An essential part of Oil Tanker Vessels, Inert gas system acts as a fire safety system on board ships. Every oil tanker 20,000 DWT and above or a tanker less than 20,000 DWT but fitted with crude oil washing system must have an IG system. Know more about the requirements of having an Inert Gas Plant Blower on board a merchant tanker ship.
While ensuring protection against explosion using the I.G System, several individual systems combine to make an efficient inert gas plant whose output must be 4-8 % of oxygen and majority of nitrogen.
One of the major components of an IG plant is its blower which acts as supplier of inert gas to cargo holds of the ship. Without the blower the whole system will fail to perform. An efficient IG blower is thus required to supply inert gas as per the requirements of a cargo tanker.
Regulations and Requirements for I.G Blower
Blowers in an I.G plant must be approved by the administration and must comply with the following:
- Minimum 2 number of blower to be fitted in I.G system.
- The capacity of each blower must be 1.25 times the overall capacity of the cargo discharge system fitted on board. This is to ensure that Inert Gas is always present in the cargo hold.
- Only 1 blower may be permitted by the administration if it fulfills the requirement stated in above point i.e. capacity must be 1.25 time cargo pumps and required spares are always available.
- A shut off arrangement must be provided in the suction and discharge connection side of the blowers.
- Generally the blowers are used for gas freeing hence an n air inlet with blanking arrangement must be provided. At normal operation, blanking arrangement is to be secured.
- Cargo tanks are pressure tested at 2500 mm water gauge and 700mm water gauge on the vacuum side. The blower pressure must not exceed the test pressure else the tank will get damage.
- Minimum pressure to be maintained by blower is 200 mm water gauge in cargo tank.
- There must be high temperature alarm (@ around 65 deg c) and a high temperature trip (@ around 75 deg c) to safeguard the blower.
- The driving media for blower can be either steam or electrical power.
- The blowers must be located at aft of the cargo tanks and cargo pump room of the ship.