1.
• PRESENTED BY:
ADITYASHRIVASTAVA
HARSHRANJAN
DEEPAKKUMAR

2.
INTRODUCTION
Hull protection system is very much essential
for the hull to protect it fromdifferent type of
natural phenomenon like hull fouling
(marine growth ) ,corrosion,erosion,
cavitation and pitting etc .

3.
CONTENTS
 WHATIS A SHIP’S HULL?
 WHYSHIP’S HULL NEED TOBE PROTECTED?
 HULL FOULING
 ANTIFOULING TECHNIQUES
1.ELECROLYTIC SYSTEM
2.CHEMICAL DOSING
3.ULTRASONIC SYSTEM
4.ELECTRO-CHLORINATION
 CORROSION
 TYPES OF CORROSION
 ANTI CORROSION TECHNIQUES
1.SACRIFICIAL ANODE
2.ICCP SYSTEM

4.
WHAT IS A HULL?
•The Ships Hull Is TheWatertight Body Of A Ship Or A Boat.
•It Protects The Cargo, Machinery, And Accommodation
Spaces Of The Ship FromThe Weather, Flooding, And
Structural Damage.
•Above The Hull Is The Superstructure Or The Deck House
Present.

5.
WHY SHIPS HULL NEED TO BE PROTECTED?
• Preventing Fouling And Corrosion Extends The Vessel's
Life.
• Increases Efficiency.
• Reduces Operational Costs .
• Avoids Marine Accidents And Expensive Repairs.

6.
WHAT IS HULL FOULING?
• A naturalphenomenon towhich all shipsare susceptible but
particularly in circumstanceswhere shipsremain idle/static
in warm/tropicalwaters.
• The startof fouling isvery dependent uponlocal conditions
andfouling intensityvariationsover time.
• The combination of warmandshallowwater isthe most
challenging and willgenerally cause fouling toattach sooner
andgrow faster.

7.
WHY HULL FOULING IS A PROBLEM?
• Foulingcan affect a ship’s hull,rudder,chests and propeller.
• Increasesunder water resistanceto propulsion.
• Blocks main engine coolingintakes.
• Loss ofspeed by up to 10% as a result ofreduced engine
revolutionsand high propellerslip.
• Increase in fuel consumption by up to 40%.
• Dry docking necessary to removefouling,cleaning costs and loss of
time.

8.
HOWTOPREVENT IT ?
1. Anti-Fouling Paint : Anti-foulingpaint is a special coating that is
applied to the hull and propellersof a marinecraft.
• The coating is used to slow down the growthof marine organisms
such as barnacles, slime,algae and mossy weed.
• In addition to anti-fouling, the coating preventscorrosionon metal
hulls and propellers.It also improveswater flow past the hull ofthe
vessel.
• Anti-foulingpaint is also known as bottom paint.

9.
• Typical anti-foulingpaint contains a biocideor a toxinin
the paint, whichis released into the area surrounding the
hullto poison any attached organisms and prevent others
from adhering to the paint.
• THE FOUR BASIC INGRADIENTS OF ANTI
FOULING PAITS ARE :
• BOICIDE
• RESIN
• SOLVENT
• PIGMENT

10.
THE THREEMAIN CATEGORIESOF THE ANTI-FOULINGPAINTS
ARE:
• Soft bottom paint - A moderatelyeffective copper-based coating used in cooler
waters in which growth potential is lower compared tothe warmer climates.It is the
cheapest coating.
• Hard bottom paint - The hard anti-foulingpaint hasmore biocide (cuprous
oxide), makingit more effective but more expensive. It offers a tough surface and
provides good finishes for the bottoms of racing boats.
• Ablativeanti-foulingpaint - Designed towear off the outer surface and still
retain amounts of biocide in the remaininglayers.It is suitable for many
environmentsand has options of either a single season or multipleseasons.

11.
FACTORS TO CONSIDER WHEN CHOOSING
ANTI-FOULING PAINT INCLUDE:
• Whether boat operates in fresh, salty, cold or warm water
• Whether the hullmaterial is steel, wood or fiber glass
• Whether boat willoperate at a fast or slow speed
• Compatibility with the paint already on the hull

12.
What is TBTand Why was it banned?
• Tributyltinor TBT is abiocidewhich cameinto beingin the 1970s’ because of its
brilliantanti fouling propertiesover ships hull as it prevents the growth of algae,
barnaclesandothermarineorganisms.
• However,TBT wasphasedout of use from 1st Jan2008 byIMOdue to following
reasons:
• TBT’s harmfuleffects causes disruption of endocrine system of marineshell fish
whichleadsto the developmentof malesex characteristics in femalesnails.
• It alsoimpairsthe immune system of organisms andmalformationsofthe shell
of shellfish.

13.
THE MAIN TYPES OF PREVENTIVE MEASURES USED
ON SHIPS ARE:
• Electrolyticsystem
• Chemicaldosing
• Ultrasonicsystem
• Electro-chlorination

14.
1. Electrolytic system
• Thisisoneofthemost commonlyusedsystemstofightbiofoulingon
ships.
• Theelectrolyticsystemconsistsofpairsof anodes,mostlycopperand
aluminum(or iron). Theanodesare mountedintheseachestorthe
strainer.
• DC currentispassedthroughthecopperanodes, whichproduce ions
thatare carriedwiththeseawaterinthewholepipingnetwork.These
copperionsintheseawaterpreventmarine organisms fromsettling
downandmultiplyingonthesurfaceofthepipes.

15.
•
• The second anode is used to prevent corrosion of the
metal surface. The iron anodes help in preventing layers
of oxide filmsof the metals from breaking down by the
corrosive agents (sulphur) of seawater. This system also
gives protection to valves, condensers, enginecooling
systems and ancillaryequipment.
• A control panel measures and monitors the output of
each of the anodes.

16.
2. Chemical Dosing
• Chemicaldosing is also a common method whichis used
to prevent marine growth inpiping network.Anti-fouling
chemicalsuch asferrous chlorideis used to dose sea
water boxes. The chemicalcoats thepipeworkwitha
protective ferrous layer to prevent corrosion.

17.
3.Ultrasonic
• High frequencywaves are also usedas a method to prevent marine growth in
piping systems. Ultrasonicsystemis supposed to be known as oneofthe
most highly effective methods to preventbiofouling. A reduction in
biofouling ofas muchas 80%is claimed by this method
• According to research,ultrasonicsis supposed to havetwo types ofeffects on
anti-fouling.
• A disturbance actionbecause ofthe high frequencywaves which rendersthe
habitat unacceptable
• A mechanical action on theorganisms which aretrying todeposit adhesive.
It not only helps in preventing it from solidifying but also acts on 4-5mm
organismswhich arealready anchored.

18.
• In the ultrasonicmethod,a wave generator produces and
sendselectrical impulsesat high frequency. These waves are
passed througha coaxial cable totransducerswhich are
mounted externally to thesea chestsor strainers.
• The transducerscontain piezoelectric ceramic crystals,which
when excited by electrical impulses,generate an ultrasonic
beam
• The mainadvantage of thissystemis thatitis non-invasive
andno partsare in contact withsea water. Moreover, no toxic
substancesare produced

19.
4. Electro-chlorination
• Electro-chlorinationisa methodinwhichchlorineisgeneratedto
produce,Sodiumhypochlorite, whichisusedtopreventfouling.
• Titaniumisusedasthecathode materialwhereastitaniumcoated with
100micro-inchesofplatinumisusedas anodes.Titaniumisan
electrochemicallyinertelementat positivevoltageslessthan 9volts.
Theanode/cathodevoltageiskept7volts.
• Chlorineisgeneratedat theanodesalongwithotherelementstoform
sodiumhyperchlorite.A largeamountofhydrogen gasisalso produced
whichshouldbeevacuatedsafely.

20.
• The layer atthe anode in consumedat arate of 6 mg/ampere
per year. However, it depends on the unitvoltages and
currentssupplied. The total outputof chlorine is afunction of
current rather thanflow throughthe unit.Thusadequate
flow is required toensure cooling and toprevent calcareous
deposits.
• 10PPMchlorine in seawater would killall marinelife quickly,
whereas 1PPM will prevent fouling. This can be tested on
board.
• It is tonotethat thissystemis designed to be used onlyin sea
water and not in fresh water.

21.
What is Corrosion?
• Corrosionis the deterioration ofa
metal as a resultofchemical
reactions between metal and
surroundingenvironment.
• Thetype of metal and the
environmentalconditions,
particularly gassesthat are in contact
with the metal, determine the form
and rate of deterioration.

22.
Reaction
• The basic process at an anodic site is the release
of iron (Fe) from the steel surface into the
environment and can be expressed as:
• Fe Fe2+ + 2e-
• During the process two electrons are generated
which must be consumed by the environment.
• 4H++ O2 + 4e- 2H2O
• 2Fe + 2H2O + O2 2Fe(OH)2
• The term Fe(OH)2 is iron oxide which can be
oxidized to form the Red-brown Fe(OH)3 called
Rust

23.
DO ALL METALS CORRODE?
• All metalscancorrode. Some, likepureiron, corrode quickly.Stainless
steel,however,whichcombinesiron andotheralloys,isslowerto
corrode andisthereforeusedmore frequently.
• All smallgroupofmetals,calledtheNobleMetals, aremuchless
reactivethan others.As a result,theycorrode rarely. Theyare, infact,
theonlymetalsthatcan befoundinnatureintheirpureform. The
NobleMetals,not surprisingly,areoftenveryvaluable.Theyinclude
copper, palladium,silver,platinum,andgold.

24.
TYPES OF CORROSION
• 1.General Attack Corrosion:
• Also known as uniformattack corrosion, general attack
corrosionis the most common type ofcorrosionand is
caused by a chemical or electrochemical reaction that
resultsin thedeterioration ofthe entire exposed surface
ofa metal.
• Ultimately, the metal deteriorates to the point offailure.
• General attack is predictable, manageable and often
preventable.

25.
• 2. Localized Corrosion
Unlike general attack corrosion,localized corrosionspecifically targets one area
of the metal structure.Localized corrosionis classified as oneofthreetypes:
PittingPitting resultswhen a small hole, orcavity, formsin the metal, usually
as a result ofDe-passivation ofa smallarea. This areabecomes anodic, while
part ofthe remaining metal becomes cathodic, producing a localized galvanic
reaction. Thedeterioration ofthis small area penetrates the metal and can lead
to failure. Thisform ofcorrosionis often difficult to detect due to the fact that it
is usually relatively smalland may be covered and hidden bycorrosion-produced
compounds
• .

26.
• Crevice corrosion: Similar to pitting, crevicecorrosionoccursat a specific
location. This type of corrosionis often associated with a stagnantmicro-
environment, like those found undergaskets and washersand clamps. Acidic
conditions, ora depletion ofoxygen in a crevice canlead to crevicecorrosion.
• Filiform corrosion:Occurringunderpainted orplated surfaceswhen
water breachesthe coating, filiform corrosionbegins at small defects in the
coating and spreads to cause structuralweakness

27.
• 3. Galvanic Corrosion:
• Galvaniccorrosion, ordissimiliarmetalcorrosion, occurs whentwodifferent
metalsare locatedtogetherina corrosive electrolyte.A galvaniccoupleforms
betweenthetwometals,whereone metalbecomestheanodeandtheother
thecathode.Theanode, orsacrificial metal,corrodes anddeterioratesfaster
thanitwouldalone, whilethecathodedeterioratesmore slowlythanitwould
otherwise.
• Threeconditionsmustexistfor galvaniccorrosion tooccur:
• Electrochemicallydissimilarmetalsmustbepresent
• Themetalsmustbeinelectricalcontact,and
• Themetalsmustbeexposedtoanelectrolyte

28.
• 4. Environmental Cracking:
• Environmental cracking is a corrosion process that can result from
a combination of environmental conditions affecting themetal
and tensile stresses .Chemical, temperature and stress-related
conditions can result in the following types of environmental
corrosion:
• Stress Corrosion Cracking (SCC)
• Corrosion fatigue
• Hydrogen-induced cracking
• Liquid metal embrittlement

29.
• 5.Flow-Assisted Corrosion(FAC):
• Flow-assisted corrosion, or flow-acceleratedcorrosion,
results when a protective layer of oxide on a metal surface
is dissolved or removed by windor water, exposing the
underlyingmetal to further corrode and deteriorate.
• Erosion-assisted corrosion
• Impingement
• Cavitation

30.
6. Intergranular corrosion
• Intergranularcorrosion is a chemicalor electrochemical
attack on the grain boundaries of a metal. This often
occurs due to impurities in the metal, whichtend to be
present in highercontents near grain boundaries. These
boundaries can be more vulnerableto corrosion than the
bulkof the metal

31.
• 7. De-Alloying:
• De-alloying,or selective leaching,is the selective
corrosion of a specific elementin an alloy. The most
common type of de-alloyingis de-zincificationof
unstabilizedbrass. The result of corrosion insuch cases is
a deteriorated andporous copper.

32.
8. Fretting corrosion
• Fretting corrosion occurs as a result of repeated wearing, weight
and/or vibration on an uneven,rough surface. Corrosion,
resulting in pits and grooves, occurs on the surface.
• Fretting corrosion is often found in rotation and impact
machinery, bolted assemblies and bearings, as well as to surfaces
exposed to vibration during transportation.

33.
9. High-Temperature Corrosion:
• Fuels used in gas turbines, diesel engines and other machinery,
which contain vanadium orsulfates can, during combustion, form
compounds with a low melting point. These compounds are very
corrosive towards metal alloys normally resistant to high
temperatures and corrosion,
• High-temperature corrosioncan also be causedbyhigh-
temperature oxidization, sulfidation and carbonization.

34.
UNDERSTANDING SACRIFICIAL ANODESON
SHIP
• Corrosion isoneof thegreatest enemies ofthe shipandits machinery.Itis also thetoughest
enemy tofight againstfor the people working ontheship.Iron is onesubstancewhich is
used in abundanceontheship. From themainbodyof theshipto thesmallest equipment
usedinoperations, iron makesits presence felt inalmostevery typeofequipment used on
board theship.
• Ashipis continuouslyincontactwithwater andmoisture ladenwindswhich makesit highly
susceptible to corrosion. Theother bodyofthe ship(mainlyhull) is continuouslyincontact
withwater, makingit extremely vulnerable to corrosion. Itis for this reason sacrificial
anodes are used to protect theparent material. Inthis article we will havea lookat the
working of sacrificialanodeson ship.

35.
How SacrificialAnodes Work
• Magnesium(Mg)
Aluminium(Al)
Zinc (Zn)
Chromium(Cr)
Iron(Fe)
Nickel(Ni)
• It can be seen from the table that for protecting iron any material
above in the series are useful. Thesemetals are preferredbecause
they are easy and cheap to replace the anodes rather than
complete a large sheet of metal.

36.
THESE ANODES ARE USED IN VARIOUS
APPLICATIONS SUCH AS :
• 1) Protecting the ship’s hull.
• 2) Protecting the ballast tanks corrosion.
• 3) Protecting the heat exchangers.
• 4) Sea chests
• The most common metals used for sacrificialanode is
zinc.

37.
FREQUENCYFORCHANGING OF ANODES
• The frequencyforchanging ofanodes dependson the application
where the anodes have been used.
• In case the anodes are attached to the ship’shull, then they are to be
checked duringdry dock which takes place after 2 to 3 years. If the
anodes are found completelycorrodedthen anodes of bigger size
should befitted, for fullycorroded meansthat the material used was
of poor quality or a large amount of material is requiredto protect
the hull. Generally,sacrificial anodes are changed at everydry dock.

38.
IMPRESSED CURRENT CATHODIC
PROTECTION
• For largerstructures, galvanicanodescan’t economically deliverenough current
to providecomplete protection.
• In this method,an impressedcurrent is appliedin oppositedirection to nullify
the corrosion current andconvert the corroding metalfrom anodeto cathode.
• ICCP systems use anodesconnected to aDC source.
• This current is givento insolubleanodelikegraphite,stainless steel or scrap
iron buriedin soil.
• The negativeterminalof DCis connected to pipelineto beprotected. The anode
is keptin backfillto increase the electricalcontact with the surrounding soil.

39.
IMPRESSED CURRENT
Advantages:
–High driving
voltage (30 V)
–Few anodes –
reduced
resistance
Disadvantages:
– components of iccp can
get eaisly damaged
– Need for
regulation/control
system
• Risk of overprotection of
highly charged materials
• Coating damages –
cathodic accouplement
– Need for/recommended
protection shield
around the anodes

40.
THANK YOU