February 2008

Automation is this pig's gig

Traditional "smart pigs"-the bulky pipeline assessment tools that ride on gas flow and are incapable of navigation-will get help soon from a U.S. Department of Energy (DOE) project that could revolutionize the pipeline inspection process. 

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

Technicians launched and retrieved the robot 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. Additions 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 8-ft, 66-lb Explorer II has 11 modules connected by articulated linkages that allow the robot to maneuver around turns of up to 90°. 

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.

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° turns, and the small diameter pipes typically found in towns and cities. 

Pipeline sections like these are "unpiggable," meaning we have to dig them up for either physical inspection or to use 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. 

Around 15% of reportable gas line incidents are the result of 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.