Construction methods · Driven piles

Corrosion protection of steel piles

Steel in the sea loses 0.1-0.3 mm a year in the splash and tidal zones, more with chlorides and pollution. Piles are protected by extra thickness, coatings, concrete jackets and cathodic protection so the bridge outlives its design life.

How bridges get built · Driven piles · Corrosion protection of steel piles

Also called: sacrificial thickness, cathodic protection, pile coatings, concrete jackets

How it is done

Add a sacrificial thickness (2-4 mm over 100 years in temperate seas, more in the Gulf) to the pipe wall in the exposed zones.
Coat the splash and tidal zone with epoxy or polyethylene wraps before driving; protect the coating during driving with a shroud.
Install sacrificial anodes or impressed-current cathodic protection for the submerged zone; concrete jackets or petrolatum wraps at the water line.

Where it fits

All steel piles in seawater, brackish estuaries and contaminated ground.

Where it does not

Trusting a coating damaged in driving; the splash zone is where piles fail first.

Plant, pace and money

PlantCoating facility, anode installation by divers, CP monitoring.

ProductivityAdds days per pier.

Cost5-15 % of the pile cost; the game's marine-grade durability option covers this.

Risks and controls

What goes wrong

Coating damage during driving, anode depletion, stray currents.

Quality assurance

Coating thickness and holiday tests, CP potential surveys after installation.

Examples

Gulf sea bridges specify cathodic protection on all piles; Japanese ports wrap the tidal zone.