Protection of Ships Lecture 1: Corrosion Lecture 2...

Protection of Ships

Lecture 1: Corrosion

Lecture 2: Antifouling

Lecture 3: Foul Release

Colin Anderson(Technical Director, International Paint, Yacht-USA)

Lecture 2: Outline

Introduction

Measurement of Hull Roughness

What is fouling?

Regulatory Issues

Antifouling Technology

Introduction: Current Issues

IMO and National Legislation: – Ship operators have a/f’s high on the agenda, by law.

Fuel prices are high (and unpredictable)– Ship operators are looking at fuel costs more closely.

All paint companies have been introducing new technology and products– Ship operators are (very) confused by all the claims and counter-

claims regarding a/f’s.

The Environment matters more and more– Ship operators want to be environmentally compliant (ISO).

Introduction: Current Issues

“Minimise Fuel costs” … “Maximum Speed” … “Less Engine wear”

Antifoulings - Why do Fast Ferries need them?

Antifoulings - Why do Navies need them?

“High Speed” … “Readiness for war” … “Noise minimisation”

“Vice Admiral Collinwood leads the second line in Royal Sovereign. Her copper bottom is clean, and she surges ahead.” Capt Alan Villier, Men ships and the sea

Battle of Trafalgar, October 21st, 1805

“Maximum cargo days” … “Lower stack emissions” … “Minimum M&R costs”

Antifoulings - Why do Tankers and Bulkers need them?

“Getting there on time” … “Minimise Fuel costs” … “Safe for the environment”

Antifoulings - Why do Scheduled Ships need them?

NEEDS = NEED TO AVOID

Meet schedulesMinimise bunker costsMinimise SOx & NOxMinimise repair cost (engines)Vessel appearance

Maximum operatingEfficiency

Drag

Minimum Fuel consumption

Antifoulings - Why do we need them?

Lloyds List, 7th November 2005

Antifoulings - Why do we need them?

There are three main resistance forces that have to be overcome when moving a vessel through sea water :

– Form or Shape– Wave-making– Friction

Frictional resistance is largely controlled by the roughness of the outer hull, and this is the main purpose of antifouling coatings.

Roughness is caused by surface deterioration or by fouling.

What causes drag?

Resistance of a Ship’s Hull

Form

Waves

Friction

Total Resistance

slow/ fast

Frictional resistance is largely controlled by the roughness of the outer hull.

As resistance increases, the vessel either slows down or has to increase

power to maintain the same speed. Either way, operational costs increase.

Why is outer hull condition important?

Surface Roughness

Corrosion & Cracking Detachment

Cold Flow Touch-up repairs

Lecture 2: Outline

Introduction


Surface Probe

The Measurement of Hull Roughness

Peak

Trough

Peak totroughheight in microns

Surface of the vessel’s hull


50mm

• Average Hull Roughness (AHR) is the mean of all the vessel’s hull roughness readings and is a measure against which the ships performance is correlated (Lecture 3).

• The standard roughness unit is the peak to trough height in microns per sample 50 mm length of the underwater hull (Rt50).

• The hull is divided into 10 equal sections, with 10 measurements each, 5 on the port, 5 on the starboard side.

• There are a total of 50 readings taken on each side, 30 on the vertical sides, and 20 on the flats.

• From the 100 measuring locations, the Average Hull Roughness is calculated, and the distribution of roughness plotted out.


Hull Roughness Measurement

Hull Roughness Histogram

The Measurement of Roughness

Hull Roughness of "Al Khaznah" (NGSCo) In & Out-Docking, October 2003

0.0%

5.0%

10.0%

15.0%

20.0%

25.0%

0 20 40 60 80 100

120

140

160

180

200

220

240

260

280

300

320

340

More

Roughness (microns)

Freq

uenc

y

In-docking: AHR = 201 microns Out-docking: AHR = 117 microns

The Measurement of Roughness

In addition to surface roughness caused by defects, fouling is the other major contributor to drag.

Control of fouling is an essential part of keeping hulls as smooth as possible, and thus keeping costs down.

Antifouling coatings are the most economical method for control of fouling.

Why Antifoulings?

“The most important cost for running a ship, after the capital expenditure, is the fuel cost.It is more important than the cost for manning of the ships.” (Johhny Eliasson, Stolt-Nielsen)

Lecture 2: Outline

Introduction


What is fouling?

What is Fouling?

Red Brown Green

WEED

Soft Bodied

Barnacles Tube Worms Mussels Other

Hard Shelled

ANIMAL

“Macro-fouling” = Weed + Animal“Micro-fouling” = Slime

Average sea water temperature

Slime (“Microfouling”): 1~2 % increase in drag

Slime (“Microfouling”): 1~2 % increase in drag

Amphora

Toxarium

Weed Fouling: Up to 10% increase in drag

Ulva (“Marine Grass”)

Ectocarpus

Shell Fouling: Up to 40% increase in drag

Barnacles can “cut through” coatings

Barnacles can grow to a considerable size

Barnacles can grow on top of other fouling

The Fuel Penalty if there is an increase in drag

Price ($/te): 250te/day te/year $/year 5% Penalty 10% Penalty

25 9,125 2,281,250 $114,063 $228,12550 18,250 4,562,500 $228,125 $456,25075 27,375 6,843,750 $342,188 $684,375

100 36,500 9,125,000 $456,250 $912,500125 45,625 11,406,250 $570,313 $1,140,625150 54,750 13,687,500 $684,375 $1,368,750175 63,875 15,968,750 $798,438 $1,596,875

Lecture 2: Outline

Introduction


What is fouling?

Regulatory Issues

• 3 Key environmental issues:

– Rate of biocide degradation

– Toxicity to non-target organisms

– Potential for bio-accumulation

DegradationDegradation

BiocideBiocide on paint surface

BiocideBiocide in water column

BiocideBiocide in sediments

The Regulatory Position

• Most antifoulings are classed as Biocidal Products.

• Biocidal Products are regulated in the same way as are pesticides.

DegradationDegradation

IMO Headquarters, London

IMO Diplomatic Conference: October 2001

In October 2001, the text for a treaty on antifouling paints was agreed by the 76 countries present at an IMO Diplomatic Conference, held in London: “International Convention on the Control of Harmful Anti-Fouling Systems on Ships” (IMO-AFS Convention).

This bans the application of TBT paints from 1/1/2003, and the use(presence) of TBT paints on ships from 1/1/2008.

Sealer coats can be used to overcoat TBT paints after 1/1/2008 (and so remove the presence of TBT products as “active” antifoulings).

25 countries signed, representing 25 % GT

Treaty open for signature Feb 2002 Entry in Force

x months 12 months

IMO AFS Convention

IMO AFS Convention

17 countries have fully ratified the convention, representing 17.43% of the world fleet.

The EU has implemented the convention for member states, so thatapplication of TBT paints is banned in EU countries.

Most Marine paints companies have stopped manufacturing and/or selling TBT paints.

IMO AFS Convention

Ships less than 400 GT but greater than 24 metres in length must carry a “self-certificate” declaration signed by the owner, verifying compliance.

Warships, naval auxiliary ships and ships on non-commercial service are exempt.

FPSOs and FSUs are not subject to the requirements to remove or seal TBT antifoulings by 2008.

Ships above 400 GT must be surveyed before being put into service and when the anti-fouling paint changed, and to comply with the convention, will have to carry an international antifouling certificate, certifying compliance.

Pending entry into force, the Classification Societies can survey ships and issue them with an interim certificate or “Statement of Compliance”(SOC) with the requirements of the IMO-AFS convention.

Sealer coats over TBT SPC antifoulings are required for compliance after 2008.

IMO AFS Convention

Legislation Update

Once the treaty has entered into force, countries who sign up must apply all the provisions to:

– ships flying their flag or under their authority– all ships present in their shipyards– all ships entering their ports or offshore terminals.

www.imo.org

Lecture 2: Outline

Introduction


What is fouling?

Regulatory Issues


• There are four main TBT free fouling control technologies currently available:

Biocidal:

– Self-polishing Copolymer (SPC)

– Hybrid SPC

– Controlled Depletion Polymer (CDP)

Foul Release

• These technologies have :

– Differing effects on roughness

– Differing abilities to resist fouling.

Lecture 3


Lecture 2 Hybrid

PRICE

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SPC

CDP

When using biocides to control fouling there are two key issues:

• Biocides (types, quantities)

• Release mechanism

Biocidal Antifouling Technology

ANIMAL

WEED

TBT Cu

BARNACLESTUBEWORMSMUSSELS

GREEN WEEDBROWN WEEDRED WEED

GREEN SLIMEBLACK SLIME

Boosters

Biocides vs Fouling Types

SLIME

Copper- Copper Metal

- Cuprous Oxide- Cuprous Thiocynate

METALLIC

Thiocarbamates(Zineb, Ziram)

Pyrithiones(Copper, Zinc)

ORGANOMETALLIC

Diuron

Seanine 211

Irgarol 1051

Preventols

ORGANIC

Due to regulations there are now only a few biocides that can be used in antifoulings. There are three main types:

A/F Biocides

Biocide Release Mechanisms

For biocides to be effective, they have to be released into the sea from the antifouling.

Sea water is alkaline (pH ~ 8) and biocidal antifoulings work by having an acidic

binder component that can dissolve in sea water, thus releasing biocides.

Acid Binder

+ Biocides

Released Biocides

Dissolved Binder

Biocide Release Mechanisms

There are three main soluble acid binder options to enable biocide release in sea water:

CDP Hybrid SPC SPC

Soluble Acid Binder

“Self-Polishing Copolymer”“Controlled Depletion Polymer”

• CDP = Controlled Depletion Polymer, based on Rosin

• Rosin (~90% Abietic Acid) comes from trees, and has been used for over 100 years in antifouling paints.

• Rosin can be used at – low level to form hard “Insoluble Matrix” antifoulings, or– high level to form soft “Soluble Matrix” antifoulings.

• Modern “Soluble Matrix” antifoulings are commonly referred to as Controlled Depletion Polymer (CDP) antifoulings.

CDP Hybrid SPC SPC

Biocidal

• Rosin has some disadvantages:– it is a brittle material, and can cause cracking and detachment– it reacts with oxygen and has to be immersed relatively quickly– It does not prevent water going into the depth of the antifouling paint film

CDP Hybrid SPC SPC

Biocidal

• With CDP products, there is a “trade-off” between good a/f performance (high rosin) and good mechanical properties (low rosin).

Mechanical Properties (decr Rosin)

A/F Performance (incr Rosin)

+

-

+

-

CDP Hybrid SPC SPC

Biocidal

• There is a slow dissolution of the paint film in sea-water, similar to the way a bar of soap disintegrates when left in water.

• This dissolution gradually slows down over time, due to the formation of insoluble materials at the surface.

• The maximum effective life is typically 36 months on the underwater sides.

• Leached layers can become thick, suppressing biocide release and increasing roughness. Care is needed to remove as much as possible before overcoating at M&R drydocking.

CDP Hybrid SPC SPC

Biocidal

Leached Layer = 75 µm

Amount depleted

Anticorrosive

CDP a/f

Non-Polishing Reference

Typical CDP Cross-Section

CDP Hybrid SPC SPC

Biocidal

Typical CDP surface scan

CDP Hybrid SPC SPC

Biocidal

Time

Bio

cide

Rel

ease

Rat

e

(mic

rogr

ams/

cm2/

day)

Critical Biocide Leaching Rate

Onset of fouling

Typical CDP Leaching Rate vs Time

CDP Hybrid SPC SPC

Biocidal

Typical CDP (Bulker, 05/05,24 mo.)

Epoxy (non a/f) in Boottop

CDP Hybrid SPC SPC

Biocidal

Weed fouling on a depleted CDP (24 mo.)

CDP Hybrid SPC SPC

Biocidal

Rough CDP surface after washing

CDP Hybrid SPC SPC

Biocidal

• The words used to describe CDP’s can be very confusing: “Hydration”, “Ablative”, “Eroding”, “Polishing”, “Self-polishing”, “Ion Exchange”.

• It is the technology in the can which matters, not the marketing claims/description on the label. There are some products which are “Sheep in wolf’s clothing” …

• Key tests for CDP a/f paints are:– Use of Rosin, or Rosin derivatives (ASTM D-1542)– Higher solids (55~60% Vol. Solids)– Thick Leached layers– Film Integrity is generally poor, and re-blasting is needed after 10 years

CDP Hybrid SPC SPC

Biocidal

CDP Hybrid SPC SPC

Biocidal

Summary:

• CDP (Rosin-based) antifoulings have thick leached layers, which limit performance and negatively affect re-coatability.

• CDP antifoulings are not as effective as SPC systems - no matter what claims are made on the label.

• CDP products are the lowest cost per sq. m “value for money”antifoulings, and are suitable for use in low fouling areas or for vessels with short dry-dock intervals.

PRICE

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CDP

CDP Hybrid SPC SPC

Biocidal

PRICE

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SPC

CDP

CDP Hybrid SPC SPC

Biocidal

Self-Polishing Copolymer (SPC) undergo a reaction (“hydrolysis”) with sea-water, to form an acid polymer which is then soluble in sea water.

This results in thinner leached layers and thus much better control of biocide

release:

CDP Hybrid SPC SPC

Biocidal

SPC Polymer + Bicodes

Acid Polymer + Biocides

Hydrolysis

Released Biocides

Dissolved Polymer

There are two main types of SPC Polymer:

– Metallic (Copper, Zinc, Tin)

– Organic (Silyl)

Metallic:

Copper Acrylate (Polymer --- COO --- Cu --- R)

Zinc Acrylate (Polymer --- COO --- Zn --- R)

Organic

Silyl Acrylate (Polymer --- COO --- Si --- R3)

CDP Hybrid SPC SPC

Biocidal

0IIC

R

CI-

Cu+Acrylic Polymer

0IIC

0¯ Na+

Copper AcrylatePolymer

CI-Na+

0 ----- Cu

=> Seawater solubility without Rosin

Copper Acrylate SPC Mechanism

• Controlled, chemical dissolution of the paint film, capable of giving long drydock intervals (up to 60 months) and smoothing.

• Predictable polishing, enabling “tailor-made” specifications by vessel type/operation.

• Thin Leached Layers, so simple cleaning and re-coating at M&R

• Ideal for Newbuildings:– Excellent weatherability– Fouling control during fitting out– Good mechanical properties (eg resistance to block squeeze etc)

SPC Features and Benefits

100 µm

Leached Layer ~ 10 µm

Amount polished off Non-Polishing Reference

Anticorrosive

Cu Acrylate SPC

Copper Acrylate SPC Cross-section

CDP Hybrid SPC SPC

Biocidal

0

5

10

15

20

25

30

35

40

45

50

0 100 200 300 400

Days from start of test

Cop

per L

each

ing

(gC

u/cm

2 /day

)

CDP Cu Ac SPC

Copper Acrylate SPC Leaching Rate

CDP Hybrid SPC SPC

Biocidal

CDP (Rosin)

Copper Acrylate SPC Perforamnce

CDP Hybrid SPC SPC

Biocidal

Container, 17 mo in-service

CDP

Cu Ac SPC

CDP Hybrid SPC SPC

Biocidal

CDP

Ro-Ro, 12 mo in-service

CDP Hybrid SPC SPC

Biocidal

Cu Ac SPC

Container, 13 mo in-service

CDP Hybrid SPC SPC

Biocidal

CDP Hybrid SPC SPC

Biocidal

Ferry, 21 mo. in service

CDP Hybrid SPC SPC

Biocidal

Tug, 36 mo in-service

Car Carrier, 37 mo in-service

CDP Hybrid SPC SPC

Biocidal

CDP Hybrid SPC SPC

Biocidal

LNG, 38 mo. In-service

ULCC, 51 mo in-service

CDP Hybrid SPC SPC

Biocidal

CDP Hybrid SPC SPC

Biocidal


ULCC, 60 mo in service

CDP Hybrid SPC SPC

Biocidal

CDP Hybrid SPC SPC

Biocidal

ULCC, 60 mo in service

Container, 62 mo in service

CDP Hybrid SPC SPC

Biocidal

CDP Hybrid SPC SPC

Biocidal


CDP Hybrid SPC SPC

Biocidal

“HMAS Warramunga” (58 mo in service)

Summary

• SPC products are the “top-of-the-range”antifoulings:

Smoothest Longest lasting (60 mo.)Easiest to re-coat

@www.intersmoothspc.com

CDP Hybrid SPC SPC

Biocidal

• The descriptions “Self-polishing” and “Self-polishing Copolymer” (SPC) are not the same:

– Self-Polishing Copolymer (SPC) :• A chemical reaction (“Hydrolysis”) is required to make the polymer or

binder system soluble in sea water• Leached Layers (LL) are thin, and smoothing occurs

– Self-Polishing only (eg CDP) :• The polymer or binder system is inherently soluble in sea water

(“Hydration”), without the need for any chemical reaction for dissolution in sea water. This is usually accomplished by having Rosin present.

• LL can become thick, and smoothing does not generally occur.

SPC Terminology

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SPC

CDP

CDP Hybrid SPC SPC

Biocidal

Hybrid SPC/CDP

PRICE

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CDP Hybrid SPC SPC

Biocidal

SPC

CDP

• Hybrid SPC technology works by a mixture of hydrolysis and hydration

mechanisms, combining SPC acrylic polymers with a certain amount of Rosin.

• Performance and price are mid-way between the CDP (Rosin based) and SPC

(Acrylic based) products.

• Vertical sides: Up to 3 years

Flats: Up to 5 years (fouling is less severe)

Copper Pyrithione (CPT) is most commonly used as boosting biocide in Hybrid SPC products. It is more effective than any of the boosters used in CDP products.

CDP Hybrid SPC SPC

Biocidal

CDP (Rosin)High volume solids contentSurface tolerant

SPCGood film propertiesPolishing controlThin leached layerControl of biocide release Best a/f performance

Hybrid SPCHigh volume solids contentPolishing controlSurface tolerantGood film propertiesControl of biocide releaseGood a/f performance

CDP Hybrid SPC SPC

Biocidal

Leached Layer = 25 µm

Antifouling

CDP Hybrid SPC SPC

Biocidal

UK Raft (7 months)

CDP Hybrid SPC SPC

Biocidal

CDP Hybrid

Singapore Raft ( 33 months )

CDP

Hybrid SPC

CDP Hybrid SPC SPC

Biocidal

Feeder Container, 15 mo in service

CDP Hybrid SPC SPC

Biocidal

CDP Hybrid SPC SPC

Biocidal

Tanker), 24 mo in service

CDP Hybrid SPC SPC

Biocidal


CDP Hybrid SPC SPC

Biocidal

Product Carrier, 24 mo in service

CDP Hybrid SPC SPC

Biocidal

General Cargo, 28 mo in service

CDP Hybrid SPC SPC

Biocidal

Bulker, 31 mo in service)

Bulker, 35 mo in service

CDP Hybrid SPC SPC

Biocidal

Summary

• Hybrid SPC products will deliver antifouling performance intermediate between CDP and SPC products.

CDP Hybrid SPC SPC

Biocidal

Hybrid SPC

PRICE

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SPC

CDP “Controlled Depletion Polymer”

“Self-Polishing Copolymer”

TBT Free Antifoulings

• There are four main TBT free fouling control technologies currently

available:

Biocidal:

– Self-polishing Copolymer (SPC)

– Hybrid SPC

– Controlled Depletion Polymer (CDP)

Foul Release

Antifouling Technology options

Lecture 3

Lecture 2 Hybrid

PRICE

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SPC

CDP

Protection of Ships Lecture 1: Corrosion Lecture 2...

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