What are Precautionary measures to minimize accumulation of static charges?

Loading rate

Initially to start with low rate so as to reduce turbulence and generation of static in the pipeline and tank itself. Once the cargo is above the levels of longitudinal or 1 mtr the gradually increase the rate, but any way 1 mtr quantity to be taken in all the tanks concerned for that parcel of cargo.

Water

Should not be loaded overall into a tank which has contained volatile petroleum distillates until the tank has been stripped.

Cargo hoses

To be thoroughly bonded so that there is adequate and continuos earthing of all metal parts through the tanker’s manifold and the tanker to sea.

Conductors introduced

During the loading of any cargo which may give rise to flammable vapours no earth conducting probe and no unearthed conductor capable of gathering charge from the liquid should be allowed inside the tank during loading. An example of this would be a metal weight on the end of a metal tape or a tin can or metal sampling can suspended from an insulated rope and floating on the surface of incoming cargo i.e. ullaging & sampling. The possibility of ignition by static tanks and compartment’s which have been discharged, but are not gas free arises when conductor is suspended in a tank and steam is also present. hence no tank washing machine or other conductor whether earthed or unearthed, should be permitted in a tank which has steam injected unless of the direct fixed type.

Loading overall

Petroleum at a temperature above its flash point should not be loaded or transferred overall. Non-volatile may be loaded only if the tanks are gas free and provided no contamination with volatile petroleum can occur.

Line clearance with air

Compressed air or inert gas should not be used to clear pipelines back to tank after loading of a distillate oil which may produce a flammable vapour unless adequate precautions are taken to stop the air or inert gas entering the tank and causing the water in the bottom to become turbulent.

Discharging cargo

To minimise the accumulation of static electricity in shore tanks at the beginning of discharging of distillate oils, which may produce a flammable vapour, pumping speeds should be kept low until shore personnel advise that pumping rates can be increased.

RAVI PRAKASH