CN113653451A

CN113653451A - Integral spiral bending limiter

Info

Publication number: CN113653451A
Application number: CN202111048074.9A
Authority: CN
Inventors: 余杨; 郭虎; 余建星; 王福程; 张凌波; 苏晔凡
Original assignee: Tianjin University
Current assignee: Tianjin University
Priority date: 2021-09-08
Filing date: 2021-09-08
Publication date: 2021-11-16

Abstract

The invention relates to an integral spiral bend limiter, which comprises a main body comprising n spiral section monomers, wherein gaps exist among the spiral section monomers, the width of the gaps is adjusted according to the actual service working condition, and the integral rigidity of the bend limiter is ensured and the bend limiter has toughness buffering according to the principle; and unidirectional fixation is adopted, namely a connecting flange is fixed at one end of the main body. The invention has the advantages of reliable connection and easy installation.

Description

Integral spiral bending limiter

Technical Field

The invention relates to a bending protection device for a flexible riser, which is suitable for limiting excessive bending of a deep-sea flexible riser.

Technical Field

Along with the sudden increase of the demand in recent years, a large amount of oil and gas are exploited, so that land oil and gas resources are gradually exhausted, and more scientific research efforts are put into deep-sea oil and gas exploitation and utilization in all countries in the world. The deep sea riser is used as a life line for ocean oil and gas exploitation and is connected with an offshore operation platform and seabed exploitation equipment, and the reliability of the performance of the deep sea riser is directly related to the safety of the whole oil and gas exploitation system. Due to the badness and uncertainty of the deep sea oil production operation environment, the deep sea riser is easy to be excessively bent under the complex load action of waves, ocean currents and the like, so that stress concentration is generated, the riser is bent or crushed and damaged, and huge economic loss is caused.

The bend limiter is an essential auxiliary component of the deep sea riser, and mainly has the functions of increasing the bending rigidity of the installation section riser and ensuring that the maximum bending degree of the riser is within a safe range so as to prevent the riser from being bent excessively to cause structural damage. The traditional bend limiter is formed by assembling a plurality of cylindrical bend limiter monomers together in a bolt or tenon-and-mortise structure mode and the like. The complex assembly mode not only consumes labor hour, but also is easy to generate fatigue failure at the connecting position in the deep sea service process to cause component failure, so that the practical production and application have great limitation.

Disclosure of Invention

The invention aims to provide an integral spiral bend limiter which is reliable in connection and easy to install. The technical scheme is as follows:

an integral spiral bend limiter comprises a main body which comprises n spiral section monomers, wherein gaps exist among the spiral section monomers, the width of the gaps is adjusted according to the actual service working condition, and the integral rigidity of the bend limiter is ensured and the bend limiter is enabled to have toughness buffering according to the principle; and unidirectional fixation is adopted, namely a connecting flange is fixed at one end of the main body.

Preferably, a reinforcing toggle plate is provided between the connecting flange and the bend limiter body.

Compared with the prior art, the equipment has the beneficial effects that:

(1) different from the traditional bend limiter, the invention adopts one-time integral molding, avoids the complicated installation process and simultaneously eliminates the potential fatigue damage hidden trouble caused by the assembly of a plurality of bolts or mortise and tenon joints.

(2) The one-way flange fixing mode is adopted, the lower end of the bending limiter is not restricted, the torque borne by the stand pipe is prevented from being transmitted to the bending limiter, and the safety and the reliability of the bending limiter are guaranteed.

(3) The spiral form's setting for limit curved ware has had the dual advantage of rigidity and certain toughness concurrently, and consequently, this device both can be used for the limit curved of straight tube, also can be used for requiring to have certain camber but the bending protection of the too big stand pipe section of bending.

Drawings

FIG. 1 is a schematic view of an integral helical bend limiter of the present invention;

FIG. 2 is a schematic representation of a "helical pitch" monomer of the present invention;

FIG. 3 is a schematic view of a coupling flange of the present invention;

the reference numbers in the figures illustrate: 1-a bend limiter body; 2-connecting flange; 3-vertical pipe (not the structure of the invention, only schematic); 11- "helical pitch"; 12-the front end surface of the spiral section; 13-rear end face of the spiral section; 21-flange bolt hole; 22-reinforced toggle plate

Detailed Description

The principles and methods of use of the present invention will now be described in detail with reference to the accompanying drawings.

Fig. 1, fig. 2 and fig. 3 respectively show the overall structure, "single spiral segment" and the assembly connection manner of the novel integral spiral bend limiter contemplated by the device of the present invention by way of example, and it can be fully understood by those skilled in the art that in practical applications, the number of the single "single spiral segment" can be increased or decreased as required to change the overall length of the bend limiter.

The spiral bend limiter main body is composed of n sections of spiral section single bodies 11, and the specific value of n is determined according to the length of a vertical pipe needing bend limiting. A certain gap exists between the spiral sections, the gap width also needs to be adjusted according to the actual service working condition, and the principle of the gap width is that the integral rigidity of the bending limiter is guaranteed, meanwhile, the bending limiter has toughness buffering to a certain degree, and the flexible vertical pipe is prevented from being damaged by absolute rigidity. Considering that the stand pipe may be subjected to the action of torque in the service process, the device is only unidirectionally fixed, namely, the flange is arranged at the upper end of the bending limiter for connecting the device, and the lower end of the bending limiter is not restricted, so that when the stand pipe is subjected to torque rotation, the torque cannot be transmitted to the bending limiter through the flange, and the stability of the bending limiter is ensured.

Referring to fig. 1, the materials of the spiral bend limiter contemplated by the present invention are corrosion-resistant materials. The length dimension of the spiral bend limiter is determined according to the length of the riser section needing bend limiting. The inner diameter of the spiral bend limiter is slightly larger than the outer diameter of the vertical pipe so as to ensure that the vertical pipe can smoothly pass through the spiral bend limiter in the installation process and reduce the friction and the abrasion in the installation process. In the installation process, the flexible riser penetrates through the spiral bend limiter, the bend limiter is moved to a designated position, the position of the connection between the riser and the platform can be the connection position, or any section needing curvature limitation in the overhanging section, and then the flange at the upper end of the bend limiter illustrated in the figure 3 is assembled through bolts, so that the installation can be completed.

Figure 2 schematically illustrates a single "helical pitch" of the bend limiter. The section of the spiral section is a rectangular section, the thickness of the section is not smaller than the wall thickness of the stand pipe, and the width of the section is slightly larger than half of the outer diameter of the stand pipe, so that the rigidity of the bend limiter can be effectively ensured, and the structure is prevented from being broken and damaged. When the stand pipe is subjected to bending moment, the spiral bend limiter sleeved on the stand pipe can bend along with the stand pipe. As the bending deformation increases, the gap on the pressure side of the "helical pitch" gradually decreases, and when the rear end surface 13 of the "helical pitch" contacts the front end surface 12, the "helical pitch" on the pressure side presses against each other to generate resistance, and the tension side generates tension because the gap becomes larger. Under the simultaneous action of the tensile force and the pressure, the rigidity of the bending limiter reaches the maximum, so that the flexible vertical pipe is prevented from generating larger bending deformation in the using process, and the flexible vertical pipe is prevented from generating excessive bending.

Fig. 3 shows an exemplary manner of assembling the helical bend limiter. When the bend limiter is conveyed to a designated position, a flange (the flange is not shown in fig. 1 and 3) is welded on the outer part of the platform or the riser, and the flange are connected with the platform or the riser by bolts. Considering that the double-end fixation can cause the torque applied to the riser to be transmitted to the bend limiter, a connecting flange is only arranged at the upper end of the bend limiter. Meanwhile, in order to ensure the strength of fixing the structure form at one end, a reinforcing toggle plate 22 is required to be additionally arranged between the connecting flange and the bend limiter main body, so that the condition that the bend limiter main body falls off from the connecting flange is avoided. The flange bolt holes 21 and the reinforcing toggle plates 22 should be uniformly arranged, so that the installation is not complicated due to too much, and the structure is not unstable due to too little.

Although the invention has been described in detail with respect to the general description and the specific examples, it is not intended to limit the scope of the invention. It will be apparent to those skilled in the art that certain changes and modifications may be made without departing from the spirit of the invention. Accordingly, such modifications and improvements are intended to be within the scope of the invention as claimed.

Claims

1. An integral spiral bend limiter comprises a main body comprising n spiral section monomers, wherein gaps exist among the spiral section monomers, the width of each gap is adjusted according to the actual service working condition, and the integral rigidity of the bend limiter is ensured and the bend limiter is enabled to have toughness buffering according to the principle; and unidirectional fixation is adopted, namely a connecting flange is fixed at one end of the main body.

2. The integrated spiral bend limiter of claim 1 wherein a reinforcing toggle plate is disposed between the attachment flange and the bend limiter body.

3. The integral spiral bend limiter of claim 1 wherein the cross-section of the spiral section is a rectangular cross-section having a thickness dimension greater than the wall thickness of the pipe to be protected.

4. The integral spiral bend limiter of claim 1, wherein the width dimension of the spiral section is greater than one-half and less than the outer diameter of the pipe to be protected.

5. The integral spiral bend limiter of claim 1 wherein the inner diameter of the spiral section is determined according to the outer diameter of the pipe to be protected.