Acoustic emission wave propagation in pipeline sections and analysis of the effect of coating and sensor location

This paper presents an experimental investigation in which acoustic emission (AE) wave was generated through a pencil lead break as a point source on two pipeline sections made of mild steel and titanium. The pipelines (bare, epoxy phenolic coated) were of same length but had two different diameters and wall thicknesses. The recorded AE signals were analysed using time and frequency domain signals, energy levels and wavelet transform to explore time-frequency features for the identification of wave modes. It is concluded that the damping behaviour of coating restricts the peaks of waves, decreases the decay time of waves and reduces the energy level in the coated pipeline. It is concluded that monitoring of coated pipeline wave propagation could be done effectively with sensor placement directly on the pipeline surface compared to sensor placement on the coating surface. A high wall thickness of pipeline results in a higher number of reflected waves and increases the decay time of waves. The coating on pipeline resists wave propagation, and different densities of coating layer and pipeline affect the velocity of the wave. This experimental work advance towards designing an alternative way to monitor changes in pipeline structures (e.g., corrosion under insulation applications).<br /> [GRAPHICS]