Brussels, Nov 2003
In response to devastating oil spillages caused by undetected corrosion in single hull tankers, such as the 1999 Erika disaster, the EU has funded an initiative that aims to simplify the process of testing the structural integrity of such ships.
It is estimated that of the approximately 7,000 medium to large tankers in service today, 5,000 have a single hull design. The huge amounts of crude oil being transported on such ships are therefore contained behind some 20 millimetres of metal.
While external corrosion of these hulls is relatively slow and easy to detect, the types of substances found within the tanker can corrode a hull at a rate of three to four millimetres a year, and this currently requires a complex and costly process to detect. The tanker must be completely emptied before testing can take place, ensuring that it is out of service for some time, and the total cost for large ships can be as high as one million euro.
However, in the course of a previous EU funded initiative, it was discovered that such corrosion can be detected using a process known as acoustic emissions testing (AT). Having established the effectiveness of this technique under experimental conditions, TÜV, an Austrian company specialising in AT technology, was selected to coordinate a Fifth Framework Programme (FP5) initiative aimed at developing a practical method of applying the process to working tankers.
As TÜV's Peter Tscheliesnig explained to CORDIS News, this requires the development not only of the specialist hardware components needed to take effective acoustic readings in explosive environments, but also of software tools to process the huge amounts of data that the process generates and to translate that data into results.
'We have validated the method and developed the required components and software tools. Once the safety of the components in explosive surroundings has been officially certified, we will move to testing the system on ships in real working conditions,' said Mr Tscheliesnig.
For this purpose, other partners in the project include the Polish register of shipping, and maritime institute in Gdansk, which provides TÜV with vital input as to the requirements of the shipping and maritime safety industries. There is also the possibility that the consortium will establish a user group including shipping companies, port authorities and classification societies to help test the methodology. 'TÜV relies on its partners for validation and testing of the system under real conditions, as it's hard to find many oil tankers in Austria,' said Mr Tscheliesnig.
The impact of such a system will be significant, according to Mr Tscheliesnig: 'A process such as this will reduce the amount of time needed to assess corrosion to two or three hours. Furthermore, the relevant authorities could carry out the test when a ship arrives in port, ensuring that potential disasters such as the Prestige are averted at the earliest opportunity.'
The benefits for the environment are clear, and Mr Tscheliesnig believes that the shipping industry will welcome the speed and relative low cost of the method. Additional safeguards against large scale environmental disasters should also contribute to boosting the industry's often damaged reputation.
Patent applications have already been registered for the AT method and its components, and with a further two and a half years of the current project remaining, the consortium hopes to develop a version of the system that can be permanently installed onboard ship, with the data being sent to remote processing sites for analysis. If they are able to achieve this, the sight of thousands of tons of oil bleeding into the environment through corroded hulls could, thankfully, become less familiar.
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