Real-time hoop strain measurement at multiple points along a flowline provides a way to monitor changes in the internal pressure gradient within the flowline. This information could be used to provide an early warning that a flow restriction is forming, locate the area of the blockage, and allow early intervention to control or eliminate deposition of material on the pipe wall. In the event of compete flow blockage, the method could be used to precisely locate the blockage. In this project, we evaluated fiber Bragg grating (FBG) sensors for measurement of hoop strain present in the wall of pressure pipe. The test were performed on a section of pipe to which multiple sensor were attached. The purpose of the testing was to characterize the hoop strain and axial strain. The advantage of FBG sensors for this application is that multiple sensors can be embedded in a single optical fiber which can then be attached to a pipeline. Each FBG sensor is wavelength encoded so that each sensors strain output signal corresponds to a known location along the length of the pipeline. Thus, it is possible to identify the location of a blockage in a pipeline by monitoring many locations along the pipe for small changes in hoop strain indicative of increased pressure drop. The presentation will include a description of the tests and analysis of the performance characterization work. The result of the tests were positive. Analysis of the data for this application shows that it is possible to achieve submicrostrain resolution and better than 2 microstrain repeatability with FBG sensors.

Date Published: 3 February 1999
PDF: 10 pages
Proc. SPIE 3541, Fiber Optic and Laser Sensors and Applications; Including Distributed and Multiplexed Fiber Optic Sensors VII, (3 February 1999); doi: 10.1117/12.339076

Published in SPIE Proceedings Vol. 3541:
Fiber Optic and Laser Sensors and Applications; Including Distributed and Multiplexed Fiber Optic Sensors VII
Alan D. Kersey; John P. Dakin; John P. Dakin; Alan D. Kersey; Dilip K. Paul, Editor(s)