Characterization of Mechanical Damage Through Use of the Tri-Axial Magnetic Flux Leakage Technology

Abstract

Management of mechanical damage is an issue that many pipeline operators are facing. This paper presents a method to characterize dents based on the analysis of the BJ Vectra Magnetic Flux Leakage (MFL) tool signals. This is an approach that predicts the severity of mechanical damage by identifying the presence of some key elements such as gouging, cracking, and metal loss within dents as well as multiple dents and wrinkles. Enbridge Pipelines Inc. worked with BJ Services to enhance the knowledge that can be gained from MFL tool signals by defining tool signal subtleties in dents. This additional characterization provides information about the existence of gouging, metal loss, and cracking. This has been accomplished through detailed studies of the ILI data and follow-up field investigations, which validate the predictions. One of the key learnings has been that the radial and circumferential components of the MFL Vectra tool are highly important in the characterization and classification of mechanical damage. Non-destructive examination has verified that predictions in detecting the presence of gouging and cracking (and other defects within dents based on tool signals) have been accurate.

Literature Review: Theory and Application of In-Line Inspection Technologies for Oil and Gas Pipeline Girth Weld Defection

“…The circumferential signal shows the positive and negative polarities in both radial and circumferential directions, and visually reflects the width and length of the defect ( Figure 9 ). This technology can effectively detect and size the defects of long-distance transport pipelines, such as metal loss (corrosion and mechanical scratch) [ 12 , 13 , 14 , 15 , 16 ]. Additionally, PetroChina Pipeline Company (Langfang, China) has, through cooperation with GE Oil & Gas Pipeline-inline-inspection Solutions (GE PII, Newcastle, UK), applied the three-axis high-resolution MFL technology in the inspection and sizing of volumetric defects in the spiral weld of long-distance transport pipelines, so as to successfully eliminate the problem of spiral weld cracking of the aged pipes in Northeast China [ 17 , 18 , 19 , 20 ].…”