Subsea Pipeline Direct Tie-In Using Pre-Deflected End
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Solution Overview
Problem
Existing direct tie-in methods for subsea pipelines require high tensile forces, leading to equipment and structural stress, and necessitate large areas for pipeline alignment, which can result in damage and buckling due to thermal expansion.
Innovation Solution
Applying a plastic deformation to create a tie-in and thermal expansion loop near the pipeline end, allowing for elastic deformation and reduced forces during connection, and using weights and buoyancy to control orientation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If direct tie-in methods are used to connect pipeline end to subsea structure, then installation cost is reduced, but very high tensile forces are applied to the pipeline and connection components
Solution Approach 1:
The patent applies preliminary action by pre-deflecting the pipeline end to a predetermined angle before the tie-in operation. This preliminary deflection is maintained during the pulling operation, allowing the pipeline to be pulled in at the correct angle without requiring excessive force to overcome misalignment, thereby reducing the peak tensile forces applied during connection.
Solution Approach 2:
The patent changes the geometric parameter of the pipeline by deflecting it to a predetermined angle relative to its longitudinal axis before tie-in. This parameter change (angular deflection) allows the pipeline to accommodate the approach angle to the subsea structure, reducing the tensile force required during the pulling operation while maintaining direct tie-in benefits.
2Reliability
If high tensile forces are applied during direct tie-in to bring pipeline end to connection point, then tie-in is completed successfully, but damage can occur to the pipeline and connector on subsea structure
Solution Approach 1:
The predetermined deflection is applied in advance before the high-force pulling operation. This preliminary geometric preparation ensures that when the pulling force is applied, the pipeline is already oriented correctly, reducing the peak force required and minimizing the risk of damage to the pipeline and connector during the tie-in completion.
Solution Approach 2:
The predetermined angular deflection acts as a cushioning mechanism by absorbing some of the stress that would otherwise be transmitted directly to the connector and pipeline during the pulling operation. This pre-positioning reduces the shock load and peak forces experienced during tie-in completion.
3Stability of the object's composition
If pipeline is pulled under high tension during direct tie-in, then thermal expansion buckling is prevented, but very high forces are required that demand high-capacity installation equipment
Solution Approach 1:
By changing the angular parameter of the pipeline through predetermined deflection, the patent reduces the magnitude of tensile force required during installation. This parameter change allows thermal expansion control to be achieved with lower-capacity equipment, as the pre-deflected configuration reduces the peak forces needed during the pulling operation.
Solution Approach 2:
The preliminary deflection prepares the pipeline in advance to require less force during the actual pulling operation. This preliminary geometric adjustment reduces the equipment capability requirements while still achieving the necessary thermal expansion control through maintained tension.
4Ease of operation
If pipeline end is deflected to align with subsea structure connection point, then direct tie-in is enabled, but large area around subsea structure is required to accommodate pipeline deflection
Solution Approach 1:
The patent changes the angular parameter of the pipeline by applying a predetermined deflection rather than requiring large lateral displacement. This parameter change (angular orientation vs. lateral position) enables direct tie-in capability while minimizing the horizontal area required around the subsea structure to accommodate the deflected pipeline configuration.
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
Minimizes forces and stresses during tie-in, reduces the area required for alignment, and compensates for thermal expansion, thereby preventing buckling and damage.
Implementation Method 1
applying a plastic deformation to a region of the pipeline at or close to an end of the pipeline to be tied-in
Implementation Method 2
elastically deforming said region to increase its radius of curvature
Implementation Method 3
compensates for thermal expansion, thereby preventing buckling and damage
Data Source
AI summary
A method of installing a subsea pipeline having a direct tie-in to a subsea structure includes, during introduction of the pipeline into the sea from a pipe laying vessel, applying a plastic deformation to a region of the pipeline at or close to an end of the pipeline to be tied-in and, either during or following tie-in, elastically deforming the region to increase its radius of curvature.