Event Title

Enhancement and Detection of Mechanical Damage MFL Signals from Gas Pipeline Inspection

Location

Snowbird, UT, USA

Start Date

1-1-1999 12:00 AM

Description

Natural gas is transported in United States through a vast network of transmission pipelines that requires routine maintenance for safe and efficient transport of this cheap form of energy [1]. In order to ensure the integrity of the system, the pipelines are periodically inspected using tools called “pigs” which are propelled inside the pipe under the pressure of natural gas. Figure 1 shows the schematic of a typical pig structure. The pig, in brief, is a magnetizer-sensor assembly, employing the magnetic flux leakage (MFL) technique for assessing the condition of the pipe. A strong permanent magnet in the pig saturates the pipe wall with magnetic flux flowing in the axial direction. When the pig encounters an anomaly as it traverses the pipe, a part of the flux leaks out. This MFL signal is detected by a flux sensitive device such as an Hall-effect sensor. An array of Hall sensors is usually installed around the circumference of the pig (between the two poles of the magnetizer) for this purpose. The signal picked up by the sensor array can be interpreted as an “magnetic image” of the condition of pipeline, where the shape and amplitude of the signal is indicative of the nature of the anomaly. The MFL data is recorded and stored using an on-board data acquisition system, and subsequently analyzed by data analysts.

Book Title

Review of Progress in Quantitative Nondestructive Evaluation

Volume

18A

Chapter

Chapter 3: Simulations, Signal Processing, Tomography, and Holography

Section

Signal Processing and Analysis

Pages

805-812

DOI

10.1007/978-1-4615-4791-4_103

Language

en

File Format

application/pdf

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Jan 1st, 12:00 AM

Enhancement and Detection of Mechanical Damage MFL Signals from Gas Pipeline Inspection

Snowbird, UT, USA

Natural gas is transported in United States through a vast network of transmission pipelines that requires routine maintenance for safe and efficient transport of this cheap form of energy [1]. In order to ensure the integrity of the system, the pipelines are periodically inspected using tools called “pigs” which are propelled inside the pipe under the pressure of natural gas. Figure 1 shows the schematic of a typical pig structure. The pig, in brief, is a magnetizer-sensor assembly, employing the magnetic flux leakage (MFL) technique for assessing the condition of the pipe. A strong permanent magnet in the pig saturates the pipe wall with magnetic flux flowing in the axial direction. When the pig encounters an anomaly as it traverses the pipe, a part of the flux leaks out. This MFL signal is detected by a flux sensitive device such as an Hall-effect sensor. An array of Hall sensors is usually installed around the circumference of the pig (between the two poles of the magnetizer) for this purpose. The signal picked up by the sensor array can be interpreted as an “magnetic image” of the condition of pipeline, where the shape and amplitude of the signal is indicative of the nature of the anomaly. The MFL data is recorded and stored using an on-board data acquisition system, and subsequently analyzed by data analysts.