Get To Know The Fit Out Requirements For An Oil Tanker!
Generally, oil tankers are said to have about eight to twelve tanks. These tanks are each divided into two to three partitions using a dividing wall. They are numbered and the one at the front is tank number one. The compartments are each referred to using their tank number. In between bulkheads there’s a small space known as cofferdam. This space is left as a security measure against fire, heat or collision.
Tankers have cofferdams at the front and behind the load tanks. For some, the cofferdams are between every two tanks. The pumps connected to the cargo lines are housed in one room known as the pump-room. For the larger tankers the pump-rooms are two. These rooms span the total scope of the whole ship.
The hull design is one of the major components in the architecture of the oil tanker. The hull is the outer structure of the oil tanker fit outs. A tanker is described as ‘single-hulled’ if it has one outer shell between the ship and the waters. Currently, most oil tankers are said to be ‘double-hulled’. There’s even a small space in between the storage tanks and the hull.
The double-hulled oil tankers fit outs have various merits that outweigh those of the single-hulled oil tankers. During emergency situations, it is easy to stabilize the double-hull. There’s less corrosion which is as a result of reduction of the saltwater ballasting. It can easily protect itself from various environmental conditions. The speed at which cargo is discharged is faster and easier. The washing of the tank is more efficient and it is better protected from the impact of any collision or grounding.
As much as it has its merit, the double-hulled ship also has some setbacks. To build one is quite costly and the operating expenses as well might be too high. The ventilation system is quite difficult to deal with. Moreover, ballast tanks will need consistent maintenance and close monitoring. It requires to be fitted with a vapour detection system otherwise the risk of an explosion is quite high. It is not easy cleaning a ballast tank for a double-hulled tanker.
• Hybrid designs
There are designs that are as a result of combining the single and double hull style. Some of these hybrid designs are the ‘double-sided’ and the ‘double-bottom’. The single-hulled ships will phase out in a few years to come.
Inert gas system
This is probably the most important part of an oil tanker’s design. Fuel oil is tough to flare up. However, hydrocarbon vapours are quite volatile especially when mixed with air at a particular concentration. The system’s purpose is to make room for atmosphere within the tanks where the hydrocarbon vapours will not ignite.
Inert gases allow an increase in lowest concentration where the vapours can ignite. Consequently, it brings down the highest concentration where vapour can burn. When the concentration of the oxygen is about 11% the lower and higher concentration come together and make the flammability disappear.
The tank is occupied by inert gas as the tank is being pumped out. It remains in this state (safe state) until the next loading of cargo.
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