Hydrogen Sulphide is a very toxic, corrosive and flammable gas. It has a very low odour threshold and a distinctive odour of rotten eggs. H2S is colourless, is heavier than air, has a relative vapour density of 1.189, and is soluble in water. ISGOTT (International Safety Guide for Oil Tankers and Terminals, 5th edt.,ICS, OCIMF, IAPH), section 2.3.6

Danger of H2S gas is well known and recognized within industry. Exposure to 700ppm in air rapidly induces unconsciousness (few minutes) and death, when more than 700ppm – immediately fatal (ISGOTT, para 2.3.6.4).

1. High Sulphur Fuel Oil cargo handling

1.1 SAFETY REQUIREMENTS

ISGOTT, at sections 2.3.6.1 - 7 describes exposure limits, typical effects of exposure to H2S and enumerate safety procedures for handling cargoes and bunkers with H2S. In section 2.3.6.5 underlined additional measures applicable in cases of Very High Concentration of H2S (100ppm in the vapour space is considered to be a reasonable threshold). Among other things it requests:

i. Vapour monitoring on deck

ii. Bridge, CCR and accommodation atmosphere monitoring

iii. Use of personal H2S gas monitoring equipment

iv. Risk assessment

v. Use of EEBD and SCBA if and when necessary

vi. Specific safety procedures and instructions to be available to ship’s crew