Method for installing C-shaped tank saddle of LNG dual-fuel oil ship

Abstract

A C-shaped tank saddle installation method of an LNG dual-fuel oil ship comprises the steps that a saddle is built in a staged mode, a strut jig frame is built with the stern face of a saddle web as a base plane, a preset longitudinal section line serves as a reference network line and is led to the ground to serve as a ground sample line, and a main body frame structure and a middle arc-shaped panel of the saddle are installed firstly; and the arc-shaped panels, the stop flat iron and the stop toggle plates on the two sides of the saddle are used as after-installation parts to be temporarily not installed and are installed when the saddle and the ship body are closed, and after the fixed saddle is installed in place, the anti-floating saddle is installed and welded. According to the invention, a unified reference network cable system from the jig frame to the dock is established, and the precision control of the whole process is realized. The post-assembly process of the upper component ensures that the fitness of the saddle and the tank body is more than 99%, and the stress concentration and fretting wear risks are greatly reduced. The safety, the reliability and the construction efficiency are improved, and the cost is reduced.

Description

Technical Field

[0001] This invention belongs to the field of marine shipbuilding and design, and specifically relates to a method for installing a C-type tank saddle on an LNG dual-fuel oil tanker. Background Technology

[0002] In LNG dual-fuel powered ships using C-type fuel tanks, the saddle is a key structure connecting the large cryogenic tank to the hull. Its construction and installation precision directly affects the stability of the tank support, the uniformity of stress distribution, and the operational safety of the ship.

[0003] Currently, the traditional methods for constructing and installing saddles typically involve either building them as a whole or fabricating them in sections and then hoisting them as a whole. These methods have the following problems: 1. High difficulty in manufacturing and hoisting: The saddle structure is complex and large in size. Turning it over and positioning it after the whole structure is built is extremely difficult, and it is easy to cause uncontrollable deformation during hoisting.

[0004] 2. Matching accuracy is difficult to guarantee: The matching degree between the arc-shaped panel on the upper part of the saddle and the actual contour of the tank depends on the precision of the previous processing. It cannot compensate for manufacturing tolerances and welding deformation, which can easily lead to insufficient contact and local stress concentration.

[0005] 3. Insufficient alignment accuracy control: The alignment of the reinforcing structure below the saddle and deck lacks a full-process accuracy control system, and the accumulated error may affect the overall structural integrity.

[0006] Therefore, there is an urgent need for a new saddle installation process that can effectively control precision, ensure structural matching, reduce welding deformation, and facilitate installation. Summary of the Invention

[0007] To address the aforementioned problems, this invention provides a method for installing a C-type tank saddle on an LNG dual-fuel tanker, aiming to achieve precise matching and alignment between the saddle and the tank body, reduce welding deformation, and facilitate installation. The technical solution adopted is as follows: A method for installing a C-type tank saddle on an LNG dual-fuel tanker, the specific steps of which are as follows: S1: Saddle mount constructed in stages A support frame is built with the stern face of the saddle web as the base. The pre-set longitudinal section line is used as the reference network line and is extended to the ground to make a ground plot line. The main frame structure and the central arc panel of the saddle are installed first. The arc panels, stop flat iron and stop elbow plate on both sides of the saddle are not installed for the time being as post-installation parts and are reserved for installation when they are joined with the hull.

[0008] S2: Saddle closing and positioning Mark the saddle positioning lines and longitudinal section lines on the deck surface of the hull section, corresponding to the reference grid lines, 15000mm from the center. Use the positioning lines and grid lines to position and install the main structure of the fixed saddle on the hull. Temporarily fix it by tack welding. After re-measuring the data, reposition it to accurately control the alignment accuracy between the saddle and the under-deck reinforcement structure, as well as the spacing, height and centerline deviation between the fixed saddles in the same group.

[0009] S3: Upper component installation After the acceptance of the C-type fuel tank, based on the measured profile data of the laminated wood support for the tank, the arc-shaped panels on both sides of the saddle, as well as the stop flat iron and stop elbow plate, are inspected, machined, or ground on site, and then installed and fixed to ensure that they match the profile of the tank.

[0010] S4: Prevents delayed installation of the float mount After the C-type fuel tank is hoisted to the fixed saddle and in place, the anti-buoyancy saddle is installed and welded. During welding, the welding heat and speed are controlled to prevent the high temperature of welding from damaging the epoxy resin material of the laminated wood at the bottom of the tank.

[0011] Furthermore, in the above-mentioned method for installing the C-type tank saddle of an LNG dual-fuel tanker, the reference network line is a 15000mm longitudinal section line, and the tolerance of the center line and horizontal baseline of the jig is controlled within ±1mm.

[0012] Furthermore, the above-mentioned method for installing the C-type tank saddle of an LNG dual-fuel tanker further specifies that the verticality deviation of the saddle web plate is ≤3mm, the height deviation of the same group of saddles is ≤6mm, the spacing deviation is ≤5mm, and the centerline deviation is ≤3mm.

[0013] Furthermore, the above-mentioned method for installing the C-type tank saddle of an LNG dual-fuel tanker further employs a low heat input of 0.75~1.18kJ / mm and a high-speed welding rate of 220~280mm / min. The welding is performed symmetrically by an even number of Korean engineers to control the interpass temperature and ensure that the temperature transmitted to the bottom of the tank is below 90℃.

[0014] Furthermore, the above-mentioned method for installing the C-type tank saddle of an LNG dual-fuel tanker further involves obtaining no fewer than six sets of data on the distance between the inner and outer edges of the tank body layer Tamm support and the center distance of the support.

[0015] Furthermore, in the above-mentioned method for installing the C-type tank saddle of an LNG dual-fuel tanker, the fixed end saddle and the sliding end saddle have the same structure, with a vertically arranged web plate. The lower part of the web plate is a square section, and the upper part is an arc-shaped section. The arc-shaped section is connected to the square section, and anti-stowing elbow plates are reinforced on both sides. The surface of the arc-shaped section is provided with an arc-shaped panel, and the sides are provided with stop elbow plates and stop flat iron.

[0016] The beneficial effects of this invention are: 1. This invention breaks away from the traditional mindset of integral installation. By adopting the strategies of "phased construction" and "post-installation of key parts", it decomposes the installation of a complex heavy structure into multiple controllable and simple steps. It also creatively proposes a process method of "post-installation based on actual tank measurement data", realizing the transformation from "manufacturing-oriented" to "adaptation-oriented".

[0017] 2. A unified reference network system was established from the jig to the dry dock, enabling precision control throughout the entire process. The post-installation process for the upper components ensured a fit of over 99% between the saddle and the tank, greatly reducing the risk of stress concentration and fretting wear.

[0018] 3. High safety and high reliability: The rear-mounted anti-buoy not only facilitates tank hoisting (without interference), but also eliminates the risk of surface heat damage to the bottom material of the tank through a special welding process.

[0019] 4. High efficiency and low cost: Phased construction reduces the difficulty of hoisting and reliance on large hoisting equipment, and reduces adjustment and rework time. Verified in the actual shipbuilding project T300K-112, this process can shorten the construction period by approximately 20% and reduce construction costs by more than 10%, resulting in significant economic benefits. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of a fixed saddle structure; Figure 2 This is a schematic diagram of the web structure; Among them, 1-support frame, 2-stop flat iron, 3-stop elbow plate, 4-saddle positioning line, 5-longitudinal section line, 7-anti-tilt elbow plate, 8-buoyancy-stopping structure, 9-web plate, 10-central arc-shaped panel, 11-arc-shaped panels on both sides. Detailed Implementation

[0021] The invention will be further described with reference to the accompanying drawings.

[0022] A method for installing a C-type tank saddle on an LNG dual-fuel tanker, applied in the actual construction of the T300K-112 vessel, such as... Figure 1 As shown, the fixed end saddle and the sliding end saddle have the same structure, with a vertically arranged web plate. The lower part of the web plate is a square segment, and the upper part is an arc-shaped segment. The arc-shaped segment is connected to the square segment, and anti-tilting elbow plates are reinforced on both sides. The surface of the arc-shaped segment is provided with an arc-shaped panel, and the sides are provided with stop elbow plates and stop flat iron.

[0023] The specific installation method is as follows: S1: Phased construction of the saddle First, using the fixed saddle web as the reference plane, a high-precision (tolerance ±1mm) support frame is constructed. The saddle web is then welded together in two pieces on the upper frame, and a "15000 longitudinal section line" is marked as the reference network line throughout the entire process, projected onto the ground as a permanent ground plot. The main frame, including the stern elbow plate and reinforcing ribs, as well as the central arc-shaped panel, are installed first. Then, the entire structure is flipped over, and the main frame, including the bow elbow plate and reinforcing ribs, is welded. The arc-shaped panels, anti-sway flat iron, and stop elbow plates on both sides are considered as later-installed components and are not installed for the time being. This process breaks down the large and complex saddle into modules that are easy to construct and hoist. During assembly, key dimensions such as the curvature of the arc-shaped panel and the verticality of the elbow plate must be strictly controlled.

[0024] S2: Saddle closing and positioning 1) During the construction phase of the main hull deck sections under the fixed saddle, the positioning line, inspection line and 15000 longitudinal section line consistent with the jig are pre-marked on the main deck surface.

[0025] 2) When closing, first hoist and fix the saddle, and use the positioning lines and network lines on the deck for precise positioning to ensure accurate alignment with the base reinforcement structure under the deck.

[0026] 3) Then install the sliding end saddle, and strictly control the spacing (tolerance ±5mm), height difference (tolerance ±6mm), and centerline deviation (tolerance ±3mm) between saddles in the same group.

[0027] S3: Precise installation of upper components After the C-type fuel tank is constructed and accepted, the actual contour data of the laminated wood support for the tank body is measured on-site using a 3D laser scanner or a high-precision total station (measurement of no less than 6 sets of data). Based on these measured data, the arc-shaped panels, stop flat irons, and stop elbow plates at both ends of the saddle are precisely installed to ensure a perfect fit between the top of the fixed saddle and the laminated wood of the tank body.

[0028] S4: Delayed installation and special welding of the anti-buoyancy seat The primary purpose of delaying the installation of the anti-buoyancy support is to facilitate the hoisting of the C-type tank. Before the C-type tank is hoisted, there are no protruding structures above the fixed saddle, providing an unobstructed hoisting passage and operating space for the tank, greatly reducing the difficulty and risk of hoisting.

[0029] After the C-type fuel tank is hoisted and positioned, the anti-buoyancy structure is installed and welded. To avoid damage to the laminated wood and epoxy resin at the bottom of the tank from the high temperature generated during welding of the anti-buoyancy seat, special process requirements are strictly followed during welding. Low heat input and fast welding are used, and welding is performed symmetrically by an even number of welders. The interlayer temperature is strictly controlled to ensure that the temperature transmitted to the bottom of the tank is below the safe threshold of 90°C, thus protecting the laminated wood and epoxy resin from damage.

Claims

1. A method for installing a C-type tank saddle on an LNG dual-fuel tanker, characterized in that, The specific steps are as follows: S1: Saddle mount constructed in stages A support frame is built with the stern face of the saddle web as the base. The preset longitudinal section line is used as the reference network line and is led to the ground as a ground plot line. The main frame structure and the central arc panel of the saddle are installed first. The arc panels, stop flat iron and stop elbow plate on both sides of the saddle are not installed for the time being as post-installation parts and are reserved for installation when they are joined with the hull. S2: Saddle closing and positioning Mark the saddle positioning line and longitudinal section line on the deck surface of the hull section, corresponding to the reference network line, 15000mm from the center; use the positioning line and network line to position and install the main structure of the fixed saddle on the hull, temporarily fix it by positioning welding, re-position it after re-measuring the data, and accurately control the alignment accuracy of the saddle and the under-deck reinforcement structure, as well as the spacing, height and centerline deviation between the fixed saddles in the same group. S3: Upper Component Installation After the acceptance of the C-type fuel tank, based on the measured tank body laminated wood support profile data, the arc-shaped panels on both sides of the saddle, as well as the stop flat iron and stop elbow plate, are inspected, machined or ground on site, and then installed and fixed to ensure that they match the tank body profile. S4: Prevents delayed installation of the float mount After the C-type fuel tank is hoisted to the fixed saddle and in place, the anti-buoyancy saddle is installed and welded. During welding, the welding heat and speed are controlled to prevent the high temperature of welding from damaging the epoxy resin material of the laminated wood at the bottom of the tank.

2. The method for installing a C-type tank saddle on an LNG dual-fuel tanker according to claim 1, characterized in that, The baseline network line is a 15000mm longitudinal section line, and the tolerance of the center line and horizontal baseline of the jig is controlled within ±1mm.

3. The method for installing a C-type tank saddle on an LNG dual-fuel tanker according to claim 1, characterized in that, The verticality deviation of the saddle web is ≤3mm, the height deviation of saddles in the same group is ≤6mm, the spacing deviation is ≤5mm, and the centerline deviation is ≤3mm.

4. The method for installing a C-type tank saddle on an LNG dual-fuel tanker according to claim 1, characterized in that, Welding employs low heat input (0.75~1.18kJ / mm) and high-speed welding (220~280mm / min), with welding performed symmetrically by an even number of Korean engineers to control interpass temperature and ensure that the temperature transferred to the bottom of the tank is below 90℃.

5. The method for installing a C-type tank saddle on an LNG dual-fuel tanker according to claim 1, characterized in that, Obtain no fewer than six sets of data on the distance between the inner and outer edges of the laminated wood supports for the tank and the center distance between the supports.

6. The method for installing a C-type tank saddle on an LNG dual-fuel tanker according to claim 1, characterized in that, Both the fixed-end saddle and the sliding-end saddle have vertically installed web plates. The lower part of the web plate is a square section, and the upper part is an arc-shaped section. The arc-shaped section is connected to the square section, and anti-tilting elbow plates are reinforced on both sides. The surface of the arc-shaped section is provided with an arc-shaped panel, and the sides are provided with stop elbow plates and stop flat iron.

7. The method for installing a C-type tank saddle on an LNG dual-fuel tanker according to claim 1, characterized in that, In step S1, the main frame structure includes a web, a supporting elbow plate, and an anti-tilting elbow plate.

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