Welded Steel Pipe Buckling Resistance via Undulation Control
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Solution Overview
Problem
Welded steel pipes used in pipelines lack sufficient buckling resistance, especially in regions prone to permafrost movement or seismic activity, where they are subjected to vertical Earth movements, leading to potential buckling issues.
Innovation Solution
A method for producing welded steel pipes involves expanding them over their entire length using a pipe expanding head to achieve an undulation wavelength ratio of not more than 0.8 or not less than 1.8, which improves buckling resistance by altering the undulation wavelength relative to the Timoshenko's buckling wavelength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If the welded pipe is expanded using a pipe expanding head, then the roundness of the welded pipe is improved, but the buckling resistance deteriorates when the undulation wavelength ratio is between 0.8 and 1.8
Solution Approach 1:
The invention changes the key parameter of undulation wavelength ratio through controlled pipe expansion. By adjusting the expansion parameters to achieve an undulation wavelength ratio outside the critical range (D ≤ 0.8 or D ≥ 1.8), the patent transforms the pipe's geometric parameters to avoid buckling while maintaining roundness. This is accomplished by controlling the movement pitch of the pipe expanding head and expansion pressure to create specific undulation patterns.
2Strength
If the undulation wavelength ratio is controlled to improve buckling resistance, then the buckling resistance is improved, but the manufacturing precision requirements increase
Solution Approach 1:
The invention implements feedback control by measuring the actual undulation wavelength ratio after expansion and comparing it with the target range. The system adjusts expansion parameters based on this feedback to ensure the undulation wavelength ratio falls within the safe range (D ≤ 0.8 or D ≥ 1.8). This closed-loop control approach maintains manufacturing precision while achieving the desired buckling resistance.
Solution Approach 2:
The invention performs preliminary calculation of the required movement pitch and expansion parameters before the actual expansion process. By pre-determining the expansion parameters that will produce the desired undulation wavelength ratio, the system avoids the need for complex real-time adjustments and reduces manufacturing precision requirements during execution.
3Strength
If the pipe expanding head moves with a specific pitch to control undulation wavelength, then the buckling resistance is improved, but the device complexity increases
Solution Approach 1:
The invention simplifies the control system by focusing on changing a single key parameter - the movement pitch of the pipe expanding head. Rather than complex multi-parameter control, the system achieves buckling resistance by controlling the undulation wavelength ratio through the movement pitch alone, reducing device complexity while maintaining effectiveness.
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
The method enhances the buckling resistance of welded steel pipes by optimizing the undulation wavelength ratio, resulting in improved deformability and resistance to buckling under bending moments, as demonstrated through Finite Element Analysis.
Implementation Method 1
expanding the welded pipe over an entire length thereof by using a pipe expanding head
Data Source
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AI summary
Provided is a method for producing a welded steel pipe having excellent buckling resistance. The method for producing a welded steel pipe according to the present embodiment includes steps of: preparing a welded pipe, and expanding the welded pipe over the entire length thereof by using a pipe expanding head such that an undulation wavelength ratio D defined by Formula (1) is not more than 0.8, or not less than 1.8: D = p/λ (1), where p is an undulation wavelength in the axial direction of the welded steel pipe, and λ is a Timoshenko's buckling wavelength as defined by Formula (2): λ = 3.44 x (r x t)1/2 (2), where r is an inner radius of the welded steel pipe and t is a wall thickness of the welded steel pipe.