CN113431014B - Ocean platform casting node with gradually-changed wall thickness and preparation method thereof - Google Patents
Ocean platform casting node with gradually-changed wall thickness and preparation method thereof Download PDFInfo
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- CN113431014B CN113431014B CN202110745462.6A CN202110745462A CN113431014B CN 113431014 B CN113431014 B CN 113431014B CN 202110745462 A CN202110745462 A CN 202110745462A CN 113431014 B CN113431014 B CN 113431014B
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02B—HYDRAULIC ENGINEERING
- E02B17/00—Artificial islands mounted on piles or like supports, e.g. platforms on raisable legs or offshore constructions; Construction methods therefor
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
- C21D1/18—Hardening; Quenching with or without subsequent tempering
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
- C21D9/08—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for tubular bodies or pipes
- C21D9/085—Cooling or quenching
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02B—HYDRAULIC ENGINEERING
- E02B17/00—Artificial islands mounted on piles or like supports, e.g. platforms on raisable legs or offshore constructions; Construction methods therefor
- E02B17/0004—Nodal points
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D2211/00—Microstructure comprising significant phases
- C21D2211/001—Austenite
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D2211/00—Microstructure comprising significant phases
- C21D2211/005—Ferrite
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D2211/00—Microstructure comprising significant phases
- C21D2211/009—Pearlite
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- Materials Engineering (AREA)
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- Physics & Mathematics (AREA)
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- Rigid Pipes And Flexible Pipes (AREA)
Abstract
A casting node with gradually-changed wall thickness for an ocean platform comprises a main body used for connecting steel structure pipe fittings, wherein the main body is integrally cast steel and comprises a central connecting pipe, 2-4 inclined pipes and 2-6 bottom pipes; the connecting ends of the central connecting pipe, the inclined pipe and the bottom pipe are intersected and converged at one position to form a node core area, the central axes of all connecting pipe fittings are intersected on two central points in the node core area, the distance between the two central points is 250-300mm, and fillet transition is arranged between the inner wall surface and the outer wall surface of two adjacent connecting pipes. The cast joint reduces the whole weight and ensures good welding performance while reducing the weight. The casting node can be formed in one step, the process is simpler, and the manufacturing cost is greatly reduced.
Description
Technical Field
The invention belongs to the field of ocean platform equipment, and particularly relates to a corrosion-resistant high-strength high-toughness cast node in a low-temperature environment.
Background
The ocean platform is the foundation for human ocean development, and the nodes are a key component in the ocean platform. The main function of the node is to connect the key and bear the load, and because the stress state of the node is relatively complicated, the stress concentration phenomenon is easily generated, so that cracks appear, and the structure is possibly failed due to further expansion, so that serious accidents occur. Therefore, the design of the node needs to meet the overall stress strength of the platform structure and also needs to meet the local strength of each component meeting the node, including the structural strength, the static strength and the fatigue strength, so as to ensure the safety of the platform. The welding joint has high internal stress and serious low-temperature cold brittleness, and stress concentration is easy to occur under the action of external force to cause joint damage and damage the safety of the platform. The cast joint has high rigidity, stress concentration coefficient of only one half of that of a welded joint, long fatigue life, strong extreme environment resistance, isotropy of cast steel and higher toughness in the thickness direction. In addition, the cost of the casting node is lower than that of the welding node, and the casting node replaces the welding node, except for individual nodes, most casting nodes can save steel by 5-15%, and the manufacturing cost is reduced by 3-30%, so that the development of ocean platform casting nodes is a future development trend.
Disclosure of Invention
The invention aims to provide a casting joint with gradually-changed wall thickness for an ocean platform, which comprises a main body for connecting steel structure pipe fittings, wherein the main body is integrally cast steel and comprises a central connecting pipe, 2-4 inclined pipes and 2-6 bottom pipes; the connecting ends of the central connecting pipe, the inclined pipe and the bottom pipe are intersected and converged at one position to form a node core area, the central axes of all connecting pipe fittings are intersected on two central points in the node core area, the distance between the two central points is 250-300mm, and fillet transition is arranged between the inner wall surface and the outer wall surface of two adjacent connecting pipes. Preferably, the main body comprises a central connecting pipe, 2 inclined pipes and 2 bottom pipes.
In the novel gradually-changing wall thickness casting node, the wall thickness of the upper parts of the pipe fittings of the central connecting pipe and the inclined pipe is gradually increased, and the wall thickness of the lower parts of the pipe fittings is uniform; the wall thickness of the central connecting pipe is gradually increased from a position 180-220mm away from the end point of the central connecting pipe, the wall thickness of the central point at the upper part of the central connecting pipe is the largest, the minimum wall thickness at the upper part of the central connecting pipe is 25-30mm, the maximum wall thickness is 35-45mm, and the wall thickness at the lower part of the central pipe is 25-30mm; the wall thickness of the inclined tube is gradually increased from the intersection area of the inclined tube and the central connecting tube, the minimum wall thickness of the upper part of the inclined tube is 20-25mm, the maximum wall thickness is 30-40mm, and the wall thickness of the lower part of the inclined tube is 20-25mm; the inclined pipe is connected with the central connecting pipe at an angle of 30-45 degrees; the bottom tube is a uniform wall thickness tube with the wall thickness of 12-15mm and is connected with the central connecting tube at an angle of 60-90 degrees.
The upper parts of the central connecting pipe and the inclined pipe are parts above the horizontal plane of the cross section of the pipe.
The maximum wall thickness of the inclined tube is positioned on the section which is perpendicular to the axial line of the central connecting tube at the center of the node.
Preferably, in the novel gradual-change wall thickness casting node, the wall thickness of the upper parts of the central connecting pipe and the pipe fittings of the inclined pipe is gradually increased, and the wall thickness of the lower parts of the central connecting pipe and the pipe fittings of the inclined pipe is uniform; the wall thickness of the central connecting pipe is gradually increased from the position 190-210mm away from the end point of the central connecting pipe, the wall thickness of the central point of the central connecting pipe is the largest, the minimum wall thickness of the upper part of the central connecting pipe is 28-30mm, the maximum wall thickness is 40-42mm, and the wall thickness of the lower part of the central connecting pipe is 28-30mm; the wall thickness of the inclined tube is gradually increased from the intersection area of the inclined tube and the central connecting tube, the minimum wall thickness of the upper part of the inclined tube is 22-23mm, the maximum wall thickness is 32-38mm, and the wall thickness of the lower part of the inclined tube is 22-23mm; the inclined pipe is connected with the central connecting pipe at an angle of 35-40 degrees; the bottom pipe is a pipe with uniform wall thickness of 13-14mm, and is connected with the central connecting pipe fitting at an angle of 70-80 degrees.
Preferably, the steel for the casting node may be pretreated, including the steps of:
(1) Quenching treatment: heating the corrosion-resistant high-strength high-toughness casting node steel casting under the low-temperature environment to 930-970 ℃, preserving the heat for 1-2h, and cooling the steel casting to room temperature at the speed of 30-50K/s;
(2) Tempering treatment: and (3) heating the corrosion-resistant high-strength high-toughness casting node steel subjected to water quenching to 450-700 ℃, preserving heat for 4-6 hours, and then cooling in air to room temperature.
The invention adopts a quenching and tempering heat treatment process when preparing the corrosion-resistant high-strength high-toughness casting node in a low-temperature environment, thereby obtaining a microstructure of tempered sorbite with a small amount of residual austenite and ferrite. The retained austenite distributed in the structure can enhance the strength and the toughness of the whole steel, and the retained austenite can effectively absorb stress in the deformation process to prevent microcracks; the tempered sorbite is a matrix structure with better toughness; the fine ferrite structure distributed in a dispersed manner can well inhibit crack propagation, and can prevent grains from growing in the phase transformation process, and in the quenching and tempering processes, the ferrite can form some superfine sub-grains along the grain boundary of the quenched prior austenite, so that the proportion of the grain boundary is increased, the content of harmful impurity elements on the unit interface is further reduced, and the toughness of the alloy is favorably improved.
Preferably, the carbon content in the steel for casting the node satisfies that C is less than or equal to 0.12 percent, and the carbon equivalent satisfies that C eq Less than or equal to 0.56 percent, reduces the whole weight of the casting node, and ensures good welding performance while reducing the wall thickness of the casting node.
Preferably, the proportion of ferrite in the steel for casting nodes is more than or equal to 10%.
Preferably, the prepared steel for the corrosion-resistant high-strength high-toughness casting node has good corrosion resistance in a low-temperature environment at-40 ℃.
Has the beneficial effects that: compared with the existing casting node, the invention has the remarkable advantages that: in the solidification process, the wall is thin and gradually becomes thick, the heat storage capacity of the molten steel in unit volume is small, and the solidification speed is relatively high; the adjacent thicknesses of the products are greatly different and gradually transition in thickness connection; the distribution positions of the risers ensure that the shrinkage stress of the whole casting is basically and uniformly distributed, and the feeding distance can usually reach 4 to 5 times of the wall thickness; the design of the pouring system can feed liquid from a low position, and the liquid is introduced by arranging a side riser or by using a gap sprue, so that the filling process is stable, slag discharge, discharge and ingate arrangement are facilitated, uniform distribution is realized as much as possible, and the shrinkage stress is uniform; the thinner the casting wall, the larger the area and the complex shape, the larger the resistance of the metal flowing in the casting mold, and at the same time, the temperature reduction is fast, the fluidity is poor, the casting is difficult to be fully poured, the casting can generate the defects of cold shut, insufficient pouring and the like, and the problem is well solved by the gradual change thickness.
Drawings
FIG. 1 is a schematic view of a progressive wall thickness cast node construction;
FIG. 2 is a schematic cross-sectional structural view of a gradual wall thickness casting joint;
FIG. 3 is a top view of a cross-sectional structure of a graded wall thickness cast node.
Wherein, 1 is a central connecting pipe fitting; 2 is an inclined tube; 3 is a connecting pipe fitting; 4 is the central axis of the inclined tube; 5 is central connecting pipe fitting central axis; and 6 is a central point.
Detailed Description
The technical scheme of the invention is further explained in detail by combining with the embodiment.
Example 1
A casting node with gradually-changed wall thickness for an ocean platform comprises a main body used for connecting a steel structure pipe body, wherein the main body is an integrally-cast steel node and comprises a main body used for connecting a steel structure pipe fitting, the main body is integrally-cast steel, and the main body comprises a central connecting pipe, 2 inclined pipes and 2 bottom pipes; the connecting ends of the central connecting pipe, the inclined pipe and the bottom pipe are mutually intersected and converged at one position to form a node core area, the central axes of all connecting pipe fittings are intersected on two central points in the node core area, the distance between the two central points is 250mm, and circular arc transition is arranged between the inner wall surface and the outer wall surface of two adjacent connecting pipe bodies. The upper part of the novel casting node with the gradually-changed wall thickness is provided with the gradually-changed wall thickness, and the lower part of the novel casting node with the gradually-changed wall thickness is provided with the uniform wall thickness; the minimum wall thickness of the central connecting pipe body is 25mm, the minimum wall thickness gradually increases from a region 200mm away from the end point of the central connecting pipe, and the thickest part is 35mm; the minimum wall thickness of the inclined tube is 20mm, the thickness of the inclined tube is gradually increased from a 200mm area, the thickest part is 30mm, and the inclined tube and the central connecting tube body are connected at an angle of 30 degrees; the bottom tube has a uniform wall thickness of 12mm, and is connected with the central connecting rod at an angle of 60 degrees. The maximum tensile strength of the cast node is 632MPa.
Example 2
A casting node with gradually-changed wall thickness for an ocean platform comprises a main body used for connecting a steel structure pipe body, wherein the main body is an integrally-cast steel node and comprises a main body used for connecting a steel structure pipe fitting, the main body is integrally-cast steel, and the main body comprises a central connecting pipe, 2 inclined pipes and 2 bottom pipes; the connecting ends of the central connecting pipe, the inclined pipe and the bottom pipe are mutually intersected and converged at one position to form a node core area, the central axes of all connecting pipe fittings are intersected on two central points in the node core area, the two central points are separated by 300mm, and circular arc transition is arranged between the inner wall surface and the outer wall surface of two adjacent connecting pipe bodies.
The upper part of the novel casting node with the gradually-changed wall thickness is provided with the gradually-changed wall thickness, and the lower part of the novel casting node with the gradually-changed wall thickness is provided with the uniform wall thickness; the minimum wall thickness of the central connecting pipe body is 30mm, the area 220mm away from the end point of the central connecting pipe begins to increase gradually, and the thickest part is 45mm; the minimum wall thickness of the inclined tube is 25mm, the thickness of the inclined tube is gradually increased from a 220mm area, the thickest part is 40mm, and the inclined tube is connected with the central connecting tube body at an angle of 45 degrees; the bottom tube is uniform in wall thickness, the wall thickness is 15mm, and the bottom tube is connected with the central connecting tube body at an angle of 90 degrees. The maximum tensile strength of the cast node is 627MPa.
Comparative example 1
An ocean platform gradual wall thickness casting node is the same as that in embodiment 1 in structure, but all pipes are pipes with the same wall thickness, and the thickness of each pipe is 35mm. The maximum tensile strength of the cast joint is 520MPa.
Comparative example 2
An ocean platform gradual wall thickness casting node is the same as the structure of the ocean platform gradual wall thickness casting node in the embodiment 1, but all pipes are pipes with the same wall thickness, and the thickness of each pipe is 25mm. The maximum tensile strength of the cast joint was 504MPa.
The above-mentioned embodiments, objects, technical solutions and advantages of the present invention are further described in detail, it should be understood that the above-mentioned embodiments are only examples of the present invention, and are not intended to limit the scope of the present invention, and any modifications, equivalent alterations and the like made within the spirit and principle of the present invention should be included in the scope of the present invention.
Claims (6)
1. A casting node with gradually-changed wall thickness for an ocean platform is characterized by comprising a main body for connecting steel structure pipe fittings, wherein the main body is integrally cast steel and comprises a central connecting pipe, 2-4 inclined pipes and 2-6 bottom pipes; the connecting ends of the central connecting pipe, the inclined pipe and the bottom pipe are intersected and converged at one position to form a node core area, the central axes of all connecting pipe fittings are intersected on two central points in the node core area, the distance between the two central points is 250-300mm, and fillet transition is arranged between the inner wall surface and the outer wall surface of two adjacent connecting pipes; the upper parts of the pipe fittings of the central connecting pipe and the inclined pipe are gradually increased in wall thickness, and the lower parts of the pipe fittings are uniform in wall thickness;
the wall thickness of the central connecting pipe is gradually increased from a position 180-220mm away from the end point of the central connecting pipe, the wall thickness of the central point at the upper part of the central connecting pipe is the largest, the minimum wall thickness at the upper part of the central connecting pipe is 25-30mm, the maximum wall thickness is 35-45mm, and the wall thickness at the lower part of the central pipe is 25-30mm; the wall thickness of the inclined tube is gradually increased from the intersection area of the inclined tube and the central connecting tube, the minimum wall thickness of the upper part of the inclined tube is 20-25mm, the maximum wall thickness is 30-40mm, and the wall thickness of the lower part of the inclined tube is 20-25mm; the inclined pipe is connected with the central connecting pipe at an angle of 30-45 degrees; the bottom pipe is a pipe with uniform wall thickness of 12-15mm and is connected with the central connecting pipe at an angle of 60-90 degrees;
the method for pretreating the steel for the casting node comprises the following steps of:
(1) Quenching treatment: heating the corrosion-resistant high-strength high-toughness casting node steel casting in a low-temperature environment to 930-970 ℃, preserving heat for 1-2h, and cooling to room temperature at the speed of 30-50K/s;
(2) Tempering treatment: and (3) heating the steel for the corrosion-resistant high-strength high-toughness casting node in the low-temperature environment after water quenching to 450-700 ℃, preserving the heat for 4-6h, and then cooling the steel to room temperature.
2. The casting joint of claim 1, wherein the upper portion of the central connecting tube and the tube member of the down tube have a gradually increasing wall thickness and the lower portion has a uniform wall thickness; the wall thickness of the central connecting pipe is gradually increased from the position 190-210mm away from the end point of the central connecting pipe, the wall thickness of the central point of the central connecting pipe is the largest, the minimum wall thickness of the upper part of the central connecting pipe is 28-30mm, the maximum wall thickness is 40-42mm, and the wall thickness of the lower part of the central connecting pipe is 28-30mm; the wall thickness of the inclined tube is gradually increased from the intersection area of the inclined tube and the central connecting tube, the minimum wall thickness of the upper part of the inclined tube is 22-23mm, the maximum wall thickness is 32-38mm, and the wall thickness of the lower part of the inclined tube is 22-23mm; the inclined pipe is connected with the central connecting pipe at an angle of 35-40 degrees; the bottom pipe is a pipe with uniform wall thickness of 13-14mm, and is connected with the central connecting pipe fitting at an angle of 70-80 degrees.
3. A casting joint as claimed in claim 1, wherein the upper part of the pipe elements of the central connecting pipe and the down tube is the part above the horizontal plane of the cross-section of the pipe elements.
4. A cast joint according to claim 1, wherein the maximum wall thickness of the down tube is in a cross section perpendicular to the axis of the central connecting tube at the centre of the joint.
5. The cast joint of claim 1, wherein the steel for the cast joint has a ferrite content of 10% or more.
6. The cast joint according to claim 1, wherein the steel for cast joint has a carbon content satisfying C.ltoreq.0.12% and a carbon equivalent satisfying C eq ≤0.56％。
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| Application Number | Priority Date | Filing Date | Title |
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| CN202110745462.6A CN113431014B (en) | 2021-07-01 | 2021-07-01 | Ocean platform casting node with gradually-changed wall thickness and preparation method thereof |
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| CN202110745462.6A CN113431014B (en) | 2021-07-01 | 2021-07-01 | Ocean platform casting node with gradually-changed wall thickness and preparation method thereof |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| NO156677C (en) * | 1984-09-21 | 1987-11-04 | Saga Petroleum | PROCEDURE FOR THE MANUFACTURE OF KNOT POINT FOR PROFESSIONAL CONSTRUCTION, SPECIFIC PLATFORM FOR USE IN CONNECTION WITH DRILLING DRILLING AND PRODUCTION OF PETROLEUM PRODUCTS. |
| CN103993244B (en) * | 2014-05-28 | 2017-05-17 | 北京京城环保股份有限公司 | Low-alloy cast steel joint as well as smelting and pouring control method and heat treatment process thereof |
| CN205173062U (en) * | 2015-11-12 | 2016-04-20 | 浙江林家昌隆阀门铸造有限公司 | Self priming pump foundry goods |
| CN208309836U (en) * | 2018-06-06 | 2019-01-01 | 中国航空规划设计研究总院有限公司 | A kind of three-dimensional mutually passes through cast steel node construction |
| CN110106445B (en) * | 2019-06-05 | 2021-04-16 | 上海大学 | High-strength high-low-temperature-toughness steel for ocean platform casting node and preparation method thereof |
| CN110939198A (en) * | 2019-11-06 | 2020-03-31 | 海洋石油工程（青岛）有限公司 | Prefabricated horizontal sheet of jacket and installation process |
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