This document discusses corrosion protection methods for underwater piles. It begins with an introduction to corrosion and the corrosion mechanisms that affect steel piles in seawater. It then describes the different zones of corrosion for steel piles and various corrosion protection methods like protective coatings, cathodic protection, anode delivery systems, and the application of fiber reinforced polymer (FRP) composites. It concludes with standards and codes from organizations like NACE and ASTM that are relevant to corrosion control system design. The key methods discussed are protective coatings, cathodic protection using sacrificial anodes, and wrapping piles with FRP composites for repair and reinforcement.

1. CONTROL 0F CORROSION ON
UNDERWATER PILES
PRESENTED BY:
Lakshay saxena

2. Content
 INTRODUCTION
 CORROSION PROTECTION METHODS
 STANDARDS AND CODES
 CONCLUSION
 REFERENCES

4. INTRODUCTION
 Corrosion is the destruction of metals and alloys by
the chemical reaction with the environment.
 During corrosion the metals are converted to
metallic compounds at the surface and these
compounds wears away as corrosion product.
 On steel piling in seawater, the more chemically
active surface areas (anodes) are metallically
coupled through the piling itself to the less
chemically active surface areas (cathodes) resulting
flow of electricity and corrosion of anodic areas.

6. CORROSION MECHANISM
OF STEEL IN SEA WATER

7. • On steel piling in seawater, the more chemically
active surface areas (anodes) are metallically
coupled through the piling itself to the less
chemically active surface areas (cathodes) resulting
flow of electricity and corrosion of anodic areas.
 Sometimes these active local areas do not shift
position end, therefore, the metal suffers localized
attack and pitting occurs.
 In general smaller the anode area relative to the
cathode area, Pitting is deeper.

8. ZONES OF CORROSION OF
STEEL PILES
• Atmospheric Zone
• Splash Zone
• Tidal Zone
• Submerged Zone

9. Corrosion Caused By The Difference
Of The Dissolved Oxygen
Concentration

10. ATMOSPHERIC ZONE
• Depending upon time of wetness, temperature,
pollutants, Atmospheric Corrosion is responsible
for a large fraction of the total corrosion.
• Corrosion rate is least in this zone(without
protection) < 0.1 mm/year.
• Paints and Coatings are used in protecting this
section.

11. SPLASH ZONE:
• The Splash zone can be characterized by as an aerated
sea water environment where exposed material are
almost continually wet.
• Corrosion rate (without protection) 0.3 mm/year.
TIDAL ZONE:
• This zone is alternately submerged in seawater and
exposed to Splash zone as the tide fluctuates.
• Corrosion rate (without protection) 0.1-0.3 mm/year.

12. SUBMERGED ZONE
• The submerged environment zone usually
characterized by well aerated water combined
with marine bio fouling organism of both the
plant and animal variety.
• Corrosion rate (without protection) 0.1-0.2
mm/year.

13. CORROSION MANAGEMENT
It is divided into three major phases:
• Phase 1 of the program is planning stage of
project.
• For the planning stage ,three main
requirements strategy, budget and schedule
needed to overcome the problem raised from
corrosion of reinforcement

14. PHASE 2
• Phase 2 of the program involves physical
assessment and actual remediation.
• Inspections for severity of corrosion are
conducted in this phase to determine what
strategy or methods are most suitable to be
applied.

15. PHASE 3
• Phase 3 of the program mainly deals with
future monitoring of the repaired structure.
• Systematically identifying and managing the
existing resources can be done by
implementing internal or external
monitoring system using current technology.

16. PROTECTIVE
COATING
CATHODIC
PROTECTION
ANODE
DELIVERY
SYSTEM
Application of
FRP
composites

17. Protective Coating
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
Metallic coatings
Inorganic Coatings
Organic Coatings

18. Protective Coatings
 Inorganic Zinc Sillicates Primers
 Aliphatic Polyurethane Topcoats
 High Build Epoxy Coatings
 Zinc Rich Epoxy Primers
 Non-Skid Deck Coatings

19. • arrest rust creep, or undercutting
of the coatings surrounding the
damaged area
• high degree of resistance to heat
and chemical spills
Inorganic
Zinc
Silicates
Primers

20. • Epoxies are generally more
abrasion and chemical resistant
than primers
• These are poor resistance of ultra
violet from sunlight and most will
chalk and fade rapidly.
High
Build
Epoxy
Coating
s

21. • optimum resistance to UV and high degrees of
flexibility and chemical resistance.
• maintain a very high level of cosmetic gloss and
color retention and can be cleaned very easily
with low pH detergents and fresh water pressure
washing.
Aliphatic
Polyuret
hane
Topcoats

22. • high level of service and are more
tolerant to compromised surface
preparation and ambient weather
conditions
• maintaining damaged areas and
breakdown of the coatings systems
Zinc Rich
Epoxy
Primers

23. • normally incorporate very course
aggregates for an exaggerated
profile.
• They are applied in very high film
builds and normally without a zinc
rich primer.
Non-Skid
Deck
Coatings

24. CATHODIC PROTECTION
 Cathodic protection is an electrochemical
process which halts the corrosion of
metals in a particular environment by
superimposing an electrochemical cell
more powerful than the corrosion cell.
 Sacrifical Anodes are fitted or bonded to
the metal to be protected.
 The implementation is simple, all you
need is an anode, a power supply and
engineering talent.

26. • These are similar to the cathodic
protection method in philosophy.
• These are designed on the design basis
of maximum current distribution for the
lowest possible cost, with the most long-
term reliability.

27. Anode delivery system
 Pile Mounted
Anode
 Retractable Anode

28.  Sled Anode  Suspension Anode

29. Application of FRP composites
 The poor durability of conventional
corrosion repairs has led to increased
interest for its replacement by fiber
reinforced polymers.
 Although dry conditions are favorable but
availability of resins that can cure in
water has made it possible.
 Saturating FRP with resin and installing
is complex but benificial in costly repairs
and rapid deterioration.

30.  Fibre reinforced polymers
have long been used for the
repair and retrofit of concrete
structural elements.
 Lightweight, high strength
and resistance to chemicals.
 Unparallel flexibility, multi-
directional.
 Twofold role: first to restore
lost flexural capacity and
second to provide resistance
to withstand expansive

31. • Figure shows impact
damage that led to both
cross-section and
breakage of the spiral
ties.
• Using FRP there is only
need to re-form the cross-
section and apply bi-
directional layers to
restore lost tensile
capacity.
• Bonding agents may be
required to assure
capillary suction of the

32. Preparatory work
 Pile surfaces were covered with marine growth that had
to be scraped off.
 Additionally, two of the four corners that were not
rounded but chamfered had to be ground using an air-
powered grinder.
 This was a difficult operation particularly for sections
that were below the water line.

33. Mesh flooring around piles

34. STANDARDS AND CODES
There are no Indian standards codes as such for the control of corrosion. The
latest editions of the following organizations’standards, codes, and
guidelines shall be used for the design of corrosion control systems:
• NACE International (formerly The National Association of Corrosion
Engineers)
• RP0169 – Control of External Corrosion on Underground or Submerged
Metallic Piping Systems
• American Society for Testing and Materials (ASTM)
• ASTM D512 – Standard Test Methods for Chloride Ion in Water
• ASTM D516 – Standard Test Method for Sulfate Ion in Water
• ASTM G51 – Standard Test Method for measuring pH of Soil for Use in
Corrosion Testing

35.  Though there is no absolute way to eliminate all
corrosion on underwater piles, there are some
effective measures to control them.
 Cathodic protection is quit simple and protective
coatings are used in vast and expensive
structures.
 The FRP composites have many advantages viz.
lightweight, posses high strength and chemical
resistance and moreover have incomparable
flexibility.
 Of the various ways of wrapping of FRP
composites , transverse wrapping is found to be
the easiest.
 Bi-directional material is the best option.
Scaffolding measures during the application of