Tankers carry close to 40% of the world's seaborne trade. In 2003, 57% of all the oil consumed in the world was transported by sea - approximately 2 200 million tonnes.
Oil tanker accidents in European waters resulted in catastrophic consequences in which structural deficiencies may have largely contributed to the accident.
In the case of the tanker Prestige, for example, which suffered a structural failure in November 2002 in heavy seas off northern Spain and developed a severe list, the investigation found that it had undergone extensive repairs 18 months prior to the accident and that these repairs were conducted under the Enhanced Survey Records, appearing to indicate that the procedures of the classification society were followed and that no shortcuts were taken. This led to a question mark over the safety of conducting large repairs on older ships.
This investigation, and others, identified the need for better understanding in areas of the detecting of defects and weaknesses during and after both survey and repairs; the reduction of any adverse effects of repairs; and the current strength requirements for deck opening securing arrangements.
ALERT therefore aimed to address this issue by concentrating on the recommendations contained in the Prestige accident investigation report that are relevant to ship repairs.
The ALERT project made a thorough examination of the practices in the field of ship repair and set out to propose improvements to the underlying processes in consultation with industry. The project critically reviewed the current and emerging technologies, identified and prioritised future R&D needs and developments, in the areas of ship repair practices, condition monitoring of ships, structural assessment methodologies and through-life management.
The main goals of the project were as follows:
- to undertake a thorough examination of current practices in the field of ship repair and propose improvements to the underlying processes in consultation with industry;
- to review existing and emerging technologies appropriate for ship-repair practices, and propose areas for the development of technologies for future application;
- to improve the efficiency of tankers by considering inspection, maintenance and repair scheduling;
- to consider a framework that will be capable of determining, rationally, the extent of repair work that an existing ship could safely undergo with minimum additional risk of structural failure;
- to promote a safe transportation system for Europe;
- to reduce human losses, injuries and environmental damage risk associated with transportation of hazardous goods by tankers;
- to encourage best practice in the tanker shipping and ship repair community;
- to effectively disseminate the results and facilitate their acceptance by European society and by industry;
- to co-ordinate these efforts and to demonstrate the positive effect of this co-ordination through the participation in Integrated Projects (IPs) and Networks of Excellence (NoEs).
ALERT consisted of five partly interdependent work packages carrying out all of the co-ordination activities. Work Package 5 is an integration package where exploitation activities, such as preparing research proposals and the dissemination of ideas generated within the project to a wider community, were carried out in the light of the studies performed in Work Packages 1 to 4.
- Work Package 1 investigated existing ship repair practices;
- Work Package 2 was a study into condition monitoring of ships;
- Work Package 3 studied the structural strength assessment of tankers; and
- Work Package 4 studied several areas of through-life management of tanker structures.
The effects of the operational profiles of tanker vessels, such as route planning and weather profiles, partial cargo loading, and heating of cargoes on the wastage (corrosion) rates and ultimately on the structural health of the vessel, were considered.
During the project workshops and seminars were held and future roadmaps for research were developed by integrating the future research and development needs identified in each of the work packages.
The results are the production of State-of-the-Art and R&D requirement reports in the following areas:
- standard practices, class society requirements for the repair of ships and alternative repair practices;
- consequences of structural reliability with new to old steel replacement;
- development of common repair, inspection and maintenance;
- non-destructive testing of welds;
- means of detecting fatigue cracks and recording presence of fatigue cracks prior to repairs or renewal;
- corrosion detection and protection, monitoring the environment in void and ballast spaces;
- contact damage on the strength of a ship's side structure and strength of securing arrangements for openings;
- global and local strength;
- influence of residual stresses;
- effect of operational profiles on structural deterioration and failures of tankers;
- legislative responsibilities, and repair and maintenance scheduling.
The investigated potential research and development (RD) areas included ship restoration practices, condition monitoring of ships, repair related structural assessment methods and through life management of ships.
Each project component was examined by one of five distinct, yet interrelated, work packages (WPs). The last WP focused on dissemination, coordination and knowledge exploitation activities. The acquired experience was communicated to industry, academia and the general public through publications, presentations in conferences and symposiums and via the project website.