Alert 23-5 – H2S released during rig reactivation activities
WHAT HAPPENED:
While a rig was quayside undergoing reactivation activities, deadly hydrogen sulfide (H2S) concentrations were
encountered within the bilge water tank in the machinery space. After the top hatch of the tank was removed,
large concentrations of H2S escaped out into the immediate surrounding atmosphere posing high risk to
personnel.
100 PPM of H2S is considered Immediately Dangerous to Life and Health (IDLH). H2S concentrations over 1,000
PPM can cause immediate collapse with loss of breathing, even after inhalation of a single breath. This corrosive
gas can pit and corrode steel, which can also affect the integrity of cargo containment systems and hull structures.
H2S is a highly flammable/explosive gas with a concentration in the air between 4.3% (Lower Explosive Limit)
and 45% (Upper Explosive Limit)….