Gas carriers can be grouped into five different categories according to the cargo carried and the carriage condition. These are as follows:Fully pressurised shipsSemi-pressurised shipsEthylene shipsFully refrigerated LPG shipsLNG shipsThe first three ship types listed are most suitable for the shipment of smaller-size cargoes of LPG and chemical gases. This is normally accomplished on short-sea and regional routes. Fully refrigerated ships are used extensively for the carriage of large size cargoes of LPG and ammonia on the deep sea routes.1. Fully pressurised shipsFully pressurised ships are the simplest of all gas carriers. They carry their cargoes at ambient temperature.They are fitted with Type ‘C’ tanks (pressure vessels) fabricated in carbon steel having a typical design pressure of about 18 barg. Ships with higher design pressures are in service and a few ships can accept cargoes at pressures of up to 20 barg.No thermal insulation or reliquefaction plant is necessary for these s...
