Stopford have featured again in this quarter’s Tank Storage Association newsletter issued today. This went out to 22 companies operating ~300 terminals in the UK and ROI. Stopford’s article focused on the safety aspect of occupied buildings at fuel storage sites. Below is our article or follow this link to the full newsletter.
Stopford Energy & Environment
Occupied Buildings at Fuel Storage Sites
One of the areas of concern for fuel storage terminals is the potential impact of an incident on others. The risk of fatality within the facility itself is relatively easy to assess, and as the number of personnel present is small and the time spent within each area is generally short, the risk is acceptable. There may be areas on the facility and in the immediate area where there are relatively high numbers of personnel and they are present for large amounts of time. These are the offices, maintenance buildings and welfare facilities, and are described as “occupied buildings”.
The acceptable risk level for these personnel is usually lower than that of the “operator” since an office worker would not expect to be exposed to as high a work-related risk as an operator. The operator is required to be in the vicinity, other personnel have no need to be in the facility and should have a “low” risk profile.
The assessment must start by looking at the potential incidents which could have an impact, which might be fire but could also be a Vapour Cloud Explosion (VCE), as seen at the Buncefield site. Computer modelling (e.g. PHAST) of incident scenarios, identified in the Safety case (Hazard Studies, HAZOP, COMAH), can be used to model the heat radiation and explosion overpressure contours. VCE are also not limited to low flash material but can be as a result of mist or vapour generated by heating a flammable above it’s flash point, potentially as a result of an initial fire.
Whenever possible the buildings should be located outside the high-risk area. Where this is not possible, as may be the case for existing facilities, the building may need protection to reduce the risk to an acceptable level, and occupancy may need to be restricted to “key” workers only, requiring non-essential workers to relocated into alternative accommodation.
Buildings within the heat and blast zones must be designed to protect the occupants from the initial incident and allow them to evacuate to a place of safety. The structure of the building should be assessed as to the pressure wave and the likely impact on the structural integrity. If the building is likely to collapse, then fatality is a very real probability. In high risk facilities the building may need to be designed to be “blast” resistant. Means of escape from the side away from the source of fire/explosion will be required.