CDI TRAXALL 770 User Manual page 7

TRAXALL 700 SERIES USER GUIDE DEVICES
OVERVIEW
Magnetic Flux Leakage (MFL) Pigs
Magnetic Flux Leakage is a form of nondestructive inline inspection that
detects corrosion, pitting, missing metal, cracks, and/or other defects in
steel pipelines.
An MFL "smart pig" such as shown here is a common inline inspection
tool:
DETECTOR
MAGNETIC POLES MAGNETIC POLES
ODOMETER WHEELS DATA RECORDER
As it travels through a pipeline, the magnetic array magnetizes the steel.
When defects are encountered, the magnetic field "leaks" from the
steel. This leakage field is sensed by the magnetic detector.
Field intensity and defect locations are usually stored by the unit's on-
board recorder.
Inline Inspection (ILI) Tool Transmitters
ILI transmitters are similar in performance
and function to the T-series transmitters,
but in lieu of pressure housings, are
designed to work in conjunction
with MFL pigs.
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