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Journal of Ocean and Ship Technology
Volume 1 Number 2

ISSN: 0975-301X
Publication Year: December 2010
Pages: 49-96
Weight: 80

Distributions of Residual Strain Components in Welded Stiffened Ship Hull Plates
S Y Kenno, S Das, M Hamdoon, J B Kennedy, R Rogge and M Gharghouri

Ship failures are often caused due to several factors, and one of the prime factors is the presence of high residual stresses resulting from the welding of stiffeners on the parent plate. A thorough experimental study using the neutron diffraction method was undertaken to determine the residual strain distributions associated with the stiffened plates typically used in ship hulls. The specimens were built of 350WT grade 9.5 mm thick steel plate stiffened by welding 127x76x9.5 angle steel stiffeners of 300W grade. This paper provides a detailed discussion on the specimens, test procedure, and the results obtained. Emphasis has been given on the resulting strain distributions when there is a stop and restart during the welding process or when a stiffener is terminated before the plate is terminated. This study shows that for these cases, the change in strain may not be a matter of concern for the ship building industry.

Laser Cladding - A Coating Process for Marine Applications
Sanjeet Kanungo

This paper highlights on relative advantages seen on laser as a tool for surface engineering applications vis-à-vis other conventional methods available such as APS and HVOF techniques. The research work was carried out on mild steel plates where three different cermets were used as surface coating materials coated both by Laser cladding and Atmospheric Plasma Spray Process. The results have been summarized below to extent possible.

Optimum Conceptual Design of an Ultra-low Motion Semi-submersible Floating Oil
and Gas Production System

R Sharma, Tae-wan Kim, O P Sha

Abstract: Economic and efficient energy resources are keys to a nation’s development. Because of their low cost and advancement in drilling and exploration technologies oil and gas based energy systems are most widely used in practice throughout the world. The inexpensive oil and gas based energy systems are used for everything from transportation of goods and people to the harvesting of crops for food to being able see at night. As the energy demand continues to rise, this is pushing further the demands for inexpensive energy solutions. Since, available reservoirs of energy rich fossil fuels at shallow and moderately deep waters have been exploited already, the fossil fuel exploration and production is being forced to move into extremely deep waters. At deep water the expenses associated with fixed production platforms are no longer feasible, and that makes a floating production platform design a far more economical choice. This paper presents a critical parameter driven optimum conceptual design of an ultra-low motion semi-submersible floating oil and gas production system. The design is carried to satisfy the given parameter of weights and dimensions of the platform topsides required for production and drilling, water depth location, and low motion requirements. The proposed design process is highly iterative process of altering the key dimensions of a ‘-column ring’ pontoon, and it meets applicable regulations and requests of the order placing agency while minimizing costs and satisfying the chosen parameters. The chosen parameters are classified into groups depending upon the scientific and technological requirements, and they are: GAaOHD-general arrangement and overall hull design, WaCL-wind and current loading, LaGL-local and global loading, WBS- weight/buoyancy/stability, HMaL–hydrodynamic motion and loading, SaSD- strength and structural design, M–mooring, and EaC–economics and cost. Overall, this paper introduces a novel design process for an ultra-low motion semi-submersible that covers the complete life cycle of the structure. Finally, we discuss one design example motivated by real world applications to show the effectiveness, usability and efficiency of our proposed model.
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