ILIA View:In-Line Inspection State-of-the-Art
For SCC
Presented by:Scott Thetford
Manager- Government RelationsGE-PII
OPS Workshop on SCCDecember 2, 2003Houston, Texas
Introduction
• Current ILI Technologies applied to SCC Detection
• Next Generation SCC ILI
Current Applied ILI Technologies
• Magnetic Flux Leakage– Axial– Transverse
• Ultrasonic– Shear wave
• Electromagnetic Acoustic Transducer
Magnetic Flux Leakage
Goal: Detection of gross SCC• MFL Coupled with other data sources
– Axial + Transverse– Axial + Elastic Wave (Wheel Coupled Shear
Wave)– MFL + DA
• While results have been good more effort needs to be applied to understand limitations.
Feature seen by Transverse Field Inspection
Feature Seen by Axial is Small to non-existent
Magnetic Flux Leakage
Axial Field + Transverse Field = Gross SCC Screening ApplicationAxial Field + Transverse Field = Gross SCC Screening Application
• Different tools for liquid and gas pipelines• Liquid Coupled UltraSonic Shear Wave – for
liquid lines (Natural Gas lines with batching)• Emat – for gas pipelines• Liquid filled wheel probes – for gas or liquid• High resolution tools for
– detection and – sizing of smallest cracks of all types
• Ideal for monitoring crack growth• Detection of hairline cracks
Ultrasonic Technologies
UltraSonic Shear Wave Crack DetectionOutline of Detection Capabilities:• Minimum crack length of 30 mm • Length accuracy +/- 5 mm• Minimum crack depth of 1 mm (2mm for mid-wall cracks)• Longitudinal orientation within +/- 10o
• Depth categorized as – < 12.5%– 12.5% to 25%– 25% to 40%– > 40% of wall thickness
• Probability of Detection > 90%
UltraSonic Shear Wave Crack Tools
Tool size range• Until 2001: 24”+ diameter• 2001 16” – 20”• 2003 10” – 14”• Challenge: space restriction in small diameters
16”-20” Tool in Service
Launch into tool trap
Sensor Carrier Array
Stress Corrosion Cracking
• Detected by Ultrasonic Crack Detection
• Excavation comparison
• Excellent prediction in size and shape
Single Crack Feature
SCC Field
• SCC featureclose-up
• Excavation vs. tool prediction
10” to 14” Now in Service
EMAT Goals
• Detection of sub-critical SCC• Determination of length and depth of axial
cracks• Operate without a liquid couplant • Cost-effective inspection• Discriminate int./ext. & injurious/non-injurious• Full wall coverage • Robust and reliable design • Similar detection targets to UltraSonic Shear
Wave Crack Detection Tools.
Wave types Emat
UltraSonic Shear Wave
Emat
SCC Detection- Live Line
Real feature: SCC Emat
length 300 mm, depth 4.5 mm
Next Generation SCC ILI
• Automated Feature Analysis.• Increased Feature Database = Increased
accuracy of failure models.• Cracking and Corrosion Combination
Tools.• Other Sensor Developments
– Gas coupled ultrasonic– Eddy current
ILI Association – founded April 2002
www.ILIAssociation.org
Thank you.
www.ILIAssociation.org