CASE C05 · NO ·
Returkraft: scaffold-free ultrasonic thickness inspection of a waste-to-energy boiler
Norwegian waste-to-energy plant Returkraft used a UT-equipped drone to measure boiler tube thickness. The manufacturer reports UT work falling from up to 300 hours to about 8 and the outage shortening by about 48 hours with no scaffolding. Probe angling on narrow curved tubes was difficult and pre-cleaning was required.
| Owner | Returkraft (waste-to-energy plant) |
| Provider | — |
| Location | Kristiansand, Norway |
| Aircraft | Flyability Elios 3 with UT payload |
| Sensors | ultrasonic thickness (UT) probe, 4K video, LiDAR |
Before
10–15 scaffolders spent about 1,700 hours erecting scaffolding inside the boiler, then NDT inspectors spent about 300 hours on UT readings.
With drones
The plant's own team flew a drone with a UT probe to take tube-wall thickness readings without entering the boiler.
Outcomes
| Metric | Value | Basis |
|---|---|---|
| UT inspection time | about 8 hours (incl. battery changes) vs up to 300 hours | Reported |
| measurements | over 150 UT readings in 2.5 hours of flight | Reported |
| outage length | about 48 hours shorter; 7 days of scaffolding avoided | Reported |
| cost | €450,000 stated as saved | Reported |
Caveats & limits
- Manufacturer case study (Flyability); the €450,000 figure is presented both as the saving and as the cost of the traditional method, so it is internally inconsistent.
- Curved narrow tubes (44.5 mm and 57 mm) required careful probe angling; the boiler cleaning system must run first and fouling may need removing.
- An earlier FPV drone could not fly the space and gave only visual data.
- Year not stated in the article; city (Kristiansand) is from the plant's public identity, not the article.
Sources
- Saving 450,000 Euros on Boiler Inspections with the Elios 3 DroneFlyability Full text read
Sources checked: 2026-10-22