Measuring equipment and method for underwater expansion bend

Abstract

The invention belongs to the field of ocean engineering, particularly relates to a measuring device and method for an underwater expansion bend, and aims to solve the problems that a traditional mechanical flange measuring instrument is low in measuring precision and large in measuring error. The device comprises a flange clamping and positioning mechanism, a flange distance measuring mechanism, an underwater optical fiber compass, a universal gradienter, a depth finder and a horizontal angle measuring mechanism, data measured by the depth finder, the underwater optical fiber compass, the universal gradienter, the measuring steel wire rope and the horizontal angle measuring mechanism are sorted, calculated and corrected, so that accurate size data of the underwater expansion bend are obtained. The problem that data measured by traditional mechanical measuring equipment cannot meet the long-distance large-size expansion bend installation requirement is solved, so that secondary reworking treatment caused by the fact that the prefabricated size of the underwater expansion bend does not meet the installation requirement is avoided, and the measurement precision of the underwater expansion bend reaches + / -0.2 degrees; precise prefabrication and efficient installation of the underwater expansion bend are guaranteed.

Description

Technical Field

[0001] The invention belongs to the field of marine engineering, and in particular relates to a device and a method for measuring an underwater expansion bend. Background Art

[0002] The underwater expansion bend is composed of flange, curved pipe section and straight pipe section, which is used to connect the platform riser and the submarine pipeline to absorb the deformation caused by thermal expansion and contraction of the submarine pipeline. After the installation of the offshore platform riser is completed, the trenching depth of the submarine pipeline meets the design requirements and then the underwater expansion bend is installed. Usually, the expansion bend is measured by a mechanical flange measuring instrument. Figure 1 First, measure the relative distance and angle between the end face of the submarine pipeline flange and the end face of the riser flange. Based on the measured data, prefabricate the underwater expansion bend on land or on a ship, and then install it by lowering it by a crane.

[0003] The expansion bend measurement requires the installation of a mechanical flange measuring instrument on the two fixed end flanges underwater. The wire rope is tightened by a tension tightener to measure the straight-line distance between the two flanges. The horizontal and vertical angles of the two flange measuring instruments can also be obtained. Figure 1 The three-dimensional size of the underwater expansion bend is calculated according to the measured distance and angle parameters, and the underwater expansion bend is prefabricated on the deck according to the measured data. The prefabricated expansion bend is installed on the two fixed end flanges to complete the installation of the expansion bend.

[0004] In the process of underwater expansion bend measurement, factors such as the weight and tightening force of the wire rope, ocean currents, the posture of the submarine pipeline, and the accuracy of the measuring instrument itself all have a significant impact on the measurement results. The larger the size of the underwater expansion bend, the more obvious the impact of these factors. At present, the measurement accuracy of traditional mechanical flange measuring instruments is 1°. When the measuring distance is 45m, the measurement distance error can reach about 70cm. In addition, it is equally important to eliminate the measurement error and accurately calculate the three-dimensional size of the expansion bend. Based on this, the present invention provides a device and method for measuring underwater expansion bends. Summary of the invention

[0005] In order to solve the above problems in the prior art, namely, the low measurement accuracy and large measurement error of the traditional mechanical flange measuring instrument, the present invention provides an underwater expansion bend measurement device and method.

[0006] In one aspect of the present invention, there is provided an underwater expansion bend measuring device, the device comprising: a flange clamping and positioning mechanism, a flange distance measuring mechanism, an underwater optical fiber compass, a universal level, a depth sounder, a horizontal angle measuring mechanism, and a measuring wire rope;

[0007] The flange clamping and positioning mechanism is fixed to the flange, the flange is fixed to the submarine pipeline, the underwater fiber optic compass is installed on the central axis of the flange clamping and positioning mechanism, the universal level and the depth sounder are installed on the plane of the flange clamping and positioning mechanism, the universal level is used to adjust the positional relationship of the flange clamping and positioning mechanism on the flange, and the depth sounder is used to measure the height from the flange to the water surface;

[0008] The horizontal angle measuring mechanism is fixed to the plane of the flange clamping and positioning mechanism, the horizontal angle measuring mechanism is rotatably connected to the flange distance measuring mechanism, and a measuring wire rope is connected to the horizontal angle measuring mechanism, and the measuring wire rope is used to measure the distance between the two flanges.

[0009] In some preferred embodiments, the flange clamping and positioning mechanism includes a base, a bracket, and a vertical arc groove plate;

[0010] The base is fixed to the bracket by means of positioning screws, two ends of the bracket are tangent to the outer circumferential surface of the submarine pipeline, and the vertical arc groove plate is fixed to the flange by means of bolts.

[0011] In some preferred embodiments, the flange distance measuring mechanism includes a vertical rotating shaft, a vertical mandrel, a bearing bush, a round nut, and a lifting ring;

[0012] The vertical rotating shaft is rotatably connected to the vertical core shaft through the bearing; the vertical rotating shaft is connected to the horizontal angle measuring mechanism, and the round nut is threadedly connected to the upper end surface of the vertical core shaft; the lifting ring is threadedly connected to the vertical core shaft, and the outer circumferential surface of the vertical rotating shaft is fixed to the measuring wire rope.

[0013] In some preferred embodiments, the horizontal angle measurement mechanism includes a horizontal angle dial and a horizontal angle measurement pointer;

[0014] The horizontal angle dial is fixed to the base, and the horizontal angle dial is coaxially fixed to the vertical core shaft, and angle grooves are set at each interval on the horizontal angle dial; the horizontal angle measuring pointer is fixed to the central axis of the outer circumferential surface of the vertical rotating shaft, and the horizontal angle measuring pointer is used to point to the horizontal angle dial, and the rotation angle of the horizontal angle measuring pointer is the horizontal angle of the flange.

[0015] In some preferred embodiments, the underwater fiber optic compass is used to measure the azimuth of an underwater structure, and the underwater fiber optic compass is fixed to the central axis of the base by positioning bolts.

[0016] In some preferred embodiments, the universal level is used to adjust the horizontality of the flange clamping and positioning mechanism on the flange and to measure the vertical tilt angle of the flange, and the universal level is fixed to the plane of the base by bolts.

[0017] In some preferred embodiments, a float is provided on the measuring wire rope at a set distance, and the float is used to provide buoyancy to offset the overhanging effect of the measuring wire rope due to gravity when a preset tension is tightened underwater.

[0018] Another aspect of the present invention provides a method for measuring an underwater expansion bend, based on an underwater expansion bend measuring device, the method comprising the following steps:

[0019] Step S10, arranging a plurality of floating balls at intervals on the measuring wire rope;

[0020] Step S20, installing the device on the two flanges, and fixing the measuring wire rope to the A and B ends of the vertical rotating shaft of the flange distance measuring mechanism respectively;

[0021] Step S30, tightening the measuring wire rope using a preset tension;

[0022] Step S40, measuring the actual length L of the measuring wire rope;

[0023] Step S50: Use the horizontal angle pointer to measure the horizontal angles ɑ1 and ɑ2 of the two flanges at the position of the horizontal angle dial, and use the underwater fiber optic compass to measure the angle between them relative to the true north direction, that is, ɑ 绝对角度1 、ɑ 绝对角度2 , 水平夹角 =|ɑ 绝对角度1 -ɑ 绝对角度2 |, the said 水平夹角 By comparing the values ​​with |ɑ1-ɑ2| through multiple groups of measurements, the horizontal angles of the flange, the submarine pipeline and the platform riser are checked, and the horizontal angles are corrected when the underwater expansion bend is prefabricated;

[0024] Step S60, calculating the vertical inclination angles γ1 and γ2 between the flange and the sea pipe according to the bubble degree of the universal level, that is, determining the upward or downward elevation angle between the flange and the sea pipe;

[0025] Step S70: derive the heights L from the two flanges to the water surface, respectively, based on the measurement data of the depth sounder. 水深1 , L 水深2 , the vertical height L1 between the two flanges is calculated to be L 水深1 -L 水深2 |;

[0026] Step S80: According to the vertical height L1 of the underwater expansion bend and the actual length L of the measuring wire rope, the vertical angle γ between the two flanges and the horizontal slant distance L2 between the two flanges are obtained by inverse trigonometric function. According to the values ​​of the vertical inclination angles γ1 and γ2, the vertical inclination angles of the two flanges are calculated, that is, γ 实际1 =|γ±γ1|,γ 实际2 =|γ±γ2| represents the actual vertical angle of the two flanges, and the vertical inclination angle is corrected during the underwater expansion bend prefabrication process.

[0027] In some preferred embodiments, the measured horizontal angles ɑ1 and ɑ2 of any of the horizontal angle measurement structures are used as calculation values, and the horizontal slant distance L2 between the flanges is calculated by trigonometric function to obtain the length L3 and width L4 of the underwater expansion bend, and the vertical inclination angles γ1 and γ2 between the two flanges and the horizontal angle ɑ 水平夹角 Be corrected.

[0028] In some preferred embodiments, the inclination angle between the two flanges and the horizontal angle ɑ 水平夹角 The method to correct it is:

[0029] The length L3, width L4, height L1 of the underwater expansion bend obtained by measuring the data, as well as the inclination angle between the two flanges and the horizontal angle ɑ between the flanges 水平夹角 , in the underwater expansion bend prefabrication link, the inclination angle between the two flanges and the horizontal angle ɑ 水平夹角 Corrections should be made to ensure the accuracy of prefabrication of underwater expansion bends.

[0030] Beneficial effects of the present invention:

[0031] The present invention arranges floats at intervals on the measuring wire rope, and the buoyancy provided by the floats offsets the gravity effect of the underwater wire rope, thereby reducing the error in the measured wire rope length caused by the sag of the wire rope after tightening the wire rope. The measuring equipment integrates a universal level, a depth sounder, a horizontal angle measuring mechanism, an underwater optical fiber compass, etc., to meet the measurement accuracy under turbid water conditions, proposes a calculation method for the three-dimensional size of the underwater expansion bend, and corrects the expansion bend measurement error caused by factors such as the underwater sag of the wire rope, the posture of the submarine pipeline, and the accuracy of the measuring instrument itself. The measurement error is reduced to ±0.2°, and the size error does not exceed 15cm, thereby ensuring the accuracy of underwater measurement data and improving the installation success rate of the underwater expansion bend. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Other features, objects and advantages of the present application will become more apparent by reading the detailed description of non-limiting embodiments made with reference to the following drawings:

[0033] Figure 1 It is a schematic diagram of the traditional mechanical underwater expansion bend measurement method;

[0034] Figure 2 It is a first-view axonometric diagram of an underwater expansion bend measuring device of the present invention;

[0035] Figure 3 It is a second perspective axonometric diagram of an underwater expansion bend measuring device of the present invention;

[0036] Figure 4 It is a cross-sectional view of a flange distance measuring mechanism in an underwater expansion bend measuring device of the present invention;

[0037] Figure 5 It is a schematic diagram of the installation of an underwater expansion bend measuring device of the present invention;

[0038] Figure 6 It is a top view of a horizontal angle measuring mechanism of an underwater expansion bend measuring device of the present invention;

[0039] Figure 7 It is a schematic diagram of a vertical angle calculation method of an underwater expansion bend measuring device of the present invention;

[0040] Figure 8 It is a schematic diagram of a method for calculating the horizontal angle of an underwater expansion bend measuring device of the present invention. DETAILED DESCRIPTION

[0041] The present application will be further described in detail below in conjunction with the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are only used to explain the relevant invention, rather than to limit the invention. It is also necessary to explain that, for ease of description, only the parts related to the relevant invention are shown in the accompanying drawings.

[0042] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0043] like Figure 2-8 As shown, see Figure 2 , a first embodiment of the present invention is an underwater expansion bend measuring device, the device comprises: a flange clamping and positioning mechanism 1, a flange distance measuring mechanism 2, an underwater optical fiber compass 3, a universal level 4, a depth sounder 5, a horizontal angle measuring mechanism 8, and a measuring wire rope 9;

[0044] The flange clamping and positioning mechanism 1 is fixed to the flange 6, the flange 6 is fixed to the submarine pipeline 7, the underwater optical fiber compass 3 is installed on the central axis of the flange clamping and positioning mechanism 1, the universal level 4 and the depth sounder 5 are installed on the plane of the flange clamping and positioning mechanism 1, the universal level 4 is used to adjust the position relationship of the flange clamping and positioning mechanism 1 on the flange 6, and the depth sounder 5 is used to measure the height from the flange 6 to the water surface;

[0045] The horizontal angle measuring mechanism 8 is fixed to the plane of the flange clamping and positioning mechanism 1, and the horizontal angle measuring mechanism 8 is rotationally connected to the flange distance measuring mechanism 2. The horizontal angle measuring mechanism 8 is connected to a measuring wire rope 9, and the measuring wire rope 9 is used to measure the distance between the two flanges 6.

[0046] The flange 6 is fixed to the submarine pipeline 7 by welding. The flange 6 and the submarine pipeline 7 are welded together before the submarine pipeline or underwater manifold is installed, and then the whole is installed underwater.

[0047] In this embodiment, the flange clamping and positioning mechanism 1 is fixed to the flange 6 by bolts, and the flange 6 is fixed to the submarine pipeline 7 by welding.

[0048] Preferably, see Figure 3 The flange clamping and positioning mechanism 1 includes a base 11, a bracket 12, and a vertical arc groove plate 13;

[0049] The base 11 is fixed to the bracket 12 by means of positioning screws, both ends of the bracket 12 are tangent to the outer circumference of the submarine pipeline 7, and the vertical arc groove plate 13 is fixed to the flange 6 by means of bolts.

[0050] Preferably, see Figure 3 , Figure 4 The flange distance measuring mechanism 2 includes a vertical rotating shaft 21, a vertical core shaft 22, a bearing bush 23, a round nut 24, and a lifting ring 25;

[0051] The vertical rotating shaft 21 is rotatably connected to the vertical core shaft 22 through the bearing 23; the vertical rotating shaft 21 is connected to the horizontal angle measuring mechanism 8, and the round nut 24 is threadedly connected to the upper end surface of the vertical core shaft 22; the lifting ring 25 is threadedly connected to the vertical core shaft 22, and the outer circumferential surface of the vertical rotating shaft 21 is fixed to the measuring wire rope 9.

[0052] Preferably, see Figure 3 , Figure 4 , Figure 5 , Figure 6 , the horizontal angle measuring mechanism 8 includes a horizontal angle dial 81 and a horizontal angle measuring pointer 26;

[0053] The horizontal angle dial 81 is fixed to the base 11, and the horizontal angle dial 81 is coaxially fixed to the vertical core shaft 22, and angle grooves are set at each interval on the horizontal angle dial 81; the horizontal angle measuring pointer 26 is fixed to the central axis of the outer circumferential surface of the vertical rotating shaft 21, and the horizontal angle measuring pointer 26 is used to point to the horizontal angle dial 81, and the rotation angle of the horizontal angle measuring pointer 26 is the horizontal angle of the flange 6.

[0054] The set horizontal angle is -60° to 0°, 0°-60°, and in this embodiment, the degree of adjacent scale grooves is preferably 0.5°.

[0055] After a predetermined tension is applied to the measuring wire rope 9 , the horizontal angle measuring pointer 26 rotates synchronously with the vertical rotating shaft 21 around the vertical core shaft 22 , so that the horizontal angle measuring pointer 26 points on the horizontal angle dial 81 .

[0056] Preferably, see Figure 2 The underwater fiber optic compass 3 is used to measure the azimuth of the underwater structure. The underwater fiber optic compass 3 is fixed on the central axis of the base 11 by positioning bolts.

[0057] Preferably, see Figure 2 The universal level 4 is used to adjust the horizontality of the flange clamping and positioning mechanism 1 on the flange 6 and measure the vertical tilt angle of the flange. The universal level 4 is fixed to the plane of the base 11 by bolts.

[0058] Preferably, see Figure 5 A float 10 is arranged on the measuring wire rope 9 at a set distance, and the float 10 is used to provide buoyancy to offset the drooping effect of the measuring wire rope 9 due to gravity when the preset tension is tightened underwater.

[0059] The set distance can be adjusted arbitrarily according to the buoyancy of the measuring wire rope 9 .

[0060] like Figure 2-8 As shown, the second embodiment of the present invention provides a method for measuring an underwater expansion bend, based on an underwater expansion bend measuring device, the method comprises the following steps:

[0061] Step S10, arranging a plurality of floating balls 10 at intervals on the measuring wire rope 9;

[0062] Step S20, installing the device on the two flanges 6, and fixing the measuring wire rope 9 to the A and B ends of the vertical rotating shaft 21 of the flange distance measuring mechanism 2 respectively;

[0063] Step S30, tightening the measuring steel wire rope 9 using a preset tension;

[0064] Step S40, measuring the actual length L of the measuring steel wire rope 9;

[0065] Step S50: Use the horizontal angle pointer 26 to measure the horizontal angles ɑ1 and ɑ2 of the two flanges 6 at the position of the horizontal angle dial 81, and use the underwater optical fiber compass 3 to measure the angle between them relative to the true north direction, that is, ɑ 绝对角度1 、ɑ 绝对角度2 , 水平夹角 =|ɑ 绝对角度1 -ɑ 绝对角度2 |, the said 水平夹角 By comparing the values ​​of |ɑ1-ɑ2| with multiple groups of measurements, the horizontal angles of the flange 6, the submarine pipeline 7 and the platform riser are checked, and the horizontal angles are corrected when the underwater expansion bend is prefabricated;

[0066] Step S60, calculating the vertical inclination angles γ1 and γ2 between the flange 6 and the sea pipe 7 according to the bubble degree of the universal level 4, that is, determining the upward or downward elevation angle between the flange 6 and the sea pipe 7;

[0067] Step S70: According to the measurement data of the depth sounder 5, the height L of the two flanges 6 to the water surface is obtained respectively. 水深1 , L 水深2 , the vertical height L1 between the two flanges 6 is calculated to be L 水深1 -L 水深2 |;

[0068] Step S80: According to the vertical height L1 of the underwater expansion bend and the actual length L of the measuring wire rope 9, the vertical angle γ between the two flanges 6 and the horizontal slant distance L2 between the two flanges 6 are obtained by inverse trigonometric function. According to the values ​​of the vertical inclination angles γ1 and γ2, the vertical inclination angles of the two flanges 6 are calculated, that is, γ 实际1 =|γ±γ1|,γ 实际2 =|γ±γ2| represents the actual vertical angle of the two flanges 6, and the vertical inclination angle is corrected during the underwater expansion bend prefabrication process.

[0069] Preferably, the horizontal angles ɑ1 and ɑ2 measured by any of the horizontal angle measuring structures 8 are used as calculation values, and the horizontal slant distance L2 between the flange 6 is calculated by trigonometric function to obtain the length L3 and width L4 of the underwater expansion bend, and the vertical inclination angles γ1 and γ2 between the two flanges 6 and the horizontal angle ɑ 水平夹角 To be corrected.

[0070] Preferably, the vertical inclination angles γ1 and γ2 between the two flanges 6 and the horizontal angle ɑ 水平夹角 The method to correct it is:

[0071] The length L3, width L4, height L1, vertical angle γ, horizontal angles ɑ1, ɑ2 of the underwater expansion bend obtained by measuring the data, as well as the vertical inclination angles γ1, γ2 between the two flanges 6 and the horizontal angle ɑ between the flanges 6 水平夹角 In the underwater expansion bend prefabrication process, the vertical inclination angles γ1 and γ2 and the horizontal angle ɑ between the two flanges 6 are respectively adjusted. 水平夹角 Corrections should be made to ensure the accuracy of prefabrication of underwater expansion bends.

[0072] The terms "first", "second", etc. are used to distinguish similar objects rather than to describe or indicate a particular order or sequence.

[0073] The term "comprise" or any other similar term is intended to cover a non-exclusive inclusion such that a process, method, article, or apparatus that includes a list of elements includes not only those elements but also other elements not expressly listed or inherent to such process, method, article, or apparatus.

[0074] So far, the technical solutions of the present invention have been described in conjunction with the preferred embodiments shown in the accompanying drawings. However, it is easy for those skilled in the art to understand that the protection scope of the present invention is obviously not limited to these specific embodiments. Without departing from the principle of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will fall within the protection scope of the present invention.

Claims

1. An underwater expansion bend measuring device, characterized in that: The device comprises: a flange clamping and positioning mechanism (1), a flange distance measuring mechanism (2), an underwater optical fiber compass (3), a universal level (4), a depth sounder (5), a horizontal angle measuring mechanism (8), and a measuring wire rope (9); The flange clamping and positioning mechanism (1) is fixed to the flange (6), the flange (6) is fixed to the seabed pipeline (7), the underwater optical fiber compass (3) is installed on the central axis of the flange clamping and positioning mechanism (1), the universal level (4) and the depth sounder (5) are installed on the plane of the flange clamping and positioning mechanism (1), the universal level (4) is used to adjust the positional relationship of the flange clamping and positioning mechanism (1) on the flange (6), and the depth sounder (5) is used to measure the height from the flange (6) to the water surface; The horizontal angle measuring mechanism (8) is fixed to the plane of the flange clamping and positioning mechanism (1), the horizontal angle measuring mechanism (8) is rotationally connected to the flange distance measuring mechanism (2), and a measuring wire rope (9) is connected to the flange distance measuring mechanism (2), and the measuring wire rope (9) is used to measure the distance between the two flanges (6).

2. The underwater expansion bend measuring device according to claim 1, characterized in that: The flange clamping and positioning mechanism (1) comprises a base (11), a bracket (12), and a vertical arc groove plate (13); The base (11) is fixed to the bracket (12) by means of positioning screws, the two ends of the bracket (12) are tangent to the outer circumference of the submarine pipeline (7), and the vertical arc groove plate (13) is fixed to the flange (6) by means of bolts.

3. The underwater expansion bend measuring device according to claim 2, characterized in that: The flange distance measuring mechanism (2) comprises a vertical rotating shaft (21), a vertical core shaft (22), a bearing bush (23), a round nut (24), and a lifting ring (25); The vertical rotating shaft (21) is rotatably connected to the vertical core shaft (22) through the bearing (23); the vertical rotating shaft (21) is connected to the horizontal angle measuring mechanism (8), and the round nut (24) is threadedly connected to the upper end surface of the vertical core shaft (22); the lifting ring (25) is threadedly connected to the vertical core shaft (22), and the outer circumferential surface of the vertical rotating shaft (21) is fixed to the measuring wire rope (9).

4. The underwater expansion bend measuring device according to claim 3, characterized in that: The horizontal angle measuring mechanism (8) comprises a horizontal angle scale (81) and a horizontal angle measuring pointer (26); The horizontal angle dial (81) is fixed to the base (11), the horizontal angle dial (81) is coaxially fixed to the vertical core shaft (22), and angle grooves are set at intervals on the horizontal angle dial (81); the horizontal angle measuring pointer (26) is fixed to the central axis of the outer circumferential surface of the vertical rotating shaft (21), the horizontal angle measuring pointer (26) is used to point to the horizontal angle dial (81), and the rotation angle of the horizontal angle measuring pointer (26) is the horizontal angle of the flange (6).

5. The underwater expansion bend measuring device according to claim 4, characterized in that: The underwater optical fiber compass (3) is used to measure the azimuth of an underwater structure. The underwater optical fiber compass (3) is fixed on the central axis of the base (11) by means of positioning bolts.

6. The underwater expansion bend measuring device according to claim 5, characterized in that: The universal level (4) is used to adjust the horizontality of the flange clamping and positioning mechanism (1) on the flange (6) and to measure the vertical tilt angle of the flange (6). The universal level (4) is fixed on the plane of the base (11) by bolts.

7. The underwater expansion bend measuring device according to claim 6, characterized in that: A floating ball (10) is arranged on the measuring steel wire rope (9) at a set distance, and the floating ball (10) is used to provide buoyancy to offset the drooping effect of the measuring steel wire rope (9) due to gravity when a preset tension is tightened underwater.

8. A method for measuring an underwater swell bend, based on an underwater swell bend measuring device according to any one of claims 1 to 7, characterized in that: The method comprises the following steps: Step S10, arranging a plurality of floating balls (10) at intervals on the measuring steel wire rope (9); Step S20, installing the device on the two flanges (6), and fixing the measuring wire rope (9) on the A and B ends of the vertical rotating shaft (21) of the flange distance measuring mechanism (2); Step S30, tightening the measuring steel wire rope (9) using a preset tension; Step S40, measuring the actual length L of the measuring steel wire rope (9); Step S50: Use the horizontal angle pointer (26) to measure the horizontal angles ɑ1 and ɑ2 of the two flanges (6) at the position of the horizontal angle dial (81), and use the underwater optical fiber compass (3) to measure the angle between them relative to the true north direction, that is, ɑ 绝对角度1 、ɑ 绝对角度2 , 水平夹角 =|ɑ 绝对角度1 -ɑ 绝对角度2 |, the said ɑ 水平夹角 Comparing the values ​​with |ɑ1-ɑ2| through multiple groups of measurements to check the horizontal angles between the flange (6), the submarine pipeline (7) and the platform riser, and correcting the horizontal angles when the underwater expansion bend is prefabricated; Step S60, calculating the vertical inclination angles γ1 and γ2 between the flange (6) and the sea pipe (7) according to the bubble degree of the universal level (4), that is, determining the upward or downward elevation angle between the flange (6) and the sea pipe (7); Step S70: According to the measurement data of the depth sounder (5), the height L of the two flanges (6) to the water surface is obtained respectively. 水深1 , L 水深2 , the vertical height L1 between the two flanges (6) is calculated to be L 水深1 -L 水深2 |; Step S80: According to the vertical height L1 of the underwater expansion bend and the actual length L of the measuring wire rope (9), the vertical angle γ between the two flanges (6) and the horizontal slant distance L2 between the two flanges (6) are obtained by inverse trigonometric function, and the vertical inclination angles of the two flanges (6) are calculated according to the values ​​of the vertical inclination angles γ1 and γ2, that is, γ 实际1 =|γ±γ1|,γ 实际2 =|γ±γ2| represents the actual vertical angle of the two flanges (6), and the vertical inclination angle is corrected in the underwater expansion bend prefabrication link.

9. The method for measuring an underwater expansion bend according to claim 8, characterized in that: The horizontal angles ɑ1 and ɑ2 measured by any of the horizontal angle measurement structures (8) are used as calculation values, and the horizontal slant distance L2 between the flange (6) is calculated by trigonometric function to obtain the length L3 and width L4 of the underwater expansion bend, and the vertical inclination angles γ1 and γ2 between the two flanges (6) and the horizontal angle ɑ are calculated. 水平夹角 Be corrected.

10. The method for measuring underwater expansion bend according to claim 9, characterized in that: The vertical inclination angles γ1 and γ2 between the two flanges (6) and the horizontal angle ɑ 水平夹角 The method to correct it is: The length L3, width L4, height L1, vertical angle γ, horizontal angles ɑ1 and ɑ2 of the underwater expansion bend obtained by measuring the data, and the vertical inclination angles γ1 and γ2 between the two flanges (6) and the horizontal angle ɑ between the flanges (6) 水平夹角 In the underwater expansion bend prefabrication process, the vertical inclination angles γ1 and γ2 and the horizontal angle ɑ between the two flanges (6) are respectively adjusted. 水平夹角 Corrections should be made to ensure the accuracy of prefabrication of underwater expansion bends.

Images