scholarly journals Investigating Polymer Fibre Optics for Condition Monitoring of Synthetic Mooring Lines

2020 ◽  
Vol 8 (2) ◽  
pp. 103 ◽  
Author(s):  
Tessa Gordelier ◽  
Phillip Rudolph Thies ◽  
Giovanni Rinaldi ◽  
Lars Johanning
Keyword(s):  
Condition Monitoring ◽  
Time Domain Reflectometry ◽  
Test Machine ◽  
Optical Fibres ◽  
Polymer Fibre ◽  
Proportional Limit ◽  
Mooring Lines ◽  
Fibre Optics ◽  
Energy Devices ◽  
Optical Time

Synthetic mooring lines are becoming a popular alternative to conventional chain mooring systems. For marine renewable energy devices, they have been considered as an enabling technology for this nascent sector, given their reduced costs and ease of deployment. However, the extreme operating environment has led to an increased interest in the ‘in-situ’ condition monitoring of these mooring lines. This paper considers the use of polymer fibre optic technology and the optical time domain reflectometry (OTDR) technique for the condition monitoring of synthetic mooring lines. To establish the operating envelope of the fibres, Polymethylmethacrylate (PMMA) polymer optical fibres are mechanically tested. Additionally, an OTDR is used to monitor fibres whilst under elongation using a tensile test machine, and the sensitivity of the system in monitoring strain is established. At the lowest strain rate, the average proportional limit and yield points of the fibres are found at 1.16% strain and 5.41% strain, respectively. Fatigue exposure of fibres up to 1.25% strain identifies no measurable effect on fibres’ proportional limit or yield point. The occurrence of significant creep is identified for fibres strained beyond 1.5%. The OTDR system is able to identify strains at and above 4%. The study identifies important criteria that should be considered in the integration of polymer optical fibres for mooring applications. Limitations are discussed and suggestions for progressing this technology are provided.

Greatly Extended Distance Pipeline Monitoring Using Fibre Optics

2005 ◽  
Author(s):  
M. Nikles ◽  
F. Briffod ◽  
R. Burke ◽  
G. Lyons
Keyword(s):  
Time Domain Reflectometry ◽  
Distributed Sensing ◽  
Fibre Optics ◽  
Distributed Temperature Sensor ◽  
Optical Time Domain Reflectometry ◽  
Pipeline Monitoring ◽  
Optical Time ◽  
Fibre Bragg Gratings ◽  
Active Flow ◽  
Single Instrument

Monitoring of the effects of hydrocarbon pipeline blockages such as may be caused by hydrates and waxes is receiving a higher level of consideration as the distributed sensing capability offered by the use of fibre optic technology matures. The extent of the hydrate or wax formation problem increases with pipeline length through the effects of cooling. The challenge is significantly greater when assuring flows in deep water and remote subsea locations. Commercially available strain and temperature sensing equipment such as discrete FBGs (Fibre Bragg Gratings) and fully distributed sensing techniques such as Raman DTS (distributed temperature sensor) and Brillouin OTDR (optical time domain reflectometry) typically offer sensing lengths of the order of 20–30km. Whilst this is in many instances a useful length, it is not sufficient to be able to monitor the whole of a pipeline which may be several hundreds of kilometres in length. The authors have developed and demonstrated a method for extending the reach of a Brillouin OTDR interrogating system such that sensing sections of conventional length (approximately 25km) can be successfully interrogated from distances well in excess of 100km without having to compromise on the performance. With a single instrument, more than 250km of sensing fibre can be monitored to within 1.5 metre resolution. By this means, temperature and strain profiles may be measured for the entire pipeline length which will enable active flow assurance measures to be taken including identifying the presence, nature and extent of blockages as they form. Consequently, any corrective action taken by the pipeline operators will be on an informed basis (such as the injection of an optimised quantity of inhibitor), and will incur a significantly lower level of risk than is currently possible. This paper describes the technology which has been developed to meet this requirement and provides results of simulated pipeline blockage effects which demonstrate this.

scholarly journals Distributed Static and Dynamic Strain Measurements in Polymer Optical Fibers by Rayleigh Scattering

Sensors ◽  
2021 ◽  
Vol 21 (15) ◽  
pp. 5049
Author(s):  
Agnese Coscetta ◽  
Ester Catalano ◽  
Enis Cerri ◽  
Ricardo Oliveira ◽  
Lucia Bilro ◽  
...  
Keyword(s):  
Optical Fibers ◽  
Time Domain ◽  
Rayleigh Scattering ◽  
Cost Effective ◽  
Time Domain Reflectometry ◽  
Dynamic Strain ◽  
Strain Measurements ◽  
Graded Index ◽  
Optical Time ◽  
Polymer Optical Fibers

We demonstrate the use of a graded-index perfluorinated optical fiber (GI-POF) for distributed static and dynamic strain measurements based on Rayleigh scattering. The system is based on an amplitude-based phase-sensitive Optical Time-Domain Reflectometry (ϕ-OTDR) configuration, operated at the unconventional wavelength of 850 nm. Static strain measurements have been carried out at a spatial resolution of 4 m and for a strain up to 3.5% by exploiting the increase of the backscatter Rayleigh coefficient consequent to the application of a tensile strain, while vibration/acoustic measurements have been demonstrated for a sampling frequency up to 833 Hz by exploiting the vibration-induced changes in the backscatter Rayleigh intensity time-domain traces arising from coherent interference within the pulse. The reported tests demonstrate that polymer optical fibers can be used for cost-effective multiparameter sensing.

scholarly journals Recent Advances in Phase-Sensitive Optical Time Domain Reflectometry (Ф-OTDR)

2021 ◽  
Vol 11 (1) ◽  
pp. 1-30
Author(s):  
Yunjiang Rao ◽  
Zinan Wang ◽  
Huijuan Wu ◽  
Zengling Ran ◽  
Bing Han
Keyword(s):  
Fiber Optics ◽  
Time Domain ◽  
Acoustic Waves ◽  
Rapid Development ◽  
Development Stage ◽  
Time Domain Reflectometry ◽  
Rayleigh Backscattering ◽  
Optical Time Domain Reflectometry ◽  
Phase Sensitive ◽  
Optical Time

AbstractPhase-sensitive optical time domain reflectometry (Ф-OTDR) is an effective way to detect vibrations and acoustic waves with high sensitivity, by interrogating coherent Rayleigh backscattering light in sensing fiber. In particular, fiber-optic distributed acoustic sensing (DAS) based on the Ф-OTDR with phase demodulation has been extensively studied and widely used in intrusion detection, borehole seismic acquisition, structure health monitoring, etc., in recent years, with superior advantages such as long sensing range, fast response speed, wide sensing bandwidth, low operation cost and long service lifetime. Significant advances in research and development (R&D) of Ф-OTDR have been made since 2014. In this review, we present a historical review of Ф-OTDR and then summarize the recent progress of Ф-OTDR in the Fiber Optics Research Center (FORC) at University of Electronic Science and Technology of China (UESTC), which is the first group to carry out R&D of Ф-OTDR and invent ultra-sensitive DAS (uDAS) seismometer in China which is elected as one of the ten most significant technology advances of PetroChina in 2019. It can be seen that the Ф-OTDR/DAS technology is currently under its rapid development stage and would reach its climax in the next 5 years.

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