CN107687558B - A combined buckling stopper for a submarine fiber-reinforced composite flexible pipe - Google Patents

Abstract

The invention discloses a combined flexure stopper for a fiber-reinforced composite flexible pipe, comprising a metal outer collar and a fiber-reinforced inner collar, wherein the metal outer collar includes a main collar, a locking collar and an elastic sealing gasket; The inner collar includes a fiber reinforced layer and a matrix protective layer; the fiber reinforced inner collar is located on the outer side of the composite pipe and is thermally fused with it, which is equivalent to locally thickening the pipe to improve the buckling resistance; The overfitting is wrapped on the outside of the fiber-reinforced inner collar, which can assist the fiber-reinforced inner collar to achieve the anti-bending function, and at the same time, the better anti-deformation performance of the metal outer collar can be used to prevent the composite pipe from excessive bending, so as to reduce the fiber Enhances stress concentration of the inner collar. The invention reasonably utilizes the bonding properties of the composite pipe material to realize the processing of the fiber-reinforced inner collar, and is supplemented by a metal outer collar to increase the local structural strength, has the advantages of a steel pipe welding type and a crimping type flexure stopper, and is widely popularized and practical value.

Description

A combined buckling stopper for a submarine fiber-reinforced composite flexible pipe

technical field

The invention relates to the technical field of auxiliary components for marine fiber-reinforced composite flexible pipes, in particular to a combined buckling stopper for deep-sea high-pressure fiber-reinforced composite flexible pipes used in oil or water transportation.

Background technique

The offshore oil and gas industry is facing deeper waters, harsher transportation environments, more complex installation conditions and wider application fields. The material properties of traditional offshore steel pipes are increasingly showing deficiencies, including their corrosion resistance, weight, flexibility and other aspects. Performance hinders its further application and development. In order to overcome these defects, a variety of new marine pipelines using plastic materials have appeared one after another, and the most widely used is the thermoplastic fiber reinforced bonded composite pipe (RTP) made by wrapping plastic fiber tapes with thermoplastic materials. The RTP pipe is in the production process. The middle fiber reinforced layer and the inner and outer plastic matrix protective layers are integrated into a whole through hot melt bonding, which has the advantages of high resistance to internal pressure, light weight, strong corrosion resistance, and fatigue resistance.

Whether it is a fiber reinforced composite flexible pipe or a steel pipeline pipe, during its service, local pit defects due to collision with other objects, local buckling caused by excessive bending during installation or under overload service, and local buckling caused by wear and corrosion. The reduction of the wall thickness will lead to the weakening of the local buckling resistance of the pipeline, resulting in the local buckling collapse of the pipeline. Since the buckling propagation pressure is lower than the local buckling pressure, once the local buckling collapse occurs, the buckling will propagate along the length of the pipeline at a high speed, which may eventually destroy the entire pipeline, causing huge economic and ecological harm. At present, the buckling problem is mainly solved by designing and installing buckling stoppers. The existing buckling stoppers are mainly configured for steel pipes, and there are few buckling stoppers designed for composite pipes.

According to the different connection methods, the steel pipe flexure stopper is mainly divided into welding type flexure stopper, additional type flexion stopper, winding type flexure stopper and inner ring type flexure stopper. The welded buckling stopper is connected with the pipelines at both ends by fine welding, and has a good buckling stop effect. It is suitable for submarine steel pipes with medium and large water depths. The disadvantage is that it is easy to produce welding defects and stress concentration, and the welding process requires It is very high and needs to take a certain way to overcome the stress concentration; the additional flexure stopper is fixed on the outside of the pipeline through interference fit, and the frictional force is used to prevent the flexion stopper from slipping, no welding is required, the installation is convenient, the cost is low, and the pipeline The hoop stiffness of the steel pipe is high, but the buckling efficiency is low, and the U-shaped crossing phenomenon may occur in the pipeline; the winding buckling stopper is to wrap several turns of steel bars on the surface of the steel pipe uniformly and tightly at a certain angle, instead of the snap-in type. The thick-walled ring sleeve of the flexure stopper can also improve the rigidity of the pipe in the circumferential direction. The two ends of the steel bar are welded with the pipeline to fix the position of the flexure stopper in the pipeline and prevent sliding. The structure is simple and the installation is convenient. Cost It has low bending stiffness and generally does not produce bending stress concentration points. The disadvantage is that the buckling stop efficiency is not high, and the strength is smaller than other buckling stoppers; the inner ring type buckling stopper is also a ring sleeve, which is mainly used for Tube in tube.

From the perspective of the use environment, the application conditions of fiber reinforced composite flexible pipes are more complicated, and they have to withstand greater bending and longer spans. The composite pipe has produced a huge challenge. The fiber-reinforced composite flexible pipe may buckling throughout its service life. Buckling will lead to fiber failure, matrix cracking, plastic yielding or delamination of the composite pipe. At present, for small diameter and application For composite pipes with low conditions, appropriately increasing the wall thickness of the pipe, especially the thickness of the reinforcement layer, can suppress the buckling of the pipe to a certain extent. However, for large-diameter pipes, complex service conditions and external high pressure in the deep sea, the thickness is greatly increased to prevent buckling. The pipe wall does not meet the economic requirements. In summary, it is a more reasonable solution to install a buckling stopper for the composite pipe, and a suitable buckling stopper form needs to be selected.

For steel pipes, there is little difference in performance in different directions. Different from steel pipes, because the material properties and structural properties of fiber-reinforced composite flexible pipes are quite different from steel pipes, especially the performance of composite pipes in the circumferential and radial directions and the axial performance are quite different, so the steel pipe is limited. Flexors cannot be used directly on fiber reinforced composite flexible pipes. Considering different flexure stoppers, the welded flexure stopper used for steel tube flexion stoppage cannot be directly welded to the composite pipe; the additional flexure stopper must first ensure the interference connection with the pipe body, otherwise the flexion stopper The efficiency is very low, and the large bending of the composite pipe is easy to cause stress concentration at the edge of the additional flexure stopper. In addition, the radial performance of the composite pipe is weak, and it is easy to cause large deformation, crushing and cracking of the pipe body; The steel bar of the bender cannot be welded with the pipe body, and cannot cooperate with the composite pipe to form an effective whole. Therefore, there is an urgent need to provide a flexure stopper specifically for the composite pipe to overcome the defects existing in the prior art.

SUMMARY OF THE INVENTION

The technical problem to be solved by the present invention is that there is no buckling stopper suitable for composite pipes in the prior art. If the buckling stopper for steel pipes is used, there are defects such as low buckling stop efficiency and poor structural reliability, so as to provide a submarine fiber reinforced composite pipe. The combined flexure stopper for flexible pipes can improve the flexion stopper efficiency of the flexure stopper without causing damage and other failures to the composite pipe body.

The invention is realized by adopting the following technical solutions: a combined buckling stopper for a submarine fiber-reinforced composite flexible pipe, the composite flexible pipe comprises an outer protective layer, a reinforcing layer and an inner lining layer in sequence from the outside to the inside, and the combined buckling stopper It includes a fiber-reinforced inner collar and a metal outer collar, the fiber-reinforced inner collar is arranged on the outer side of the composite flexible pipe reinforcement layer, and is hot-melt bonded with the composite flexible pipe reinforcement layer; the metal outer collar is arranged in the fiber reinforcement. The outer side of the collar and the interference fit with the fiber-reinforced inner collar.

Further, the metal outer collar includes a main collar and a locking collar, the main collar is a cylindrical sleeve, a raised ring is provided on the inner wall of one end of the main collar, and an inner wall is processed on the inner wall of the other end. thread; the locking collar is arranged between the main collar and the composite flexible pipe with one end machined with an internal thread, and is threadedly connected with the main collar, that is, the outer surface of the locking collar is machined with a thread inside the main collar Thread matching external thread.

Further, the fiber-reinforced inner collar is manufactured on the outer surface of the reinforcing layer of the composite flexible pipe and bonded to it by hot-melt winding technology. The fiber-reinforced inner collar includes a fiber-reinforced layer and a matrix protective layer, and the fiber-reinforced layer is similar to The reinforcing layer of the composite flexible pipe is a sleeve structure formed by the fiber tape pre-impregnated with the hot-melt matrix liquid and then wound in right and wrong directions, and the type, winding angle, layer density, etc. of the fiber tape are not limited. The matrix material of the outer protective layer is the same, and the fiber material can be the same or different; the fiber reinforcement layer is covered and bonded to the outside of the composite flexible pipe reinforcement layer, and the matrix protection layer is covered and bonded to the outer side of the fiber reinforcement layer, and is protected from the composite flexible pipe. Layer bonding, the adjacent layers are all hot-melt bonded without leaving gaps, so that the fiber-reinforced inner collar and the composite flexible tube are fused into a whole.

Further, both ends of the fiber-reinforced inner collar are respectively transitioned to the composite flexible tube through a transition cone, and the raised ring and the locking collar are evenly matched with the transition cone, such as the The cross section can be a right-angled trapezoid to match the gradient of the transition cone. The beveled taper fits together to clamp and lock the fiber-reinforced inner collar in the middle.

Further, the thickness of the fiber reinforced layer is not less than the thickness of the composite flexible pipe reinforced layer, the thickness of the base protective layer is not less than the thickness of the outer protective layer of the composite flexible pipe, the base material is consistent with the base material of the fiber reinforced layer, and the thickness of the base protective layer is The length is the same as that of the fiber reinforcement layer, and is bonded with the fiber reinforcement layer to form a complete sleeve.

Further, elastic sealing washers are also provided on the inner wall of the raised ring and the inner wall of the locking collar, and the elastic sealing washer adopts a high-density rubber ring, which is bonded and connected with the raised ring and the locking collar, and is elastic. The thickness of the sealing gasket is larger than the thickness of the gap between the main collar raised ring, the locking collar and the composite flexible pipe. Therefore, after the metal outer collar is installed, the elastic sealing washer is squeezed to cause interference deformation, which can form Good sealing effect.

Further, the inner diameter of the main collar is slightly smaller than the outer diameter of the fiber-reinforced inner collar, and the inner diameter of the raised ring is larger than the outer diameter of the composite flexible tube.

Further, the length of the main collar is greater than the length of the fiber-reinforced inner collar.

Further, the main collar is composed of two symmetrical saddle plates with a semi-circular cross-section. The two saddle plates are hinged on one side and bolted on the other side. The internal threads on the plate are interconnected, and the main ferrule after connection has a complete thread passage.

Further, the locking collar is formed by splicing two half-circles, and intercommunicating external threads are provided on the outer surfaces of the two half-circles. The outer thread of the main collar is screwed into it.

Compared with the prior art, the advantages and positive effects of the present invention are:

The combined flexure stopper for a composite flexible pipe proposed by the present invention includes a fiber-reinforced inner collar and a metal outer collar:

First, a fiber-reinforced inner collar is set outside the pipe with the outer protective layer peeled off, and the fiber-reinforced inner collar and the pipe body are bonded together by hot-melt bonding. The wound fiber reinforcement layer similar to the reinforcement layer structure is used to lift the local ring of the pipeline. It can be regarded as the local thickening of the composite flexible pipe layer after bonding with the pipe reinforcement layer, which ensures that the performance of the flexure stopper pipe section and other pipe sections maintains the same performance of the structural section, and effectively improves the buckling resistance of the pipe without weakening. Other properties of the pipeline (tensile properties, resistance to internal pressure, etc.) are equivalent to the welded buckling stopper of the steel pipe; from the perspective of local design, the fiber type, density and winding angle of the fiber reinforced layer can be based on the actual requirements of the pipeline. Adjusted to enhance buckling resistance, with high flexibility; the tapered transition at both ends of the fiber reinforced layer smoothes the stress distribution and prevents stress concentration in the transition section; the matrix protective layer effectively protects the fiber reinforced layer and prevents its structure from being worn and corrosion.

The metal outer ring wrapped on the outer side of the fiber-reinforced inner ring also has the effect of preventing flexion. The interference fit with the fiber-reinforced inner ring is formed by withholding, which further increases the hoop rigidity of the flexure stopper, and through the metal components The rigidity overcomes the bending of the pipe in the bend stopper section to reduce the local bending stress, and also protects the fiber-reinforced inner collar that is prone to excessive wear and damage due to local protrusion during the laying, which plays a good auxiliary role, similar to the steel pipe. The crimped buckling stopper.

From the perspective of local design, first, the provision of the elastic sealing gasket overcomes the problem that the fiber reinforced inner ring is easily worn at the non-interference section with the metal outer ring, and also has the function of sealing to prevent the inner interference section from being damaged. Corrosion leads to changes in structure and performance; secondly, the setting of the left and right transition cones is also reasonable. On the one hand, it is to match the cone transition at both ends of the fiber reinforcement layer. The metal outer ring is axially fixed, and it is not necessary to form excessive interference pressure on the outer surface of the fiber reinforced outer ring to use the friction limit. This design takes into account the lack of radial performance of the composite flexible pipe, and will not cause the pipe in the bend stopper section to occur. Excessive radial deformation; thirdly, even if the interference pressure of the metal outer ring on the fiber-reinforced inner ring is too large due to uncontrollable factors, because the buckle pressure of the metal ring only acts on the inner ring, the The local rigidity enhancement can effectively reduce the radial deformation of the pipeline; fourth, the split-half structure of the metal outer ring and the locking collar facilitates the installation and removal of the flexure stopper, and the design of the locking collar facilitates the metal outer ring Adjustment of the degree of fit between the fiber-reinforced inner collar.

In conclusion, the present invention combines the fiber-reinforced inner collar with the metal outer collar, similar to the combination of two types of flexure stoppers, the welded steel tube flexure stopper and the crimped type flexure stopper. After fully considering the actual structure and material characteristics of the composite flexible pipe, application conditions and other factors, after analyzing the deficiencies of each flexure stopper and using its advantages reasonably, a new combined flexure stopper is designed, which greatly increases the composite flexible pipe. buckling efficiency.

Description of drawings

1 is a schematic diagram of the overall structure of the combined flexure stopper according to an embodiment of the present invention;

FIG. 2 is a schematic exploded view of the combined flexure stopper structure according to the embodiment of the present invention;

3 is a schematic cross-sectional view of the combined flexure stopper according to an embodiment of the present invention.

Detailed ways

In order to more clearly understand the above objects, features and advantages of the present invention, the present invention will be further described below with reference to the accompanying drawings and embodiments. It should be noted that the embodiments of the present application and the features in the embodiments may be combined with each other in the case of no conflict.

This embodiment discloses a combined buckling stopper for a submarine fiber-reinforced composite flexible pipe. For the convenience of description, the flexible pipe will be referred to as a composite pipe for short. Referring to FIG. 2 and FIG. 3 , the composite pipe 1 includes external protection from the outside to the inside. Layer 11, reinforcing layer 12 and inner lining layer 13, the combined flexure stopper includes a fiber-reinforced inner collar 2 and a metal outer collar 3, and as shown in FIG. 3, the fiber-reinforced inner collar 2 includes a fiber-reinforced layer 21 and The structure and manufacturing method of the matrix protection layer 22 and the fiber reinforcement layer 21 are similar to the reinforcement layer 12 of the composite pipe 1 , and they are all made of fiber tapes pre-impregnated with a thermoplastic matrix that is heated and melted by machine winding. The fiber reinforced layer 21 covers the surface of the reinforced layer 12, which is equivalent to thickening the reinforced layer 12. After comprehensively considering the hoop stiffness enhancement effect of the fiber reinforced inner jacket, radial deformation performance, pipeline load and other factors, the thickness is set as 100% to 120% of the reinforcement layer, fiber tape laying density (mass ratio), and fiber tape winding angle can be different from the reinforcement layer 12, depending on the requirements for buckling resistance of the pipe body under different application conditions and environmental conditions. The base protective layer 22 is a protective layer covering and bonded to the outer surface of the fiber reinforced layer 21 , similar to the outer protective layer 11 of the composite pipe 1 , the base material is the same as that of the outer protective layer 11 , and the thickness is 100% to 120% of the outer protective layer 11 . , has the effect of water-proof, anti-corrosion and anti-wear.

Correspondingly, the two ends of the fiber reinforced layer 21 are transition cone surfaces 23 from thick to thin, and the cone angle is not more than 45°. During processing, the cone surface is kept as smooth as possible, and the base protective layer 22 is also uniformly covered on the cone. face. The fiber reinforced layer 21, the matrix protective layer 22, the reinforcing layer 12, and the matrix protective layer 22 and the outer protective layer 11 are all hot-melt bonded by the same material matrix without leaving a gap, so that the fiber reinforced inner collar 2 and the composite pipe 1 fused into a whole.

The metal outer collar 3 includes a main collar 31 and a locking collar 32. The metal outer collar 3 covers the outer surface of the fiber-reinforced inner collar 2 to increase the strength of the flexure stopper and resist the bending of the pipeline. The main collar 31 is a metal cylinder, preferably a steel material, the length of which is slightly larger than the length of the fiber-reinforced inner collar 2 by about 110%-115%. Both ends of the inner wall are specially processed: one end is provided with a raised ring 33 through a transition cone, the inner diameter of the raised ring 33 is larger than the outer diameter of the composite pipe 1, and the transition cone between the raised ring 33 and the fiber reinforced layer 22 23 contours are matched; the inner wall of the other end is machined with an internal thread 34. The inner diameter of the main collar 31 is slightly smaller than the outer diameter of the fiber-reinforced inner collar 2 , and the main collar 31 is snapped in, thus resulting in an interference contact. The locking collar 32 is a circular ring with a trapezoidal section, the material is the same as that of the main collar 31 , its inner diameter is larger than the outer diameter of the pipe, and an external thread is machined on the outside to match the inner thread 34 of the main collar. The front end surface of the locking collar 32 is a conical surface, which matches the contour of the transition conical surface 23 . In addition, an elastic sealing washer 35 is provided on the inner walls of the locking collar 32 and the raised ring 33. The elastic sealing washer 35 is a thin-walled circular ring in shape and is made of high-strength rubber, which is required to be waterproof and corrosion-resistant. Fatigue performance, its thickness is greater than the difference between the inner diameter of the raised ring 35 of the main collar 31 and the outer diameter of the composite tube 1, and the difference between the inner diameter of the locking collar 32 and the outer diameter of the composite tube 1, the purpose is between the above two structural gaps It is squeezed to produce a certain initial interference, so as to protect the tube body, disperse the stress and dampen the shock.

In order to facilitate installation, the main collar 31 is designed as two saddle plates with a semicircular cross-section, one side (A side) of the two saddle plates is hinged, and the other side (B side) is connected by bolts, forming a complete The main ferrule, the bolt connection is a radially protruding elongated flange plate 36, and a threaded hole 37 is processed on it. After the two saddle plates are butted together, the two eye plates 36 are in close contact with each other and the threaded holes 37 at the same position are also aligned. The locking collar 32 can be processed into two symmetrical semi-circular rings, and the outer surface of the locking collar 32 joined by the semi-circular rings forms a complete external thread, which can be connected to the inner thread 34 of the main collar.

For the combined flexure stopper described in this embodiment, when in use, the fiber-reinforced inner collar can be installed in various ways. In the manufacturing process, it is directly arranged on the outside of the reinforcing layer of the composite pipe that has not yet prepared the outer protective layer. First select the position of the flexure stopper, and wind the fiber prepreg tape at a specified angle in both directions at the specified position until the fiber reinforced layer reaches the specified thickness. Both ends are processed into transition cones, and the fiber reinforced layer is made after the matrix is cooled and solidified; then the matrix protective layer is uniformly processed on the outside of the fiber reinforced layer, and the matrix protective layer and the outer protective layer of the composite pipe, the matrix protective layer and the fiber are reinforced. The layers as well as the fiber reinforced layer and the composite pipe reinforced layer are all hot-melt bonded without leaving a gap, so that the fiber reinforced inner collar and the composite pipe are fused into a whole.

After the preparation of the fiber-reinforced inner collar, firstly press the main collar with the elastic sealing gasket to the outside of the fiber-reinforced inner collar, and move the main collar raised ring transition cone closely to the fiber-reinforced inner collar by moving slightly. The ring transitions to the conical surface, maintains the structural position and locks the main collar with bolts; then connect the locking collar to make the threaded passage complete and place the elastic sealing washer, and then screw the locking collar between the main collar and the composite pipe , until the front end surface of the locking collar and the transition cone surface of the fiber-reinforced inner collar closely fit and produce a certain amount of interference, and finally the thread is locked to complete the entire installation process. At this time, the metal outer collar has interference with the fiber-reinforced inner collar Contact and limit the axial displacement, the schematic diagram of its overall structure is shown in Figure 1.

In the combined flexure stopper proposed by the embodiment of the present invention, the fiber-reinforced inner collar is a structure bonded with the composite pipe as a whole, which is used to improve the local strength of the pipe, especially the hoop stiffness, and can be regarded as a part of the reinforcement layer , the performance of the buckling stopper pipe section and other pipe sections maintains the same performance of the structural section, which effectively improves the buckling resistance of the pipeline without weakening other performances of the pipeline. In the fiber-reinforced inner collar, the fiber type, density, winding angle, etc. of the fiber-reinforced layer can be adjusted according to the actual requirements of the pipeline to enhance the buckling resistance, with high flexibility; the transition of the tapered surfaces at both ends of the fiber-reinforced layer is gentle It can improve the stress distribution and prevent the stress concentration in the transition section; the matrix protective layer can effectively protect the fiber reinforced layer.

In order to make up for some deficiencies after the fiber-reinforced outer ring is installed, the metal outer ring is added to match the fiber-reinforced outer ring. The metal outer ring also has the effect of preventing buckling. Reasonably share the internal and external pressure loads on the fiber reinforced layer, further increase the hoop rigidity of the flexure stopper, and overcome the bending of the flexure stopper section of the pipeline through the rigidity of the metal member to reduce the local bending stress, and also protect the laying cause. The fiber-reinforced inner collar, which is locally protruding and prone to excessive wear and tear, plays a good supporting role. The existence of the metal outer ring increases the overall strength of the flexure stopper, and the structural design is ingenious and reasonable.

In the metal outer ring, the provision of the elastic sealing gasket overcomes the problem that the fiber reinforced inner ring is easily worn at the non-interference section with the metal outer ring, and also has the function of sealing; on the one hand, the left and right transition cones cooperate with fiber reinforcement On the other hand, the metal outer ring is axially fixed by the interference fit of the tapered surface, and it is not necessary to form excessive interference pressure on the outer surface of the fiber reinforced outer ring to use the friction limit. This design takes into account The lack of radial performance of the composite pipe will not cause excessive radial deformation of the pipe in the bend stopper section; because the buckle pressure of the metal collar only acts on the fiber-reinforced inner collar, and the pipe section with the fiber-reinforced inner collar It has higher strength to withstand the radial deformation caused by the buckling of the metal outer ring; the split-half structure of the metal outer ring and the locking collar facilitates the installation and removal of the flexure stopper, and the design of the locking collar facilitates the metal outer sleeve. Adjustment of the fit between the ring and the fiber-reinforced inner collar.

The above are only preferred embodiments of the present invention, and are not intended to limit the present invention in other forms. Any person skilled in the art may use the technical content disclosed above to make changes or modifications to equivalent changes. The embodiments are applied to other fields, but any simple modifications, equivalent changes and modifications made to the above embodiments according to the technical essence of the present invention still belong to the protection scope of the technical solutions of the present invention without departing from the content of the technical solutions of the present invention.

Claims (9)

1. a combined type flexure stopper for a submarine fiber-reinforced composite flexible pipe, the composite flexible pipe comprises an outer protective layer, a reinforcing layer and an inner liner successively from outside to inside, it is characterized in that, the combined type flexure stopper comprises a fiber-reinforced inner sleeve a ring and a metal outer ring, the fiber-reinforced inner ring is arranged on the outer side of the reinforcing layer of the composite flexible pipe, and is hot-melt bonded with the reinforcing layer of the composite flexible pipe; the metal outer ring is arranged on the outer side of the fiber-reinforced inner ring, and Interference fit with fiber reinforced inner collar, The metal outer collar includes a main collar and a locking collar, the main collar is a cylindrical sleeve, a raised ring is arranged on the inner wall of one end of the main collar, and an inner thread is processed on the inner wall of the other end; The locking collar is arranged between the main collar having one end machined with an internal thread and the composite flexible pipe, and is threadedly connected with the main collar. 2 . The combined flexure stopper according to claim 1 , wherein the fiber-reinforced inner collar comprises a fiber-reinforced layer and a matrix protective layer, and the fiber-reinforced layer is covered and bonded to the outside of the composite flexible pipe reinforcement layer, 2 . The matrix protective layer is covered and bonded on the outside of the fiber reinforced layer, and is bonded with the outer protective layer of the composite flexible pipe, and the fiber reinforced inner collar and the composite flexible pipe are hot-melt bonded as a whole. 3 . The combined flexure stopper according to claim 2 , wherein both ends of the fiber-reinforced inner collar are respectively transitioned to the composite flexible tube through a transition cone, and the raised ring and the locking collar are both Compatible with transition cones. 4 . The combined flexure stopper according to claim 2 , wherein the thickness of the fiber reinforcement layer is not less than the thickness of the reinforcement layer of the composite flexible pipe, and the thickness of the base protective layer is not less than the thickness of the outer protection layer of the composite flexible pipe. 5 . Thickness, the length of the base protective layer is consistent with the length of the fiber reinforcement layer. 5. The combined flexure stopper according to claim 3 or 4, wherein an elastic sealing washer is further provided on the inner wall of the raised ring and the inner wall of the locking collar, and the elastic sealing washer is made of high-density rubber ring. 6 . The combined flexure stopper according to claim 5 , wherein the inner diameter of the main collar is slightly smaller than the outer diameter of the fiber-reinforced inner collar, and the inner diameter of the raised ring is larger than the outer diameter of the composite flexible tube. 7 . 7 . The combined flexure stopper according to claim 6 , wherein the length of the main collar is greater than the length of the fiber-reinforced inner collar. 8 . 8 . The combined flexure stopper according to claim 7 , wherein the main collar is composed of two symmetrical saddle plates with semicircular cross-sections, one side of the two saddle plates is hinged, and the other side is hinged. 9 . Side bolt connection. 9 . The combined flexure stopper according to claim 8 , wherein the locking collar is formed by splicing two semi-circular rings, and intercommunicating external threads are provided on the outer surfaces of the two semi-circular rings. 10 .

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