High resolution imaging of pressurised water supply lines

This paper proposes a computationally efficient, nondestructive, and medium range guided wave imaging of pressurized water supply lines based on the time reversal (TR) technique. A send-receive transducer is inserted in the water column from a single access point and used to measure multi–input–multi–output (MIMO) pressure wave signals that propagate along the waveguide. The resulting high frequency (10 kHz-100 kHz) signals are processed by the TR-MUltiple SIgnal Classification (TR-MUSIC) algorithm to provide high-resolution images the water pipe system. The resulting images reveal the pipe wall inner and outer condition with millimeter resolution. The proposed technique is tested and validated in lab as well as in field scale facilities on pressurized water-filled viscoelastic high-density polyethylene (HDPE) pipes. In particular, we successfully imaged (i) a straight 6.5 m long, water-filled 90 mm HDPE lab pipe containing a small blockage with thickness 7.65 mm and a length 97 mm and (ii) a 36.5 m long section water-filled 160 mm HDPE pipe containing three T-connections and a small blockage with thickness 16 mm and length 95 mm.