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Introduction to Remote Field Testing

Introduction

Theory of Operation

Theory (cont,) - The Zones

Probes

Instrumentation

Signal Interpretation

Reference Standards

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RFT Probes

Probes for inspection of pipe and tubing are typically of the bobbin (ID) variety. These probes use either a single or dual excitation coil to develop an electromagnetic field through the pipe or tube. The excitation coils are driven by alternating current. The sensing coil or coils are located a few tube diameters away in the remote field zone. Probes can be used in differential or absolute modes for detection of general discontinuities, pitting, and variations from the I.D. in ferromagnetic tubing. To insure maximum sensitivity, each probe is specifically designed for the inside diameter, composition, and the wall thickness of a particular tube.