The comprehensive repair programme to the outer caisson at the 90-year-old Prince Edward Graving Dock in the Port of Durban has now been completed, and the dry dock is back in commission.
The 35-metre-long, 900-tonne outer caisson was refurbished at a cost of R30-million – the third phase of the repairs to the structure.
But, while the outer caisson was handed over to Transnet National Ports Authority (TNPA) last December, the commissioning period was longer than planned.
“Although the contractors made up for time lost due to an overrun of private repairs on the Africa Mercy ship in August, which delayed the start of the caisson repair project, further delays were experienced towards the end of the project,” said Durban port manager, Moshe Motlohi.
First of all, heavy rains in late November and early December delayed the application of the corrosion protection – a procedure which is sensitive to weather conditions (wind, rain and humidity).
After the completion of the corrosion protection, the dry dock was flooded to test the caisson and determine how much ballast was needed to keep it in position. It was then docked at the end of the dry dock so concrete could be pumped into the structure when the suppliers reopened after the festive season shutdown.
