CASE STUDY

Type of Structure Ports and Harbours

Client Marina Developments Ltd

Treatment Types Galvanic Cathodic Protection, Coatings

Project Value £1.2m estimated

Project Duraction May 2012 on-going in four-phases

Ocean Village Marina is situated in the shelter of Southampton Water, and provides berths for up to 375 privately owned vessels and is the site of Royal Southampton Yacht Club [RSYC]. The marina is surrounded by shops, restaurants, cinemas and bars, and offers outstanding recreational facilities with a new hotel planned for the site in the near future.

The marina is bounded by a stone quay wall to the north and steel sheet piling to the remaining border. The RSYC is elevated above the marina on two sheet piled caissons. Pontoons providing access to the marina moorings are anchored in positioned by tubular mooring piles driven into the basin floor.

 

In 2005 a survey identified perforation caused by accelerated low water corrosion [ALWC] to around 50% of the tubular mooring piles and evidence of ALWC to around 25% of remaining tubular piles. The perforated piles were subsequently replaced with new pre-coated tubular piles. A further investigation carried out in 2007 with an increased scope identified further corrosion to the sheet piled walls and caissons of the RSYC. Above mean tide level this was generally of aesthetic concern however further ALWC was identified at low water level and in a number of locations had resulted in perforation of the sheet piling.

ALWC is a particularly aggressive form of microbial corrosion which effects steel in seawater near low water level and presents as bright orange deposits upon a black/grey sludge which when removed reveals a bright steel finish. Corrosion rates of ALWC can be up to 10x greater than typical corrosion rates with the potential for up to 1mm of section loss per side per year in severe cases.

 

Corrosion Engineering Solutions Ltd, working with a main contractor, was tasked with developing a scheme to arrest the propagation of corrosion to the sheet piled walls and the sheet piled caissons of the RSYC.

CES developed a scheme which included the installation of a galvanic cathodic protection system utilising sacrificial aluminium anodes to arrest corrosion between the pile toe and mean tide level and the application of a two part epoxy coating system between mean tide and quay level with an expected design life of 20-years to first maintenance.

The two treatment approach was necessary due to the different environmental situations of the submerged pile sections below mean tide and the typically atmospherically exposed steel above mean tide.

 

The sacrificial anodes are designed to be installed within the in-pans of the sheet piles where they will be unobtrusively positioned to prevent damage to passing vessels and will be attached using bespoke brackets welded to the in-pan web.

The coating system requires the removal of all marine growth and corrosion products above mean tide via manual means and grit blasting to provide a suitable finish for the application of the new coating.

The finished work will offer a robust corrosion control solution with an aesthetically pleasing finish appropriate for the marina and its surrounding developments.

 

 

For further information please contact:
Corrosion Engineering Solutions Ltd
Unit S1, 64-66 Akeman Street,
Tring, Hertfordshire, HP23 6AF