This paper describes the use of FOX-TEK's long gage-length FT fiber optic sensors (FOS) for monitoring the integrity of pipelines and refinery components. Site assessment protocols and installation methods are described, in addition to the different FOS configurations required to monitor component integrity. It is shown how sensor information can also be used for process control, involving the monitoring of line temperature, pressure, and pipe wall thinning. Models are described that allow the operator to interpret field data to detect corrosion rates, pipe bending, movement and buckling.
This paper presents an investigation of the application of "long gage" fiber optic sensors (FOS) to monitor the behaviour and integrity of pipelines. A description of the long gage sensor technology is provided, together with the sensor system developed for structural applications. Tests were conducted on pipe sections under a variety of load conditions, including internal pressure, axial compression, bending and local buckling. Long gage sensors were boneded to the pipes and displacements measured using a FOX-TEK FTI 3300 instrument that employs an interferometric technique to obtain displacements to an acuracy of 20 microns. Results obtained showed that the FOS could track changes in loads, detect prebuckling deformations, and measure post-buckling plastic strains. The long gage sensors were then applied to a tailings pipeline in northern Alberta (Canada) to monitor continuously the pipe wall thinning due to erosion/corosion. Employing the FTI 3300 with a PC containing an Aircard for wireless transmission, test data were monitored remotely through internet access. Using analytical models in combination with real-time measurements of the pipe's response, predictions of the operational lifetime for the pipe were made.
This paper presents an overview of ISIS Canada's development and application of fiber optic sensing systems in a variety of civil infrastructure projects. Three types of fiber optic sensors have been utilized in ISIS projects-to-date: fiber Bragg gratings (FBGs), Fabry-Perot sensors, based on measuring displacement between two fibers; and a new sensor called a `long gauge (LG)', which employs a low coherence interferometry technique to measure deformations over gauge lengths ranging from 10 cm to 40 m. Details on the operation of the LG system are described below. Applications of the FBG and LG sensors are given for several ISIS projects that also involved the rehabilitation and strengthening of concrete structures using advanced composite materials.
An economical, fiber optic sensor which monitors atomic oxygen erosion of polymer matrix composites has been developed into a functional prototype. The self-contained prototype featuring automated data collection has been tested in two different atomic oxygen beam facilities. Results show very good correlation of the sensor's response under different operating conditions.
A digital database with full user interaction is being developed to assist in the selection of black, white, reflective and transmissive spectrally selective materials. The database will include the optical, thermal, mechanical, physical, electrical and chemical properties of the surfaces and materials, as well as the space environment and contamination effects. The present paper presents an overview of the database project and describes in detail the atomic oxygen/vacuum ultraviolet sub-module of the space-environment module of the database. The purpose of the paper is to make the community aware of the project, to encourage participation, and to identify areas where community involvement is requested.
Damage assessment within composite structural components can be undertaken with embedded optical fiber sensors in two very different ways: the optical fibers can be damage sensitized so they fracture when the composite is critically loaded or they can be made into very sensitive strain sensors that can detect acoustic energy released when the composite is subjected to sufficient load to cause internal damage. We shall report on our latest research for these two approaches. This includes the results of impact tests on the first full scale aircraft composite leading edge instrumented with a 'damage assessment system' comprising a multilayered, embedded grid of 250 damage sensitized optical fibers. We shall also report on the extension of this work to glass fiber/epoxy shells, and the first correlation of acoustic emission signals (detected by embedded interferometric fiber optic sensors) to specific cracks and delaminations within Kevlar/epoxy specimens.
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