Curvature Sensor in Flexible Pipe Armour
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Solution Overview
Problem
Flexible pipes used in deep and ultra-deep water environments face challenges in monitoring curvature due to high tension loads and extreme conditions, which can lead to damage from excessive bending, and existing solutions struggle to accurately determine true curvature amidst strain along the pipe length.
Innovation Solution
A curvature sensor is integrated within the flexible pipe body, utilizing strain sensors positioned within a neutral plane and offset from it to measure bending strain independently of tensile strain, allowing for continuous monitoring of curvature along the pipe length, and coupled with a topside end fitting for data collection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a curvature sensor is integrated within the flexible pipe body to monitor bending, then the ability to detect excessive bending is improved, but the sensor may be overstrained and damaged by high tension loads in deep water environments
Solution Approach 1:
The curvature sensor is segmented into multiple strain sensors positioned at different locations within the tensile armour layer. This segmentation allows the sensor system to distribute the mechanical stress and avoid single-point failure under high tension loads while maintaining curvature monitoring capability.
Solution Approach 2:
The curvature sensor acts as an intermediary element embedded within the tensile armour layer structure. It mediates between the structural components by measuring strain without bearing the full structural load, allowing curvature detection while being protected from excessive stress through its integration into the armour layer architecture.
2Measurement precision
If strain sensors are positioned within the tensile armour layer to measure bending strain, then curvature measurement capability is improved, but it becomes difficult to distinguish true bending strain from tensile strain along the pipe length
Solution Approach 1:
Strain sensors are positioned at specific local locations within the tensile armour layer, including both on and off the neutral plane. This local quality differentiation allows the system to capture both bending strain (off neutral plane) and tensile strain (on neutral plane) separately, enabling accurate curvature measurement by comparing the differential strain signals.
Solution Approach 2:
The measurement approach transitions from a single-dimensional strain measurement to a multi-dimensional strain field measurement by positioning sensors at different locations within the armour layer cross-section. This dimensional expansion allows separation of bending and tensile strain components through spatial differentiation of the strain signals.
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
Enables accurate detection of excessive bending, allowing for timely remedial action to prevent pipe damage, while avoiding overstraining the sensor through its sliding capability within the tensile armour layer, thus enhancing the pipe's durability and operational reliability.
Implementation Method 1
A first strain sensor is positioned within a neutral plane of the curvature sensor and a second strain sensor is positioned offset from the neutral plane. The first and second strain sensors each sense strain caused by bending of the flexible pipe body.
Implementation Method 2
A temperature sensor is provided within the curvature sensor and the temperature sensor measures temperature within the curvature sensor. The curvature of the flexible pipe body is determined from the strain and temperature measured by the first and second strain sensors and the temperature sensor.
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
A flexible pipe body comprising an elongate curvature sensor and a tensile armour layer. The elongate curvature sensor incorporates a strain sensor arranged to provide an indication of bending strain applied to the curvature sensor. The tensile armour layer comprises helically wound tensile armour wires. The curvature sensor is positioned within the tensile armour layer helically wound adjacent to at least one tensile armour wire such that bending strain applied to the flexible pipe body is transmitted to the curvature sensor The curvature sensor is smaller than an adjacent tensile armour wire in at least one of depth and width and arranged to slide longitudinally relative to the adjacent tensile armour wire.