Image Challenge

Tanker loading / unloading lines are unique pipeline assets in the oil & gas industry. The pipeline presented by the client for this case study was 30” in diameter, connecting  a shore-based installation to a subsea pipeline end manifold (PLEM). The PLEM connected to a buoy by a flexible hose for the critical task of loading tankers.  Due to its position in the pipeline system this pipeline was deemed a critical asset in the operators network, since there was no alternative means to import or export the product.

The loading line in this case, by design, could not be inspected with conventional inspection approach’s due to the following challenges:

  • Single access
  • No traps - subsea line end
  • Cleanliness
  •  Single flow direction


Image Solution

Although alternatives such as conventional inspection services in combination with subsea traps or tethered UT solutions do exist, a free-swimming bi-directional MFL or UT solution, in combination with a pre-inspection cleaning approach was the most suitable approach to obtain high quality inspection data in these marine pipelines.

When working with the operator it was established that the 30” pipeline could be connected subsea to an alternate 48” pipeline, providing the opportunity to utilize a bi-directional solution.  Critical elements for this inspection included:

  • Asymmetrical cleaning/gauging
  • Custom built tool stopper plug as a contingency for overshoot
  • Subsea tool approach monitoring system
  • 30” RoCorr MFL bi-directional inspection system
  • Turnkey project execution including pumps, frac. tanks, temporary pipe modifications and liquid handling


Image Benefit


Free swimming - not restricted in both distance and bends.


Inspection tool can be pumped in both directions ensuring the tool can always be recovered.

Tool approach monitoring and operational support allows tool speed to be closely monitor and controlled. MFL technology is a robust and proven technology known to be least sensitive to debris.


High resolution MFL data quality, 100% coverage in one single pass meeting strict regulatory requirements. Additionally tool records both directions.


Bi-directional approach avoids the need for costly pipe modifications for launching/receiving, while MFL technology does not require a liquid medium.