ERW Reel-Lay Steel Pipe Joint Orientation Against Spooling Buckling
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Solution Overview
Problem
ERW steel pipes used in reel-lay installation of submarine pipelines face issues with high yield ratio and low uniform elongation due to processing strains during pipe formation, leading to increased risk of local buckling and fracture when subjected to compressive and tensile strains during spooling.
Innovation Solution
The method involves successively joining ERW steel pipes with girth welds such that the seam position of one pipe faces areas from the 2 o'clock to 4 o'clock or 8 o'clock to 10 o'clock positions of adjacent pipes, optimizing tensile characteristics to reduce axial strains and enhance buckling resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If ERW steel pipes are used to reduce production cost, then manufacturing cost is reduced, but the pipes exhibit high yield ratio and low uniform elongation due to processing strains, increasing risk of buckling and fracture
Solution Approach 1:
The patent applies local quality by positioning the seam (area of lower tensile characteristics) at specific locations along the pipe circumference. By strategically placing the seam away from high-stress zones during reel-lay installation, the pipe maintains adequate buckling resistance while using cost-effective ERW construction. This local optimization of seam positioning resolves the contradiction between using inexpensive ERW pipes and ensuring sufficient reliability.
2Ease of manufacture
If ERW steel pipes are used to reduce production cost, then manufacturing cost is reduced, but the pipes exhibit low uniform elongation, increasing risk of local fracture during spooling
Solution Approach 1:
The patent addresses the low uniform elongation issue by applying local quality through strategic seam positioning. The seam location is optimized to minimize stress concentration during spooling operations, thereby reducing the risk of local fracture despite the inherently lower uniform elongation of ERW pipes. This allows cost-effective ERW construction to achieve acceptable performance.
3Reliability
If seam position is optimized to reduce buckling risk, then buckling resistance is improved, but manufacturing complexity increases due to precise positioning requirements
Solution Approach 1:
The patent applies preliminary action by pre-determining and specifying the optimal seam positioning angles (e.g., 45° to 135° or 225° to 315° relative to the vertical axis) before installation. This pre-planned positioning guidance simplifies the installation process by providing clear positional targets, reducing the actual complexity during field operations while maintaining improved buckling resistance.
4Reliability
If seamless steel pipes are used to prevent buckling and fracture, then buckling resistance is improved, but production cost increases
Solution Approach 1:
The patent resolves this contradiction by applying local quality optimization to ERW pipes through strategic seam positioning. Instead of requiring expensive seamless pipes throughout, the invention makes ERW pipes with localized seam placement perform adequately by minimizing stress concentration at the seam during critical operations like reel-lay installation. This achieves comparable reliability to seamless pipes at lower cost.
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 significantly reduces the risk of buckling and fracture by maintaining axial strains within a safe range, even when high-Y/T low-uEl regions are positioned at the reel inner or outer sides during spooling, resulting in a long steel pipe with improved buckling resistance.
Implementation Method 1
successively girth-welding longitudinal ends of steel pipes for a line pipe
Implementation Method 2
electric resistance welded (ERW) steel pipes
Data Source
AI summary
A long steel pipe for reel-lay installation formed of electric resistance welded (ERW) steel pipes and having high buckling resistance and a method for producing the long steel pipe for reel-lay installation are provided. The long steel pipe is formed by successively butt-joining longitudinal ends of the ERW steel pipes by girth welding so that girth welds are formed. The ERW steel pipes are successively butt-joined in the pipe longitudinal direction such that the 0 o'clock cross-sectional position or the 6 o'clock cross-sectional position of one of adjacent ERW steel pipes faces an area from the 2 o'clock cross-sectional position to the 4 o'clock cross-sectional position or an area from the 8 o'clock cross-sectional position to the 10 o'clock cross-sectional position of the other of the adjacent ERW steel pipes.