User:Noahsandvold/sandbox

Consequences of spillage

There is a constant looming inevitability of an accident that may occur. The shipping industry and there is no perfect way to ensure that there will be no accident. In the past there have been major tragedies that have occurred and have instilled a sense of fear that a tanker will crash again. The exxon Valdez crashed off the coast of where about 10.8 million US gallons of oil were spilled into the Prince Williams Sound gained notoriety and scared people then there was the one that shook america. The BP oil spill where 210 million gallons of oil spilled from BP’s Deepwater Horizon oil. These terrify people and with this the consequences bringing another tanker into existence transporting LNG needs to be understood.

LNG has not gained this notoriety as oil has. In fact the LNG sector is know to have a very good safety rector in terms of cargo loss. There have been close to 80,000 loaded port transits with no loss of containment failure. (Pitblado, 2004) In the 1970’s two ships ran aground but due to the strength and integrity of the tanks there was no spilling. The goal is to have no containment spills taking operational safety and operation very seriously with training and regulations at an all time high.

With the inevitably of a collision happening and the negligence that has to be taken into account with the possibility of a ship running aground simulations must be run to understand what would happen if these events were to happen.

Paik (2001) gives an interesting analysis that shows spherical carriers can withstand a 90 degree side-on collision with another similar LNG carrier at 6.6kts (50% of normal port speed) with no loss of LNG cargo integrity. This drops to only 1.7kts for a fully loaded 300,000 dwt oil tanker collision into an LNG carrier. Although 90o collisions are credible in open water such large oil tankers only enter a few US ports and thus collision is not generally credible. However it would need to be considered in an analysis of those ports when considering port geometry. (Pitblado, 2004)

With these simulations being run the conclusion was that as long as the containment system were not struck then the possibility of a spill is very unlikely. But on the other hand the containment system is incredibly strong but once the containment system is deformed leakage will occur. Basically, the containment system can not be deformed and if it is it will leak. Because of the design of the tanks and the separation of tanks this ensures the likelihood that not every tank and the entire load of the ship would be lost. If the integrity of one of the tanks were to fail this does not mean that all of the tanks are going to fail. Every tank is isolated and this ensures safety and integrity of the ship and its systems.

HAZID Performed a risk assessment calculation of the likelihood of a LNG spill and from their calculations they have taken into account all of the precautions, training, regulations and the changing technology from history to presto to future they have come to the figure that the likelihood of an accident is much less than 1 and 100,000 visits. (Hazard Identification) team members included marine classification engineers, naval architects, structural specialists, marine officers, risk analysts, and process, mechanical and safety engineers. (Pitblado, 2004) They came to this number by trying to create events in which there would be an accident and they created a few very unlikely events that could possibly happen to come to this figure. Obviously, this isn't a perfect estimate and there is always the possibility that an accident could occur at this very moment but the thing to consider is that it is a fairly safe from of transportation. One thing to take into account is that this figure was generated off of accidents, for example collisions, groundings and operational error. With the safeguard put into place this is why the figure is so low. The figure does not take into account terrorist activity like piracy and terrorism threats.

Even with this for there to be an accident the breach go through four or five very strong and reinforced barriers to even get the the containment tank and the tank can hand a bit of deformation before the integrity of the tank fails. Looking at the terrorist attack and weapons that are used. Because of the strength of the tank the likelihood that any of these weapons that are commonly used by terrorists would not be enough to breach the integrity of the tanks. But if it were to breach the tank in some way the gaseous natural gas would ignite immediately and would burn and be a very serious fire. But, without anly lasting effects that would harm the public. The strength of the tanks and the ship are very strong ensuring the integrity of its cargo and the people the are on and influenced by the ship.

With the risk the potential for disaster has a limit but because of the nature of the cargo there is still other things that need to be taken into account. Because “Liquefied Natural Gas (LNG) represents an important potential energy source for the US over the next 30 years and will contribute to energy security and diversity.” (Pablo, 2004) there needs to be more precaution the need to be put into place and the nature of the fuel needs to be looked at. The state that allows natural gas to be in its liquefied states calls for it to be resting at -234 degrees fahrenheit. At this state it can be extremely volatile because of the density of the fuel. At it liquified state the volume of natural gas shrinks 600 times and this increased the energy per area dramatically. With the ignition temperature of this fuel is 1004 degrees fahrenheit and its boiling point being -260 at atmospheric pressure that creates an incredibly violent and destructive explosion leaving the surrounding area in ruins. With this to take into account the precautions that need to be put in place and the scenarios the need to be looked at have to be put in with the utmost scrutiny. There is always the possibility of something going there needs to be as much done to prevent that from occurring.

https://en.wikipedia.org/wiki/LNG_carrier