CAS - Cost effective Inspection and Structural Maintenance for Ship Safety and Environmental Protection throughout its Life Cycle
Overview
Background & policy context:
For oil tankers to be more environmentally-friendly throughout their life cycle, the IMO (International Maritime Organisation) has set forth a condition assessment scheme 'CAS' for single hull tankers and also worked to develop a similar type of code for double hull tankers, which involve huge amounts of measurement information.
Performing those inspections efficiently requires processing measurement information on a real-time basis, resulting in cost savings because fast assessment of the ship's condition and decision-making could be done while the ship is still in the dock for maintenance. Measurement information consists of thickness measurements, visual assessment of coating and detection of cracks. In the existing situation, because there is no standardisation of data, the information is recorded manually on ship drawings or tables, which makes handling very difficult. Measurement information takes a long time to report and to analyse, leading to some repairs being performed at the next docking of the ship.
Reporting these structural measurements efficiently requires processing measurement information on a real-time basis. This would result in cost savings because a faster assessment of the ship’s condition and quicker decision-making could be done while the ship is still in the dock for maintenance.
Reliability of the analysis of the measurement reports could also be significantly improved by the use of electronic displays, associated with automatic warning devices in case of excessive deterioration of the structure. This is to be compared with today’s existing paper measurement reports, which are checked manually, page by page, by surveyors.
Objectives:
The CAS system is built around the design of an exchange standard format to describe, in a neutral way, the structural data and associated measurements. All tools used in the ship hull monitoring process are expected to have this exchange standard format incorporated.
The system includes such innovative features as:
- the development of a simplified and flexible ship electronic model which can be refined to fit the needs of classification inspections;
- additional measurement information into the ship model;
- automatic updating of the measurement information into the ship model;
- the integration of robotics;
- easy handling of measurement information using virtual reality;
- immediate worldwide access.
The system developed is applicable to any ship type, but, due to the current focus on tankers and bulk carriers, these ships are used as the main case studies.
Methodology:
The re-engineering of the process was to include the definition of a standard exchange database, called Hull Condition Monitoring (HCM). The HCM was to be tuned up by all the partners intervening in the process, and, as studies and tests would be performed by the partners, in the course of the project, new features would be incorporated into the standard.
Systematic comparison and consistency checks of measurement campaigns will trigger electronic alerts. Repair decisions and residual lifetime of the structure will be calculated with modern methods of risk-based maintenance modelling, with the interesting feature that the model will be updated after each measurement campaign.
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