Gas Magnetic Flux Leakage Technology

Gas Magnetic Leakage

­With natural gas magnetic flux leakage (GMFL) technology from TDW, pipeline operators can harness the accuracy of MFL technology while improving its speed profile, ensuring successful inspections for volumetric metal loss.

Our large-diameter GMFL tools are designed to facilitate the addit­ion of an active speed control unit. Together, the technologies prevent speed excursions — an ongoing risk in high-velocity natural gas pipelines — that can interfere with data accuracy. The GMFL tool negotiates a pipeline’s internal diameter (ID) reductions smoothly, and the tool design enables consistent drag in the line to further improve velocity profiles.

Not only does GMFL technology help ensure a successful inspection, it also delivers accurate sizing and detection of metal loss and other ferrous anomalies, helping operators extend their pipeline system’s useful life.

Best used for: natural gas pipelines

Key features:

  • Scaled for pipelines measuring 8 inches to 48 inches in diameter.
  • Detects and reports volumetric metal loss at 10 percent wall loss or greater.
  • Capability to inspect some dual diameter lines.
  • Preliminary and final results are delivered within 30 to 60 days so operators can prioritize immediate, 60-day, and 180-day conditions related to metal loss.


  • What’s the difference between GMFL technology and MFL technology? Both technologies provide reliable detection and sizing of internal and external metal loss. However, MFL is best suited for smaller-diameter liquids pipelines, while our GMFL tool is designed specifically for natural gas to reduce speed excursions, and for pairing with our speed control technology for accurate metal loss inspections in high pressure and flow gas lines.
  • What other technologies can be used with GMFL? The tool can be easily combined with additional TDW technologies, including XYZ mapping and deformation technology, to minimize tool runs, saving operators time and money.