About 3D Measurements
Advanced 3D Laser Scanning and Floor Scanning are the techniques used at DEKRA to measure both the volume of storage tanks, and defects in the floor of large tanks. Cisterns can be measured if they can hold the media. So in order to get an accurate measure, the volume of the storage tank and the cistern needs to be measured.
3D Laser Scanning of storage tanks and cistern
Traditional methods to measure the volume of storage tanks and the cistern included the use of measuring tape and extrapolating data from the original design drawings. Such methods were both time consuming and could often result in a high level of uncertainty. At DEKRA our experts use 3D laser scanning to rapidly and accurately calibrate the volume of the storage tank and the cistern.
DEKRA’s high precision volume calibration techniques are based on 1,000,000 measures per second
The resulting 3D laser data delivers a large amount of geometrical data about the cistern, which is also able to be used for other purposes. During the measurement using this method, we also detect changes and deformations in the structure, which can be used for strength calculations.
The method visualizes the structure of the cistern and can also produce high resolution photographic images. From the data collected it is possible to evaluate the cistern according to:
- Deformations of the shell and the bottom
- Inclination of the cistern
- Volume and 3D drawings of the internal
It is also possible to rapidly and efficiently compare and follow up deviations by comparing the measurements over an extended period of time.
3D hand laser scanning of object surfaces
Handheld 3D laser tools are used to gain very quick assessment information about the outer surface of objects, where pitting can be easily measured and or monitored. As the method is very quick, the downtime is minimized. 3D handheld tools are very easy to use to gain assessment data in a fast and straightforward way.
3D Floor scanning of storage tanks
DEKRA uses two different types of technique to inspect the floor of storage tanks: Magnetic Flux Leakage (MFL) and Magnetic Eddy Current (MEC). The Magnetic Flux Leakage (MFL) technique is a rapid and robust corrosion detection technique. It relies upon strategically placed hall effect sensors to detect any magnetic leaking field created by corrosion. Together with additional techniques the position of any corrosion on the topside or bottom side of the tank bottom can easily and rapidly be detected. The Magnetic Eddy Current (MEC) technique uses the eddy-current technique together with a magnetic field.
Used together, DEKRA’s experts deploy these two techniques to perform:
- Top and bottom plate corrosion views
- Detection of corrosion on the underside > 20% loss of wall thickness
- High inspection speed up to 1m/s
- Plate thickness up to 30 mm for MEC and up to 20 mm for MFL
- A detailed and easy-to-understand visualized report
DEKRA has several other methods that are combined to report the complete status and condition of the storage tank. Together with the floor scanning, DEKRA’s experts use ultrasonic testing (UT) for areas where a more precise evaluation is needed, guided waves for pipes connecting to the storage tank and UAV visual methods for the storage tank roof and its overall condition. Magnetic wheel scanners are used to investigate the storage tank shell by using ultrasonic testing to scan part of the wall and, finally, 3D laser scanning is used to calibrate the storage tank volume and detect any deviations in the structure.