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Q&A with Terra Inspectioneering

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Picture of Meenal Datar

Meenal Datar

Membership specialist

Marien van den Hoek, co-founder and commercial director of Terra Inspectioneering, explains why you need drones and robotics



After working for big companies in the process industry for more than 40 years, I started my own company in 2012, because I had a vision that in the new era of inspections in dangerous confined spaces, we should replace the people with robotics.

It’s very, very difficult to make changes in the process industry and initially take-up was low. Acceptance was hindered by legislation. Which is far behind what you can actually do with drones. In 2016 I came together with two other companies and we founded a company called RoNik Inspectioneering. We had three sets of expertise. One company specialised in inspections compliance with the rules and regulations for the process industry. One company was a start-up company developing drone hardware and software for the process industry, because normal commercial drones are not suitable. And then there was myself. After many years I know all the big customers in the industry and I had my network. By bringing those three elements together we could give our customers in the process industry a total service package. From that time, we were already very specialised in confined spaces. We started our own research and development department developing hardware and software with one theme – to develop full inspection procedures in the process industry.

In 2019 we were approached by Terra Drone, a worldwide drone inspection company headquartered in Tokyo in Japan. They already had their own drone inspection companies in about 30 countries, but they were all related to outside inspections, for example for flare stacks and infrastructure like bridges and power lines. None of those companies had anything on confined spaces, so Terra took a stake in the company and from that moment our technology, that we developed here in the Netherlands, has been deployed over all of those existing 30 countries.

There has been a lot of reluctance when it comes to drones, but in 2018 the CEO of Dow, Jim Fitterling, announced that by 2025 but there will be no more people in confined spaces in Dow. Everybody had been avoiding drone technology because they thought it was risk but then Dow made it a directive. Shell followed and BP followed, and others, under the new wave of acceptance.



A key driver for using drones is safety, because you don’t want to have people in these dangerous environments. 80% of the accidents which happened in the process industries are either working in a confined space, or working at height. If you have a very high storage tank of about 30 metres you are in a confined space and you have to work at height. We can eliminate this.

The second thing that is very important is the time reduction on the inspection cycles. If you have a tank of about 60 metres in diameter, normally you have to bring everything in piece by piece through the manhole to build the scaffolding, and then have everybody working on the inspection. One is example is a customer in the Netherlands who would once inspect their big tanks by means of rope access. That would take three weeks with five people to do the complete inspection internally. Of course, they had all the issues of five people being continually in the confined space so it was the highest risk, and the work permit process was very complicated with trying to guarantee the safety of all those people.

By doing this with drones, inspections now take just three days with only a maximum of four people. This kind of huge difference is feasible right now.

Also, because the inspection time is much less, the uptime of your asset or your tank is much higher.

Another example is a big terminal that was in discussions with the authorities about the status of the tank, the predicted lifetime and suitable inspection intervals. We introduced a fully detailed plan and digital inspection method. The authorities were astonished. There is so much data available using this method compared to the data that is usually taken manually. Also, because this data is taken automatically, the quantity is much better and it’s repeatable. Normally when an inspector goes in a tank, he has a piece of paper and writes down the values. He may take photographs but that’s it. Perhaps when he comes back in the office, the original value was 6.3 but he can’t read it so he enters 6.8 into the Excel sheet. Secondly, maybe he can’t remember quite where he was in the tank when he took a particular picture. The drone takes thousands of measurements so the data is much better. By proving this to the authorities we were able to reschedule the inspection interval from 10 years to 17 years.



Our approach is to focus on digitalising the inspection process, particularly the report for the customer that’s given to the authorities to prove compliance with legislation, and also the safety report. These reports are much more reliable using digital technology. The first step is improving the data capturing. The interest is not so much with what drones we’re flying.

When a drone enters a tank, it is effectively flying in a Faraday cage, with no compass or GPS. At this moment, when we do non-entry, we still have to rely on pilots and a lot of the quality is determined by their capability. We are working now to fully automate these drones so they can fly on their own. We are building a network right now that will allow an operator to go to a screen, give it the code, put the drone inside the tank and then it flies on its own exactly where you have determined that it needs to fly. The inspector doesn’t have to be in the field, you only need one operator to make sure that everything is going okay with the drone. The inspector can still say behind the screen and see the real data streaming from the drone. This is a new shift in the whole inspection methodology. We’ve started that already but it’s still in development.



There is a lot of resistance to drones, because the culture of the process industries is so conservative, so we have to fight against this. One of the hurdles is that people automatically think that the drones are dangerous. On the other hand they consider it safe to have people working up scaffolding on ropes at 30 metres in a confined space because they’ve known this and been used to it for 20 years. When you take a realistic view of this, it’s complete craziness to send people into a dangerous environment, just because you’re used to it.

A new maintenance trend that a lot of companies are implementing is risk-based inspection, RBI. This can give very good results, and also one of the things it predicts, amongst others, is the lifetime of your asset using model. If you don’t have the data these RBI systems are unreliable, or they predict values with a much broader spread, for example an asset life of 12 and 16 years, but which is it? You need the right data and the right quality of data. Drones can give 1,000 times more data than manual means. If you feed this into an RBI system you can do a very precise prediction as to what your lifetime will be, instead of giving a spread of four years. The next step will be to bring the value-adds of this kind of calculation. The people who take RBI seriously should realise that they need quality data, and that drone technology is the best alternative.


For more information:

Marien van den Hoek will give a presentation entitled ‘No more people in confined spaces using drone VT/UT measurements’ at 10.30 am CET on 17 March 2021, as part of The Terminal of Tomorrow, StocExpo’s online conference. Visit for more information and to book tickets.

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