Online Storage Tank Floor Inspection

Storage Tank Floor Condition Assessment Without Taking Tanks Out of Service

Traditionally, storage tanks are taken out of service to manually perform floor inspections. Now with Diakont’s trusted service and innovative technology, our experienced technicians can safely deploy the Stingray system while tanks remained filled and in-operation. This new capability allows tank owners to understand current tank integrity, so that turnarounds can be planned strategically and effectively. As the energy industry pushes towards greater digitalization, this opens a door to create digital twins for tanks, allowing information to be tracked and analyzed. Diakont takes a modern approach with its tooling, using arrays of non-destructive examination (NDE) sensors housed within an explosion-proof enclosure. Equipped for hazardous environments, the Stingray is Class 1, Division 1 certified to ensure process safety. Based upon Diakont’s award-winning industry experience, our work has been recognized and is trusted by the world’s leading oil and gas companies. By implementing our services, tank owners can eliminate the high cost of tank downtime by conveniently obtaining data. This not only allows operators to prioritize tanks for turnaround but also exceeds API 653 and EEMUA 159 inspection requirements without causing risk to people, property, or the environment.


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Ensuring Safety

Ensuring process and personnel safety are the primary focus for Diakont onstream storage tank floor inspections. Our personnel safety program provides the framework that our field technicians use ensure a safe working environment. Diakont inspection personnel are:

  • Basic Plus trained
  • RSO trained
  • OSHA 10/30 certified
  • Trained in first aid/CPR/AED
  • Equipped with proper PPE
  • Empowered with stop-work authority
High-resolution NDE

Diakont tank robotic inspection tools are equipped with a patented suite of NDE sensors to assess storage tank floor integrity. The modern SLAM navigation is unmatched to conventional out-of-service practices, since it continually records robot positioning while building a map fused with encoded NDE data. When floor or suspended sediment prevents cameras from receiving clear images, the 3D sonar imaging is used for navigational and obstacle avoidance purposes. Our comprehensive MFL+UT NDE package uses complementary inspection methodologies running simultaneously across the entire tank floor:

  • Magnetic Flux Leakage (MFL) is a robust sensor that detects anomalies in almost any surface condition. It is equipped with an array of hall effect sensors.
  • Ultrasonic Testing (UT) measures the absolute floor thickness in high resolution, and assesses size and depth of any indications for characterization and measurement purposes. It uses an array of 96 sensors to provide 100% overlapping inspection coverage. In addition to measuring floor plate thickness, the UT sensors can be used to measure coating thickness.

Diakont performs a complete UT scan around the perimeter of the tank floor in the critical zone.

To meet code requirements, the Diakont tank inspection tooling measures and maps any out-of-plane settlement throughout the tank floor.

Environmental Stewardship

Diakont technicians and services take serious precautions during the tool launch and retrieval process to ensure effective environmental protection. To prevent VOC vapor release, the manway hatch is only opened for a very short period during launch and retrieval, while the fill valve is blocked, to keep any vapor emissions to an absolute minimum. Careful practices are also employed to contain any liquid drips during retrieval.


API 653 & EEMUA 159 Code Compliance

By not having to take tanks out of service for examination, you can significantly reduce the cost of inspections. This allows the opportunity to plan out-of-service periods during down seasons based on data provided from your final report. Our knowledge and experience with API 653 and EEMUA 159 over the years can ensure your tanks are compliant with standards and safe for operational requirements.

Company Brand Image

The promotion of regulatory tank inspections provides evidence your company is actively making efforts to protect personnel health and the environment. To the public eye, these measures display a positive brand persona whereas detrimental problems like leakages or contamination are hard to recover from. Being aware of these will help promote your company and tank integrity.


Inspection Details

Once onsite at the tank facility, Diakont technicians deploy a mobile diagnostic lab to a safe location near the storage tank. Technicians check all grounding, then power on the equipment on the ground for a complete function test and calibration. To verify the Stingray NDE sensor calibration, Diakont technicians use a verification test plate of the same thickness as the storage tank floor (including built-in anomalies in accordance with API 653 standards). After verifying system functionality and sensor calibration, Diakont technicians load the Stingray tool into the deployment tripod. Diakont technicians use a crane to lift the deployment tripod and Stingray tool to the tank roof. Technicians remove the manway and take extra precautions to limit vapor release while lowering the Stingray into the tank.

Diakont technicians lower the Stingray tool to the tank floor and configure the on-board sonar navigation. Diakont technicians then drive the Stingray tool to the edge of the first floor plate and scan the entire tank floor plate by plate. Each plate and the annular ring are scanned using MFL and UT, creating a comprehensive NDE map of the tank floor. Two Diakont technicians operate the Stingray system; a robot operator and an NDE technician. The NDE technician monitors the sensor data in real-time. If any large anomalies are discovered, the technicians can go back and rescan to characterize the defect on location.


Final Reporting

Following the inspection, Diakont internal data analysis team reviews the NDE data, and generates a comprehensive digital report, reviewed and approved by a Diakont Level III. This report includes a complete floor map, even in cases where a drawing was not previously available.

In cases where a complete code-compliant API 653 inspection is requested, a Diakont certified inspector examines the tank and reviews all inspection data prior to issuance of the API 653 results.


Personnel and process safety are Diakont’s primary focuses when conducting storage tank floor inspections. All of Diakont’s inspection personnel are OSHA 10/30 certified, Basic Plus trained, RSO trained, trained in first aid/CPR/AED, and are equipped with proper PPE and SCBA equipment.

Before turning on any equipment, Diakont inspection technicians ground the field office, robotic equipment, tank, and generator. Diakont technicians go above and beyond API safety standards to eliminate static electrical hazards on the ground and the tank roof.