A method of preventing stern tube flooding during ship launching

Abstract

The application discloses a method for preventing stern tube from water entry during ship launching, which comprises the following steps: installing a first pipeline at the lower oil inlet of the stern tube and a second pipeline at the upper oil outlet, when the ship is launched, a certain pressure gas is introduced into the stern tube through the first pipeline, so that the III sealing ring is tightly pressed on the stern shaft, even if the seawater enters the second chamber during the launching of the ship, the seawater will not enter the stern tube through the III sealing ring, and the third pipeline is connected with the lower port of the second chamber between the II sealing ring and the III sealing ring at the rear of the stern tube, and the fourth pipeline is connected with the upper port, during the launching of the ship, whether the seawater flows out from the end of the third pipeline can be observed to judge the sealing performance of the I sealing ring and the II sealing ring at the rear of the stern tube, so that the purpose of preventing the seawater from entering the stern tube during the launching of the ship is achieved, and the sealing performance of the stern sealing is also detected.

Description

Technical Field

[0001] This invention relates to the field of shipbuilding technology, and in particular to a method for preventing water from entering the stern pipe when a ship leaves the dock. Background Technology

[0002] Many ships employ a multi-ring simplex stern seal. The rings, arranged from stern to foremost, are numbered 1 / 2 / 3. Two rings (numbers 1 and 2) have their lips turned backwards, while one ring (number 3) is turned forward to prevent oil leakage. The space between rings 1 and 2 is cavity I, and the space between rings 2 and 3 is cavity II. Cavity II contains low-pressure air, which continuously escapes from the stern during navigation. The oil pressure inside the stern tube presses ring 3 against the stern shaft, preventing low-pressure air from entering the stern tube. Cavity II acts as a barrier between the oil and seawater, thus preventing the risk of oil leakage into the seawater.

[0003] During shipbuilding, in order to make full use of the dry dock, the shipyard will build two ships at the same time. When one ship is about to leave the dry dock, the other ship may be in a half-ship state. When the dry dock is flooded, the half-ship will also float.

[0004] Due to the construction cycle, oil cannot be injected into the stern pipe when the ship is halfway through its voyage, nor can the complete sealing of the stern seal be verified. The stern seal cannot perform its function, which requires the shipyard to take effective measures to prevent seawater from entering the stern pipe through the stern seal. Therefore, how to design a method to prevent water from entering the stern pipe when leaving the dock has become an urgent problem to be solved. Summary of the Invention

[0005] In view of this, the present invention provides a method for preventing water from entering the stern pipe when a ship leaves the dock, in order to solve the problems existing in the background art.

[0006] A method for preventing water from entering the stern pipe when a ship is undocking includes the following steps:

[0007] S1, before the ship leaves the dock, a first pipeline is installed at the lower oil inlet of the stern pipe and a second pipeline is installed at the upper oil outlet. A third pipeline is connected to the lower port of the second chamber between the No. II and No. III sealing rings at the stern pipe, and a fourth pipeline is connected to the upper port. The height distance X1 from the end of the fourth pipeline to the center line of the shaft system is greater than the height between the seawater outside the ship and the center line of the shaft system.

[0008] The first pipeline is connected to a gas source at its end. The first pipeline is equipped with a pressure regulating valve for adjusting the gas pressure in the stern tube. The second pipeline is equipped with a safety valve to prevent the gas pressure in the stern tube from over-pressurizing and causing the lip of the No. III sealing ring to flip over.

[0009] S2, when half of the ship is out of the dock, set the pressure value of the safety valve, and at the same time adjust the pressure regulating valve to fill the stern pipe with gas at a specific pressure. The gas presses the No. Ⅲ sealing ring tightly against the stern shaft, and the No. Ⅲ sealing ring forms a sealed state.

[0010] Check if the gas pressure inside the stern tube is stable. If it is stable, it means that the sealing performance of the No. 3 sealing ring meets the requirements; otherwise, the No. 3 sealing ring is not sealing properly, and the ship should stop leaving the dock.

[0011] S3. During the process of half-ship leaving the dock, observe whether seawater flows out from the end of the third pipeline. If seawater flows out, it means that seawater has entered the second chamber from outside the hull, and the sealing rings No. 1 and No. 2 at the stern pipe are not sealing properly.

[0012] Preferably, the first pipeline is provided with a first shut-off valve, an air filter, a pressure regulating valve and a pressure gauge along the airflow direction.

[0013] Preferably, after the No. Ⅲ sealing ring forms a sealed state in step S2, observe whether the pressure gauge reading remains unchanged. If it does, it indicates that the gas pressure in the stern pipe is stable and the sealing performance of the No. Ⅲ sealing ring meets the requirements; otherwise, the No. Ⅲ sealing ring is not tight, and the ship should stop leaving the dock.

[0014] Preferably, the gas source is a nitrogen cylinder, and the pressure regulating valve is a pressure reducing valve.

[0015] Preferably, a blind flange or a second shut-off valve is installed at the end of the second pipeline, and the second shut-off valve is closed when gas is introduced into the stern pipe.

[0016] Preferably, a collection tank is also placed at the lower end of the third pipeline. The collection tank is used to collect seawater that enters the second chamber from outside the ship and is discharged along the third pipeline.

[0017] Preferably, after the sealing ring III forms a seal in step S2, the air pressure inside the stern tube is greater than the seawater pressure outside the hull.

[0018] The beneficial effects of this invention are:

[0019] This invention installs a first pipeline at the lower oil inlet and a second pipeline at the upper oil outlet of the stern tube. When the ship is halfway out of dock, gas at a certain pressure is introduced into the stern tube through the first pipeline, which can tightly press the No. III sealing ring onto the stern shaft. Even if seawater enters the second chamber during the half-ship outing process, it will not enter the stern tube through the No. III sealing ring. Furthermore, by connecting a third pipeline to the lower port of the second chamber between the No. II and No. III sealing rings at the stern tube and a fourth pipeline to the upper port, the sealing performance of the No. I and No. II sealing rings at the stern tube can be determined by observing whether seawater flows out from the end of the third pipeline during the half-ship outing process. This achieves the goal of preventing seawater from entering the stern tube when the ship is out of dock, and also enables the testing of the stern seal's sealing performance. Attached Figure Description

[0020] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a schematic diagram of the structure of the present invention.

[0022] Figure 2 This is a schematic diagram of the stern shaft rear seal.

[0023] The labels in the diagram mean:

[0024] 1 is a nitrogen cylinder, 2 is the first shut-off valve, 3 is an air filter, 4 is a pressure reducing valve, 5 is a pressure gauge, 6 is a safety valve, 7 is the second shut-off valve, 8 is the stern pipe, 9 is the third pipe, 10 is a small barrel, 11 is the first pipe, 12 is the second pipe, 13 is the fourth pipe, and 14 is the stern shaft. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of this invention clearer, the invention is described below with reference to specific embodiments shown in the accompanying drawings. However, it should be understood that these descriptions are merely exemplary and not intended to limit the scope of the invention. Furthermore, descriptions of well-known structures and technologies are omitted in the following description to avoid unnecessarily obscuring the concept of the invention.

[0026] The terminology used in this disclosure is for the purpose of describing particular embodiments only and is not intended to be limiting of the disclosure. The singular forms “a,” “the,” and “the” as used in this disclosure and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the term “and / or” as used herein refers to and includes any and all possible combinations of one or more of the associated listed items.

[0027] It should be understood that although the terms first, second, third, etc., may be used in this disclosure to describe various information, such information should not be limited to these terms and should not be construed as indicating or implying relative importance. These terms are only used to distinguish information of the same type from one another. For example, without departing from the scope of this disclosure, first information may also be referred to as second information, and similarly, second information may also be referred to as first information.

[0028] To better understand the technical solution of the present invention, the present invention will be described in detail below with reference to the accompanying drawings.

[0029] This invention provides a method for preventing water from entering the stern pipe when a ship is leaving dry dock, specifically including the following steps:

[0030] S1, before the ship leaves the dock, install the first pipeline 11 at the lower oil inlet of the stern pipe 14 and the second pipeline 12 at the upper oil outlet. Connect the lower port of the second chamber between the sealing ring II and the sealing ring III at the rear of the stern pipe to the third pipeline 9 and the upper port to the fourth pipeline 13.

[0031] The first pipeline 11 is equipped with a pressure regulating valve 4 for adjusting the gas pressure inside the stern tube 14, and the end of the first pipeline 11 is connected to a gas source 1.

[0032] Preferably, the first pipeline 11 is further provided with a first shut-off valve 2, an air filter 3, and a pressure gauge 5. The first shut-off valve 2, air filter 3, pressure regulating valve 4, and pressure gauge 5 are arranged sequentially along the airflow direction. The first shut-off valve 2 can be installed on the first pipeline 11 or at the outlet of the gas source 1. In this embodiment, the gas source 1 is a nitrogen cylinder, and the pressure regulating valve 4 is a pressure reducing valve. The nitrogen cylinder 1 contains a sufficient amount of nitrogen. After the nitrogen is depressurized by the pressure regulating valve 4, it enters the stern tube. The nitrogen with a certain pressure presses the No. III sealing ring tightly against the stern shaft, so that the No. III sealing ring is always in a sealed state.

[0033] The air filter is used to filter the gas to ensure that the low-pressure nitrogen entering the stern tube is clean enough and to prevent the stern tube from being contaminated.

[0034] The second pipeline 12 is equipped with a safety valve 6 to prevent the air pressure in the stern pipe 14 from over-pressurizing and causing the lip of the No. III sealing ring to flip over.

[0035] The end of the second pipeline 12 is equipped with a blind flange or a second shut-off valve 7. When the end of the second pipeline 12 is equipped with a second shut-off valve 7, the second shut-off valve 7 is closed when gas is introduced into the stern pipe 14, so as to maintain a stable pressure state in the stern pipe.

[0036] The lower end of the third pipe 9 is also equipped with a liquid collection tank 10, which is used to collect seawater that enters the second chamber from outside the ship and is discharged along the third pipe 9.

[0037] The height distance X1 from the end of the fourth pipe 13 to the center line of the shaft system should be greater than the height between the seawater outside the ship and the center line of the shaft system, so as to prevent the seawater outside the ship that enters the second chamber due to the blockage of the third pipe from flowing out from the end of the fourth pipe 13.

[0038] S2, when the ship is halfway out of the dock, close the second shut-off valve 7, set the pressure value of the safety valve 6 (i.e., set the pressure threshold that will not cause the lip of the No. 3 sealing ring to flip over), and at the same time adjust the pressure regulating valve 4 to fill the stern pipe 14 with gas at a specific pressure. The gas will press the No. 3 sealing ring tightly against the stern shaft, and the No. 3 sealing ring will form a sealed state. After the No. 3 sealing ring forms a sealed state, the air pressure in the stern pipe should be greater than the seawater pressure outside the ship.

[0039] After a period of time, observe whether the reading of pressure gauge 5 remains unchanged. If it does, it indicates that the gas pressure in the stern pipe 14 is stable and the sealing performance of sealing ring III meets the requirements; otherwise, sealing ring III is not tight and the ship should stop leaving the dock.

[0040] S3, during the process of half-ship leaving the dock, observe whether seawater flows out from the end of the third pipe 9. If seawater flows out, it means that seawater has entered the second chamber from outside the hull, and the sealing rings No. 1 and No. 2 of the stern pipe are not sealing properly.

[0041] It should be understood that the described embodiments are merely some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

Claims

1. A method for preventing water from entering the stern pipe when a ship is leaving dry dock, characterized in that, Specifically, the following steps are included: S1, before the ship leaves the dock, a first pipeline (11) is installed at the lower oil inlet of the stern pipe (14), a second pipeline (12) is installed at the upper oil outlet, a third pipeline (9) is connected to the lower port of the second chamber between the sealing ring II and the sealing ring III at the rear of the stern pipe, and a fourth pipeline (13) is connected to the upper port. The height distance X1 from the end of the fourth pipeline (13) to the center line of the shaft system is greater than the height between the seawater outside the ship and the center line of the shaft system. The first pipeline (11) is connected to a gas source (1) at its end. The first pipeline (11) is equipped with a pressure regulating valve (4) for adjusting the gas pressure in the stern tube (14). The second pipeline (12) is equipped with a safety valve (6) to prevent the gas pressure in the stern tube (14) from over-pressure and causing the lip of the No. III sealing ring to flip. S2, when half of the ship is out of the dock, set the pressure value of the safety valve (6) and adjust the pressure regulating valve (4) at the same time to fill the stern pipe (14) with gas at a specific pressure. The gas presses the No. Ⅲ sealing ring tightly onto the stern shaft, and the No. Ⅲ sealing ring forms a sealed state. Check whether the gas pressure inside the stern tube (14) is stable. If it is stable, it means that the sealing performance of the No. 3 sealing ring meets the requirements; otherwise, the No. 3 sealing ring is not tight and the ship should stop leaving the dock. S3, during the process of half the ship leaving the dock, observe whether seawater flows out from the end of the third pipeline (9). If seawater flows out, it means that seawater enters the second chamber from outside the hull and the sealing rings No. 1 and No. 2 of the stern pipe are not sealed tightly.

2. The method for preventing water from entering the stern pipe when a ship is leaving dry dock according to claim 1, characterized in that, The first pipeline (11) is provided with a first shut-off valve (2), an air filter (3), a pressure regulating valve (4) and a pressure gauge (5) along the airflow direction.

3. The method for preventing water from entering the stern pipe when a ship is leaving dry dock according to claim 2, characterized in that, After the sealing ring III forms a seal in step S2, observe whether the reading of the pressure gauge (5) remains unchanged. If it does, it means that the gas pressure in the stern pipe (14) is stable and the sealing performance of the sealing ring III meets the requirements; otherwise, the sealing ring III is not tight and the ship should stop leaving the dock.

4. The method for preventing water from entering the stern pipe when a ship is leaving dry dock according to claim 2, characterized in that, The gas source (1) is a nitrogen cylinder, and the pressure regulating valve (4) is a pressure reducing valve.

5. The method for preventing water from entering the stern pipe when a ship is leaving dry dock according to claim 1, characterized in that, The end of the second pipeline (12) is equipped with a blind flange or a second shut-off valve (7). When gas is filled into the stern pipe (14), the second shut-off valve (7) is in the closed state.

6. The method for preventing water ingress into the stern pipe when a ship is leaving dry dock according to claim 1, characterized in that, The lower end of the third pipe (9) is also equipped with a liquid collection tank (10), which is used to collect seawater that enters the second chamber from the outside and is discharged along the third pipe (9).

7. The method for preventing water ingress into the stern pipe when a ship is leaving dry dock according to claim 1, characterized in that, After the sealing ring III forms a seal in step S2, the air pressure inside the stern tube is greater than the seawater pressure outside the hull.

Images