Assisting with Inspection and Assessment of Buried Pipe

Broadband Electromagnetic (BEM) technology offers a cost effective method for direct assessment evaluations through traditional excavations as well as keyhole openings. Researchers have developed a Full Encirclement Unit (FEU) using BEM sensors to measure wall loss on metal piping without the need to remove the coating. This new examination tool can enable internal and external corrosion investigations and perform precise defect location and mapping. The next step is to implement the BEM system to assist with pipeline inspections and assess risk on aging infrastructure.

Inspecting short pipeline segments in High-Consequence Areas (HCAs)—particularly un-piggable transmission lines and cased and uncased pipelines under railroads, highways, and small river crossings—is challenging and expensive. High-resolution magnetic flux leakage (MFL) technology has been used to detect, locate, and characterize metal loss in natural gas transmission pipelines since the 1970s for long distance pipelines and it continues to be considered the most advanced and reliable pipeline inspection technology.

Since early 2000, researchers at GTI and their partners have developed a modified MFL sensor that features a tethered inspection system with a special fitting that enables it to enter and move in the pipeline to inspect corrosion. Coiled tubing pushes and pulls the MFL inspection system in the pipeline from above ground with the use of a hydraulic system. The patented MFL sensor is designed with a unique technique to reduce drag forces drastically. The inspection happens in real time and in live operating conditions without interrupting customer services.

The initial tethered MFL inspection system developed is suitable for 4-inch-diameter pipelines operating at less than 60 psi and has been tested successfully with utilities at several locations. On-going research supported by OTD includes modifications and testing of a 12-inch MFL system to inspect larger-diameter, higher-pressure pipelines.

GTI is working with Pipecrawlers to transfer an unpiggable pipe inspection platform technology developed for off-shore applications to the on-shore natural gas industry. The Pipline Crawler uses brush drive technology to transport sensors to perform integrity assessments for lengths of up to 3 miles from a single excavation. The current version of the tool is designed for 10” to 12” diameter pipe and transports MFL sensors. GTI performed a market assessment for Pipecrawlers and OTD to determine the potential value of transferring the technology to the natural gas industry. Demonstrations are planned for the first half of 2013.