Method and apparatus for inspection of corrosion and other defects through insulation

摘要

Detection of corrosion and other defects in piping is needed to prevent catastrophic pipeline failure. Sensors, systems and methods are provided to enable detection of such defects. These apparatus and methods are configured to characterize pipe protected by insulation and conductive weather protection. The sensors may utilize inductive and/or solid state sensing element arrays operated in a magnetic field generated in part by a drive winding of the sensor. Multiple excitation frequencies are used to generate the magnetic field and record corresponding sensing element responses. Relatively high excitation frequencies may be used to estimate the properties of the weather protection and sensor lift-off while lower frequencies may be used to detect internal and external pipe damage. Linear arrays may be moved to generate damage images of the pipe providing size and location information for defects. Two dimensional sensor arrays may be used to provide imaging without moving the sensor.

主权项

1. A system for detecting damage in a hollow cylinder through an outer non-conducting layer which is further surrounded by a thin conducting layer, the system comprising:
a sensor having an array of sensing elements and a drive winding, the sensor configured to be positioned outside of the thin conducting layer to sense the hollow cylinder through the non-conducting layer and the thin conducting layer; an analyzer operably connected to the sensor and configured to drive a current in the drive winding at a plurality of measurement frequencies and to measure a response of each sensing element in the array at each measurement frequency; and a processor configured to
estimate at least one material property of the thin conducting layer from at least the response of the sensing elements of the array at a first measurement frequency among the plurality of measurement frequencies,estimate a spacing between the thin conducting layer and the hollow cylinder, and a wall thickness of the hollow cylinder from at least the response of the sensing elements of the array at a second measurement frequency among the plurality of measurement frequencies, where the second measurement frequency is a lower frequency than the first measurement frequency, anddetermine damage to the hollow cylinder based on the estimates.