Corrosion detection by EMAT on above-ground storage tanks


  • The Voliro T can take 200 measurements each hour, saving days over scaffolding installation and disassembly.
  • There is no surface preparation necessary for the EMAT payload.
  • Create a better plan of action for your time and cost-sensitive shutdown
  • Digitize your asset with accurate and traceable data
  • Ensure the integrity of your storage tanks by adhering to all applicable local regulations, standards, and codes.

Problem Description

When storing liquid chemicals, it is essential to minimize the possibility of leaking. Corrosion of storage tanks can lead to environmental damage and financial losses. You must thus assure the safety and reliability of your tanks. Our customer is a prominent Southern European refinery operator. They sought two options utilising the Voliro T. The first step was to measure the thickness of visually identified corrosion areas on their tank prior to their shutdown in order to assess if repairs were necessary. The second step was to conduct a comprehensive inspection in accordance with code standards. (Inspection rules and industry standards require that all bulk storage tanks be examined at least intervals of five years for in-service (on-stream) inspections and ten years for out-of-service (off-stream) inspections).

Solution Description

The Voliro T was equipped with the EMAT sensor payload. The EMAT is a non-contact device that generates and detects ultrasound in electrically conducting or magnetic materials.The EMAT is ideally suited for checking regions where the surface condition is not always optimal for normal thickness gauging, such as highly corroded areas. EMAT operates without the requirement for liquid coupling, and the majority of the time the surface does not require preparation.

As there were no areas that needed repair identified, the Voliro T performed thickness measurements on the entire tank walls and roof. This saved the installation and tear-down of some 615 cubic meters of scaffolding – which would have required 400 person-hours of labour. A trained pilot and qualified NDT inspector working in tandem can capture about 200 measurements per hour.

The Voliro T is highly adaptable. At the same refinery, it is feasible to move to the next location and begin inspections with minimal preparation, for example, to an additional storage tank, overhead pipeline, or flare stack. Additionally, it can collect additional data than existing methods. Using the Voliro T, each measurement is time-stamped. Once the data has been downloaded from the system, a reporting tool correlates the measurement's time stamp and GPS position with the sensor measurement (complete A-scan) and the screen grabs from the two cameras. The whole video feed is also accessible, allowing for complete inspection traceability.