Brillouin-scattering-based fiber optic distributed strain and temperature sensors
(DSTS) has been applied to measure the longitudinal and hoop strain in an internally
pressurized 1.8 m long end-capped steel pipe with wall thinning defects. The preembedded
defects, which constitute 50–60% of inner wall thickness to simulate the
structural degradation by corrosion in pipes, are discriminated by use of the
corresponding strain measurements in the axial and hoop directions along the pipe with
our distributed strain and temperature sensor system using 10 cm spatial resolution. The
locations of structural indentations are found and distinguished by use of their
corresponding strain–pressure data. These results are quantified in terms of the fiber
orientation, defect size and depth, and behavior relative to those of unperturbed pipe
sections.