Transmission, Distribution, & Refining
Development of an EMAT In-Line Inspection System for Detection, Discrimination and Grading of Stress Corrosion Cracking in Pipelines

DE-FC26-01NT41154

Goal: The goal is to develop improved in-line inspection techniques to measure corrosion in natural gas pipelines.

Objectives: The objective of this project is to develop sensors employing electromagnetic and acoustic technology (EMAT) for the detection of low-level stress corrosion cracking (SCC) anomalies in natural gas pipelines. The work will result in the development of a suitable platform for attachment to an in-line inspection tool (ILI) and generation of the necessary processing software to be integrated with existing systems.

Performers: Tuboscope Pipeline Services – product management and research products

Accomplishments:

  • Designed sensor head and mechanical housing of inspection tool,
  • Configured high specification data acquisition system and relevant software and hardware, and
  • Built pull-test mule.

New technology to detect, evaluate, and grade SCC in pipelines is needed by the pipeline industry. If undetected, SCC can lead to pipeline failure and there is currently no economical method for locating and grading SCC in natural gas pipelines. Any acceptable method to solve this problem must also be able to differentiate SCC from other benign pipeline features in order to eliminate the potentially high costs of unnecessary remedial work.

Tuboscope Pipeline Services is developing a sensor that uses electromagnetic and acoustic technology (EMAT) to grade corrosion cracks. In Phase I, a number of accomplishments have been achieved. First, the sensor head and mechanical housing arrangement on the pipeline inspection tool were designed. Issues of relevance for this design were the layout of the correct electromagnetic excitation system, the engineering of the mechanical system to ensure controlled “stand-off” between the head and the pipe-wall, and the interfacing of the head with control features on the main tool body (i.e. orientation, inter-head relative position sensing mechanisms). A design for the laboratory-based system was created that could be readily fabricated in a mechanically robust and cost-effective manner. A 16-bit, 128-channel data acquisition system was configured and the relevant hardware and software features were interfaced. 
 

EMAT System

Progress has also been made on the pull-test mule; a unit to allow assessment of the effectiveness of the new EMAT sensor heads under dynamic conditions as they traverse through real pipeline samples at varying velocities and different sensor standoffs. Compact and efficient prototype printed circuit board assemblies (control circuit, firing circuit, power supplies, preamplifier, and signal band pass filter) were designed, built, tested, and operated. These were tested in the lab with manually positioned EMATs on a flat plate and full pipe. Various high level software packages were developed to capture, process, and display EMAT data from the full pipe. All tests were done with rudimentary, permanent magnet EMATs, for which the transmitter and receiver must be manually aligned and the coils taped to the pipe.

Current Status and Remaining Tasks: The following Phase I tasks remain to be completed: 1) Evaluation of test mule results with reappraisal of the hardware features on the EMAT sensor heads and indication of the fuller features required of the data capture system, 2) a full dynamic structural analysis of the EMAT sensor housing for the prototype tool with completion of the designs for the electrical connection system, and 3) fabrication and testing of an onboard real time acquisition, initial processing, and data storage system with the incorporation of previously developed algorithms.

Phase II will involve the fabrication of the full set of EMAT sensor heads for the prototype ILI tool and the integration of the system into the ILI platform. After final modifications are completed, a suitable customer pipeline will be identified for testing the tool under actual pipeline conditions and data sets will be collected. Complete final analysis of the data sets will complete validation of the EMAT in-line inspection tool.

Project Start: September 30, 2001
Project End: January 1, 2005

Anticipated DOE Contribution: $640,895
Performer Contribution: $453,205

Contact Information:
NETL – Daniel Driscoll (daniel.driscoll@netl.doe.gov or 304-285-4717)
Tuboscope Pipeline Services – Jeff Aron (jaron@varco.com or 713-799-8158)

Additional Information:
Final Report [PDF-3883KB] 
Fossil Energy Techline: Moving Natural Gas Reliability to Consumers

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