49.5mm; S84: Weld and fix it in the pre-compressed state. Remove the temporary tie rods after welding.

[0107] Example 2: Application of DN250 hot water pipe compensator; This example is applied to a hot water transmission pipeline in a heating network. The nominal diameter of the pipeline is DN=250mm, the design working temperature is T2=120℃, the design pressure is P=0.8MPa, the length of the compensating pipe section is L=40m, and the installation ambient temperature is T1=15℃.

[0108] The outer diameter of the movable nozzle is D=273mm, and the radial clearance is δ=1.8mm; the guide belt is evenly distributed at four points at 90°, with a width of B=49mm; the maximum compression compensation of the bellows is Δmax=120mm; the total height of the sealing packing before filling is H0=65mm, and after compaction is H1=48mm, with a compression ratio η=26.2%; the length of the guide tube is calculated according to L1=L0×0.85-Δmax (since P=0.8MPa<1.0MPa, the coefficient is taken as 0.85), L0=380mm, so L1=203mm; the pre-compression amount Δ0=0.012×40×(120-15)×0.5=25.2mm. The remaining structure is the same as in Example 1, and the installation steps are the same as in Example 1.

[0109] Example 3: Application of DN400 high-temperature steam pipeline compensator; This example is applied to a high-temperature steam pipeline in a power plant. The pipeline has a nominal diameter of DN=400mm, a design operating temperature of T2=450℃, a design pressure of P=2.5MPa, a compensating pipe section length of L=30m, and an installation ambient temperature of T1=25℃.

[0110] The movable nozzle has an outer diameter D = 426 mm and a radial clearance δ = 2.2 mm; the guide belt is evenly distributed at four points at 90° intervals, with a width B = 77 mm; the maximum compression compensation of the bellows is Δmax = 150 mm; the total height of the sealing filler before filling is H0 = 80 mm, and after compaction is H1 = 58 mm, with a compression ratio η = 27.5%; the length of the guide tube is L1 = 285 mm (calculated using a coefficient of 0.75); the pre-compression amount Δ0 = 0.012 × 30 × (450 - 25) × 0.5 = 76.5 mm; the chrome plating layer thickness is 0.045 mm, and the hardness is HV = 820. The remaining structure is the same as in Example 1.

[0111] Comparative Example 1: Single-layer sealing compensator without a second-layer sealing structure; the same pipe parameters as Example 1, but only a bellows is used as a single-layer sealing structure, without a second-layer seal consisting of sealing packing, packing, sealing ring and guide band, and without a retaining ring limiting structure.

[0112] Comparative Example 2: Compensator without a guide tube structure; same as Example 1, but without a guide tube 13 installed inside the bellows.

[0113] Comparative Example 3: The movable connector was not chrome-plated; it was the same as in Example 1, but the surface of the movable connector was only machined to Ra=1.6μm and was not chrome-plated, with a surface hardness of HV=180.

[0114] Comparative Example 4: Unreasonable radial clearance design; same as Example 2 (DN=250mm), but the radial clearance δ between the second sleeve and the movable connector is 3.5mm.

[0115] Comparative Example 5: No pre-deformation was applied; the same as Example 1, but no pre-compression treatment was performed during installation, and it was directly welded and fixed in its natural length state.

[0116] Experiment Example 1: Comparative Test of Sealing Performance; Experimental Method: The sealing performance of the compensators of Example 1, Comparative Example 1, and Comparative Example 3 was tested. Nitrogen gas was introduced at the design pressure of 1.6 MPa and maintained for 24 hours. The leakage rate was measured using the pressure drop method. Then, tiny leakage points (0.2 mm in diameter) were artificially created on the bellows, and the overall leakage rate was tested again.

[0117] Experimental indicators: initial leakage rate (mL / min), overall leakage rate after bellows leakage (mL / min), 24-hour pressure drop (MPa); Data acquisition: pressure changes were monitored using a precision pressure gauge, and the leakage gas flow rate was measured using a gas flow meter. Experimental results: as shown in Table 1. Figure 1 As shown.

[0118] Table 1: Sealing performance data of Example 1 and Comparative Examples 1 and 3

[0119]

[0120] From Table 1 and Figure 1 It can be seen that Example 1 had the lowest initial leakage rate, only 0.8 mL / min, compared to 1.2 mL / min in Comparative Example 1. Comparative Example 3, due to the lack of chrome plating on the movable connector, experienced accelerated wear of the sealing packing, resulting in an initial leakage rate of 15.6 mL / min. When the bellows leaked, the double-sealing structure of Example 1 came into play, increasing the overall leakage rate to only 12.5 mL / min, while Comparative Example 1, lacking a second seal, leaked directly to 285.0 mL / min, an increase of approximately 237 times. This result demonstrates that the double-sealing structure effectively prevents significant leakage after the main seal fails. The sealing packing and packing maintain continuous pressure on the surface of the movable connector after compaction, forming an effective sealing band. The absence of chrome plating in Comparative Example 3 led to a 3-5 times increase in the coefficient of friction, accelerating the wear of the sealing material and reducing the seal life.

[0121] Experiment Example 2: Comparison Experiment of Compensation Performance and Fatigue Life; Experimental Method: Axial fatigue tests were conducted using Examples 1, 2, 2, and 5. Reciprocating cycles were performed within ±50% of the designed compensation range at a frequency of 0.5 Hz and an internal pressure of 1.0 MPa. Fatigue life was recorded. The compensation stiffness and maximum compensation amount were tested.

[0122] Experimental parameters: axial compensation stiffness (N / mm); maximum compensation amount (mm); fatigue life (cycles); influence coefficient of the guide tube on flow resistance; experimental results: as shown in Table 2. Figure 2 As shown.

[0123] Table 2: Compensation performance and fatigue life index data of Examples 1 and 2 and Comparative Examples 2 and 5

[0124]

[0125] From Table 2 and Figure 2 It can be seen that, due to the application of pre-deformation, the fatigue lives of Examples 1 and 2 reached 18,500 and 22,800 cycles respectively, while Comparative Example 5, without pre-deformation, had a bellows that was always in a stress state biased to one side during operation, resulting in a fatigue life of only 12,300 cycles, a reduction of approximately 34%. Pre-deformation keeps the compensator in a neutral position within the temperature variation range, reducing the stress amplitude and extending the fatigue life. Comparative Example 2, lacking a flow guide tube, had the medium directly scouring the inner wall of the bellows, resulting in a flow resistance coefficient of 1.58, 41% higher than the 1.12 of Example 1. Long-term scouring would lead to bellows thinning and reduced service life. The flow guide tube forms a smooth flow channel, reducing eddy current losses and protecting the bellows from high-speed medium scouring.

[0126] Experiment Example 3: Wear resistance performance comparison experiment; Experimental method: The moving nozzle-sealing packing pair of Example 1, Example 3 and Comparative Example 3 were used to conduct reciprocating friction test, with a stroke of 100mm, a frequency of 1Hz, a contact pressure of 5MPa, and continuous operation for 10,000 cycles. The wear amount and friction coefficient were measured.

[0127] Experimental parameters: coefficient of friction; wear amount after 10,000 cycles (μm); remaining thickness of sealing filler (mm); surface temperature rise (°C); experimental results: as shown in Table 3. Figure 3 As shown.

[0128] Table 3: Abrasion resistance performance data of Examples 1, 3 and Comparative Example 3

[0129]

[0130] From Table 3 and Figure 3It can be seen that the coefficient of friction of the chromium-plated surface in Example 1 is only 0.08, and the wear is 35 μm, while the coefficient of friction of the unplated surface in Comparative Example 3 is 0.32, which is 4 times that of Example 1, and the wear is 168 μm, which is 4.8 times that of Example 1. The remaining thickness of the sealing filler is reduced to 8.6 mm. Example 3 has the best wear resistance due to the chromium plating layer thickness of 0.045 mm and hardness HV=820, with a wear of only 28 μm. The high hardness and low roughness of the chromium plating layer significantly reduce the coefficient of friction and reduce wear. At the same time, the surface temperature rise also decreased from 45℃ in Comparative Example 3 to 12℃ in Example 1, a reduction of 73%, which reduces the impact of thermal aging on the sealing material. The hardness of the chromium plating layer HV≥800 is much higher than that of the base steel HV=180, which improves the wear resistance by 5-8 times. Moreover, the smooth surface (Ra=0.6 μm) reduces the scraping effect of micro-protrusions on the sealing material.

[0131] Experiment Example 4: Comparison Experiment of Guiding Accuracy; Experimental Method: The guiding accuracy was tested using the compensators of Example 2 and Comparative Example 4. Under the condition of maximum compensation, the radial offset of the second sleeve relative to the movable connecting pipe was measured using a laser displacement sensor, and the gap change in 8 directions around the circumference was measured.

[0132] Experimental indicators: maximum radial offset (mm); circumferential clearance non-uniformity (%); circumferential wear non-uniformity of sealing packing (%); Experimental results: as shown in Table 4. Figure 4 As shown.

[0133] Table 4: Guiding accuracy data of Example 2 and Comparative Example 4

[0134]

[0135] From Table 4 and Figure 4 It can be seen that Example 2, using a reasonable radial clearance δ=1.8mm (which conforms to the 1.5-2.5mm range for DN>300, although DN=250 is close to 300), combined with a four-point 90° evenly distributed guide strip, has a maximum radial offset of only 0.25mm and a circumferential clearance non-uniformity of 8.5%. Comparative Example 4, due to an excessively large radial clearance δ=3.5mm, exceeding the recommended value, resulted in the guide strip being unable to effectively restrain the seal, leading to a maximum radial offset of 1.82mm and a clearance non-uniformity of 68.2%. This resulted in one side of the clearance almost disappearing while the other side had an excessively large clearance, causing the sealant wear non-uniformity to reach 85.6%, leading to localized rapid failure. A reasonable radial clearance combined with an evenly distributed guide strip design can effectively limit radial offset, ensure uniform stress on the sealant, and extend the seal life. Excessive clearance can cause the second sleeve to become eccentric under gravity and medium pressure, causing the guide strip to lose its restraining effect.

[0136] Experiment Example 5: Comparative Experiment on Temperature Compensation Effect; Experimental Method: Temperature cycling tests were conducted using Examples 1, 2, and 5 to simulate a complete cycle from the installation temperature to the operating temperature and back to the installation temperature. The displacement of the compensator, the force on the fixed bracket, and the stress on the bellows were measured. 50 temperature cycles were performed.

[0137] Experimental parameters: maximum displacement of the compensator (mm), maximum force on the fixed support (kN), maximum stress of the bellows (MPa), and residual deformation after 50 cycles (mm); Experimental results: as shown in Table 5. Figure 5 As shown.

[0138] Table 5: Temperature Compensation Effect Index Data of Examples 1 & 2 and Comparative Example 5

[0139]

[0140] From Table 5 and Figure 5 It can be seen that after applying a pre-compression of 49.5 mm in Example 1, the compensator gradually releases from -49 mm to 0 mm during the heating process, and then stretches to +32 mm, with relatively balanced displacement changes. The maximum stress of the bellows is 185 MPa. In Comparative Example 5, no pre-deformation was applied. The compensator was at its natural length in the cold state and was directly stretched to +81 mm (close to the maximum compensation amount) after heating. The bellows stress reached 312 MPa, which is 69% higher than that in Example 1. The fixed support was subjected to a force of 15.8 kN, which is 86% higher than that of 8.5 kN in Example 1. After 50 cycles, the residual deformation of Comparative Example 5 was 5.8 mm, while that of Example 1 was only 1.2 mm, indicating that the pre-deformation design effectively reduced the stress amplitude and reduced the cumulative plastic deformation. The pre-deformation coefficient k=0.5 keeps the compensator in the middle position within the temperature range, avoiding the high stress state at the extreme position, which is a key factor in extending fatigue life.

[0141] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A graphite-sealed corrugated compensator, characterized in that, include: The corrugated pipe is a thin-walled, multi-layered, fully enclosed structure. A fixed connecting pipe is attached to the left end of the bellows; A movable connector is connected to the right end of the bellows. A retaining ring is welded to the left end of the movable connector. The surface of the movable connector on the right side of the retaining ring is machined and chrome-plated. A flow guide tube is coaxially installed inside the bellows. One end of the flow guide tube is welded and fixed to the left inner wall of the bellows, and the other end extends suspended to the right side of the bellows without contacting the right inner wall of the bellows. The first sleeve is fitted over the corrugated pipe. A first end ring is provided on the inner left side of the first sleeve. The first end ring is welded to the outer wall of the fixed pipe. The second sleeve is fitted onto the outside of the chrome-plated portion of the movable connector, and the diameter of the second sleeve is smaller than the diameter of the first sleeve. The sealing packing and packing are disposed in the cavity between the second sleeve and the movable connecting pipe, and from left to right are packing, sealing packing, and packing. A sealing ring with a groove is welded to the second sleeve. The guide belt is inserted into the groove of the sealing ring and is located between the sealing ring and the second sleeve; The second end ring is disposed on the inner wall of the right side of the first sleeve, and the second end ring is welded to the outer wall of the second sleeve; The bellows forms the first layer of sealing structure, and the sealing packing, packing, sealing ring and guide strip form the second layer of sealing structure, thus forming a double sealing structure.

2. The graphite-sealed corrugated compensator according to claim 1, characterized in that, The first and second sleeves are located outside the corrugated pipe and form a guiding function through the sleeve structure; the sealing filler and packing are made of flexible graphite material.

3. The graphite-sealed corrugated compensator according to claim 1, characterized in that, The total length of the guide tube The guide tube is shorter than the effective compensation length of the bellows, forming a structure that is fixed at one end and free at the other; the sealing packing and packing are compacted by a hydraulic press to maintain pressure on the inner wall of the second sleeve.

4. The graphite-sealed corrugated compensator according to claim 1, characterized in that, The left end of the second sleeve forms a blocking structure against the retaining ring. When the movable connecting pipe moves to the left relative to the first and second sleeves, causing the bellows to compress and deform, the limit position of the retaining ring moving to the right is the position of the left end of the second sleeve. A radial gap is provided between the second sleeve and the movable connecting pipe. When the pipe diameter hour, When the pipe diameter hour, .

5. The graphite-sealed corrugated compensator according to claim 1, characterized in that, The guide belt is installed in a uniformly distributed manner. The compensator uses a three-point 120° evenly distributed design for... The compensator is evenly distributed at four points at 90°, and the circumferential angle deviation of the guide belt is controlled within... Within; the width of the guide strip Satisfying the relation ;in, The guide strip width is in mm. The outer diameter of the movable nozzle is in mm.

6. A method for installing the graphite-sealed corrugated compensator according to claim 1, characterized in that, Includes the following steps: S1: Perform surface treatment on the movable connector, weld a retaining ring at the left end of the movable connector, and perform turning and chrome plating on the surface of the movable connector on the right side of the retaining ring. S2: Connect the fixed pipe to the left end of the bellows and the movable pipe to the right end; install the guide tube coaxially inside the bellows; S3: The first sleeve is fitted onto the outside of the corrugated pipe. The first end ring is provided on the inner left side of the first sleeve. The first end ring is welded to the outer wall of the fixed pipe. S4: The second sleeve is fitted onto the outside of the chrome-plated part of the movable connector, and the diameter of the second sleeve is smaller than the diameter of the first sleeve; S5: Fill the cavity between the second sleeve and the movable connecting pipe with sealing material and compact it to form a sealed cavity; S6: Insert the guide belt into the groove of the sealing ring, press it into the sealing cavity, and weld the sealing ring to the second sleeve to form the second sealing structure; S7: A second end ring is provided on the inner wall of the right side of the first sleeve, and the second end ring is welded to the outer wall of the second sleeve so that the left end of the second sleeve forms a blocking structure against the retaining ring. S8: Based on pipeline design temperature and installation temperature According to the relation Calculate pre-compression ;in, This is the pre-compression amount, in mm; The coefficient of linear expansion of the pipeline is expressed in mm / (m·℃), and is taken as 0.012 for steel pipes. The length of the compensation pipe section is in meters (m). The design operating temperature is expressed in °C. The ambient temperature at which the installation is performed is expressed in °C. The pre-deformation coefficient is set to 0.

5. Temporary tie rods are installed between the flanges at both ends of the compensator; the bellows (2) is pre-compressed by adjusting the nuts on the temporary tie rods. The distance; the compensator is welded and fixed in the pre-compression state, and the temporary tie rod is removed after welding is completed.

7. The installation method according to claim 6, characterized in that, In step S1, the welding position of the retaining ring is determined according to the following steps: First, mark the welding position on the left end of the movable connector. The welding position satisfies the following relationship: ;in, This is the distance from the left end face of the retaining ring to the left end of the movable connector, in mm. This refers to the length of the second sleeve, in mm. This represents the maximum compression compensation of the bellows, in mm. To allow for a safety margin, the value should be within the range of 5-10mm; Then weld the retaining ring at the marked location; Next, the surface of the movable connecting pipe on the right side of the retaining ring is machined to achieve a surface roughness of [specific value missing]. ; Finally, the surface of the machined movable joint is chrome-plated, with a chrome plating thickness of [missing information]. After chrome plating, the surface roughness is achieved through fine grinding or polishing. ,hardness .

8. The installation method according to claim 6, characterized in that, In step S2, the installation of the guide tube is carried out according to the following steps: First, weld the fixed connecting pipe to the left end of the bellows, and then weld the movable connecting pipe to the right end of the bellows. Then, based on the natural length of the bellows... and maximum compression compensation According to the relation Calculate the length of the guide tube ;in, This refers to the length of the guide tube, in mm. The natural length of the bellows is expressed in mm. This represents the maximum compression compensation of the bellows, in mm; coefficient. Selected based on work pressure, when pressure When the pressure is 0.85, the value is taken as 0.

85. Take 0.75 at that time; Then according to the calculated length Prepare a guide tube by coaxially installing the guide tube inside the bellows. Weld one end of the guide tube to the left inner wall of the bellows, and let the other end extend to the right side of the bellows without contacting the right inner wall of the bellows, forming a structure that is fixed at one end and free at the other.

9. The installation method according to claim 6, characterized in that, In step S5, the filling and compaction of the sealing material are carried out according to the following steps: First, packing, sealing packing, and packing are placed sequentially from left to right in the cavity between the second sleeve and the movable tube. Then measure and record the total height of the sealing packing and packing before filling. The unit is mm; Next, a hydraulic press is used to compact the sealing packing and packing, controlling the compression rate during the compaction process. The compression ratio According to the relation Calculate; where, Compression ratio, in percentages (%) This represents the total height before filling, in mm. This is the total height after compaction, in mm; Finally, the compression ratio Control the compaction within the range of 20%-30%, and measure the total height after compaction. Confirm compression ratio After passing the test, compaction is completed to form a sealed cavity.

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