software class
Programs incorporate more hull integrity analysis
Classification societies have developed software to improve tanker hull integrity analysis, enhance structural rules and reduce onboard risks
G
reater emphasis on safety and structural integrity has driven classification societies to enhance their hull analysis
software. Societies have included 3D and finite element modelling (FEM), improved user interfaces, and updated software to remain within the IACS’s Common Structural Rules (CSR) as these are changed. RINA has incorporated 2D and 3D modelling
and FEM into its Leonardo Hull structural analysis software. This helps RINA validate and calibrate its own tanker design compliance rules with CSR as the society provides technical services to shipyards and owners, says RINA’s head of technical services, Dino Cervetto, who is in charge of developing technical instruments. “We are updating Leonardo Hull software
in line with the development of CSR. It has 2D and 3D analysis of hull transverse sections for hull girder, plating and stiffener strengths. This was designed with features for modelling structures such as bulkheads, stools, and trunks within tanker designs. Leonardo Hull supports tanker lifecycle requirements, including planned maintenance management, which is updated with hull scantlings survey measurements,” Mr Cervetto explains. “These features make Leonardo Hull an
invaluable tool for the design and maintenance of oil tankers, where the possibility of optimising steel renewal strategy plays a fundamental role from an operational point of view. The software
RINA’s Leonardo Hull software includes 3D models for tankers
allows the user to perform a reliable structural analysis over the entire cargo area of the ship. This is accomplished by using automatic generation of loads, easy editing of structural properties, easy detection of user mistakes, and automatic performance of rule checks.” Software processes include analysis of nodal displacement and element stresses, which are checked under RINA and CSR strength criteria for yielding, buckling and fatigue of structural details. Other features include analysis of corrosion rates, calculation of renewal thickness and prediction of steel renewal dates for each structural element. Other class societies have upgraded
programs that aid crew hull inspections. This year, DNV improved the interface for shore- based superintendents in the latest version of its
Nauticus hull integrity software. The program helps crew identify and record hull structural defects, such as corrosion and cracks. This helps operators avoid costly off-hire periods, expensive immediate repairs, and prepare for drydockings, says DNV’s project manager for ship structures and concepts, Päl Wold. This is part of a service package that incorporates
training in hull competence, inspection manuals, data analysis and technical support. “The software helps with owners’ hull condition monitoring, inspection planning, and storing of inspection and hull condition reports,” Mr Wold says. The service is especially relevant for tankers,
given the focus on vetting requirements. “Shipowners can set up inspection schemes and we provide the competence for crew in respect to training, hull manuals and the software. Owners
Premuda fits Four Island with hull monitoring system
Italian shipowner Premuda has used RINA’s Leonardo suite of software for structural investigations on its Aframax tanker Four Island. The ship was fitted with a Pegaso Systems hull monitoring system, which provided detailed information to the master on the stresses acting on the hull structures. Strain data were collected during various operational phases, such as loading, discharging, and during
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voyages, enhancing the safe operation of the ship, says RINA’s head of technical services, Dino Cervetto. “In this type of analysis, it is essential
to select the most representative structural elements to be gauged, while keeping their number within practical parameters. In fact, the number of measurement points is such as to provide a clear and comprehensive
picture of the stresses acting on the ship,” Mr Cervetto explains. “A precise 3D analysis carried out by
Leonardo Hull provided a clear indication of the areas where the wave-induced stresses reached the most significant values for the representative loading conditions of the ship. Based on these results, it was possible to install the optimal number of stress gauges.”
Tanker Shipping & Trade I October/November 2011 I 23
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