KR20100052197A - Stress monitoring system and method for pipelines during underwater pipelaying - Google Patents

Abstract

PURPOSE: Stress measurement apparatus and method of a pipeline under the attachment of the pipeline at the bottom of the sea are provided to be able to attach in a stable range of acceptable stress by obtaining the information on the stress applied to a pipeline in real time. CONSTITUTION: A stress measurement apparatus of a pipeline during the attachment of the pipeline at the bottom of the sea comprises a detection pipe(20). The detection pipe is separated from the working line to arrange at the inside of the pipeline attaching toward the bottom of the sea. The detection pipe includes a plurality of sensors in the longitudinal and circumferential directions. The sensors are formed in order to measure the extension amount or the contraction amount on the curvature change of the detection pipe depending on the curvature change of the attaching pipeline. The sensor includes an optical fiber sensor.

Description

Stress Monitoring System and Method for Pipelines during Underwater Pipelaying}

The present invention relates to an apparatus for laying pipelines, and more particularly, to an apparatus for laying a subsea pipeline by submerging a pipeline worked in an offshore working vessel (submarine) into water.

In general, oil pipelines, gas pipes, water pipes, etc. are not only on the land but also to install pipelines on riverbeds or seabeds across rivers, rivers or seas.

Pipelines used in such oil pipelines, gas pipes, water pipes, power plant intake pipes, etc., are usually 0.5 to 1.0 m or more in diameter, and are several hundred meters to tens of kilometers in length and work on water or sea. Because of this, many restrictions are placed on the work laid under natural conditions.

For example, in the conventional method of installing a subsea pipeline, a comparatively short length of pipe manufactured on land is moved to the sea by using a sea work line (laying line, laying line), and then a short length pipe is welded and joined at the same time. The lay barge method is typical of sinking pipes to the sea floor while moving the work line.

However, as shown in Figure 1, the long length of the pipe-in (P) is constructed in the marine work ship when the submerged position or the buoyancy, wave, wave, and movement of the working ship (when settling underwater or seabed) During sedimentation from the working line to the seabed for reasons such as shaking or instability), this stress is displaced along the length and circumference of the pipeline from the working line and settles towards the sea floor. Many stress changes are formed, and these stress changes continuously change in conjunction with the sedimentation of the pipeline.

On the other hand, as a means of measuring the stress of a conventional pipeline, there is a case of using an equipment called an 'inspection pig'. The pigtail is configured to be able to move from one side to the other, and the pigs can determine the distance and speed of travel along the pipeline, and the at least one sensor is configured to be in close contact with the inner diameter of the pipeline being moved. The overall stress can be measured. (See Republic of Korea Registration No. 10-0853110)

However, the inspection pig, which runs the inner diameter of the installed pipeline, is for the final safety inspection of the pipeline after installation, and practically it cannot be used during the laying of the pipeline from the sea to the sea floor.

Although it is very rare to obtain the stress information of the sedimentation pipeline by attaching a fixed sensor to the inner or outer diameter of the conventional pipeline, the stress information also changes continuously along the longitudinal direction of the pipeline injected into the water from the sea. As a result, it was difficult to obtain fast and accurate stress information in real time on the pipeline being settled.

Therefore, the present invention is to solve the conventional problems as described above, the object is the stress acting on the pipeline from the external force (pipe load, wave, tide, etc.) during the laying of the pipeline settled from the sea working line to the sea floor The present invention provides a stress measuring method and a stress measuring device for acquiring information in real time and performing laying work within a stable allowable stress range.

In addition, the present invention is to provide a stress measuring device having a sensing means that is difficult to write an electrical signal, and can secure a stress measurement value of a remote point hundreds to thousands of meters away.

The present invention for achieving the above-mentioned problems and to remove the conventional drawbacks is to move the work line of the sea, and to sediment injection of the pre-fabricated pipeline into the water when laying the pipeline on the seabed, from the sea line The actual stress of the pipeline from the stress information of the sensing pipe interlocked with the pipeline being laid by using the sensing pipe disposed inside the pipeline laid in the direction and having a plurality of sensors in its longitudinal and circumferential directions. Characterized in that the information is obtained in real time.

At this time, the sensor, so as to obtain the stress information of the pipeline by the optical fiber sensor for measuring the amount of elongation or shrinkage according to the change in curvature of the sensing pipe in conjunction with the change in curvature of the sinking pipeline.

From the above means, the present invention collects the stress information for each position in the longitudinal direction and the circumferential direction of the pipeline being settled from the sea to the sea floor in real time, so that the stable stress of the pipeline during the laying operation can be continuously implemented, laying It is possible to prevent damage to the pipeline during operation, which can further improve the efficiency of laying work.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

2 is a schematic view showing the laying of the subsea pipeline according to an embodiment of the present invention, Figure 3 is a longitudinal cross-sectional view (a) and a cross-sectional view (b) of the detection pipe according to an embodiment of the present invention, 2 and 3, the stress measurement of the pipeline according to the present invention, so that it is possible to detect in real time the stress generated during the laying of the pipeline (P) rather than after the laying of the pipeline (P) According to the present invention, the stress measuring device according to the present invention is fixed to the tip of the pipeline P before being settled from the sea working line (see FIG. 1), and is being laid (sedimented). It is to be provided with a sensing pipe 20 located in the pipeline (P).

The detection pipe 20 according to the present invention is to have a length enough to reach the pipeline (P) is laid (settled) completed on the seabed from the work line 1 of the sea. One end of the sensing pipe 20 is fixed to the working line 1 of the sea, and the other end 20a located inside the pipeline P being laid (settled) is laid (settled) to the seabed. It consists of a free end extending to the pipeline (P) to be located.

That is, the stress measurement of the pipeline P being laid (settled) away from the working line 1 of the sea according to the present invention toward the sea floor is provided with a sensing pipe 20 interlocked with the pipeline P, By acquiring the stress information of the sensing pipe 20, the actual stress information of the pipeline P being laid is calculated and obtained from the stress information of the sensing pipe 20.

At this time, the work line 1 of the sea continuously collects the stress change for a specific point (circumferential direction and longitudinal direction) for the pipeline (P) being laid (settled) through the detection pipe 20, and processing this And a controller 30 for displaying.

As shown in FIG. 3, the sensing pipe 20 according to the present invention includes a plurality of sensors 10 along its longitudinal and circumferential directions. The sensor 10 has a proportional number of installations in its longitudinal and circumferential directions in proportion to its accuracy and precision, and does not limit the installation interval of each sensor 10.

The sensing pipe 20 is placed at the center of the initial pipeline P, and is injected into the water at the same rate as the settling speed of the pipeline P, and the free end 20a is placed near the sea bottom. (Sedimentation) After being injected to extend to the completed pipeline P, the injection of the detection pipe 20 is stopped, and thus, the detection pipe positioned between the sea work line 1 and the seabed pipeline P ( By using 20), the stress information of the pipeline (P) that is continuously laid (settled) in conjunction with the movement of the work line 1 is obtained.

For example, as shown in Figure 2, at the "A" or "B" point that causes a lot of stress changes during laying, depending on the degree of deflection (curvature change) of the pipeline (P) to lay (settling) therein Sense pipe 20 is also located in close proximity to or close to one side of the inner peripheral surface of the pipeline (P).

That is, Figure 4 shows a longitudinal cross-sectional view (a) and a cross-sectional view (b) showing the shape of the sensing pipe at the point where such a large curvature change, that is, a stress change, as shown above, the pipeline (P) The detection pipe 20 which is deformed in correspondence with the degree of deformation of the c) collects information on the elongation or shrinkage of the detection pipe 20 through the sensor 10 installed in the longitudinal direction and the circumferential direction. From the obtained information, the control unit 30 of the marine work line 1 can compare and obtain the stress information of the pipeline P from the stress information of the sensing pipe 20.

The stress information through the sensor 10 of the sensing pipe 20 continuously acquires stress information about the longitudinal direction and the circumferential direction of the pipeline P being laid (settled) continuously toward the sea floor.

Various sensors may be provided as the sensor 10 provided in the sensing pipe 20 to measure the degree of change in the elongation or shrinkage of the sensing pipe 20, but preferably the length of the sensing pipe 20 is continuous. It is preferable to use an optical fiber sensor provided in the optical fiber. That is, by installing a plurality of optical fiber sensors that are easy to install in the longitudinal direction in the circumferential direction on the inner circumferential surface of the sensing pipe 20, elongation to a specific point in the longitudinal direction and the circumferential direction for the sensing pipe 20 or The amount of shrinkage can be obtained.

When the optical fiber sensor is extended by an external force (change in the curvature (d) of the pipeline), the cross-sectional area of the optical fiber is reduced, and thus the degree of light passage is detected (LAM: light attenuation method). It is widely used in the precision industry. Due to the adoption of the optical fiber sensor, the control unit 30 according to the present invention should additionally include an optical signal generator, an optical signal collector, and an optical signal processor. In addition, the detailed description by the optical fiber sensor that is used for the common, conventional will be omitted.

Ideally, the diameter of the sensing pipe 20 according to the present invention is formed to substantially coincide with the inner diameter of the pipeline P, so that the stress change of the pipeline P through the sensors 10 arranged at equal intervals in the circumferential direction thereof. It is possible to collect more accurate stress information of the sensing pipe 20 to be interlocked with the same, but the load of the sensing pipe 20 is added to increase the stress change of the pipeline (P) to be laid or its installation And the diameter of the sensing pipe 20 should be determined in consideration of the difficulties of the removal operation.

On the other hand, Figure 5 shows a cross-sectional schematic diagram of the pipeline according to another embodiment of the present invention, the sense pipe 20 according to the present invention, the pipeline (P) of the pipeline (P) at the time of laying the pipeline (P) In order to prevent damage to the detection pipe 20 in contact with the inner circumferential surface, and to facilitate the separation and recovery of the detection pipe 20 from the pipeline (P) that has been laid later, It is preferable to provide rollers 21 which can be provided in the circumferential direction and the longitudinal direction thereof.

Referring to the working steps using the stress measuring device of the pipeline according to the above structure as follows.

First, after moving the pre-fabricated short length pipe to the sea, the work line is positioned at the installation start position of the subsea pipeline P, and then the detection pipe at the center of the pipeline P initially laid (settled). The tip 20a of 20 is located.

Subsequently, the worker of the working ship welds and joins a short length of pipe and continuously sinks the pipeline P in water in connection with the movement of the position of the simultaneous working ship that manufactures the pipeline P, together with the sensor 10. The detection pipe 20 with the built-in is also injected into the water in the same way as the sedimentation rate of the pipeline (P), wherein the detection pipe 20 is a portion where a large stress of the pipeline (P), that is, laying (sedimentation) Only the stress information from the sea to the sea floor is enough to obtain the stress information of the pipeline (P) in progress, the detection pipe 20 injected with the initial pipeline (P) as described above is free When the tip 20a, which is a stage, reaches the submarine pipeline P which has been laid (sedimented), further injection is stopped, and a state fixed to the work line 1 is achieved.

The detection pipe 20 which is in this position-fixed state then causes a change in stress in response to the stress information (change in curvature d) of the pipeline P, which is subsequently laid down (settled). The sensor 10 continuously collects the stress change of 20 in real time, so as to continuously obtain actual stress information on the longitudinal and circumferential directions of the pipeline P being laid (settled) from the collected values. Will be.

In this way, the control unit 30 in which the stress information of the pipeline P being laid (settled) is collected is the operator when the corresponding portion of the pipeline P exceeds the stable (allowable) range of the stress from preset limit information. By adjusting the laying work of the pipeline P such as the moving speed of the work line 1 and the underwater filling speed of the pipeline P, the damage of the pipeline P being laid can be prevented in advance. If there is a concern that the situation may be caused, the laying work should be stopped immediately.

Subsequently, after the laying of the subsea pipeline P is completed, the detection pipe 20 according to the present invention is separated and recovered from the pipeline P laid on the sea bed using a winch or the like.

The present invention is not limited to the above-described specific preferred embodiments, and various modifications can be made by any person having ordinary skill in the art without departing from the gist of the present invention claimed in the claims. Of course, such changes will fall within the scope of the claims.

1 is a schematic view showing the installation work of the conventional subsea pipe pine

Figure 2 is a schematic diagram showing the laying work of the subsea pipeline according to an embodiment of the present invention

3 is a schematic cross-sectional view of a sensing pipe according to an embodiment of the present invention.

Figure 4 is a schematic cross-sectional view according to the operating state of the detection pipe according to an embodiment of the present invention

5 is a cross-sectional schematic diagram of a pipeline according to another embodiment of the present invention.

<Description of the symbols for the main parts of the drawings>

(P): pipeline

(1): Working ship (laying ship)

10.sensor

(20): detection pipe

21: roller

30: control unit

Claims (7)

In the apparatus for measuring the stress generated in the pipeline (P) during the laying of the pipeline by laying down the pre-fabricated pipeline in the water by moving the working line of the sea, Arranged inside the pipeline (P) laying away from the working line toward the sea floor, comprising a sensing pipe 20 having a plurality of sensors 10 in the longitudinal direction and the circumferential direction Stress measuring device of pipeline during laying of subsea pipeline. The method of claim 1, wherein the sensor 10, Stress measuring apparatus of the pipeline during laying of the subsea pipeline, characterized in that to measure the amount of elongation or shrinkage with respect to the curvature change of the sensing pipe 20 in conjunction with the change in curvature of the pipeline during laying. The method of claim 2, wherein the sensor 10, Stress measuring apparatus of pipeline during laying of subsea pipeline, characterized in that it is an optical fiber sensor. The method of claim 1, The sensing pipe 20 is disposed at the center of the pipeline P which is separated from the working ship into the water, and the stress of the pipeline during laying of the subsea pipeline is characterized in that the free end is configured to extend to the sea bottom. Instrumentation. The method of claim 1, Stress measuring apparatus of the pipeline during laying of the subsea pipeline, characterized in that the outer circumferential surface of the detection pipe 20, a plurality of rollers 21 is provided in close contact with the inner circumferential surface of the pipeline. When moving the work line of the sea, and pre-fabricated pipeline is sedimented and injected into the sea to install the pipeline on the sea floor, it is disposed inside the pipeline P being laid from the work line toward the sea floor, the longitudinal direction And the actual stress of the pipeline P from the stress information of the sensing pipe 20 interlocked with the pipeline P being laid by using the sensing pipe 20 having a plurality of sensors 10 in the circumferential direction. Stress measurement method of the pipeline during laying of the subsea pipeline, characterized in that to obtain information. The method of claim 6, When measuring the stress of the sensing pipe 20 through the plurality of sensors 10, the seabed characterized in that it detects the curvature change of the bending detection pipe 20 in conjunction with the change in the curvature of the pipeline (P) in laying Method of measuring the stress of the pipeline during laying of the pipeline.

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