A construction method suitable for laboratory floor on FLNG ship

Abstract

The application relates to the technical field of offshore engineering ship deck floor construction, in particular to a construction method suitable for a laboratory floor on an FLNG ship, which comprises the following steps: pretreatment and precision repair of a steel deck; arranging steel anchoring members according to a 300mm*300mm grid and welding; after sand blasting and rust removal of the whole plate to P2 level, spraying an epoxy anti-rust primer on the whole plate; binding a full layer of galvanized steel wire mesh on the upper surface of the anchoring members, pouring deck filler and embedding the steel wire mesh in the middle; and layer-by-layer construction of an epoxy mortar floor system with a total thickness of 5mm. Through the process resetting of welding before coating, the double anti-cracking structure of the anchoring members and the steel wire mesh and the 5mm epoxy mortar floor system, the problems that the FLNG laboratory floor is prone to cracking and corrosion under the working conditions of marine salt mist, equipment vibration and chemical corrosion are solved, and the method is suitable for the construction of the laboratory floor on the upper module of the FLNG.

Description

Technical Field

[0001] This invention relates to the field of marine engineering vessel deck floor construction technology, and specifically to a construction method applicable to the laboratory floor of an FLNG ship. Background Technology

[0002] The laboratory within the TOPSIDE superstructure process module of the FLNG unit is a core functional enclosed compartment, which must meet the 20-year design service life of the offshore platform. The compartment is constantly exposed to marine salt spray penetration, temperature fluctuations, and high humidity, and continuously subjected to vibrations from surrounding process equipment and micro-deformations of the platform. Furthermore, experimental operations pose risks of acid, alkali, and organic reagent spillage and residue, placing stringent requirements on the structural stability, fatigue crack resistance, salt spray resistance, chemical corrosion resistance, and cleanliness and durability of the flooring.

[0003] Currently, the industry still widely uses a conventional construction process combining traditional ship deck coverings with civilian epoxy flooring for modular laboratory flooring in this type of marine engineering. This traditional process has serious shortcomings in adapting to the complex operating conditions of FLNG (French LNG reactors), and after long-term service, it reveals the following unavoidable structural defects, causing the flooring system to experience functional failure within a short period of 5-8 years, far from meeting the 20-year design service life requirement: I. Current construction specifications typically employ a process of "applying an overall anti-corrosion coating to the deck → welding anchor fasteners → manually touching up the welded areas with paint." This process suffers from a fundamental technical flaw: the high-temperature arc generated during welding directly ablates and destroys the already cured and intact anti-corrosion coating system around and at the base of the fasteners. Subsequent manual touch-up painting is constrained by the limited operating space and complex weld geometry, making it impossible to quantitatively control the paint film thickness. This easily leads to coating quality defects such as pinholes, runs, missed areas, and interlayer overlaps, especially at the base of the anchors and the corners of the welds, where the anti-corrosion coating has natural blind spots. When the steel anchors are completely sealed inside by the subsequently poured deck material, these micro-corrosion defects, under the combined action of marine salt spray, condensation, and oxygen, form localized electrochemical corrosion cells. The rust products (iron oxides) expand in volume several times, and the resulting expansion stress continues to act on the surrounding cladding layers, causing interlayer peeling, hollowing and radial cracking, which directly damages the structural bond and integrity between the floor and the steel deck.

[0004] II. In traditional ship deck covering construction specifications, once steel anchoring fasteners are used for mechanical connections, steel wire mesh or fiber reinforcement layers are no longer added as crack-resistant structures. This design logic may be barely applicable in static or low-vibration ship compartments, but for FLNG facilities, the laboratory floor is continuously subjected to multi-directional, broadband vibration excitation from process equipment and alternating strain caused by the longitudinal bending of the hull. In the absence of a flexible crack-resistant reinforcement layer, cement-based or polymer-based covering layers will rapidly develop, propagate, and penetrate under alternating stress, eventually leading to fatigue cracking. Once the cracks penetrate, marine salt spray and liquid chemicals will travel along the crack channels directly to the steel deck substrate, accelerating pitting corrosion and stress corrosion cracking (SCC) of the steel structure, seriously threatening the safety of the superstructure.

[0005] III. Existing laboratory flooring typically employs single- or double-coat epoxy thin-film systems, with a total dry film thickness usually only 0.8–1.2 mm. While these thin-film coatings initially exhibit a good appearance, their insufficient thickness and limited cross-linking density during curing mean they remain essentially organic polymers, inherently permeable to water vapor, chloride ions, and small organic solvents. Under the combined conditions of high salt spray, high humidity and heat, and frequent contact with chemical reagents in FLNG (Fluorescent Liquid Gas), the coating rapidly plasticizes, swells, powders, or blisters. Deterioration in density allows corrosive media to penetrate the coating layer, further exacerbating the vicious cycle of anchor corrosion and coating deterioration. Furthermore, the impact and scratch resistance of this thin-film system is insufficient for accidental mechanical impacts such as equipment movement or heavy object drops.

[0006] In summary, traditional laboratory flooring construction methods are ill-suited to the complex conditions of FLNG TOPSIDE modules, including vibration, salt spray, and chemical corrosion, and cannot meet the required 20-year design life. Therefore, a specialized flooring construction process adapted to these laboratory conditions needs to be developed. Summary of the Invention

[0007] The purpose of this invention is to address the shortcomings of the prior art by providing a construction method suitable for laboratory floors on FLNG ships, thereby solving the problems mentioned in the background section.

[0008] To achieve the above objectives, the present invention provides the following technical solution: A construction method for laboratory flooring on an FLNG ship includes the following steps: Step S1: Pre-treat and precision repair the steel deck base surface, remove surface debris and correct local deformation areas to ensure that the deck flatness meets the requirements of subsequent construction. Step S2: Mark the positioning lines on the steel deck surface after Step S1, and lay out the steel anchors according to the preset grid of 300mm×300mm. Use a symmetrical segmented welding process to weld the anchors to the deck surface, control the welding heat input to reduce deformation, ensure that all anchors are perpendicular to the deck surface and are firmly welded, and match the anchor height with the design thickness of the subsequent deck covering. All anchors are welded before the whole plate is sandblasted, rusted and coated with anti-corrosion coating. Step S3: The entire deck structure with completed anchor welding is uniformly sandblasted and rust-removed to a rust removal grade of CB / T 3230 P2. After sandblasting and cleaning, a high-pressure airless spraying device is used to spray the entire area of ​​the steel deck and all welded anchors to form a continuous and seamless marine epoxy anti-rust primer anti-corrosion isolation layer. Step S4: After the anti-corrosion primer has fully cured, galvanized steel wire mesh is fully laid on the steel deck surface. The mesh size of the steel wire mesh is 40mm×40mm and the wire diameter is 2.5mm. The mesh pieces are overlapped and connected, and fixed to the upper surface of the anchor by binding. Then, the deck lining is poured, and the galvanized steel wire mesh is poured in layers to ensure that the galvanized steel wire mesh is embedded in the middle of the lining layer thickness. After the lining is applied, the entire surface is leveled and smoothed. After curing, the laitance is removed by grinding and cleaning. Step S5: Apply the epoxy mortar flooring system in layers on the cured deck material surface. The system consists of an epoxy undercoat, an epoxy intermediate mortar layer, an epoxy topcoat, and a matte functional surface layer, with a total thickness of 5mm.

[0009] As a preferred technical solution of the present invention, the pretreatment of the steel deck base surface in step S1 includes removing welding slag, large-particle oxide scale, oil stains and water accumulation from the deck surface, and the correction is fire correction to ensure that the deck flatness does not exceed 5mm.

[0010] As a preferred technical solution of the present invention, the dry film thickness of the marine epoxy anti-rust primer in step S3 is not less than 175μm, and the weld root and anchor dead corner are thickened by spraying, and the dry film thickness of the thickened area is not less than 50μm greater than that of the surrounding area.

[0011] As a preferred technical solution of the present invention, a sealing process is further included between step S3 and step S4: after the marine epoxy anti-rust primer has been fully cured, a curable anti-corrosion sealant is applied to the root of the anchor and the area around the weld to form a physical isolation sealing layer with a thickness of not less than 2mm, covering the heat-affected zone of the weld and the weak parts of the anti-corrosion coating. After the sealant has been cured, galvanized steel wire mesh is laid.

[0012] As a preferred technical solution of the present invention, the galvanized steel wire mesh in step S4 has a mesh size of 40mm×40mm and a wire diameter of 2.5mm, and the overlap width of the lap connection is not less than 50mm; the deck dressing is specifically made by using deck dressing certified by a classification society, mixing it according to the standard ratio, and spreading it within 30 minutes, and it is strictly forbidden to add water and reuse it during the spreading process; the curing time is not less than 24 hours at room temperature of 25℃, and the curing time is adjusted according to the hydration reaction rate based on the site temperature.

[0013] As a preferred technical solution of the present invention, during the construction of the epoxy lower coating in step S5, colored sand is simultaneously sprinkled on the surface after the epoxy lower coating liquid is applied to form an embedded layer of colored sand aggregate; the epoxy intermediate mortar layer is formed by mixing epoxy resin mixture with colored sand and then coating; during the construction of the matte functional surface layer, the surface is treated with micro-anti-slip treatment so that the floor surface can maintain flatness and cleanness while having dry and wet anti-slip properties.

[0014] As a preferred embodiment of the present invention, in step S5, the epoxy lower coating and the epoxy upper coating each independently adopt an amine-cured epoxy resin system; the matte functional surface layer adopts a polyurethane or modified epoxy system; the total dry film thickness of the epoxy lower coating, epoxy intermediate mortar layer, epoxy upper coating and matte functional surface layer is 5 mm, wherein the dry film thickness of the epoxy lower coating is 0.5~1.0 mm, the dry film thickness of the epoxy intermediate mortar layer is 2.0~3.0 mm, the dry film thickness of the epoxy upper coating is 0.8~1.2 mm, and the dry film thickness of the matte functional surface layer is 0.05~0.3 mm.

[0015] As a preferred embodiment of the present invention, the weight ratio of epoxy resin mixture to colored sand in the epoxy intermediate coating mortar layer is 1:10; the epoxy upper coating is applied 1 to 3 times, and the dry film thickness of each layer is controlled at 0.3 to 0.5 mm; the matte functional surface layer is applied 1 to 2 times.

[0016] As a preferred technical solution of the present invention, after the epoxy mortar flooring system described in step S5 is constructed, it shall be cured at 25°C for no less than 7 days. During the curing period, mechanical impact and contact with chemical reagents shall be prohibited. After the curing period, an adhesion pull-out test shall be conducted. At least one set of pull-out adhesion test shall be conducted for every 100m². The adhesion between the epoxy undercoat and the surface of the deck dressing shall be no less than 5MPa.

[0017] Compared with the prior art, the beneficial effects of the present invention are: I. This invention employs a dual-reinforcement structure of steel anchors and galvanized steel wire mesh. The steel anchors are welded to a 300mm x 300mm grid, and the galvanized steel wire mesh is bound and fixed to the upper surface of the anchors and embedded in the middle of the deck lining layer thickness, forming a dual-reinforcement system of "structural anchoring + internal tensile strength," rigidly locking the lining layer to the steel deck. This structure effectively counteracts the alternating strain caused by multi-directional, broadband vibration excitation of the FLNG upper module equipment and the longitudinal bending of the hull, improving the bonding strength and integrity between the lining layer and the steel deck, suppressing the occurrence of floor delamination, delamination, and structural cracking, and helping the laboratory floor maintain long-term structural stability under complex marine engineering conditions.

[0018] II. This invention adopts a process route of "welding steel anchors first → overall sandblasting and rust removal → overall high-pressure airless spraying of anti-corrosion coating". After all steel anchors are welded together in one go, the entire deck structure is uniformly sandblasted and rust removed (CB / T 3230 P2 grade). Then, the entire deck area and all anchors are coated with high-pressure airless spraying of marine epoxy anti-rust primer (dry film thickness ≥175μm). The weld roots and dead corners of the anchors are thickened with spraying (increased by ≥50μm), forming a continuous, dead-angle-free full-area anti-corrosion protective layer. This process can avoid the inherent defects of traditional processes such as high-temperature ablation of the coating by welding, uneven thickness of manual touch-up paint and missed coating, reduce the risk of micro-area electrochemical corrosion after the anchors are sealed inside the coating, reduce the structural impact of rust product expansion on the coating layer, and help the anti-corrosion life of the floor system adapt to the 20-year design and use requirements of the FLNG platform.

[0019] III. This invention employs a marine-grade epoxy mortar flooring system with a total thickness of 5mm, consisting of a layered composite structure of an epoxy lower coating (0.5~1.0mm), an epoxy intermediate mortar layer (2.0~3.0mm), an epoxy upper coating (0.8~1.2mm), and a matte functional surface layer (0.05~0.3mm). Compared to the traditional 1.0~2.0mm thin-coat epoxy flooring used in marine laboratories, this invention utilizes a thick-coat composite structure, exhibiting higher density, corrosion resistance, impact resistance, wear resistance, and anti-slip performance in both dry and wet conditions. Attached Figure Description

[0020] Figure 1 This is a process flow diagram of the flooring construction method for the FLNG marine laboratory of the present invention; Figure 2 This is a schematic diagram of the floor structure of the FLNG marine laboratory of the present invention; Detailed Implementation

[0021] The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby providing a clearer and more explicit definition of the scope of protection of the present invention. Example

[0022] This embodiment uses the steel deck of the laboratory on an FLNG ship as the construction object and is implemented according to the following steps.

[0023] Step S1: Pre-treatment and precision repair of steel deck base surface A preliminary cleaning was carried out on the entire steel deck of the FLNG laboratory to remove obvious welding slag, large oxide scale, oil stains and water from the deck surface.

[0024] Fire-based straightening methods were used to straighten localized deck deformation areas, ensuring the deck flatness did not exceed 5mm. After straightening, the deck surface was cleaned to remove oxide scale and welding slag residue generated during the straightening process.

[0025] Step S2: Install welded steel anchors After step S1, mark the positions on the steel deck surface and lay out the steel anchors according to the standard 300mm×300mm rectangular grid.

[0026] A symmetrical segmented welding process was used to weld the anchors to the deck surface, controlling the welding heat input to reduce deformation. All anchors were ensured to be perpendicular to the deck surface and firmly welded, without any incomplete welds, detachments, or misalignment. The anchor height matched the design thickness of the subsequent deck covering. All steel anchors were welded before the entire deck was sandblasted, derusted, and coated with anti-corrosion paint.

[0027] Step S3: Overall sandblasting and rust removal followed by anti-corrosion spraying The entire deck structure, with its anchors welded, is then placed in a sand chamber for uniform sandblasting and rust removal, achieving a rust removal grade of CB / T 3230 P2. Following sandblasting, a vacuum cleaner is used for thorough cleaning of the entire area.

[0028] Under clean and dry conditions, a high-pressure airless spraying system was used to apply a comprehensive coating to the entire steel deck and all welded anchors. The coating used was a marine epoxy anti-rust primer with a dry film thickness of at least 175 μm. Thicker coatings were applied to the weld roots and corners of the anchors, with the dry film thickness in these thickened areas increasing by at least 50 μm compared to the surrounding areas, forming a continuous, seamless marine epoxy anti-rust primer layer.

[0029] Sealing process between steps S3 and S4 After the marine epoxy anti-rust primer has fully cured, apply a curable anti-corrosion sealant to the base of the anchors and the area around the weld to form a physical isolation sealing layer with a thickness of not less than 2 mm, covering the heat-affected zone of the weld and the weak points of the anti-corrosion coating. Galvanized steel wire mesh is then laid after the sealant has cured.

[0030] Step S4: Wire mesh embedding and deck lining pouring After the anti-corrosion primer and sealant have fully cured, galvanized steel wire mesh is fully laid on the steel deck surface. The wire mesh has a mesh size of 40mm × 40mm and a wire diameter of 2.5mm. The mesh panels are overlapped, with an overlap width of not less than 50mm, and are fixed to the upper surface of the anchors with steel wire to prevent the wire mesh from arching, loosening, or shifting.

[0031] The deck dressing uses deck dressing certified by a classification society. After mixing according to the standard ratio, it must be spread within 30 minutes; re-addition of water and reuse is strictly prohibited. The dressing is poured in layers, ensuring that the galvanized steel wire mesh is embedded in the middle of the dressing layer thickness, neither touching the bottom nor exposed. After the dressing is applied, the entire surface is leveled and smoothed, and cured at a normal temperature of 25℃ for no less than 24 hours. After curing, the surface is finely sanded to remove laitance and vacuumed clean.

[0032] Step S5: Layered construction of 5mm thick epoxy mortar flooring On the cured deck dressing surface, an epoxy mortar flooring system is applied in layers with a total thickness of 5mm. From bottom to top, it includes an epoxy undercoat, an epoxy intermediate mortar layer, an epoxy topcoat, and a matte functional surface layer.

[0033] First layer: Epoxy undercoat. An amine-cured epoxy resin system is used, mixed evenly at a weight ratio of A:B = 2:1. The mixture is then applied evenly to the treated surface using a roller or brush. After coating, colored sand is sprinkled onto the surface to form an embedded layer of colored sand aggregate, enhancing interlayer adhesion. The dry film thickness is 0.5~1.0 mm.

[0034] Second layer: Epoxy intermediate mortar layer. Mix the epoxy resin mixture with colored sand at a weight ratio of 1:10 until homogeneous, and apply using a trowel. The dry film thickness is 2.0~3.0mm. Wipe the coating tools clean with a cloth frequently during application to ensure a smooth surface.

[0035] Third layer: Epoxy top coating. An amine-cured epoxy resin system is used, mixed evenly at a weight ratio of A:B = 2:1. The mixture is then applied evenly using a roller or brush, applying 1-3 coats, with each coat maintaining a dry film thickness of 0.3-0.5 mm. The total dry film thickness is 0.8-1.2 mm.

[0036] Fourth layer: Matte functional surface layer. Use a polyurethane or modified epoxy system, thoroughly mixed at a weight ratio of A:B = 10:1, and applied using a roller, applying 1-2 coats. The mixed material must be used within 20 minutes. A micro-anti-slip treatment is applied to the surface during construction, ensuring the floor surface remains smooth and clean while providing anti-slip properties in both wet and dry conditions. The dry film thickness is 0.05-0.3mm.

[0037] Maintenance and Acceptance. After the entire epoxy mortar flooring system is completed, it should be sealed and cured at 25℃ for no less than 7 days. During the curing period, mechanical impact and contact with chemical reagents are prohibited. After the curing period, an adhesion pull-out test should be conducted. At least one set of pull-out adhesion tests should be conducted for every 100m². The adhesion between the epoxy undercoat and the decking surface should not be less than 5MPa.

[0038] The above-described embodiments are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention.

Claims

1. A construction method for a laboratory floor suitable for FLNG ships, characterized in that, Includes the following steps: Step S1: Pre-treat and precision repair the steel deck base surface, remove surface debris and correct local deformation areas to ensure that the deck flatness meets the requirements of subsequent construction. Step S2: Mark the positioning lines on the steel deck surface after Step S1, and lay out the steel anchors according to the preset grid of 300mm×300mm. Use a symmetrical segmented welding process to weld the anchors to the deck surface, control the welding heat input to reduce deformation, ensure that all anchors are perpendicular to the deck surface and are firmly welded, and match the anchor height with the design thickness of the subsequent deck covering. All anchors are welded before the whole plate is sandblasted, rusted and coated with anti-corrosion coating. Step S3: The entire deck structure with completed anchor welding is uniformly sandblasted and rust-removed to a rust removal grade of CB / T 3230 P2. After sandblasting and cleaning, a high-pressure airless spraying device is used to spray the entire area of ​​the steel deck and all welded anchors to form a continuous and seamless marine epoxy anti-rust primer anti-corrosion isolation layer. Step S4: After the anti-corrosion primer has fully cured, galvanized steel wire mesh is fully laid on the steel deck surface. The mesh size of the steel wire mesh is 40mm×40mm and the wire diameter is 2.5mm. The mesh pieces are overlapped and connected, and fixed to the upper surface of the anchor by binding. Then, the deck lining is poured, and the galvanized steel wire mesh is poured in layers to ensure that the galvanized steel wire mesh is embedded in the middle of the lining layer thickness. After the lining is applied, the entire surface is leveled and smoothed. After curing, the laitance is removed by grinding and cleaning. Step S5: Apply the epoxy mortar flooring system in layers on the cured deck material surface. The system consists of an epoxy undercoat, an epoxy intermediate mortar layer, an epoxy topcoat, and a matte functional surface layer, with a total thickness of 5mm.

2. The construction method for a laboratory floor on an FLNG ship according to claim 1, characterized in that: The pretreatment of the steel deck surface in step S1 includes removing welding slag, large oxide scale, oil stains and water from the deck surface. The straightening is fire straightening to ensure that the deck flatness does not exceed 5mm.

3. The construction method for a laboratory floor on an FLNG ship according to claim 1, characterized in that: The dry film thickness of the marine epoxy anti-rust primer mentioned in step S3 shall not be less than 175μm, and the weld root and anchor dead corner areas shall be thickened by spraying, with the dry film thickness of the thickened area increasing by not less than 50μm compared with the surrounding area.

4. The construction method for a laboratory floor on an FLNG ship according to claim 1, characterized in that: Between steps S3 and S4, a sealing process is also included: after the marine epoxy anti-rust primer has fully cured, a curable anti-corrosion sealant is applied to the root of the anchor and the area around the weld to form a physical isolation sealing layer with a thickness of not less than 2mm, covering the heat-affected zone of the weld and the weak parts of the anti-corrosion coating. After the sealant has cured, galvanized steel wire mesh is laid.

5. A construction method for a laboratory floor on an FLNG ship according to claim 1, characterized in that: The galvanized steel wire mesh in step S4 has a mesh size of 40mm×40mm and a wire diameter of 2.5mm. The overlap width of the lap joint is not less than 50mm. The deck dressing is specifically made of deck dressing certified by a classification society. After mixing according to the standard ratio, it is spread within 30 minutes. It is strictly forbidden to add water and reuse it during the spreading process. The curing time is not less than 24 hours at room temperature (25℃). The curing time is adjusted according to the hydration reaction rate based on the site temperature.

6. A construction method for a laboratory floor on an FLNG ship according to claim 1, characterized in that: During the construction of the epoxy undercoat in step S5, colored sand is simultaneously sprinkled on the surface after the epoxy undercoat liquid is applied to form an embedded layer of colored sand aggregate; the epoxy intermediate mortar layer is formed by mixing epoxy resin mixture with colored sand and then coating; during the construction of the matte functional surface layer, the surface is treated with micro-anti-slip treatment so that the floor surface can maintain flatness and cleanness while having anti-slip performance in both dry and wet conditions.

7. A construction method for a laboratory floor on an FLNG ship according to claim 1, characterized in that: In step S5, the epoxy lower coating and epoxy upper coating each independently adopt an amine-cured epoxy resin system; the matte functional surface layer adopts a polyurethane or modified epoxy system. The total dry film thickness of the epoxy lower coating, epoxy intermediate mortar layer, epoxy upper coating, and matte functional surface layer is 5 mm, wherein the dry film thickness of the epoxy lower coating is 0.5~1.0 mm, the dry film thickness of the epoxy intermediate mortar layer is 2.0~3.0 mm, the dry film thickness of the epoxy upper coating is 0.8~1.2 mm, and the dry film thickness of the matte functional surface layer is 0.05~0.3 mm.

8. A construction method for a laboratory floor on an FLNG ship according to claim 6, characterized in that: The epoxy resin mixture and colored sand in the epoxy intermediate mortar layer have a weight ratio of 1:10; the epoxy upper coating is applied 1 to 3 times, and the dry film thickness of each coat is controlled at 0.3 to 0.5 mm; the matte functional surface layer is applied 1 to 2 times.

9. A construction method for a laboratory floor on an FLNG ship according to claim 1, characterized in that: After the epoxy mortar flooring system described in step S5 is completed, it shall be cured at 25°C for no less than 7 days. During the curing period, mechanical impact and contact with chemical reagents shall be prohibited. After the curing period, an adhesion pull-out test shall be conducted. At least one set of pull-out adhesion test shall be conducted for every 100m². The adhesion between the epoxy undercoat and the deck dressing surface shall be no less than 5MPa.

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