Friday, 27 January 2012

Stack scare

The 100-metre high sulphuric acid C-plant stack sways in the wind as the City Fire Department stands by in case it topples

More than 1 000 people were evacuated from site at Foskor on Wednesday morning after fears that the 100-metre high sulphuric acid stack might topple. This after staff reported at around 9am that the stack at C-plant was swaying abnormally in the strong wind. As a precautionary measure, staff and contractors - other than about 50 critical personnel - were evacuated. The B- and C-plants were closed and all gases purged from the system ‘just in case’. The John Ross Parkway was closed to traffic between East Central Arterial and the Harbour Arterial, again in what was deemed a ‘precaution’.

Cause of the excess movement of the stack, which disperses sulphur dioxide to air, was linked to operational failure of a five-ton counterbalance weight located in the peak of the stack. Engineers scaled the stack and adjustments were made to stabilise the counterweight. ‘Because of the height of the stack and the potential danger, we regarded this as a ‘near miss’ and took an appropriate ultra-cautious approach,’ said Vice President of Foskor’s the Acid Division, Nathi Nkomzwayo. ‘We will continue to have surveyors monitoring the situation over the next few weeks.’ Roads were re-opened in the afternoon and the plants were again started.