NoPig Metal-Loss Detection System for Non-Piggable Pipelines

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• Onshore Transmission Pipeline
• In-Line Inspection/Pigging
• Emerging Technology
• Pipeline Condition
• Integrity Management
• Systems Development

Main Objective

The NoPig Pipeline Inspection System has been developed for detecting metal loss anomalies on small diameter non-piggable pipelines from above ground.

Public Abstract

The NoPig Pipeline Inspection System has been developed for detecting metal loss anomalies on small diameter non-piggable pipelines from above ground. Contact points at two places no farther than 500 meters from each other are needed. The technology makes use of the skin effect. It utilizes a difference between magnetic fields at low and high frequency produced by electric currents passed through the pipe under test. The low frequency current will distribute itself and travel throughout the entire cross section of the pipe. The high frequency current will travel along the outer surface of the pipe (Skin effect). Both currents generate a magnetic field which shape is dependent on the presence of a defect.

This dependence is discovered due to use of different frequencies. The difference in the magnetic field shapes at different frequencies are caused by e.g. internal or external corrosion, and possibly gouges, and cracking. The System has achieved success in reliably detecting immediate response defects on 3" to 12" diameter pipes. More accurate sizing of these defects from the information gained from these inspections would lead to an improved external and internal pipeline-monitoring device for pipelines that can not be inspected by current in-line technology. The instrument and software development and improved practice in applications of the system will lead to improved detection capabilities for scheduled response defects. The NoPig technology can be applied to larger diameter pipelines but requires advanced system and software development and extensive practical application to identify pipeline anomalies and to discriminate defects.
Objectives:
- Confirm the NoPig System provides accurate pipeline metal-loss detection within present specifications.
- Improve the system to be able to discriminate between defects.
- Apply the technology to larger diameter pipelines for metal-loss detection and discrimination