KR20200029310A - Method for longitudinal inclining test for semi-submersible rig - Google Patents

Abstract

Provided is a longitudinal slope testing method for a semi-submersible rig ship. The slope testing method, which tests a slope of the semi-submersible rig ship including a hull comprising a pontoon part, a deck part and a column part connecting the pontoon part and the deck part, includes: a step (a) of draining ballast water of the pontoon part to position a draft line of the hull at a side surface of the pontoon part; and a step (b) of moving a load in a bow direction of the pontoon part or a stern direction of the pontoon part and changing the center of gravity of the hull by changing distribution of the ballast water of the column part.

Description

Method for longitudinal inclining test for semi-submersible rig}

The present invention relates to a method for inclining test of a ship, and more particularly, to a method for longitudinal inclining test of a semi-submersible rig ship.

Since the ship is a floating body floating on the sea, it is essential to predict the movement of the ship by external force to grasp and adjust the behavior of the ship smoothly. One of the basic information required for this is the center of gravity of the hull. The measurement of the center of gravity is very important because the hull rotates around the center of gravity and can be grasped based on the center of gravity even when the hull moves in translation.

To measure the center of gravity, a test method known as an inclination test is used. The center of gravity depends on the mass distribution of the hull and can vary depending on the density of each part of the hull or the shape of the hull. The center of gravity can be calculated from the model at the time of ship design, but the actual center of gravity of the dried ship may not match this for various reasons, so the inclination test is conducted directly from the ship as the final stage of ship construction.

However, there are many types of ships, and accordingly, the shape and structure of the hull are also diverse. Therefore, a more suitable or efficient test method may be required. For example, in the case of a vessel of a special shape such as a semi-submersible rig ship composed of a pontoon and a column instead of a general streamlined hull, measurement accuracy is reduced or unnecessary process is applied by applying the inclined test method that was generally performed before. As a result, inefficiencies and problems occurred.

Republic of Korea Patent Publication No. 10-2015-0050720, (2015. 05. 11)

The technical problem of the present invention is to solve this problem, and to provide a method for longitudinal inclination test of a semi-submersible rig line, through which the inclination test of a semi-submersible rig line is conducted more accurately and efficiently.

The technical problem of the present invention is not limited to the problems mentioned above, and other technical problems not mentioned will be clearly understood by those skilled in the art from the following description.

The longitudinal inclination test method of the semi-submersible rig ship according to the present invention comprises: a half-submersible comprising a hull consisting of a pontoon part, a deck part, and a column part connecting the pontoon part and the deck part. A method for inclining test of a semi-submersible rig, the method comprising: (a) draining the equilibrium water of the pontoon part and placing the water line of the hull on the side of the pontoon part; And (b) changing the equilibrium water distribution of the column part to move the load in the forward direction of the pontoon part or the stern direction of the pontoon part and changing the center of gravity of the hull.

In the step (a), the ballast water of the pontoon part is completely drained, and the ballast water of the column part (b) can be exchanged between a plurality of columns constituting the column part without being drained.

The ballast water of the step (b) is exchanged between at least two different columns constituting the column portion spaced apart in the longitudinal direction of the pontoon portion, so that the distribution can be changed in the longitudinal direction of the pontoon portion.

The pontoon portion is a twin-acting type consisting of at least two pontoons arranged side by side in the longitudinal direction. It can be exchanged between connected columns.

The ballast water of step (b) may be moved along the longitudinal pipe inside the pontoon part connected to at least two different columns constituting the column part.

Before the step (b), the step of constructing a hole for measuring the amount of movement of the ballast water above the column of the ballast tank may be further included.

Before the step (b), the hull may be further connected to the berth wall of the berthing facility and a rope to limit the movement radius.

ADVANTAGE OF THE INVENTION According to this invention, the inclination test of a ship can be performed more efficiently and more accurately. In particular, a new test method that utilizes the structural characteristics of the semi-submersible rig can more accurately measure the center of gravity of the semi-submersible rig and eliminate unnecessary processes to increase the efficiency of the slope test. In addition, it is possible to conveniently conduct an inclined test near the docking facilities on the coast, not to the deep-watered outward port, thus ensuring the safety and convenience of the test.

1 is a flow chart showing a longitudinal gradient test method of a semi-submersible rig line according to an embodiment of the present invention.
FIG. 2 is a side view of a semi-submersible rig line showing a slope test process according to the slope test method of FIG. 1.
3 is a front view of the semi-submersible rig line of FIG. 2.
4 is a rear view of the semi-submersible league ship of FIG. 2.
5 is a view showing the inclination test principle according to the inclination test method of the present invention.

Advantages and features of the present invention and methods for achieving them will be clarified with reference to embodiments described below in detail together with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but may be implemented in various different forms, and only the present embodiments allow the disclosure of the present invention to be complete and the ordinary knowledge in the art to which the present invention pertains. It is provided to fully inform the possessor of the scope of the invention, and the invention is only defined by the claims. Throughout the specification, the same reference numerals refer to the same components.

Hereinafter, with reference to Figures 1 to 5 will be described in detail with respect to the longitudinal gradient test method of the semi-submersible rig line according to an embodiment of the present invention. The description proceeds by referring to the remaining drawings together as necessary based on the flowchart of FIG. 1.

1 is a flow chart showing the longitudinal inclination test method of the semi-submersible rig line according to an embodiment of the present invention, Figure 2 is a side view of the semi-submersible rig line showing the inclination test process according to the inclination test method of Figure 1, 3 is a front view of the semi-submersible rig line of FIG. 2, FIG. 4 is a rear view of the semi-submersible rig line of FIG. 2, and FIG. 5 is a view showing the inclination test principle according to the inclination test method of the present invention. In FIGS. 2 to 4, the bow portion positioned in front of the hull (or equivalent to the pontoon portion) is labeled as 'F', and the stern portion positioned at the rear side is labeled as 'R'.

In addition, in this specification, the deck portion of the semi-submersible rig ship (see 10 in FIG. 2) may mean the entire structure including the upper deck of the hull and the derrick formed thereon (see 11 in FIG. 2). In addition, the pontoon part (see 30 in FIG. 2) may mean a buoyancy control structure (which may be formed in a streamlined or other various shapes) arranged in the horizontal direction at the lower end of the semi-submersible rig line. In addition, the column portion (see 20 in FIG. 2) may be formed of a connection structure having a shape such as a plurality of columns or legs connecting the deck portion and the pontoon portion, and the shape is not particularly limited.

1 and 2, the longitudinal inclination test method of a semi-submersible rig line according to the present invention is a method for finding a vertical center of gravity position of a semi-submersible rig line (see 1 in FIG. 2). It has the characteristic of moving the load in the longitudinal direction (the bow direction or the stern direction of the hull) rather than the lateral load movement. In particular, the movement of the load proceeds through a change in the distribution of the ballast water filled in the column portion (see 20 in FIG. 2) of the semi-submersible rig ship 1, so as to move it by placing a large weight on the upper deck as in the prior art It can solve many problems (long time, high cost, risk, etc.). In addition, in a unique way of floating the pontoon portion (see 30 in FIG. 2) at the bottom of the semi-submersible rig ship 1 and changing the distribution of the ballast water on the column portion 20, the hull by the pontoon portion 30 Through the effect of increasing the water plane, it is possible to secure both stability and measurement accuracy of the slope test. In addition, according to this, it is possible to conduct an inclination test as much as possible with a small draft, and it has the advantage of being able to conduct an inclination test more safely and conveniently near a shallow docking facility.

Specifically, the longitudinal inclination test method of the semi-submersible rig ship according to the present invention comprises a hull consisting of a pontoon part, a deck part, and a column part connecting a pontoon part and a deck part. In an inclination test method of a submersible rig (semi-submersible rig), (a) draining the ballast water of the pontoon part 30 to place the water line of the hull on the side of the pontoon part 30 (S200); And (b) changing the ballast distribution of the column part 20 to move the load in the forward direction of the pontoon part 30 or the stern direction of the pontoon part 30 and changing the center of gravity of the hull (S500). do. These steps can complete the gradient testing process by itself or in combination with other associated steps. Hereinafter, the entire inclination test process of the present invention including these steps will be described in more detail through an embodiment of the present invention.

First, a step (S100) of preparing a hull for an inclination test is performed. These steps are the process of removing various tools, residual water, residual oil, etc. mounted in the hull so that the pure self-weight of the semi-submersible rig 1 to be tested is known, and supply of electricity, gas, water, etc. previously installed in the hull. And dismantling and unloading the line. Through this process, the elements that can interfere with the measurement of the center of gravity are removed as much as possible, and only the minimum elements including inspection personnel and test equipment (such as a pendulum that can measure the angle of rotation inside the hull) are boarded in the hull.

Subsequently, the hull is fixed by connecting the hull of the berthing facility (see B in FIGS. 3 and 4) with a rope (S200), and draining the ballast water of the pontoon part 30 to reduce the water line of the hull to the pontoon part ( 30) It is located on the side (S300). That is, by moving the hull to a point adjacent to the inner wall B, the movement radius can be limited, and the draft of the hull can also be adjusted to the depth of the coast. That is, the inclination test of the present invention does not need to proceed by moving to a deep-water outer port, and thus can be conducted on the coast adjacent to the quay wall B in a state where the draft of the semi-submersible rig 1 is lowered. Therefore, there is no need to waste manpower and time in unnecessary processes such as considering weather conditions in an external port or mobilizing a number of tug boats to move an external port, etc., and is located around the inner wall B by the rope 33 The test can be carried out very safely.

At this time, the rope 33 may be connected using structures such as bollards formed on the pontoons 30 and the inner walls B, for example. The rope 33 means a member or structure on a line that is connected between the hull and the inner wall B and can transmit tension, and materials or shapes within these limits are not particularly limited. As shown in Figure 2, the rope 33 is connected to the central portion of the hull in the longitudinal direction can be formed so as not to limit the moment formed during the longitudinal load movement.

Then, the step (S400) of measuring the light weight proceeds. Light weight can be measured, for example, by measuring the draft directly from the inner wall (B) and using the drainage amount calculated therefrom. As described above, since there is no need to move to the outer port, by directly measuring the draft and the like around the inner wall B, the influence of unstable conditions on the sea can be excluded and the measurement process can be performed more conveniently and accurately. Through these steps, the light weight can be measured and compared to the design value. If necessary, the light weight can be repeatedly measured while changing the draft, and the number of repetitions can be appropriately adjusted.

Then, by changing the distribution of the ballast water of the column part 20, the load is moved in the forward direction or the stern direction of the pontoon part 30 (that is, in the longitudinal direction of the hull or equivalent pontoon part) and the center of gravity of the hull is changed. (S500). The ballast water is spaced apart in the longitudinal direction of the pontoon part 30 and exchanged between at least two different columns constituting the column part 20 (refer to FIG. 2). Therefore, for the longitudinal direction of the pontoon part 30, The distribution will change. The ballast water is, for example, a first ballast tank (21a) formed inside the first column (21) located on the bow side of the pontoon part (30), and the second column located on the stern side of the pontoon part (30) (22) can be exchanged between the second ballast tank (22a) formed therein, from the first ballast tank (21a) of the first column (21) to the second ballast tank (22a) of the second column (22) It can be moved or back again. The ballast water can be moved in this way by controlling a pump or the like in the hull. In particular, the longitudinal moment can be generated by moving the hull load of the semi-submersible rig line 1 and changing the center of gravity through exchange of ballast water between different columns. As will be described later, the position of the center of gravity of the hull can be calculated by calculating the relationship between the change in center of gravity and the moment as an equation. The detailed calculation process of the center of gravity position will be described later in more detail.

In particular, during the inclination test, the ballast water of the pontoon part 30 may be completely drained, and the ballast water of the column part 20 may not be drained as described above, but be exchanged between a plurality of columns constituting the column part 20. You can. For example, in the draft adjustment process of the above-described pontoon part 30, the ballast water of the pontoon part 30 is completely drained, and the ballast water of the column part 20 is input and output to adjust the draft of the hull. Thereafter, the ballast water of the column unit 20 may cause a longitudinal gradient while changing distribution without draining. Thus, by maintaining the floating state of the pontoon part 30 on the sea level by draining the ballast water of the pontoon part 30, compared to the case of semi-submersible riggers, which are generally kept submerged in the sea water up to the column part. You can secure a significantly larger water plane. Therefore, even if the buoyancy is increased by the increased water-repair area and the longitudinal inclination is caused, the hull is stably maintained and the measurement of the inclination angle described later can be made very accurately. In addition, by completely draining the seawater in the pontoon part 30, the fluid flow in the pontoon part 30 can be completely eliminated, so variables that adversely affect the measurement of the center of gravity, such as fluctuation of the center of gravity due to unnecessary fluid flow, are also removed in advance. can do.

The pontoon part 30 may be, for example, a catalytic type consisting of at least two pontoons 31 and 32 arranged side by side in the longitudinal direction, and the equilibrium number of columns connected to the player side of different pontoons 31 and 32 [ It can be exchanged between the above-described first column (21)] and the columns connected to the stern side of the different pontoons (31, 32) (may be the second column (22) described above). The exchange of ballast water between the columns can be controlled to proceed simultaneously and evenly in different pontoons 31 and 32, and through this, it can stably induce the longitudinal inclination of the hull made of the twin-type pontoon part 30. . In the case of the catamaran type, the pontoons 31 and 32 arranged side by side in the transverse direction can reduce unnecessary lateral fluctuations.

The ballast water 30 is connected to at least two different columns (which may be the first column 21 and the second column 22 described above) constituting the column unit 20 as shown in FIG. 2. ) It can be moved along the longitudinal pipe (30a) inside. That is, as described above, the pontoon part 30 is maintained in a drained state without receiving the ballast water in the inner ballast tank (not shown), but moves the ballast water between the different columns using the inner pipe 30a. Can provide. In order to measure the movement amount of the ballast water, a hole may be installed directly above the ballast tank of the column part 20, and the construction of the hole is before the ballast water distribution is changed, that is, the ballast water distribution of the column part 20 described above. It can be performed at an appropriate time before changing the center of gravity of the hull while moving the load in the forward or stern direction of the pontoon part 30 by changing. For example, a sounding pipe or the like in the ballast tank may be installed through the hole and measurement may be performed. It is also possible to measure other measured values, such as the flow rate of the ballast water, by using various measuring devices as necessary. Holes or other fixtures can be removed as needed after the slope test.

Thereafter, the longitudinal inclination angle of the hull is measured by the longitudinal moment of the hull generated according to the change in the distribution of the ballast water of the column 20, and the center of gravity is calculated therefrom (S600). That is, as described above, the pontoon part 30 is floated on the sea surface and the distribution of the ballast water of the column part 20 is changed to induce a longitudinal inclination of the hull and from this, the intended center of gravity of the hull can be calculated. The process of calculating the center of gravity will be described with reference to FIG. 5.

FIG. 5 illustrates a state in which the ballast water has moved from the first ballast tank 21a of the first column 21 to the second ballast tank 22a of the second column 22. When the ballast water is moved in this way, the ballast water distribution of the column part 20 is changed to the longitudinal direction of the hull (or equivalently, the pontoon part 30), causing the longitudinal inclination of the hull. Therefore, the angle of the sea level with respect to the hull is changed and the longitudinal inclination angle θ of the hull is generated. As described above, since the test is conducted while the pontoon part 30 floats on the sea level, the position of the sea level can also be generated and changed at the point where the pontoon part 30 is located, as shown. However, the sea level (A, A ') on the drawing is exaggerated to explain the principle, the actual sea level fluctuation and the magnitude of the resulting inclination angle may be a very small angle of about 1 degree. In FIG. 5, this situation is illustrated in the form of a relative positional change of sea level (A, A ') relative to the hull.

Referring to the drawings, the position of the center of gravity G to be measured is reduced to the length of the line segment KG, which is a vertical distance from the ship bottom point K. Since the line segment KG is the line segment KM, which is the height from the bottom point (K) to the meta center (M), is subtracted from the line segment GM, which is the length from the center of gravity (G) to the meta center (M), the following relational expression is obtained.

(Equation 1) KG = KM-GM

On the other hand, when the load moves within the hull, the mass distribution changes and the center of gravity fluctuates. At this time, the moving distance of the load (that is, the distance that the ballast water is moved and may be the distance between the two ballast tanks to which the ballast water is exchanged) is called d, and the moved load (ie, the weight of the ballast water moved) is called w , If the total weight of the hull (corresponding to the displacement) is W, the line segment GG ', which is the distance between the center of gravity (G) and the point of change (G') of the center of gravity, load w, and the distance d of the load, The following relationship is established between the total weight W of the hull.

(Equation 2) w × d = W × GG '

This refers to the equilibrium of the force of the buoyancy at the moment of movement of the hull relative to the center of gravity (G) caused by the movement of the load and at the point of change (G ') of the center of gravity moved from the original center of gravity (G). According to the geometrical relationship shown in the figure, the length of the double line segment GG 'may be approximated by multiplying the value of tanθ by the line segment GM, which is the distance between the metacenter (M) and the center of gravity (G). When the angle is sufficiently small, it is used that the value of sinθ can be approximated to the value of tanθ). Therefore, the following relationship is derived.

(Equation 3) w × d = W × GM × tanθ

Accordingly, when the above equations 1 and 3 are combined, the following results are obtained.

(Equation 4) KG = KM- (w × d) / (W × tanθ)

In Equation 4, the length of the line segment KM may be calculated in advance from the model during design. In addition, the value of tanθ can be obtained by directly measuring θ, or by using the pendulum installed in the hull, using the ratio between the length of the pendulum and the distance that the end of the pendulum has moved. The remaining variables constituting the equation are all measurable values as described above, so the position of the center of gravity (G) of the hull can be calculated from equation (4).

The position of the center of gravity calculated in this way can be compared with the design value, similar to the light weight described above. In particular, in order to more accurately determine the position of the center of gravity, the process of calculating the center of gravity, repeating the process of moving the load by changing the ballast water distribution of the column unit 20, and calculating the center of gravity (S700). The number of repetitions may be, for example, several times or more, and the number of times may be appropriately increased or decreased as necessary. In this way, the longitudinal inclination test of the semi-submersible rig line 1 can be carried out.

Since the inclination test method is performed simply by moving the ballast water using a pump inside the semi-submersible rig ship 1, the overall test time is greatly shortened by the method of moving a large heavy object with a crane or the like. In addition, the problem that the cost is low, the safety is guaranteed, and the movement distance of the load can be relatively long due to the longitudinal load movement is also completely solved by moving the ballast water using the pump and pipeline in the hull. Can be solved. In addition, by increasing the water plane by floating the pontoon part 30 at sea level, the hull is stably maintained even when causing inclination, and the measurement of the inclination angle is made very accurately. Since it can proceed, it has the advantage of being able to conduct a slope test more safely and conveniently near a shallow berthing facility. In addition, since it is possible to completely remove unnecessary fluid flow by completely draining the seawater in the pontoon part 30, it is possible to obtain more accurate measurement results by removing variables that adversely affect the center of gravity measurement in advance.

Although the embodiments of the present invention have been described with reference to the accompanying drawings, those skilled in the art to which the present invention pertains may be implemented in other specific forms without changing the technical spirit or essential features of the present invention. You will understand. Therefore, it should be understood that the embodiments described above are illustrative in all respects and not restrictive.

1: Semi-submersible league ship 10: Deck section
11: Derek 20: Column
21: first column 22: second column
21a: First ballast tank 22a: Second ballast tank
30: pontoon part 30a: piping
31, 32: Pontoon 33: Rope
A, A ': Sea level B: Quay
G, G ': center of gravity θ: tilt angle
M: Meta Center K: Seonjeom

Claims (7)

In the inclination test method of a semi-submersible rig comprising a hull consisting of a pontoon part, a deck part, and a column part connecting the pontoon part and the deck part,
(a) draining the equilibrium water of the pontoon part and positioning the water line of the hull on the side of the pontoon part; And
(b) a longitudinal inclination test method of a semi-submersible rig ship, comprising changing the equilibrium water distribution of the column part to move the load in the forward direction of the pontoon part or the stern direction of the pontoon part and changing the center of gravity of the hull. According to claim 1,
In the step (a), the ballast water of the pontoon part is completely drained, and the ballast water of the column part of the step (b) is not drained, and the longitudinal slope of the semi-submersible rig line exchanged between the plurality of columns constituting the column part. Test Methods. According to claim 1,
The ballast water of the step (b) is arranged to be spaced apart in the longitudinal direction of the pontoon part and is exchanged between at least two different columns constituting the column part, the longitudinal direction of the semi-submersible rig line whose distribution changes with respect to the longitudinal direction of the pontoon part Inclination test method. According to claim 3,
The pontoon portion is a twin type consisting of at least two pontoons arranged side by side in the longitudinal direction, wherein the number of equilibrium in step (b) is different from the columns connected to the player side of the pontoons, and different stern sides of the pontoons Method of longitudinal tilt test of semi-submersible rigs exchanged between connected columns. According to claim 1,
The ballast water of the step (b) is a longitudinal inclination test method of a semi-submersible rig ship that is moved along a longitudinal pipe inside the pontoon part connected to at least two different columns constituting the column part. According to claim 1,
Before the step (b), the longitudinal slope test method of the semi-submersible rig ship further comprising the step of constructing a hole for measuring the amount of movement of the ballast water directly above the ballast tank of the column. According to claim 1,
Before the step (b), the longitudinal inclination test method of the semi-submersible rig ship further comprising the step of connecting the hull with the inner wall of the berthing facility and a rope to limit the moving radius.

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