The Merchant Shipping (Fire Protection: Small Ships) Regulations 1998

Cargo tank purging or gas freeing Requirements for ships constructed after 1 September 1984

25.—(1) In every tanker of Class VII(T) of under 500 tons arrangements for purging and/or gas freeing shall be such as to minimize the hazards due to the dispersal of flammable vapours in the atmosphere and to flammable mixtures in a cargo tank.

(2) The operation shall be such that the flammable vapour is discharged—

(a) through the vent outlets as specified in regulation 23 of the Merchant Shipping (Cargo Ship Construction) Regulations 1997(1); or

(b) if the ship is one constructed on or after 1st February 1992, through outlets at least 2 metres above the cargo tank deck with a vertical efflux velocity of at least 30 metres per second during the gas-freeing operation; or

(c) through outlets at least 2 metres above the cargo tank deck with a vertical efflux velocity of at least 20 metres per second and through devices (other than flame screens) complying with Schedule 3 of Merchant Shipping Notice MSN 1671 so as to prevent the passage of flame into the cargo tanks;

until the flammable vapour concentration in the outlet has been reduced to 30 per cent of the lower flammable limit. Thereafter, gas-freeing may be continued at the cargo tank deck level.

(1)

S.I. 1997/1509.