MoniTank Validation Completed
With the efforts of five consortium partners – Brunel University London, Floteks, Integrity NDT, IRIS and TWI – MoniTank site trials and validation activities have been completed successfully. The trials took place at Integrity NDT field facilities in Yenikent Ankara, and covered a period of almost 6 months, with continuous testing and monitoring over 2 months on two different vessels.
Prior to Validation
In order to up-scale system performance and to create a data background for upcoming industrial tests, the consortium started initial Monitank system testing in the Integrity NDT laboratories. In order to provide compatibility with prior TWI activities, The Ankara Middle East Technical University laboratories were utilised and corrosion simulation, together with crack simulation trials, were implemented (special thanks to Prof. Dr. İshak Karakaya from the Materials Science department).
During this stage, continuous improvements on both hardware and software were implemented via communication with the manufacturer, Arlentus Control, and software developer, IRIS. Knowhow generated from these applications has helped in directing the MoniTank team in preparation for upcoming industrial applications.
In order to make the final simulation prior to the validation stage, a single wall tank was transferred to the Integrity of NDT laboratories and rigorous testing continued. At this stage, comparisons with market leader acoustic emission product ‘Vallen’ were implemented. Validation and system performance field-site trials continued on the single wall tank. A summary of activities prior to validation was as follows:
- Single Wall Tank Corrosion Simulation and Localisation
- Single Wall Tank Crack Simulation and Localisation
- Single Wall Tank Detection Tests
- Plate Localisation Tests
- Two Assets Simultaneous Acquisition Tests
- Two System (Vallen and MoniTank) Simultaneous Corrosion Test
- Attenuation Tests
- Magnetic Installation Box Stability Tests
Integrity NDT rented a field-trial site for the project duration in order to facilitate all the MoniTank validation activities. The site is approximately 20×20 metres, with container premises for placing and covering the equipment, electricity supply, water system, WC, etc, is provided by Integrity NDT.
The site is located in Yenikent, which is west of the capital of Turkey, Ankara. The site location was fairly close to the Integrity NDT office, which gave the opportunity to continuously monitor equipment condition and allowed the MoniTank team to introduce and action regular events.
Assets and Installation
The project consortium focussed on two main assets; ‘single’ and ‘double-wall’ underground storage tanks. In addition to these, ex-service exposed and cylindrical tank conditions were monitored in order to observe system performance under varying geometries and conditions.
Both tanks are cylindrical, as seen in the figures, measuring 4.8-metres-long with a circumference of 5.2 metres. The single wall tank has a thickness of 5 mm, while the double-wall tank has a thickness of 8 mm (5+3 mm). The burying operation was managed by the installation team, and special bone cables were used to provide underground durability along with guy ropes to stabilise sensor position. At each step, system stability was tested using metal balls or pencil breaks and the installation team made sure of the safe installation of the system.
Firstly, two tanks were half-buried in order to create controlled events then, secondly, the continuous monitoring stage with liquid circulation was implemented. Using software adjustments, the acquisition unit was pushed to the limits during a 2-month trial.
Monitoring and Test Stage
As seen in the previous pictures, from the open side of the tanks, controlled corrosion and crack simulations were introduced regularly and the localisation algorithm was tested under different conditions. During this monitoring stage, system parameters, such as board and localisation threshold, were changed regularly to optimise the underground system performance. Additionally, liquid circulation between the tanks was implemented to test the effect of circulation signal and assess the filtering options. Introduced liquid accelerated the inside corrosion in the tanks, which enhanced the corrosion and signal significantly. After signal processing and rigorous analysis, corrosion signal and localisation were assessed and optimisations were performed.
During the monitoring stage, sensor stability checks with metal balls were implemented using a small pipe introduced to the tank’s upper surface.
Having a liquid medium inside and a sand medium outside, acoustic emission propagation, attenuation and signal characteristics were found to differ significantly from above-ground tests. However, the MoniTank system successfully detected and reasonably localised all the signals that were gathered.
MoniTank system activities continue with the certification of the complete system. After this final stage, a commercial MoniTank product will be ready to enter the market!