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Target reliability for submerged floating tunnels
Published in Hiroshi Yokota, Dan M. Frangopol, Bridge Maintenance, Safety, Management, Life-Cycle Sustainability and Innovations, 2021
C.M.P. ‘t Hart, D.J. Peters, O. Morales-Nápoles, S.N. Jonkman
Ships have been used over the ages to transport people and goods, inland but also across seas and oceans. The external loads on the structure are related to weather and wave loads. Internally ships are loaded by self weight and cargo loads. The initial buoyancy is passive, the weight of the ship together with all vertical loads equalize the weight of the displaced water (Archimedes force). If the ship is loaded or unloaded, the buoyancy force will become higher or lower (responsive buoyancy). Ships can be equipped with ballast tanks to assure equilibrium and for stabilizing matters. By actively adjusting the contents of the ballast tanks, the buoyancy is re-actively changed. The risk acceptance criteria are set by decision makers. The Marine Safety Committee of the International Maritime Organization has published a Formal Safety Assessment (FSA) in (IMO 2000). In this assessment, the risk on ships in maritime circumstance can be objectified into two main parts;the risk of accidents with fatalitiescost benefit optimization
A methodology for the holistic, simulation driven ship design optimization under uncertainty
Published in Pentti Kujala, Liangliang Lu, Marine Design XIII, 2018
L. Nikolopoulos, E. Boulougouris
For centuries the backbone of global trade and prosperity has been international shipping, with the vast majority of transportation of raw material as well as manufactured goods being conducted through seaborne trade. While the 20th century saw the expansion of shipping coincident with the industrial revolution, the first decade of the 21st posed a series of challenges for commercial shipping. The economic recession combined with a fall in freight rates (due to tonnage overcapacity as well as a global economic slowdown in terms of growth per capita) has threatened the financial sustainability of numerous companies. At the meantime, following the Kyoto protocol and the societal pressure for greener shipping gave birth to a number of international environmental regulations legislated by the UN International Maritime Organization (IMO) and classification societies that set the scheme for future as well as existing ship designs. Among others, future vessels’ carbon emissions are controlled both by technical and operational measurements while the must also incorporate ballast treatment facilities to mitigate the risk reduced biodiversity (especially in sensitive ecosystems such as reefs) due to the involuntary carriage of evasive species inside water ballast tanks.
The Application of MARPOL and Prevention of Pollution to the Marine Environment
Published in David House, Seamanship Techniques, 2019
The IMO has introduced new legislation for member countries since 2002. A recent development has been the ‘micro kill’ separator that can remove sediment from water during ballasting. It addresses the problem of not introducing non-indigenous species into ballast water by ensuring that micro-organisms are not allowed to enter ballast tanks. The system also treats ballast in transit by ultraviolet (UV) light, which destroys or renders inactive, various biological organisms prior to de-ballasting. The system has already been installed on many ships, thought to be the first examples of water ballast treatment systems placed aboard operational vessels.
Ballast water high-efficiency allocation optimisation modelling with dynamic programming for revolving floating cranes
Published in Ships and Offshore Structures, 2018
Zhi Jie Liu, Jian Yu Jiang, Cheng Xin Lin, De Ping Sun
According to the pipe layout mode of the ballast system, the ballasting pump system can be divided into branch pipe type, annular total pipe type, total pipe type, and tube tunnel type. The tube tunnel type ballast system is generally used as shown in Figure 1. Its basic working principle is as follows. When ballast tanks need to be filled, the ballast pumps inhale sea water from the sea or other tanks by main pipes, and transfer them into the ballast tanks by the branch pipes. De-ballasting can be achieved by discharging ballast water into the sea using the ballast pumps or the stripping ejectors. In this paper, the tube tunnel type ballast system is studied.
Simplified fatigue analysis of structural details of an ageing LPG carrier
Published in Journal of Marine Engineering & Technology, 2018
The major oil and gas companies have a maximum age on gas-tankers to be 20–25 years old, regardless of the actual condition of the ship. Most of the oil and gas companies require the ships to be in better condition than minimum class requirement, and require ships older than 15 years to have a Condition Assessment Programme – CAP rating of 1 or 2, where CAP 1 is very good condition, CAP 3 is class limit and CAP 4 is below class limit (IACS 2012). Concerning functional ageing, the sea water ballast tanks are a weak link. The ballast tanks have a very corrosive environment with sea water when filled and a humid salty environment when empty (Ask 2015).
Numerical analysis of the correlation between the pitting severity and surface roughness of corroded specimens
Published in Ships and Offshore Structures, 2022
Firman A. Nugroho, Wadhah Garhuom, Gyde Andresen-Paulsen, Sören Ehlers
The steel samples come from a bulk carrier built in 1974 and rebuilt into pipelayer Lorelay in 1986. The port history of the ship can be seen at http://www.shipspotting.com/gallery/photo.php?lid=2095945. The steel was taken from the transverse floor plates of the ballast water tank during repair in Holland in 2004 (Neumann 2018). Furthermore, the ballast tank cycling frequency and duration are recorded in the ballast water record book (Germanischer Lloyd Sec.2, 2013). This book entry is maintained onboard the ship for a minimum two-year period after the last entry has been made and should be available for inspection at all reasonable times. The inspection relates to the corrosion protection (coating and sacrificial anodes or impressed current) and maintenance repair for the ballast tank (IACS 2015). Accordingly, the coating system and its maintenance include years of ballasting and de-ballasting processes, i.e. accelerating the corrosion rate due to repeated wet – dry exposure to seawater. During dry exposure during de-ballasting, or emptying, the ballast tank becomes prone to corrosion due to the saline environment, ambient oxygen concentration, relative humidity, and operational temperature. The operational temperature range varies according to the shifting day – night temperatures, which produce condensation due to dew accumulation on the surface of the corroded specimen and its corrosion product, Fe(OH)2. During the de-ballasting process especially – undertaken along the bulk carrier’s trading route – the temperature and NaCl concentration become variable and affect corrosion in the ballast tank (Gardiner and Melchers 2003). Moreover, Paik et al. (2004) found that the seawater temperature significantly affects corrosion wastage. The heated fuel oil tank near the ballast tank may accelerate the corrosion process, so the coating material for ballast tank selection should consider the glass transition temperature, i.e. 50°C – 60°C, where the epoxy coating materials become plastic, and thus prone to local delamination. This delamination is aggravated with dew adsorption during condensation on the surface, reducing the coating adhesive’s strength and leading to corrosion attacks at the surface interface (Lee and Kim 2005).