Water-gas test method for SPB tank of FLNG ship

Abstract

The invention relates to an FLNG ship SPB tank steam test method in the technical field of FLNG ship construction, and the method comprises the steps: S1, pasting stress sheets on the outer peripheral surface and the inner surface of a cavity of an SPB tank, and testing a monitoring system; s2, liquid is injected into the SPB tank, and a manhole is closed after the water level is confirmed; s3, gas is injected into the SPB tank, after the pressure of the SPB tank body is increased to 0.075-0.077 Mpa, the pressure is maintained for preset time, and airtightness inspection is completed; s4, after the airtightness check is completed in the step S3, pressure relief treatment is carried out, pressurized liquid is discharged, and the dome and the tank top of the SPB tank are flushed; and S5, the inner cavity of the SPB tank is cleaned and checked, and drying treatment is carried out after checking. According to the invention, various data of the whole process from the beginning of water adding to the end of pressure relief can be collected, accurate air tightness experiment data can be obtained, the pressure sheets are arranged inside and outside the tank body, the time and strain conditions of each measurement point are recorded, the stress of the measurement points is finally calculated and compared with a theoretical stress value, and accurate measurement of the structural strength of the SPB tank body is realized.

Description

Technical Field

[0001] The present invention relates to the technical field of FLNG ship construction, and in particular to a water vapor test method for a SPB tank of a FLNG ship. Background Art

[0002] The main application scenario of SPB tanks is the storage and transportation of liquefied natural gas. SPB tanks have broad application prospects in the energy industry, mainly based on their own unique advantages: (1) Independent construction from the hull: This design shortens the delivery cycle of the overall project; (2) No liquid level loading restrictions: Simple operation and maintenance, no heating system is required for isolated empty tanks; (3) High tank capacity utilization: The flat deck facilitates the layout of the process modules on board.

[0003] After the SPB tank is installed on the hull, a water vapor test is required to obtain the air tightness data and structural strength data of the tank. The prior art does not have any specific process and regulations or specific operating procedures for the water vapor test. It only stipulates that the stress monitoring data shall not exceed the theoretical calculated stress value (calculated according to the yield strength of different materials). Summary of the invention

[0004] In view of the defects in the prior art, the object of the present invention is to provide a water vapor test method for the SPB tank of an FLNG ship.

[0005] According to 1. provided by the present invention, a FLNG ship SPB tank water vapor test method comprises the following steps:

[0006] S1, attach stress sheets to the outer surface of the SPB tank and the inner surface of the cavity, and test the monitoring system;

[0007] S2, inject liquid into the SPB tank and close the manhole after the water level is confirmed;

[0008] S3, inject gas into the SPB tank, and maintain the pressure of the SPB tank body for a predetermined time after the pressure increases to 0.075-0.077Mpa, completing the air tightness inspection;

[0009] S4, after completing the airtightness check in step S3, perform pressure relief processing to discharge the pressurized liquid and flush the dome and tank top of the SPB tank;

[0010] S5, clean and inspect the inner cavity of the SPB tank, and dry it after inspection.

[0011] In some implementations, in step S1, the location where the stress sheet is posted in the SPB tank cavity is the stress concentration point in the tank.

[0012] In some implementations, in step S1, the position where the stress sheet is posted on the outer peripheral surface of the SPB tank is the contact position between the SPB tank and the FLNG hull base.

[0013] In some implementations, in step S2, the liquid injected into the SPB tank is a mixed liquid of water and a rust inhibitor, and the concentration of the rust inhibitor is 300-500 mg / L.

[0014] In some implementations, in step S2, the amount of liquid injected into the SPB tank is 40-50% of the volume of the SPB tank.

[0015] In some embodiments, in step S3, after the SPB tank is sealed, the air inlet valve is opened for pressurization. When the pressure value reaches 80% of the design value, some air inlet valves are closed and the sealing of the flange is checked with soapy water. After the pressure is increased to the design value, all air inlet valves are closed and the pressure is maintained for 2-3 hours. If the pressure change is within the predetermined value range, the sealing of the SPB tank meets the standard.

[0016] In some embodiments, in step S3, when the pressure value is less than or equal to 0.07 MPa during the pressure maintenance process after the pressure is increased to the design value, it is considered that the sealing does not meet the standard.

[0017] In some implementation modes, in step S4, during the pressure relief process, the manhole can be opened only after the pressure gauge reading reaches zero.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] The water vapor test method for the SPB tank of an FLNG ship of the present invention can collect various data from the beginning of water addition to the end of pressure relief, obtain accurate airtightness experimental data, and by setting pressure plates inside and outside the tank body, record the time and strain of each measuring point, and finally calculate the stress of the measuring point and compare it with the theoretical stress value, so as to realize the accurate measurement of the structural strength of the SPB tank body. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Other features, objects and advantages of the present invention will become more apparent from the detailed description of non-limiting embodiments made with reference to the following drawings:

[0021] Figure 1 This is a basic flow chart of the water vapor test of the SPB tank of the FLNG ship of the present invention;

[0022] Figure 2 This is a schematic diagram of the pipeline arrangement structure of the corresponding device for the water vapor test of the SPB tank of the FLNG ship of the present invention;

[0023] Figure 3 This is a schematic diagram of the arrangement of various interfaces on the SPB tank dome in the water vapor test of the FLNG ship SPB tank of the present invention;

[0024] Figure 4It is a schematic diagram of the stress sheet pasting structure in the water vapor test of the SPB tank of the FLNG ship of the present invention. DETAILED DESCRIPTION

[0025] The present invention is described in detail below in conjunction with specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those of ordinary skill in the art, several changes and improvements can also be made without departing from the concept of the present invention. These all belong to the protection scope of the present invention.

[0026] This embodiment provides a method for testing the water vapor of the SPB tank of an FLNG ship. Before the water vapor test is performed, Figure 1 As shown in the schematic diagram, the pipeline and equipment layout is completed, mainly the centrifugal pump ① for water injection is arranged at the dock, the buffer tank ② is arranged at the dock, the pipeline ③ is successfully connected according to PID, and various pressure gauges and valves on the pipeline are installed. Figure 2 After the dome interfaces are connected, mainly connect the drainage and transfer water pipeline ④ to the E1 interface, connect the safety valve ⑤ to the 16C interface, connect the water supply pipeline ⑥ to the N8B interface, connect the pressurized pipeline ⑦ to the N9A interface and connect the pressure gauge ⑧ to the N1 interface.

[0027] The method of water vapor test mainly includes the following steps:

[0028] S1, attach stress sheets to the outer surface of the SPB tank and the inner surface of the cavity, and test the monitoring system. Figure 3 As shown in the figure, the stress sheet placement position in the SPB tank cavity is the stress concentration point in the tank. The stress concentration point of the SPB tank is obtained based on the stress model calculation and analysis of some parts of the tank body that are subject to greater stress. The stress sheet placement position on the outer surface of the SPB tank is the position where the tank body contacts the FLNG hull base, which is used to monitor the impact of water added to the tank on the base.

[0029] S2, inject a mixed liquid of water and rust inhibitor into the SPB tank, wherein the concentration of the rust inhibitor is 300-500 mg / L liquid. When the mixed liquid injection value reaches 45% of the SPB tank volume, stop injecting water, and close the manhole after the water level is confirmed.

[0030] S3, after sealing all the openings on the dome of the SPB tank, start pressurizing, open the air inlet valve, and slowly add compressed air into the SPB tank through the pressurized pipeline ⑦. Observe the reading of the pressure gauge ⑧. When the pressure reaches 80% of the design value, close some of the air inlet valves and check the tightness of the flange with soapy water. Continue to pressurize to 0.075~0.077Mpa, close all air inlet valves, and maintain the pressure for 2 hours. If the pressure value is not less than 0.07Mpa, the sealing of the SPB tank is good and meets the standard requirements. Weather temperature and other reasons will cause slight changes in the pressure value. Therefore, when the pressure value is not less than 0.07Mpa, the sealing of the SPB tank is still within the range required by the standard. When the pressure value is less than or equal to 0.07Mpa, it is considered that the sealing does not meet the standard. If a leak occurs during the pressurization process, the pressurization must be stopped, and the leak must be repaired before pressurization. If the pressure drops slowly due to weather during the pressure maintenance process, it is acceptable, such as dropping to 0.07MPa. In other cases, it is considered that the pressure maintenance is unsuccessful and the test will be repeated after repair.

[0031] S4, after completing the airtightness check in step S3, perform pressure relief, discharge the pressurized liquid, and flush the dome and tank top of the SPB tank. During the pressure relief process, it is necessary to gradually and slowly open the pressure relief valve on the pipeline ⑦ until it is fully opened. For safety reasons, it is strictly forbidden to open the manhole during the pressure relief process until the pressure gauge reads 0. The water discharge used for water vapor testing must meet local laws and regulations and comply with GB / T 18918-2002 "Urban Industrial Wastewater Discharge Standard". The direct discharge standard is: PH between 6-9, COD not exceeding 500mg / L, sulfur content not exceeding 400mg / L, and no heavy metals.

[0032] S5, after draining the water, start to dismantle the equipment and clean the tank. Visually there are no obvious solid particles, debris and other oil stains, and dry the SPB tank. In addition to checking the deformation of the stress concentration point with stress monitoring data, the deformation of all tanks inside and outside should also be visually checked.

[0033] The water-gas test method for the SPB tank of an FLNG ship provided in this embodiment can collect various data from the beginning of water addition to the end of pressure relief, obtain accurate airtightness experimental data, and by setting pressure plates inside and outside the tank body, record the time and strain conditions of each measuring point, and finally calculate the stress of the measuring point and compare it with the theoretical stress value, thereby realizing accurate measurement of the structural strength of the SPB tank body.

[0034] In the description of the present application, it should be understood that the terms "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0035] The above describes the specific embodiments of the present invention. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art can make various changes or modifications within the scope of the claims, which does not affect the essence of the present invention. In the absence of conflict, the embodiments of the present application and the features in the embodiments can be combined with each other arbitrarily.

Claims

1. A FLNG ship SPB tank water vapor test method, characterized in that: The steps include: S1, attach stress sheets to the outer surface of the SPB tank and the inner surface of the cavity, and test the monitoring system; S2, inject liquid into the SPB tank and close the manhole after the water level is confirmed; S3, inject gas into the SPB tank, and maintain the pressure of the SPB tank body for a predetermined time after the pressure increases to 0.075-0.077Mpa, completing the air tightness inspection; S4, after completing the airtightness check in step S3, perform pressure relief processing to discharge the pressurized liquid and flush the dome and tank top of the SPB tank; S5, clean and inspect the inner cavity of the SPB tank, and dry it after inspection.

2. The FLNG ship SPB tank water vapor test method according to claim 1, characterized in that: In the step S1, the location where the stress sheet is posted in the SPB tank cavity is the stress concentration point in the tank.

3. The FLNG ship SPB tank water vapor test method according to claim 2, characterized in that: In the step S1, the posting position of the stress sheet on the outer peripheral surface of the SPB tank is the contact position between the SPB tank and the FLNG hull base.

4. The FLNG ship SPB tank water vapor test method according to claim 1, characterized in that: In the step S2, the liquid injected into the SPB tank is a mixed liquid of water and a rust inhibitor, and the concentration of the rust inhibitor is 300-500 mg / L.

5. The FLNG ship SPB tank water vapor test method according to claim 4, characterized in that: In the step S2, the amount of liquid injected into the SPB tank is 40-50% of the volume of the SPB tank.

6. The FLNG ship SPB tank water vapor test method according to claim 1, characterized in that: In step S3, after the SPB tank is sealed, the air inlet valve is opened for pressurization. When the pressure reaches 80% of the design value, some air inlet valves are closed and the sealing of the flange is checked with soapy water. After the pressure reaches the design value, all air inlet valves are closed and the pressure is maintained for 2-3 hours. If the pressure change is within the predetermined value range, the sealing of the SPB tank meets the standard.

7. The FLNG ship SPB tank water vapor test method according to claim 6, characterized in that: In the step S3, when the pressure value is less than or equal to 0.07 MPa during the pressure maintenance process after the pressure is increased to the design value, it is considered that the sealing performance does not meet the standard.

8. The FLNG ship SPB tank water vapor test method according to claim 7, characterized in that: In step S4, during the pressure relief process, the manhole can be opened only after the pressure gauge reading reaches zero.

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