Underwater piles corrosion

1. CONTROL OF CORROSIONON UNDERWATER PILES
NADEEM AKHTAR
17CEB207

2. • Structures that are used for the transfer of loads from the superstructure
to the sub surface strata are known as Foundation. And Piles are a type of
foundation i.e. Deep Foundation. For a hydraulic structure such as
bridges, dams, etc. the piles are driven into the ground and under the
water strata.
• Piles normally used in underwater structures are subjected to corrosion.
Corrosion reduces the structures stability and longevity. There is
absolutely no method for elimination of corrosion; but corrosion
protection measures can be employed for controlling the effects of
corrosion.
INTRODUCTION
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3. On steel piling in sea water, the more
chemically active surface areas (anodes)
are metallically coupled through the
piling itself to the less chemically active
surface areas (cathodes) resulting in a
flow of electricity and corrosion of the
anodic areas.
The metals also suffer localized
attack and pitting occurs. Fig.1. Mechanism of localized corrosion developing
on metal in a solution containing oxygen
CORROSION MECHANISM OF STEEL IN SEA WATER
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4. Fig. 2. Marine pile revealing several
distinct areas of attack.
ZONES
SPLASH
ZONE
SUBMERGED
ZONE
TIDAL
ZONE
• Atmospheric Zone
• Splash Zone
• Tidal Zone
• Submerged Zone
ZONES OF CORROSION OF STEEL PILES
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5. • Before deciding on the methods for control of corrosion to be applied,
conceptual and feasibility studies have been carried out. Typically, corrosion
management can be divided into three major phases.
Phase 1
Phase 2
Phase 3
CORROSION MANAGEMENT
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6. PHASE
1
Phase 1 of the program is the programmatic
assessment or planning stage of the project
(Cause & degree of damage, availability of
expertise, remaining service life)
PHASE
2
Phase 2 of the program involves
physical assessment and actual
remediation.
PHASE
3
Phase 3 of the program mainly deals
with future monitoring of repaired
structure.
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7. CORROSION PROTECTION METHODS
PROTECTIVE COATING
CATHODIC PROTECTION
FIBRE REINFORCED
POLYMER COMPOSITE
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8. In order to protect metals from corrosion,
the contact between the metal and the
corrosive environment is to be cut off. This
is done by coating the surface of metals
with a continuous non-porous material inert
to the corrosive atmosphere.
Surface coatings are broadly classified into
three:
a) Metallic coatings
b) Inorganic Coatings
c) Organic Coatings
1. PROTECTIVE COATING
Fig. 3. External pile paint coating
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9. • Cathodic protection (CP) is a technique used to control the corrosion of a
metal surface by making it the cathode of an electrochemical cell.
• A simple method of protection connects the metal to be protected to a more
easily corroded "sacrificial metal" to act as the anode.
• The implementation is simple, all you need is an anode, a power supply and
engineering talent.
2. CATHODIC PROTECTION
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10. Fig. 4. Arrangement of cathodic protection Fig. 5. Pile mounted Anode
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11. • Fibre reinforced polymers (FRP) are mostly used for the repair and rehabilitation
of concrete structural elements.
• The composites are very light in weight, are resistant to chemicals, have high
strength and in fabric form have high degree of flexibility.
• The corroded part of the structure element is carefully removed and the FRP
composite induced concrete is applied. The FRP provides the lost tensile capacity
and it also provides the steel with lateral support.
• When the FRP is applied with concrete, the spreading of corrosion to other piles
is protected and it also ensures protection from UV radiations.
3. FRP COMPOSITES
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13. CONCLUSION
• As there is no absolute way for elimination of all corrosion from under water
piles, there are some effective methods or ways to control them.
• Cathodic protection is found to be most simple to understand and use and
are largely used in marine conditions.
• The Fibre Reinforced Polymer composites have many advantages in
comparison to conventional methods - they are lightweight, are chemical
resistant and possess high strength and have high degree of flexibility.
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14. THANK YOU