Overview
The background of this project is related to technical safety in conjunction with the competitiveness of the EU industry. Corrosion damages and fatigue cracks are the main causes for structural failures of all surface transport products such as, ships, road tankers and railway tank cars. Examples are catastrophic ship accidents with a tremendous pollution of the maritime environment or fatal explosions during the use of transport vehicles. To prevent structural failures, maintenance and inspection has to be carried out. These activities require high efforts and are usually performed while the transport product is out of service. Such kinds of maintenance are often referred to as "preventive maintenance". Defects have to be identified in time to enable appropriate repair. However, preventive maintenance activities are usually carried out on a time driven or routine basis.
As an example, transport products for cargo such as, crude oil and pressurised gases have to be taken out of service for visual inspection and subsequent non-destructive tests (NDT). Findings then have to be repaired at a later stage. This procedure is time-consuming and expensive, especially so, as the lost service time decreases the competitiveness of the European transport industry. Despite this high effort, the risk of not detecting the onset of a defect is still implied in this maintenance process and thus failure within the next service period may occur.
It has been proven that Acoustic Emission (AE) technology detects active cracks and enables the evaluation of active corrosion. By the application of permanent AE sensors on predetermined hot spots of ships and tank cars, the conventional maintenance and inspection can be replaced by a cost effective and condition-based detection of defects and their follow-up in time.
The main objectives of the project were:
- Final prototype of monitoring equipment for transport products;
- Generic maintenance and an inspection programme using the AE monitoring technology;
- Drafts for standardisation.
The proposed maintenance process has been based on monitoring the status of the structural integrity in terms of developing fatigue cracks and active corrosion using the Acoustic Emission (AE) technology. It has been proven that AE detects active cracks and based on the results of EU-funded project Corrosion Detection of Ships (EVG1-CT-2002-00067), it is evident that AE is able to detect and evaluate active corrosion, allowing countermeasures to be implemented much sooner. This means on the one hand, more safety and on the other, a larger saving of resources.
By the permanent application of AE sensors (on pre-determined hot spots) the conventional maintenance and inspection can be replaced by a cost-effective and condition-based detection of defects and their follow-up in time. The result of the project was an overall strategy for the maintenance and inspection, including the necessary AE equipment for the different transport products. Reasonable follow-up NDT methods were validated. By the on-line measurement the method will also increase the safety of all transport products.
Funding
Results
The main results of the CORFAT project have been identified as follows:
- Confirmation of the fact that the application of the new non-destructive methodology allows evaluation of the ship hull or tank shell condition, taking into consideration the defects caused by corrosion and fatigue cracks;
- Confirmation that owners/users are interested in using this method, considering that it improves safety and reduces repair costs due to the continuous monitoring of defects on transport;
- The proposed method can also be used to monitor other steel structures, where corrosion and fatigue cracks happen very often, e.g. floating docks, oil rigs, steel bridges, steel towers, wind farms;
- Improved ergonomics, meaning the improvement of human working conditions (safety), especially compared with those when obtaining measurement results from the same places using conventional NDT methods.
Innovation aspects
The Project's main innovative aspect was the proposal of a maintenance process based on monitoring the status of the structural integrity in terms of developing fatigue cracks and active corrosion using the acoustic emission (AE) technology. Research shows that AE detects as well as evaluates active corrosion.
Furthermore, the project aimed at studying and developing a new monitoring technology based on acoustic emission testing (AT), combined with follow-up NDT for monitoring the status of structural integrity in terms of developing and proceeding fatigue cracking and active corrosion. In addition to studying AE from fatigue cracking and corrosion in a laboratory, background noise occurrence during different environmental and operational conditions were also investigated.
Policy implications
The new monitoring method proposed and utilised by the CORFAT project had the following socio-economical impacts:
- Increase of the attractiveness of work on transport products (ships, railway tank cars and road tankers) monitored by the new methodology and based on acoustic emission testing (AT). Due to the fact that the safety of the crew will be increased, the new monitoring methodology will have an impact on the human psyche and people will be more likely to take a job in transportation;
- AE monitoring during the service period will help to detect regions degraded by corrosion and/or fatigue cracks and will allow the shortening of out-of-service time and the decrease of repair costs;
- The usage of an AE system for continuous monitoring of structural health will increase the operational safety, as well as ecologically impact on the environment;
- Safety during emergency situations could be increased by AE monitoring;
- In addition to the the application on transport products, the new technology could be adapted and installed in other industrial fields for the monitoring of various structures during the service period. Costs could be saved because the monitored device would not have to be taken out of service (time and cost intensive), leading to increased competitiveness, as well as company reputation;
- Further development and implementation of the new methodology will also assist standardisation societies and inspection authorities in their work and monitoring during service could help to prevent breakdowns or failure during service periods and save worker's lives and decrease the damage of installations.
Strategy targets
1. An efficient and integrated mobility system:
1.4. Acting on transport safety;
1.5. Service quality and reliability.