Reelable Mechanically Lined Pipe Strain Distribution
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Solution Overview
Problem
Mechanically lined pipes (MLPs) face issues with buckling and wrinkling during the reeling process due to significant plastic moment mismatch between pipe joints, leading to high compressive strains and potential buckling, which current methods attempt to mitigate by increasing pipe thickness at a significant cost or by using repeated overpressure and pressure-relieving steps.
Innovation Solution
A reelable mechanically lined pipe design with a liner thickness calculated using the formula t=a0j(εD0.75)igj+0.16, where ε is the maximum reeling strain, and g is the radial insertion gap, and extending the length of clad overlay welds from 50 mm to 100 mm to 4 times the outer diameter of the host pipe, to distribute strain and prevent wrinkling without increasing the pipe's thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the liner thickness is increased to prevent wrinkling during reeling, then the resistance to buckling and wrinkling is improved, but the manufacturing cost increases significantly
Solution Approach 1:
The patent applies parameter changes by modifying the liner thickness parameter according to a specific mathematical formula that relates thickness to reeling strain, outer diameter, and material properties. This allows optimization of the thickness parameter to prevent wrinkling while avoiding excessive thickness that would increase cost. The formula t = a0j(εD0.75)igj + 0.16 provides a precise parameter setting that balances structural integrity with manufacturing economy.
Solution Approach 2:
The patent applies preliminary action by pre-calculating and pre-determining the optimal liner thickness before manufacturing begins. The design process involves calculating the maximum reeling strain based on the reel diameter and pipe dimensions, then using this information to determine the required thickness in advance. This preliminary calculation prevents wrinkling issues before they occur during the actual reeling operation, avoiding the need for costly repairs or redesigns.
2Stability of the object's composition
If the pipe thickness is increased to accommodate high bending moment mismatch, then the structural stability is improved, but the manufacturing cost and device complexity increase
Solution Approach 1:
The patent applies parameter changes by using a comprehensive design formula that incorporates multiple parameters including reeling strain, outer diameter, material yield strength, and Poisson's ratio. This multi-parameter approach allows for precise optimization of the liner thickness to handle bending moment mismatch without simply increasing overall pipe thickness. The formula accounts for the specific loading conditions and material properties to determine the minimum required thickness for structural stability.
Solution Approach 2:
The patent applies copying by using established theoretical models and formulas from structural mechanics to predict and prevent buckling behavior. The design formula is based on copied knowledge from classical shell theory and buckling analysis, allowing engineers to apply proven theoretical frameworks to practical pipeline design without needing to conduct extensive experimental testing for each specific case.
3Ease of operation
If conventional reeling methods are used with standard liner thickness, then the ease of operation is maintained, but the liner wrinkles and buckling occurs under significant plastic moment mismatch
Solution Approach 1:
The patent applies preliminary action by calculating and determining the optimal liner thickness before the reeling operation begins. The design process involves computing the maximum reeling strain based on the reel diameter and pipe dimensions, then using this information to specify the required thickness in advance. This preliminary determination ensures the liner is properly sized to handle the anticipated reeling strains without wrinkling, maintaining reliability while keeping the reeling process itself simple and straightforward.
Solution Approach 2:
The patent applies self-service by designing the liner thickness to be self-sufficient in resisting buckling and wrinkling during reeling. The calculated thickness provides inherent structural stability that allows the pipeline to be reeled without requiring additional support structures, external reinforcement, or complex control systems. The liner essentially serves itself by having sufficient thickness to resist the compressive strains generated during reeling operations.
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 solution allows for safe reeling and unreeling of MLPs by concentrating strain in the overlay welds, reducing liner wrinkling effects and maintaining cost-effectiveness, even with high bending moment mismatches, without the need for increased pipe thickness.
Implementation Method 1
During the expansion, the inner pipe undergoes a plastic deformation while the outer layer undergoes either elastic or plastic deformation
Implementation Method 2
concentrating strain in the overlay welds, reducing liner wrinkling effects
Data Source
AI summary
A reelable mechanically lined pipe (MLP) (30) having at least a liner (32) and an outer pipe (34), the outer pipe having an outer diameter, DH, with the MLP formed from a plurality of pipe joints having conjoining girth welds (36), wherein the ends of each pipe joint terminate with clad overlay welds (40) having a length in the range Lmin=100 mm and Lmax=4DH, and wherein the liner thickness, t, is equal to or less than a value calculated by formula I as defined.