Optical Fiber Strain Sensor Jacket for Pipeline Joint Monitoring
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Solution Overview
Problem
Current methods for monitoring structural joint strain in oil and gas pipelines, such as visual inspections and intelligent pigs, provide intermittent and costly measurements, failing to offer real-time monitoring of conditions leading to potential joint failure.
Innovation Solution
A structural joint strain monitoring apparatus comprising a jacket with optically coupled fibre grating strain sensors that can be mechanically connected to the joint, allowing for real-time strain and temperature measurements using optical fibre strain and temperature sensors, which are interrogated using fibre grating interrogation apparatus.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If visual inspections using ROVs or intelligent pigs are used to monitor pipe joints, then structural parameters such as corrosion, cracks and pipe thickness can be measured, but only intermittent measurements are provided and inspection is costly
Solution Approach 1:
The patent replaces mechanical inspection systems (ROVs, intelligent pigs) with an optical sensing system. Optical fibre strain sensors are mechanically coupled to a jacket that surrounds the pipe joint, enabling continuous strain monitoring without requiring physical entry into the pipeline or complex mechanical inspection equipment. This substitution enables continuous measurement while eliminating the intermittency and high costs of traditional mechanical inspection methods.
Solution Approach 2:
The patent introduces a jacket as an intermediary element between the pipe joint and the optical sensors. The jacket is fitted around the pipe joint and mechanically coupled to optical fibre strain sensors, which transfer strain information from the joint to the sensors. This intermediary structure enables continuous monitoring while protecting the sensors and facilitating their installation without requiring pipeline shutdown or complex access arrangements.
2Productivity
If electrical strain gauges, inclinometers and accelerometers are located on the pipes to monitor joints, then continuous monitoring is achieved, but the device complexity increases
Solution Approach 1:
The patent changes the measurement parameter from multiple electrical parameters (strain, inclination, acceleration requiring separate sensors) to a single optical parameter (strain) measured by optical fibre sensors. The optical fibre sensors measure strain in the jacket, which encompasses all movement and loading conditions affecting the joint, thereby simplifying the monitoring system while maintaining continuous monitoring capability.
Solution Approach 2:
The optical fibre strain sensors in the jacket serve multiple functions simultaneously: they monitor strain in multiple directions, detect joint movement, and provide continuous monitoring data. The single optical sensing system replaces multiple specialized electrical sensors, reducing device complexity while achieving comprehensive continuous monitoring of the pipe joint conditions.
3Loss of time
If a jacket means is used to encase the joint with optical fibre strain sensors, then real-time strain monitoring is achieved, but the device complexity increases
Solution Approach 1:
The patent extracts the sensing function from complex electrical instrumentation and isolates it into simple optical fibre strain sensors that are mechanically coupled to the jacket. The optical fibres are thin, flexible, and require minimal mounting hardware, thereby reducing the overall complexity of the jacket-sensor assembly while enabling real-time strain monitoring through optical interrogation techniques.
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 real-time monitoring of joint conditions, reducing the risk of failure by providing continuous strain and temperature data for health monitoring, fatigue analysis, and process management, thereby extending joint life and ensuring pipeline safety.
Implementation Method 1
an optical fibre strain sensor mechanically coupled to the jacket means at a measurement location, the optical fibre strain sensor to be optically coupled to optical fibre strain sensor interrogation apparatus
Data Source
AI summary
Structural joint strain monitoring apparatus 92 comprises jacket means 52 in the form of first and second jacket elements 62, each having a primary jacket part 62a and substantially perpendicular secondary jacket part 62b which together define a compartment for receiving a joint, between two pipes 54, 56, to be monitored. The jacket means 52 additionally comprises two primary web elements 76, 78 provided between the primary and secondary jacket parts 62a, 62b. Three fiber Bragg grating (FBG) strain sensors 96, 98, 100 and an FBG temperature sensor 102 are provided within an optical fiber 104, bonded to the primary web elements 76, 78 and each end of the second jacket element 62 respectively, for measuring strain or temperature at their respective locations. The FBG sensors 96, 98, 100, 102 are optically coupled, via optical fiber 104, to optical fiber sensor interrogation apparatus 94, operable to interrogate each FBG sensor.