Pipeline Integrity at Facilities – Inspecting Tank Lines Using Robotic ILI Tools

Many storage tank assets, including facility pipelines, were installed decades ago and now require inspection to ensure safe operating conditions.  Proactive storage tank operators are implementing inspection programs to verify integrity, however most tank lines lack pig launchers/traps so the industry is faced with the challenge of finding inspection solutions.  Proactive inspections are often performed to verify integrity and reduce insurance premiums.

Presented by Jonathan Minder at the 2015 NISTM Above Ground Storage Tank Conference in Galveston, TX

Diakont’s robotic in line inspection (ILI) service has proved to be a viable solution and storage tank operators implemented the inspections in parallel with API 653 inspection when the tanks are taken out of service.  Diakont’s robotic ILI crawlers are equipped with multiple non-destructive examination (NDE) modules including EMA ultrasonic sensors, pulsed eddy current sensors, laser profilometry sensors and high resolution cameras.  Prior to deploying inspection teams on site, Diakont technicians work with storage tank operators to establish inspection objectives, analyze the pipeline geometry, select appropriate sensor technologies, and create a customized inspection plan.


Diakont maintains at least two barriers of process safety:

  • Nitrogen blanket used on uncleaned, non-purged liquid lines
  • Oxygen concentration monitored both at the tool and at the downstream end of the pipe
  • Robotic crawlers are explosion proof tools


Inspection Process
  • Launch tool through pipe opening – Diakont technicians easily launch the robotic crawler via 2-man lift without requiring pig launcher.
  • Perform visual inspection – Diakont technicians drive the inspection tool through the entire length of the pipe to confirm the geometry and fittings.
  • Conduct ILI autoscan – Diakont technicians perform an auto scan of the pipe wall using ultrasonic testing sensors to collect preliminary data and identify pipe features.
  • Perform manual feature characterization – Diakont technicians drive the ILI crawler back to any areas with potential anomalies that were identified during the autoscan for enhanced measurement with laser profilometry sensors.
Storage Tank Line Inspection

Diakont recently completed a storage tank line inspection for a major North American pipeline operator at a terminal.  The project consisted of a 36” carbon steel pipe, connecting a 55,000 bbl gasoline storage tank to a manifold.  The tank line was approximately 750’ and the operator had little documentation about the pipe characteristics because the asset was acquired through a purchase. The tank line had not been inspected since the construction in 1970 and required remaining wall thickness assessment as well GIS mapping.

Following the inspection procedure outlined above, Diakont technicians successfully inspected the storage tank line and verified the integrity.  Diakont NDE specialists reviewed the integrity data in real time throughout the inspection and provided daily reports to the operator who put the tank line back in operation following the inspection

Robotic Crawler Advantages

Diakont technicians remotely control robotic ILI crawlers which adds versatility to the inspection process; tools have the ability to reverse direction and accommodate parameter changes, or stop and review features of interest.

Diakont robotic crawlers navigate virtually any pipe challenges including diameter changes, steep inclines, vertical section, 1.5D bends and unbarred tees.

Utilizing a combination of sensors, Diakont ILI crawlers provide comprehensive integrity data and provide benchmark information for future risk analysis.

Robotic ILI crawlers provide an ideal solution for storage tank operators to verify pipeline integrity instead of blind replacement.

Learn more about Diakont’s storage tank line inspection solution