Feature 2 | CAD/CAM UPDATE 3D reality check for CAS
Follow-up action on SENER’s three year, EU-funded, Condition Assessment System project sees inspection measurements gathered on a working ship successfully plug into its original 3D block model.
A
s one of the follow-up actions to the EU-funded Condition Assessment System (CAS)
project, CAD/CAM specialist SENER has exported the 3D model of a block for a four year old tanker for use in conjunction with inspection data gathered during its operation. The results, according to Bureau Veritas manager project department, Philippe Renard, who project-managed the three year CAS project, were “remarkable”. SENER exported the FORAN 3D
model of a section of the double bottom of Bahía Uno, using the Hull Condition Model (HCM) standard file, to be used by BV to run the 3D model-based monitoring tools it developed as part of CAS, which ended in April 2008. Bahía Uno, built in 2004 at Astilleros
de Murueta in Spain and classed by BV, is a double-hull tanker supply vessel with a length of 71.01m, a breadth of 15.6m, depth of 7.75m and draught of 5.6m. The remit of the CAS project was
to improve the reliability of ship condition assessment by attaching all measurements taken on commercial ships while they are trading all over the world (steel plates and stiffeners thickness measurements, cracks position and coating condition) to the numerical virtual 3D model of the ship. A critical element of this aim was the development of electronic tools that would cut out the manual handling and interpretation of thickness measurements and simplify the handling of all thickness data, right from the measurement through to using the data in the most complex condition assessment tools, allowing definitive repair decisions to be made on the spot. SENER’s follow-up exercise looked to
bring these aims to reality, cutting the time and costs involved in processing thickness studies of the structure of a
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Bahia Uno – the 2004-built tanker, a section of whose 3D model was used to check the EU-funded CAS project.
ship in operation. The HCM directly relates the ship’s structural elements with the measurements taken onboard, allowing 3D visualisation. By updating the HCM at each survey or repair, throughout the vessel’s life, a continuous basis will be established for analysing the ship’s condition and identifying trends and changes. In detail, the The FORAN 3D model
incorporates virtual reality techniques and can offer immediate worldwide access. Systematic comparison and consistency checks of measurement during inspection campaigns can include thickness measurements, visual assessments of coatings, and visual inspection for cracking, which will trigger electronic alerts. According to SENER, “repair decisions and residual lifetime of the structure can thus be calculated with modern methods of risk-based maintenance modelling, while the model can be updated after
each measurement campaign”. “We were a little surprised,” said BV’s
Mr Renard. “The model was perfectly readable in 3D and enabled us to incorporate it into the commercial tools we developed as part of CAS. We could see all the details of the stiffeners and cut-outs, etc, and add in the thickness measurements that had been carried out onboard, navigating our way around the block and using all the functionality of the tools, especially as they related to the thickness measurement of the block. The accuracy of the results were a bit of a surprise, because this was not a new ship.” “With this test, BV and SENER
test the results of the CAS project in a real vessel,” said SENER. “This project is expected to speed up the failure monitoring process and repair times with the aim of reducing marine disasters, specially caused by tankers and bulk carriers.” NA
The Naval Architect July/August 2009
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