| Heavy fractions, such as fuel oil become very | | | | boilers along the length of the vessel's deck. |
| thick and sluggish when cold, and in order that | | | | Generally the catwalk or flying bridge is used for |
| such oils can be loaded and discharged without | | | | this purpose. |
| delay it is necessary to keep them heated. Today | | | | The main cargo heating steam and exhaust pipes |
| the oil trade is so vast and wide spread that the | | | | being secured to either the vertical or horizontal |
| average oil tanker may be trading in the tropics | | | | girder work immediately below the foot treads. |
| one voyage and the Artic conditions in the next. | | | | At intervals, manifold is arranged from which the |
| It is therefore necessary that cargo heating | | | | steam for he individual cargo tanks is drawn. Each |
| systems be designed to cope with extreme | | | | tank has its own steam and exhaust valves, |
| conditions. | | | | which enables the steam to be shut off or |
| Due to the fact that a loaded tanker has | | | | reduced on any of the tanks at will. Generally the |
| comparatively little freeboard, the temperature of | | | | main steam lines are well lagged, but it is obviously |
| the seawater through which the vessel is passing | | | | impractical to lag the individual lines leading from |
| is of major significance. Cold water washing | | | | the manifold to the cargo tanks. |
| around the ship's side, bottom and across the | | | | The heating arrangements in the actual cargo |
| decks rapidly reduces the temperature of the | | | | tanks consist of a system of coils, which are |
| cargo and makes the task of heating it much | | | | spread over the bottom of the tank at a distance |
| harder. Warm seawater, however, has the | | | | of six to eighteen inches from the bottom plating. |
| reverse effect and can be very useful in helping | | | | In wing tanks it is usual practice to extend the coil |
| to maintain the temperature of the cargo with a | | | | system as far as the turn on the bilge but not up |
| minimum amount of steam. Steam is used to | | | | the ship's side. |
| heat the oil inside ship's tank. It is piped from the | | | | |