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Locating Defective Couplings in 2″ PE Gas Mains

Project Overview

A gas distribution utility on the U.S. West Coast needed to remove outdated couplings from the network, but the coupling locations were not utility records. Rather than digging hundreds of costly, unnecessary excavations in their respective suburban neighborhoods, the gas utility looked to ULC and our suite of live gas main inspection and locating technologies to pinpoint the fittings for efficient removal—supporting distribution integrity and safety while significantly reducing excavations and overall project costs.

gas main coupling locating

Industry: Gas Distribution

Location: West Coast U.S.

Project Duration: 12 Days

Business Areas Addressed:

  • Distribution Integrity Management (DIMP)
  • QA/QC
  • Safety


  • Minimal excavations by use of 34 total pits to inspect over 2 miles of pipeline
  • Pinpoint location and mark-out of 57 fittings for removal
  • Visual assessment and location verification of additional pipeline features, including 38 3-way tees
  • No disruption of service to customers—all work performed live

Project Detail

A West Coast natural gas utility recently entrusted ULC’s experienced technicians along with our advanced inspection technology to pinpoint the location of outdated couplings within their 2” PE distribution mains. Unmapped couplings are traditionally very challenging to locate based on existing records as they are non-detectable using receivers or tracer wire. Utilizing live gas main inspection technology, the operator can visually identify coupled pipe segments and other features within the pipe—and even provide pinpoint accurate mark-out and mapping of the feature locations.

Project Planning: Live camera system entry into the gas main requires strategic entry points to reduce unnecessary excavation and lower costs. ULC’s operations team collaborated with the gas utility customer through the project planning stage to identify entry points. The utility’s contractors provided all excavation for camera entry.

Site Preparation: ULC field teams hold a variety of operator qualifications to conduct inspection work as well as supporting tasks. For camera entry into 2″ PE mains, ULC used electrofusion fittings with an angular branch so the equipment could enter the main under live conditions.

Live Gas Main Inspection: Once the live gas main CCTV equipment was set up on-site, ULC’s crew began the inspection. The motorized cable feeder allows the camera system operator to focus more on the inspection and less time maneuvering the camera in order to provide the highest quality inspection. Manually pushed camera systems result in a more fitful inspection, likely resulting in the operator missing key features inside the pipeline. The wide-angle view and LED lighting inside the main enabled the crews to see the full circumference of the pipe and inspect the entirety of the coupling. Once the camera travels as far as it can, which is upwards of 400ft in a single direction, the camera is returned to the launch tube and launched again in the opposite direction.

Identification of Couplings: The images below show examples of couplings within the 2″ PE gas main. Couplings were white or grey in color, which contrasted well with the yellow PE material. In addition to couplings, ULC was able to identify and map out 3-way tees and other features.

gas main coupling locating mapping


Utilizing ULC Technologies’ Live Gas Main Inspection Services, our crews were able to inspect over 2 miles of pipeline using 34 total excavations over the span of 12 days. The deployment of live gas main CCTV cameras to provide in-pipe intelligence reduces excavation costs associated with guesswork. The data obtained and street mark-out delivered showed the exact location of the couplings which were then excavated and remediated by the gas utility and contractor as part of the utility’s distribution integrity management program (DIMP). Additional features, such as 3-way tees, were also marked out and mapped. All of ULC’s inspections were performed under live gas conditions, meaning there was never a disruption of service to customers.

To learn more about ULC’s live gas main inspection services or get a quote for our live gas main inspection camera systems, please contact us through the website. Inspection can be performed in mains ranging in diameter from 2″ up to 48″ as well as gas services as small as 1/2″ in diameter.

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