DOE: Pipeline Robot Revolutionizes Inspection Process

December 7, 2007 // Published as a news service by IHS

The wireless, self-propelled Explorer II proved its worth in September 2007 when it was tested in a live 8-inch distribution main pressurized at 100 pounds per square inch.

The robot was launched and retrieved multiple times as it inspected - with cameras and sensors - a section of the Northwest Fuels gas line in Brookfield, Pa.

The Explorer II improves upon the highly successful Explorer I robot, which won an R&D 100 Award in 2004.

Innovations added to the Explorer II include:

• Nondestructive evaluation (NDE) capability, achieved by a separately funded remote eddy field current sensor that examines both internal and external pipe walls for detection of loss.
• Lithium-polymer battery packs that increase mission time.
• A remote location system for absolute positioning during inspections.

According to DOE, both the Explorer I and Explorer II robots feature enormous improvements over traditional "smart pigs" - the bulky pipeline inspection tools that are directly driven by gas flow and not capable of navigation.

The 8-foot, 66-pound Explorer II has 11 modules connected by articulated linkages that allow the robot to be maneuvered around turns of up to 90 degrees. Being self-propelled means the robot does not have to rely on the gas stream to move it along and being semi-autonomous means its range is much greater than the typical tethered inspection device, said DOE.

Until now, pipeline cleaning or inspection devices have been limited to fairly straight, large-diameter lines because they could not be navigated through difficult or narrow areas such as Y- and T-joints, 90-degree turns and the small diameter pipes typically found in towns and cities. Pipeline sections like these are called "unpiggable," meaning that they have had to be dug up for either physical inspection or for employing short-range tethered inspection devices.

Nearly 30% of the 1.3 million miles of gas transmission and distribution pipelines in the U.S. are unpiggable because of couplings and size restrictions. Because of this, and increasingly stringent regulatory requirements for pipeline inspection, Explorer II is expected to be a great boon to the industry, said DOE.

The Explorer II can maneuver through most gas lines, including many of the previously unpiggable lines, to inspect great stretches of pipe, often with only one access point. The unique abilities of Explorer II could potentially reduce the number of gas line incidents, such as gas leaks and ruptures.

Around 15% of reportable gas line incidents are caused by internal corrosion, averaging $3 million annually in property damage, said DOE. Explorer II can spot corrosion and other defects before they escalate into pipe failure, fugitive methane emissions or accidents.

The Explorer II was developed by engineers at Carnegie Mellon University in a cooperative agreement with DOE Office of Fossil Energy (OFE). The DOE National Energy Technology Laboratory (NETL) manages the ongoing project for the OFE.

Preliminary testing of the maneuverability and inspection capabilities of Explorer II took place at the Carnegie Mellon unpressurized "pipe farm" laboratory in February 2007, minus the new NDE inspection sensors. A second preliminary test at Carnegie Mellon, also in unpressurized pipe, tested the robot's abilities with the new sensors in place. Further development is planned to increase the robot's versatility and extend its range, said DOE.

Source: U.S. Department of Energy (DOE) National Energy Technology Laboratory (NETL).