CUI Inspection Using MsS Guided Wave System

Corrosion Under Insulation (CUI) Inspection

Magnetostrictive Sensor (MsS) guided wave testing is effective in maintaining the mechanical integrity of pipelines with insulation and jacketing. MsS probes are only 2 inches wide and insulation only needs to be removed at the probe’s installation location. The dead zone length of the MsS probe is about 4 inches from the center of the probe along each direction with no near field length with a 360° continuous probe.

The MsS guided wave testing uses high frequency ultrasonic waves of 64-, 90-, 128-, 180-, and 250-kHz center-frequency to reduce the interaction between traveling guided wave and geometric features such as simple pipe supports, welded pipe supports, and clamps, thus increasing inspection range. Using high frequency increases sensitivity of defect detection and spatial resolution. Due to these merits, MsS guided wave system is used for PMI inspection in order to find weld locations and also used for CUI and internal wall corrosion inspection to detect defects over a long distance.

Welded Pipe Support

The illustration below shows guided wave testing data acquired at 32-, 64-, and 128-kHz center frequencies. The 32-kHz data shows strong reflection and trailing signals from the welded pipe supports at about 10 and 30 ft, but the 128-kHz data shows an elbow signal around 50 ft due to much less interaction with the pipe supports. High-frequency guided waves provide both a longer inspection range and higher defect detection sensitivity if piping is attached or welded with many geometric features.

CUI Inspection Data