The incident occurred in connection with work on an H2S reactor in the oily water treatment plant. Two operators, an apprentice and two work-experience pupils climbed to the top of the 14-metre-high H2S reactor to check its condition.

Toxic H2S flowed out through a venting valve on the top, and the people who had climbed up were exposed to the gas to varying degrees. Four of them eventually managed to get down by themselves, while the fifth needed assistance.

Emergency measures were implemented and those who participated in the response – risking their own life and health at times – helped to reduce the consequences of the incident.  

Actual consequences

Five people were hospitalised, with four discharged after a day and one after three days. No material damage or environmental harm were registered.

Potential consequences

H2S is a highly toxic gas. The dispersal analysis performed shows that the personnel were exposed to potentially fatal concentrations. Under slightly different circumstances, one or more of the exposed people could therefore have died.

Findings of the investigation

The PSA investigation detected several regulatory breaches, including inadequate management of activities, resources, processes and competence. It has also found deficiencies in the shift roster and shift changeover, as well as inadequacies in the leadership and execution of emergency response assignments.


On the basis of its findings from the investigation, the PSA issued operator company Statoil the following order.

Pursuant to section 69 of the framework regulations on administrative decisions, see sections 4, 5 and 6 of the management regulations on risk reduction, barriers and management of health, safety and the environment respectively, we order Statoil to take the necessary measures to ensure that activities which could expose personnel to harmful concentrations of H2S or other noxious substances at Sture can be conducted in an acceptable manner. See section 5.1.1 of the report. The effect of the measures must be verified.

The deadline for complying with this order is 1 June 2017. The PSA must be notified when the order has been complied with.