Gas tanker ships are specialised vessels designed to carry gaseous substances.
However, contrary to the name, the contents of a gas tanker ship are carried in liquified form.
LNG gas is mainly tapped from underground reserves, oil fields and sometimes below seabeds.
So, before transportation by sea, it needs to be liquified, and this is done through various means such as cascade process or refrigerant process.
They comprise the majority of the gas tanker ship fleet. Over 800 vessels are presently registered as LPG carriers or Liquified Petroleum Gas.
These are mainly propane, butane, butadiene, propylene, and anhydrous ammonia.
The cargo-carrying capacity of gas tanker ships in terms of volume ranges from 500 to as much as 100000 cubic meters depending on the vessel.
Modern LNG carriers can be as large as up to 150000 cubic metres.