The goal of this project is to develop a multi-purpose sensor to be run inside a pipeline that can determine ovality of the pipe, structural defects in the pipe, wall thickness, the velocity/flow rate of gas within the pipe, and potentially detect external defects. The sensor will be integrated with an autonomous robotic platform providing a flexible in-line natural gas pipeline inspection tool.

Los Alamos National Laboratory

Location:
Los Alamos, New Mexico 87545

The Los Alamos National Laboratory (LANL) has been developing acoustic sensor techniques for pipeline structural integrity monitoring. The LANL sensors included both acoustic and optical measurement techniques (for this test only) as orthogonal sensor systems for added robustness. The focus is now to concentrate on a single acoustic sensor, and integrate it with an autonomous robotic platform under development by independently funded DOE/NETL projects.

In pipeline monitoring, the ultimate objective is to identify the locations that have defects, and obtain an accurate measurement of the defects. During the normal inspection process, it is typically difficult to characterize every kind of defect (e.g., small cracks, gouges, etc.) while a sensor transport system is moving rapidly through the pipeline. It is often desirable to first identify suspect regions (e.g., dents) inside the pipe quickly as the transporter (e.g., robot) is moving through, and then go back to those suspect regions for detailed post analysis at slower speed. This capability to do post analysis at slower speed simplifies the sensor design significantly. The proposed acoustic sensor can be used in both modes, but not simultaneously. It can be switched to the fast mode, where it can detect the presence and measure dents while the robotic transporter is moving at its normal speed. One then switches to the high resolution post analysis mode, where the acoustic sensor determines defects such as gouges and cracks.

The advanced senor under development in this project (when coupled with an autonomous robotic platform) could provide an alternative, highly flexible in-line tool for the inspection of currently un-piggable (un-inspectable) natural gas pipelines.

• Demonstrated the concept of an acoustic non-contact technique for determining the variation in the internal cross-section of a pipe (ovality) to better than 0.1-mm resolution. This was accomplished with two separate transducers; however, it was later determined that a single transducer could achieve the same result.
• Developed and demonstrated an acoustic technique that allows the thickness of pipe to be determined. Current approaches require direct physical contact between an acoustic probe and the pipe material. An adaptation of this method for non-contact measurement using electromagnetic acoustic transducers (EMAT) has been attempted.
• Demonstrated the capability to launch a sound wave in a gas-filled pipeline and couple it to the surrounding metal pipe, allowing it to then propagate along the pipe. This may allow the use of acoustic waves to determine structural integrity of the pipe wall.
• Developed a method for separating CO2 from methane by acoustic means, which could become useful in the process of determining natural gas energy content.
• Specified design parameters for integration of the sensor with a robotic platform and develop a preliminary design for the integrated sensor.

During fiscal 2005, LANL and DOE determined that the technique being developed was not mature enough to continue further.

$250,000

$0

NETL – Daniel Driscoll (daniel.driscoll@netl.doe.gov or 304-285-4717))
Los Alamos National Laboratory/LANL – Diphen Sinha (sinha@lanl.gov or 505-667-0062)

July 2005 Project Report: Acoustic Sensor for Pipeline Monitoring [PDF-1687KB]