UOE Steel Pipe Waveform Shape for Buckling Resistance
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Solution Overview
Problem
Steel pipes in pipeline structures experience reduced deformation performance due to buckling, particularly at welded portions, where stiffness differences between the base material and welded sections lead to lower buckling resistance and increased likelihood of fracture.
Innovation Solution
A UOE steel pipe with a waveform outside diameter shape is manufactured to prevent local minima within specific ranges from the circumferential welded portions, enhancing buckling resistance by controlling the shape through die expansion and cutting or adjusting expander dies to ensure even stiffness across the pipe.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If weld reinforcement is applied to increase local stiffness at welded portions, then buckling resistance at welded portions is improved, but the waveform shape with local minima is created which reduces overall deformation performance
Solution Approach 1:
The invention applies local quality by creating a waveform shape with specific local characteristics (maximum points and minimum points) at controlled positions. The local minima are intentionally positioned outside the critical range from welded portions, while local maxima provide stiffness enhancement. This localized geometric modification allows different parts of the pipe to have different functional characteristics without compromising overall performance.
Solution Approach 2:
The waveform shape is pre-formed during the pipe manufacturing process using expanding dies before the pipe is installed or welded. This preliminary action of creating the controlled waveform pattern ensures that when the pipe is later subjected to bending loads, the stiffness distribution is already optimized to prevent buckling at welded portions while maintaining overall deformation performance.
2Strength
If the yield ratio of base material is increased to improve deformation performance, then single pipe deformation resistance is improved, but welded portion deformation performance remains limited due to stiffness differences
Solution Approach 1:
Instead of uniformly increasing the yield ratio throughout the entire pipe (which would not help the welded portion specifically), the invention applies local quality by modifying the geometric shape to create localized stiffness variations. The waveform pattern provides additional stiffness precisely where needed (at strategic positions away from welded portions) without requiring changes to the base material properties, thus maintaining material consistency while achieving differential stiffness distribution.
Solution Approach 2:
The invention changes the geometric parameters of the pipe (creating a controlled waveform shape with specific amplitude, wavelength, and position characteristics) rather than changing material parameters (yield ratio). This parameter change in geometry allows the pipe to achieve enhanced deformation performance at welded portions by distributing stress more effectively, without being constrained by material property limitations.
3Manufacturing precision
If expander dies are used to correct circularity, then pipe end circularity is improved, but unwanted local minima are created in the waveform shape that reduce buckling resistance
Solution Approach 1:
The invention applies local quality by carefully controlling the positioning of waveform maximum and minimum points. The local minima are intentionally positioned outside the critical range (2.06λ to 3.86λ) from welded portions, while local maxima are positioned within this range to provide stiffness enhancement. This selective positioning ensures that the circularity correction function is fulfilled without creating harmful geometric features at critical locations.
Solution Approach 2:
The invention changes the parameters of the expanding process (die position, expansion force, die shape) to achieve a controlled waveform pattern with specific characteristics. By adjusting these parameters, the process simultaneously achieves two functions: correcting pipe end circularity for proper alignment and creating a beneficial waveform shape that enhances buckling resistance, rather than merely correcting circularity and inadvertently creating harmful local minima.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach improves buckling resistance by approximately 15% by preventing buckling at the welded portion and distributing deformation across the base material, enhancing the overall deformation performance of the steel pipe structure.
Implementation Method 1
A plastically deformed pipeline buried in extremely deformed ground is also affected later on by large displacements
Implementation Method 2
When an excessive displacement acts on the pipeline, a steel pipe making up the pipeline becomes bent, the compressive side of the pipeline buckles
Data Source
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AI summary
A UOE steel pipe according to the present invention is used for forming a structure by performing butt circumferential welding, and characterized by being shaped to have an outside diameter shape in a waveform in a longitudinal direction. The UOE steel pipe is formed to have no local minimum of the outside diameter shape in the waveform within a predetermined length from both longitudinal end portions. Specifically, a UOE steel pipe according to a first embodiment of the present invention is formed with control to have no local minimum of the outside diameter shape in the waveform within a range from 2.26λ to 3.86λ (where λ is an initial buckling half-wavelength of the UOE steel pipe) from both longitudinal end portions. In a UOE steel pipe according to a second embodiment of the present invention, a flat portion where a variation amount in the pipe diameter is equal to or less than 0.02 percent of an outer diameter of the UOE steel pipe is provided at least to a range of 2λ from both longitudinal end portions in the longitudinal direction.