A method for air pressure test of a liquid tank for up and down communication with a ballast tank

Abstract

The application provides a liquid tank air pressure test method for up and down communication ballast tanks, through scientific design of a ship cargo tank side platform structure form, setting of multiple general size water holes, design of reusable sealing tooling and hatch cover, effective use of ship body tightness tooling, effective guarantee of the tightness test process of the side of the cargo tank area, further guarantee of the construction integrity of the cargo tank area, avoidance of narrow space construction, guarantee of the safety of ship construction, further guarantee of the coating integrity of the cargo tank area, meeting of the cross operation requirements of various processes, and facilitation of the shortening of the wharf period.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of gas pressure test methods of liquid tanks, in particular to a liquid tank gas pressure test method for upper and lower communication ballast tanks. BACKGROUND

[0002] In order to verify the water-tight integrity of the liquid tank of the ship, the suitability of the liquid tank structure, and the weather-tight integrity of the ship structure / outfitting, a hull tightness test needs to be performed. The tightness test includes a fillet weld gas pressure test, a vacuum test, and a liquid tank gas pressure test. Since the fillet weld gas pressure test has high assembly and welding requirements for the ship structure construction, it is easy to fail to check due to the unsmooth gas path. The universality of the vacuum test is poor, and ordinary tooling cannot cover the angular and linear positions. Therefore, the liquid tank gas pressure test is usually performed in the liquid tank, and the specific process is to inject compressed air into the closed liquid tank, and after reaching the specified pressure and duration, the penetration of the weld is checked by spraying a test liquid (such as a soap solution, which should be heated below 0℃) on the surface of the weld under test. The test can be performed in the shipyard during the stage of section assembly, total assembly, or loading, but the integrity of the structure needs to be ensured and a closed liquid tank needs to be formed.

[0003] With the continuous development and iteration of liquefied gas ships, the double hull side of the liquid tank area usually adopts the structure form of upper and lower communication ballast tanks at present, that is, the upper and lower communication of the top ballast tank, the side ballast tank, the bottom edge ballast tank, and the double bottom ballast tank. Compared with independent ballast tanks, the upper and lower communication ballast tanks can simplify the ballast system piping. However, the liquid tank gas pressure test for the upper and lower communication ballast tanks is usually performed on the whole closed liquid tank after the ballast tank and the liquid tank are completely folded. Since the liquid tank has been hoisted into the liquid tank, and there is a large amount of structure (including but not limited to thermal insulation and anti-rolling structure) between the liquid tank and the ship body, the distance between the tank body and the inner shell plate of the cargo tank side is only about 700mm. Once penetration problems are found during the above test process, personnel need to enter the narrow space for construction, which is difficult to operate. In addition, the thermal insulation auxiliary materials on the surface of the liquid tank are flammable, and the construction has safety hazards.

[0004] Therefore, it is urgent to find a new liquid tank gas pressure test method suitable for the upper and lower communication ballast tanks. SUMMARY

[0005] The purpose of the embodiments of the present application is to provide a liquid tank gas pressure test method for upper and lower communication ballast tanks, which solves the problem that once penetration problems are found in the existing liquid tank gas pressure test method, personnel need to enter a narrow space for construction, which is difficult to operate and has safety hazards.

[0006] Provided is a liquid tank air pressure test method for up-and-down communication ballast tanks, the ballast tanks including a top ballast tank, a side ballast tank and a bottom ballast tank, the liquid tank air pressure test method including the following steps:

[0007] The bottom ballast tank and the side ballast tank are mounted and folded in the liquid tank area, and a segmented joint is arranged at the end of the folded side ballast tank;

[0008] A platform structure is arranged in the side ballast tank near the segmented joint, the platform structure is laid in the side ballast tank and fixedly connected with the inner side wall and the outer side wall of the side ballast tank, the side ballast tank and the bottom ballast tank are enclosed by the platform structure to form a closed side-bottom ballast tank section, and the platform structure is provided with a passage hole and a plurality of water flow holes;

[0009] The water flow holes are sealed by sealing tools, and the passage hole is sealed by a door cover, and an air inlet pipe, an air inlet valve and a pressure gauge are arranged on part of the door cover;

[0010] Compressed air is injected into the side-bottom ballast tank section through the air inlet pipe, the air pressure in the side-bottom ballast tank section is increased to a preset value, then the air inlet valve is closed, the pressure gauge is observed and a stable state is maintained for a preset time, and then the air pressure is reduced to a test air pressure;

[0011] The welds below the platform structure are inspected, including all boundary welds and pipe penetration welds;

[0012] After the air pressure test is completed, the pressure in the side-bottom ballast tank section is completely released, and the sealing tools and the door cover are removed;

[0013] The side-bottom ballast tank section below the platform structure is painted, and then the liquid tank, the top ballast tank and the full-width deck section are hoisted and installed in sequence;

[0014] The liquid tank is subjected to a whole-tank air pressure test again, and the welds above the platform structure are detected.

[0015] In an embodiment, the sealing of the passage hole by the door cover includes:

[0016] A seat ring is fixedly installed on the upper surface of the platform structure, and the seat ring is overlapped on the upper surface of the platform structure at a preset distance from the edge of the passage hole;

[0017] Bolt holes are uniformly formed on the seat ring in the circumferential direction of the seat ring, and a first bolt that can be detached is installed in the bolt hole;

[0018] A first rubber sheet is arranged on the upper surface of the seat ring;

[0019] A door cover is arranged on the first rubber sheet. The seat ring, the first rubber sheet and the door cover are fixedly connected from bottom to top by the first bolt, and finally fixed and sealed by the first nut.

[0020] In one embodiment, the sealing of the water outlet using a sealing fixture includes:

[0021] The sealing fixture includes a square plate, a second bolt, a second rubber sheet, a clamping block, and a second nut; the second rubber sheet is fixed to the upper surface of the square plate, the second bolt is vertically arranged at the center of the upper surface of the square plate, and the clamping block is movably mounted on the second bolt via the second nut;

[0022] Below the platform structure, the second bolt is passed through the water flow hole so that the square plate covers the water flow hole, and the side length of the square plate is greater than the inner diameter of the water flow hole;

[0023] Above the platform structure, a clamping block is installed on the second bolt, and then the second nut is installed and tightened to make the square plate and the second rubber sheet fit tightly against the lower surface of the platform structure to block the drainage hole.

[0024] In one embodiment, removing the access door cover further includes:

[0025] Remove the first nut, the first bolt, and the first rubber sheet, retain the seat ring, and weld the bolt holes on the seat ring closed.

[0026] In one embodiment, the square plate has bevels of a predetermined depth and angle of 45° around its four edges, and the second rubber sheet is connected to the square plate at the bevels by adhesive.

[0027] In one embodiment, watertight transverse bulkheads are arranged at the bow and stern of the bottom ballast tank section, and watertight longitudinal girders are arranged at the ends of the bottom ballast tank section away from the bottom ballast tank.

[0028] In one implementation, a seat ring is welded onto the upper surface of the platform structure.

[0029] In one embodiment, the step of forming a closed side-bottom ballast tank assembly by means of a platform structure includes sealing off all temporary process holes and pipe openings on the side-bottom ballast tank assembly.

[0030] In one embodiment, the plurality of water flow holes are evenly spaced on the platform structure, and the clearance between the water flow holes and the edge of the hull structure is 50mm.

[0031] In one embodiment, the seat ring is 10mm away from the edge of the channel hole, and the overlap width on one side is 60mm.

[0032] The liquid tank air pressure test method for the upper and lower communication ballast tank in the application has the beneficial effects:

[0033] By scientifically designing the structure form of the ship cargo hold side platform, setting multiple general size water holes, designing reusable special sealing tooling, and effectively using the ship body tightness tooling, the tightness test process of the cargo hold area side is effectively ensured to move forward, thereby ensuring the construction integrity of the cargo hold area, avoiding the narrow space construction, ensuring the safety of shipbuilding, and further ensuring the coating integrity of the cargo hold area, while meeting the cross operation requirements of each process, which is beneficial to shorten the wharf period. BRIEF DESCRIPTION OF DRAWINGS

[0034] In order to more clearly illustrate the technical solutions of the embodiments of the application, the drawings needed to be used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the application, and therefore should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can also be obtained without creative labor on the basis of these drawings.

[0035] Figure 1 It is a liquid tank transverse sectional view of an upper and lower communication ballast tank according to an embodiment of the application;

[0036] Figure 2 It is a side view of a side bottom ballast tank section according to an embodiment of the application;

[0037] Figure 3 It is a structural schematic diagram of a platform structure according to an embodiment of the application;

[0038] Figure 4 It is a local schematic diagram of a platform structure according to an embodiment of the application;

[0039] Figure 5 It is Figure 4 a structural schematic diagram of the A area; Figure 1 ;

[0040] Figure 6 It is Figure 4 a structural schematic diagram of the A area; Figure 2 ;

[0041] Figure 7 It is a connection structure schematic diagram of a door cover and a passage hole according to an embodiment of the application;

[0042] Figure 8 It is Figure 7 a structural schematic diagram of the D area;

[0043] Figure 9 It is Figure 4Structure schematic view of middle B area;

[0044] Figure 10 For Figure 9 Sectional view along E direction;

[0045] Figure 11 For Figure 10 Partial schematic view.

[0046] 110, side ballast tank, 111, inner side wall of side ballast tank, 112, outer side wall of side ballast tank, 120, bottom ballast tank, 121, watertight longitudinal floor, 130, top ballast tank, 131, segmental lap joint, 140, watertight transverse bulkhead, 150, full-width deck unit, 200, platform structure, 210, passage hole, 230, water flow hole, 310, seat ring, 311, bolt hole, 320, first rubber sheet, 330, first bolt, 340, first nut, 400, door cover, 410, air inlet pipe, 420, air inlet valve, 430, safety valve, 440, pressure gauge, 450, handle, 500, sealing tool, 510, square plate, 511, bevel, 520, second rubber sheet, 530, second bolt, 540, pressing block, 550, second nut, 600, liquid tank, 610, heat insulation. DETAILED DESCRIPTION

[0047] In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some but not all of the embodiments of the present application. The components of the embodiments of the present application described and shown in the drawings herein can be arranged and designed in various different configurations.

[0048] Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the claimed present application, but only represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the scope of protection of the present application.

[0049] Referring to Figure 1The ballast tanks include a top ballast tank 130, a side ballast tank 110 and a bottom ballast tank 120. The up-and-down communication ballast tank refers to the top ballast tank 130, the side ballast tank 110 and the bottom ballast tank 120 being arranged in up-and-down communication. The liquefied gas carrier cargo hold area is provided with one liquid tank for each cargo hold. After the liquid tank 600 is installed in place, the full-width deck section is hoisted, and the up-and-down communication ballast tank forms a sealed liquid tank. For this sealed liquid tank, the space between the liquid tank and the inner hull plate of the cargo hold is small, and the thickness of the heat insulation 610 of the liquid tank is added, so that the distance between the tank body and the inner hull plate of the cargo hold is only about 700 mm, and the space between the liquid tank and the cargo hold is narrow. In addition, the auxiliary material of the heat insulation 610 on the surface of the liquid tank is a flammable material. Once the liquid tank air pressure test is unqualified, personnel need to enter the narrow space for construction, and the construction operation is difficult. In the face of the above problems, the inventor provides a method of first performing a half-tank air pressure test on the side and bottom ballast tank section of the double hull, that is, first detecting the weld of the side and bottom ballast tank section. After the lower half-tank air pressure is qualified, painting is performed, and then the liquid tank and the full-width deck section are installed. Finally, an air pressure test is performed on the whole tank to detect the weld of the upper half-tank.

[0050] Referring to Figures 1-11 , the application provides a liquid tank air pressure test method for an up-and-down communication ballast tank, which specifically comprises the following steps:

[0051] The bottom ballast tank 120 and the side ballast tank 110 are carried and folded in the liquid tank area, and a segmented joint 131 is arranged at the end of the folded side ballast tank 110. The segmented joint 131 can be arranged at a vertical height of 17685 mm.

[0052] A platform structure 200 is arranged in the side ballast tank 110 near the segmented joint 131, the platform structure 200 is laid in the side ballast tank 110 and fixedly connected with the inner side wall 111 of the side ballast tank and the outer side wall 112 of the side ballast tank, the side ballast tank 110 and the bottom ballast tank 120 are enclosed by the platform structure 200 to form a closed side and bottom ballast tank section, and the side and bottom ballast tank section can include six side ballast tank sections and six bottom ballast tank sections 12. The platform structure 200 is provided with a passage hole 210 and a plurality of water flow holes 230, the size of the passage hole 210 is HO800*600 mm, and the diameter of the water flow hole 230 is 120 mm.

[0053] The water flow hole is sealed by using a sealing tool 500, and the passage hole 210 is sealed by using a door cover 400, referring to Figure 5 , part of the door cover 400 is provided with an air inlet pipe 410, an air inlet valve 420 and a pressure gauge 440, and further includes a safety valve 430 and a handle 450. For the door cover without ventilation, the air inlet structure is not designed, and can be seen from Figure 6 .

[0054] Compressed air is injected into the side bottom ballast tank section through the air inlet pipe 410, raising the air pressure in the side bottom ballast tank section to a preset value. Then, the air inlet valve 420 is closed, the pressure gauge 440 is observed, and the pressure is maintained for a preset time to reach a stable state. Then, the air pressure is reduced to the test air pressure. For example, the air pressure can be raised to, for example, 0.02 MPa, the air inlet valve is closed, the pressure gauge is observed, and the pressure is maintained for about one hour to reach a stable state. Then, the air pressure is reduced to the test air pressure, for example, 0.015 MPa.

[0055] For welds of the platform structure below 200, spray soap solution for inspection, including all boundary welds and pipe penetration welds; this includes two inspections, the first of which should be carried out immediately after applying soap solution, and the second of which should be carried out, for example, after five minutes.

[0056] After the air pressure test is completed, the pressure inside the side bottom ballast tank section is completely released, and the sealing fixture 500 and the door cover 400 are removed.

[0057] Paint the ballast tank sections below 200 on the side bottom of the platform structure. After painting, the liquid tank 600, the top ballast tank 130 and the full-width deck section 150 are hoisted and installed in sequence.

[0058] Next, a full-tank air pressure test was conducted on the liquid tank to inspect the welds of the platform structure above 200 mm.

[0059] In the above implementation process, by scientifically designing the platform structure form on the side of the ship's cargo hold structure and effectively using the hull tightness tooling, while ensuring the integrity of the construction in the cargo hold area, the tightness test process of the side and bottom of the cargo hold area is moved forward to before the lifting of the liquid tank. This ensures the integrity of the welding and assembly work of the ballast tank structure on the side and bottom of the cargo hold area and the completion of the air pressure test before the liquid tank is lifted. This avoids construction in confined spaces, ensures the safety of ship construction, and further ensures the integrity of the painting in the cargo hold area. At the same time, it meets the needs of cross-operation of various processes and helps to shorten the dock cycle.

[0060] This application does not limit the sealing method between the door cover 400 and the channel hole 210. To facilitate the installation and removal of the door cover, in one embodiment, sealing the channel hole 210 using the door cover 400 includes:

[0061] See Figure 7 and Figure 8 A seat ring 310 is fixedly installed on the upper surface of the platform structure 200. Specifically, the seat ring 310 is welded on the upper surface of the platform structure 200. The seat ring 310 overlaps the edge of the channel hole 210 at a preset distance L1 on the upper surface of the platform structure.

[0062] Bolt holes 311 are evenly opened on the seat ring 310 along the circumference of the seat ring 310, and a detachable first bolt 330 is installed in the bolt holes 311.

[0063] A first rubber sheet 320 is arranged on the upper surface of the seat ring 310, and the thickness of the first rubber sheet 320 is 5mm.

[0064] A door cover 400 is arranged on the first rubber sheet 320. The seat ring 310, the first rubber sheet 320 and the door cover 400 are fixedly connected from bottom to top by the first bolt 330, and finally fixed and sealed by the first nut 340. The thickness of the door cover 400 is 16mm.

[0065] This application does not limit the structure of the sealing fixture, as long as it can seal the water outlet. In one embodiment, sealing the water outlet 230 using the sealing fixture 500 includes:

[0066] See Figures 9-11 The sealing fixture 500 includes a square plate 510, a second bolt 530, a second rubber sheet 520, a clamping block 540, and a second nut 550. The second rubber sheet 520 is fixed to the upper surface of the square plate 510, the second bolt 530 is vertically arranged at the center of the upper surface of the square plate 510, and the clamping block 540 is movably mounted on the second bolt and fixed to the square plate 510 by the second nut 550. The square plate 510 can be 8mm thick and 150mm long and wide.

[0067] Below the platform structure 200, the second bolt 530 is passed through the water flow hole 230 so that the square plate 510 covers the water flow hole, and the side length of the square plate 510 is greater than the inner diameter of the water flow hole.

[0068] Above the platform structure 200, a clamping block 540 is installed on the second bolt 530, and then the second nut 550 is installed and tightened so that the square plate 510 and the second rubber sheet 520 are tightly attached to the lower surface of the platform structure 200 to block the water hole 230.

[0069] By using a specially designed sealing fixture 500, the water outlet is sealed from below the platform structure. By placing the square plate and the second rubber sheet on the same side as the gas, it can be ensured that the water outlet is completely sealed.

[0070] In one implementation, removing the door cover further includes:

[0071] Remove the first nut 340, the first bolt 330, and the first rubber sheet 320, leaving the seat ring 310 on the platform structure 200, and then weld the bolt holes 311 on the seat ring 310 shut. This allows for the disassembly and reuse of most parts, and retaining the seat ring reduces work difficulty. Sealing the eight bolt holes 311 on the seat ring by welding prevents corrosion caused by the inability to paint the seat ring and platform structure.

[0072] In one implementation scheme, see Figure 11 The square plate 510 has bevels 511 of a preset depth (4mm) and an angle of 45° on all four edges. The second rubber sheet 520 is connected to the square plate 510 at the bevels 511 by adhesive. By creating the bevels, the connection area and connection strength between the rubber sheet and the square plate can be increased.

[0073] In one embodiment, watertight transverse bulkheads 140 are arranged at the bow and stern of the side bottom ballast tank section, respectively, and watertight longitudinal girder 121 is arranged at the end of the bottom ballast tank section away from the side bottom ballast tank. This further ensures that the side bottom ballast tank 110 and the bottom ballast tank 120 form a complete side bottom ballast tank section after the watertight transverse bulkheads 140 and watertight longitudinal girder 121 are welded together.

[0074] In one implementation, the platform structure that encloses the side ballast tanks and bottom ballast tanks into a closed side-bottom ballast tank assembly includes sealing off all temporary process holes and pipe openings on the side-bottom ballast tank assembly.

[0075] In one embodiment, multiple drainage holes 230 are evenly spaced on the platform structure 200, with a clearance L3 of 50mm between the drainage holes 230 and the edge of the hull structure. This clearance between the drainage holes and the edge of the hull structure prevents interference between the sealing fixture and the hull structure during use.

[0076] In one embodiment, the seat ring 310 maintains a distance of L1 = 10 mm from the edge of the channel hole 210, the single-sided overlap width L2 is 60 mm, and the plate thickness of the seat ring 310 is, for example, 20 mm.

[0077] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A method for pressure testing of a liquid tank in a ballast tank with upper and lower interconnected sections, wherein the ballast tank includes a top ballast tank, a side ballast tank, and a bottom ballast tank, characterized in that, The liquid tank pressure test method includes the following steps: The bottom ballast tank and the side ballast tank are mounted and closed in the liquid tank area, and a segmented lap joint is arranged at the end of the closed side ballast tank. A platform structure is arranged inside the side ballast tank near the segmented joint. The platform structure is laid inside the side ballast tank and fixedly connected to the inner and outer walls of the side ballast tank. The platform structure forms a closed side bottom ballast tank section by enclosing the side ballast tank and the bottom ballast tank. The platform structure is provided with passage holes and multiple water flow holes. All temporary process holes and pipe openings on the side bottom ballast tank section are sealed. The water flow hole is blocked by a sealing fixture, and the channel hole is sealed by a door cover. Some of the door covers are equipped with an air inlet pipe, an air inlet valve, and a pressure gauge. Compressed air is injected into the side bottom ballast tank section through the air inlet pipe, and the air pressure in the side bottom ballast tank section is raised to the preset value. Then the air inlet valve is closed, the pressure gauge is observed and maintained for a preset time to reach a stable state, and then the air pressure is reduced to the test air pressure. The welds below the platform structure were inspected by spraying soap solution, including all boundary welds and pipe penetration welds; After the pneumatic test, the pressure inside the side bottom ballast tank section was completely released, and the sealing fixtures and access door covers were removed. Paint the ballast tank sections below the platform structure, and then hoist the liquid tanks, install the top ballast tanks and the full-width deck sections in sequence. Next, a full-tank pressure test was conducted on the liquid tank to inspect the welds above the platform structure.

2. The method for testing the pneumatic pressure of a liquid tank in a ballast tank with upper and lower connections according to claim 1, characterized in that, The method of using the door cover to seal the channel hole includes: A seat ring is fixedly installed on the upper surface of the platform structure, and the seat ring overlaps the upper surface of the platform structure at a preset distance from the edge of the channel hole. Bolt holes are evenly drilled on the seat ring along the circumference, and a detachable first bolt is installed in the bolt holes; A first rubber sheet is arranged on the upper surface of the seat ring; A door cover is arranged on the first rubber sheet. The seat ring, the first rubber sheet and the door cover are fixedly connected from bottom to top by the first bolt, and finally fixed and sealed by the first nut.

3. The method for testing the pressure of a liquid tank in a ballast tank with upper and lower connections according to claim 1, characterized in that, The method of using sealing fixtures to block the water flow hole includes: The sealing fixture includes a square plate, a second bolt, a second rubber sheet, a clamping block, and a second nut; the second rubber sheet is fixed to the upper surface of the square plate, the second bolt is vertically arranged at the center of the upper surface of the square plate, and the clamping block is movably mounted on the second bolt via the second nut; Below the platform structure, the second bolt is passed through the water flow hole so that the square plate covers the water flow hole, and the side length of the square plate is greater than the inner diameter of the water flow hole; Above the platform structure, a clamping block is installed on the second bolt, and then the second nut is installed and tightened to make the square plate and the second rubber sheet fit tightly against the lower surface of the platform structure to block the drainage hole.

4. The method for testing the pneumatic pressure of a liquid tank in a ballast tank with upper and lower connections according to claim 2, characterized in that, The removal of the access cover also includes: Remove the first nut, the first bolt, and the first rubber sheet, retain the seat ring, and weld the bolt holes on the seat ring closed.

5. The method for testing the pneumatic pressure of a liquid tank in a ballast tank with upper and lower connections according to claim 3, characterized in that, The square plate has bevels of a preset depth and angle of 45° around its four edges, and the second rubber sheet is connected to the square plate at the bevels by glue.

6. The method for testing the pressure of a liquid tank in a ballast tank with upper and lower connections according to claim 1, characterized in that, Watertight transverse bulkheads are arranged at the bow and stern of the bottom ballast tank section, and watertight longitudinal girder plates are arranged at the ends of the bottom ballast tank section away from the side ballast tank.

7. The method for testing the pneumatic pressure of a liquid tank in a ballast tank with upper and lower connections according to claim 2, characterized in that, The seat ring is welded to the upper surface of the platform structure.

8. The method for testing the pressure of a liquid tank in a ballast tank with upper and lower connections according to claim 1, characterized in that, The multiple water flow holes are evenly spaced on the platform structure, and the clearance between the water flow holes and the edge of the hull structure is 50mm.

9. The method for testing the pneumatic pressure of a liquid tank in a ballast tank with upper and lower connections according to claim 2, characterized in that, The seat ring maintains a distance of 10mm from the edge of the channel hole, and the overlap width on one side is 60mm.

Images