Crude Oil Carrier Research Articles

ASPECTS OF CORROSION CONTROL IN SHIPS‘ TANKS

ABSTRACTShips' tanks, particularly in crude oil or product carriers, face a wide range of corrosive environments varying from sea water to an assortment of cargoes with varying concentrations and temperatures. The corrosion mechanism is outlined, and the effect of oxygen, temperature, water velocity, salinity, and pH upon the reaction is considered. Galvanic corrosion due to cathodic heating coils can, and does, cause serious pitting in the bottom plates. Coatings and cathodic protection combine to give almost complete protection against corrosion. The effect of various cargoes upon corrosion and coatings is discussed. There are six basic classes of tank coatings which are briefly described and their performance in various cargoes is given.Also dealt with are surface preparation and application since they affect coating performance appreciably. In addition, emphasis is given to worker health and safety during the surface preparation and application procedures.

Computer modelling of electrostatic conditions and hazards in tank washing

The paper describes how a computer program developed at Culham Laboratory for solving Poisson's equation in complex three-dimensional structures can be used for quantitative interpretation of electrostatic fieldmeter observations in practical situations. Computations are presented relating to interpretation of electrostatic conditions during shipboard studies of tank washing operations in the cargo tanks of crude oil carriers. The paper also discusses how the program was used to assess electrostatic ignition hazards by modelling possible discharge situations involving slugs of water and calculating the discharge energies which would be available as a function of geometric and electrostatic conditions.

On the Manoeuverability of Ship having Small Length-beam Ratio

The radical growth in the transportation of crude oil has brought forth the enlargement of crude oil carriers, and the systematic studies on the economic potential have proposed the possibility to change the hull form by reducing length-to-beam ratio (L/B).As a consequence, it has become quite inevitable to investigate the manoeuverability at an early stage in the design of large tankers.Under such circumstances, one of the greatest concerns of the authors is the manoeuverability of a newly designed ship which is characterized by the stocky hull form with such a smaller L/B ratio as 5.0.In order to find out the scale effect upon manoeuverability and to confirm the accurate performances, two large 30 m models, one for a conventional V. L. C. C. now in service and the other for a newly designed U. L. C. C., have been subjected to various tests at sea. Systematic model tests by geosim small models, of course, have been conducted in an experimental tank.The result of these tests reveals that the new ship has rather superior performances to those of the conventional one, mainly due to the larger rudder fitted with the former.In addition, the scale effect on the normal force of rudder has been examined, and also the flow around rudder has been analyzed from the records of rudder force generated by a steering.These data contribute to refine a simulation program which has been developed so far for the prediction of the manoeuverability.A whole aspect of the research is outlined in this paper.