DEVELOPMENT OF NONLINEAR HARMONIC SENSORS FOR DETECTION OF MECHANICAL DAMAGE

摘要

In a joint effort with Tuboscope Pipeline Services of Houston, Texas, Southwest Research Institute adapted its nonlinear harmonic (NLH) sensing technology for use on a new in-line inspection system (smart pig). Nonlinear harmonics, an AC magnetic method for detecting local anomalies of stress and plastic deformation, shows promise of improved characterization of mechanical damage defects such as gouged dents, even though the dents may have re-rounded. The SwRI-Tuboscope project produced a sensor design, electronic design and sensor suspension design that are directly adaptable to a multitechnology ILI system. This paper describes the NLH method, the sensor, circuit and suspension designs and shows some typical results from pipeline mechanical damage. The DOE’s National Energy Technology Laboratory in Morgantown, West Virginia, as part of its Natural Gas Infrastructure Reliability program provided funding for this work.