Evidence of Accelerated Low Water Corrosion was identified in the sheet piles at East India Dock. ALWC is an aggressive and localised form of low water corrosion which can occur in tidal and brackish water in steel maritime structures. Corrosion rates in regions affected by ALWC can be 1mm per side per year or more, quickly exceeding design allowances. This process will rapidly compromise the affected structure, increasing repair costs and perhaps rendering the structure no longer fit for purpose.
Halcrow, the international consulting engineers, identified localised thinning of the sheet piles and recommended that urgent remedial action was required.
GSS, along with others, were invited to tender and in due course were successful in this bid.
To re-inforce weakened areas on the sheet piles the contract required the fabrication of 10mm metal plates, bent to match the profile of the Frodingham 5 sheet piles, to be welded in place, under water, This was achieved by lowering the plates from a crane to be temporarily affixed, the diver then entered the water in a protective basket to effect the permanent welding fixture.
GSS commissioned the design of the 100 kilo anodes. They were delivered to our yard and welded to fabricated fixing brackets. Prior to for delivery to site the anodes were checked using a potential meter to ensure their suitability for the intended application. These too were lowered by crane to predetermined positions and welded into place, underwater.
GSS (Plant) Ltd, Rhu Marina,
Rhu, Argyll & Bute,
G84 8LH,
SCOTLAND
T: 01436 821277
F: 01436 821288
E: info@gssplant.co.uk