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Case Study: In-Service Diesel Tank Inspection

An Energy Operator approached Nexxis to develop a solution for inspection of their diesel tank while remaining in-service.
Service tank inspection laser

An Energy Operator approached Nexxis to develop a solution for inspection of their diesel tank while remaining in-service. The client only had a single ignition fuel storage tank 1500m3.

The client wanted to achieve some clear objectives and outcomes;

  • Perform the inspection without the need to shutdown
  • Perform the inspection online
  • Avoid the need to empty the tank
  • Avoid the need for Temporary storage
  • Extend the 10 yearly statutory inspections by 4 years

In-Service inspections often involve CSE (Confined Space Entry) by trained personnel. This presents unnecessary risk and our team strive to eliminate CSE.

Evaluation & Simulation

At Nexxis, our first step in this process is to evaluate and where required, create a simulation of the inspection. Our Solutions analysts work with the client to determine historical approaches, outcomes and obstacles – and then work on creating a more efficient and safer approach. This often circles back to the equipment selection or customization. An in-service inspection, in particular, requires a very specific inspection device that must be rated for the environment and ideally that can be operated remotely.

Depending on the findings of our simulations, we will then move forward and create a methodology, including detailed visualisations, to put to the client for appraisal.

This outcome focussed approach allows us to streamline processes, improve data collection, fine-tune equipment and create a more comprehensive approach to inspection and ultimately data collection. See figure 1.1 below for an example of our evaluation methodology;

Nexxis Methodology

The Solution

After assessing the plans, a submergible robotics system with an integrated cleaning attachment and UT thickness probe along with a high-definition camera system. The robotic crawler we used was suitable for submersion in diesel fuel and was customized to offer cleaning function, RVI and UT capabilities.

The estimated cost saving for this type of inspection was around $500k

A time saving of 3-4 weeks vs a 3-day detailed inspection All outcomes achieved including a 4 year extension by authorities.

Diesel Tank InspectionDiesel Tank Inspection


The resulting inspection provided a range of benefits to the client including;

  • Reduced Risk (No CSE required)
  • Reduced Work Scope during Shutdown
  • Estimated $500k cost saving
  • Delayed tank emptying for an additional 4 years

Additionally, the inspection sparked interest from employees and operators, highlighting the possibilities of robotic inspection and illustrating the positive outcomes. With goals of 80% CSE reduction by 2020, it’s important to drive the implementation of the best technology into the industry in addition to creating an educated workforce.

Using the Nexxis ‘Evaluation & Simulation’ approach, our clients are able to rely on not only time and cost-saving in the short-term, but the collation of better, more effective data long-term, which means those cost-efficiencies will grow over time.

Discover more about our full range of robotic inspection equipment or contact us today for a no-obligation chat.

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