Reel-Lay Pipe Bending With Internal Mandrel Hold-Back
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
During spooling of subsea pipelines, particularly for CRA-lined pipes, the issue of internal wrinkling and buckling arises due to the difference in material properties between the outer and inner walls, leading to potential flow restrictions and reduced fatigue life, which existing methods fail to adequately address without introducing discontinuities or requiring expensive materials.
Innovation Solution
A method and apparatus involving an internal mandrel with longitudinally-spaced elements and a tensile link to resist radially-inward deformation of the inner surface during bending, using an external mandrel for curvature and allowing the mandrel to bend with the pipe while applying hold-back tension to prevent wrinkling, and optionally using a pressurized fluid to resist deformation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a lined pipe is bent during spooling, then the pipe can be wound onto a reel for subsea deployment, but the inner liner sleeve undergoes radially-inward plastic deformation causing wrinkling and buckling
Solution Approach 1:
An internal mandrel is introduced as an intermediary element inside the pipe during spooling. The mandrel extends beyond the bending zone and is held stationary while the pipe bends around the reel, physically supporting the inner liner sleeve and preventing radially-inward deformation that causes wrinkling and buckling.
Solution Approach 2:
The internal mandrel applies preliminary counter-action to the radially-inward forces that would otherwise cause the liner sleeve to wrinkle and buckle during bending. By being in place before and during the bending process, the mandrel prevents the harmful deformation rather than correcting it afterward.
2Loss of substance
If the inner liner sleeve is made thinner to reduce cost, then material costs decrease, but the liner becomes more susceptible to wrinkling and buckling during bending
Solution Approach 1:
The internal mandrel serves as a protective intermediary that allows thin-walled liner sleeves to be spooled without wrinkling or buckling. The mandrel provides the necessary structural support during bending, enabling the use of thinner, more cost-effective liner materials while maintaining reliability.
Solution Approach 2:
The introduction of the internal mandrel changes the mechanical parameters of the system during spooling. By providing external support from the inside, the mandrel effectively increases the buckling resistance of the thin liner sleeve without requiring changes to the liner material or thickness.
3Productivity
If the pipe is bent with a small radius to fit on the reel, then spooling efficiency increases, but the stresses and strains in the pipe wall increase causing greater ovalisation and wrinkling
Solution Approach 1:
The internal mandrel acts as a mediator between the reel and the pipe during spooling. It allows the pipe to be bent to the required small radius for efficient spooling while preventing excessive ovalisation and wrinkling by supporting the inner liner sleeve throughout the bending process.
Solution Approach 2:
The internal mandrel modifies the stress distribution parameters during bending. By providing internal support, the mandrel changes the way forces are distributed through the pipe wall, reducing the degree of ovalisation and wrinkling even when bending to small radii required for high-speed spooling.
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 effectively mitigates wrinkling and buckling during spooling, ensuring smooth fluid flow and extended pipe life by maintaining the structural integrity of the CRA liner while minimizing deformation and operational costs.
Implementation Method 1
resisting radially-inward deformation of an inner surface of the pipe with respect to the longitudinal axis during bending
Implementation Method 2
applying tension through an elongate tensile hold-back element that is anchored outside a trailing end of the pipe and extends internally along the pipe to hold an internal mandrel at the bending zone against frictional force arising between the internal mandrel and the pipe advancing past the internal mandrel
Implementation Method 3
applying tension through an elongate tensile hold-back element
Implementation Method 4
at least part of the pipe undergoes plastic deformation during bending along the longitudinal axis
Data Source
AI summary
A method and apparatus for bending a pipe to mitigate internal wrinkling, with particular benefit when bending a lined pipe upon spooling. Bending is performed continuously by advancing the pipe through a bending zone while an internal mandrel is held at the bending zone to resist wrinkling. In one variant, the mandrel comprises longitudinally-spaced pipe-engaging elements and a tensile link between the elements allows relative movement between the elements. A holdback connection on one of the elements applies hold-back force to that element to be transmitted to the other element via the tensile link. In another variant, the mandrel comprises an elongate pipe-engaging body with a hold-back connection at one end of the body. The body is flexible to bend with the pipe and is shaped to engage an inner surface of the pipe along most of the length of the body.