Augmenting MFL Tools with Sensors That Assess Coating Condition

Project Categories

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• Onshore Transmission Pipeline
• Gas Pipeline
• In-Line Inspection/Pigging
• Pipeline Condition

Main Objective

Investigate the development of new sensors and instrumentation that could work with currently available MFL in-line inspection tools to detect external coating disbondment. Much like the bore diameter sensor and inertial guidance systems that are being added to MFL tools, these sensors would not add substantial cost or complexity to a normal MFL survey. Moreover, coating assessment during in-line inspection will help pipeline owners assess the general health of the coating protecting their pipeline system.

Public Abstract

External coatings are routinely used to protect transmission pipelines from corrosion; however, coatings may degrade or disbond over time enabling corrosion to occur. Transmission pipeline operators often use magnetic flux leakage (MFL) in-line inspection tools to detect metal loss corrosion defects. Rather than finding the cause of a problem, failure of the coating within a corrosive environment, MFL corrosion surveys only find the result of the problem, corrosion defects that may permanently alter the pressure carrying capacity of the pipeline. Stress corrosion cracking (SCC) can be detected using in-line inspection technology, but the availability of tools is limited and the cost of inspection is high compared to MFL inspection. SCC almost always occurs at disbonds - direct coating assessment could indicate future problems that could degrade the serviceability of the pipeline.
The objective this work is to develop new sensors to detect external coating disbondment that could work with currently available in-line inspection tools for minimal additional cost to perform the inspection. As part of this work, the capability of this sensor will be demonstrated at an in-line inspection vendor facility. The value of a successful outcome of this project would be the ability to use a single MFL in-line inspection run to detect and size corrosion locations and assess coating condition for the entire pipeline.