Lloyd’s List events Conference;

Prevention and Management of Marine Corrosion

April 2 and 3, 2003 Radisson SAS Portman Hotel London W1

Economics of Coatings/Corrosion Protection of Ships Selecting the correct type of anticorrosion protection

for underwater applications on new buildings

Speaker: Johnny Eliasson

Stolt-Nielsen Transportation Group B.V. Karel Doormanweg 25

3115 JD Scheidam, Harbour 565 P.O.Box 249, 3100 AE Schiedam

The Netherlands Tel: ++31 10 409.0894 Fax: ++31 10 409.0898

Mobile: ++31 6 520 854.70 email - jeliasson@stolt.com

Summary

The economics of coating and other corrosion protection aspects of ships have changed dramatically over the years due to changes in the materials and solution technologies employed, and changes in the regulatory environment. This is specially true for these past 10-15 years, and the presentation briefly discusses some of these changes, and the economical consequences this have had on the cost of running ships. The topics that are discussed are: changes in the use of hull coatings including consequences from the new ban on certain anti fouling paints, changes in the emphasis in ballast and cargo tank corrosion protection, SOLAS Part A-1, Regulation 3-2, changes to traditional coatings and the more common use of modern two component coatings.

The generic methods of preventing or mitigating corrosion on ship hulls, and other vital parts are briefly outlined; preventing access to the electrolyte, reversing the flow of electrons, corrosion resistant alloys and design corrosion allowance. Some of the more important areas that need protections are ballast tanks, under water hull, topsides, decks, internal “dry” spaces and cargo tanks. Protection alternatives for these areas are discussed, including cost estimates.

The antifouling alternatives available to us now (ablative, hybrid, hydrolyzing, foul release, etc.) after the IMO-ban on TBE biocides are discussed, including cost aspects. Some of the economical and ecological consequences from non-performing antifouling paints are suggested.

A research / test program with propeller coating, using a silicone based material, is also discussed.

Background Ships were historically constructed by wood. The decay from bacteriological and

animal attacks was in general mitigated by using hard tight wood, and by treating the wood with “poisoned” tar or oil paint. Later the ships was constructed from steel other forms of “decay” became dominating, and other solutions to prevent such decay (rust) was employed.

Fouling was first reported on a papyrus dated around 412 BC (according to Dr. Maxim Candries, Dpt of Marine Technology, Newcastle, UK) in which is mentioned they used arsenic and sulfur mixed with Chian oil to help mitigate the problem.

Christopher Columbus wrote “All ships were covered with a mixture of tallow and pitch in hope of discouraging barnacles and teredo, and every few months a vessel had to be hoed down and graven on some convenient beach.”

In 1625, William Beale filed the first patent for an antifouling recipe, that was based on iron powder, copper and cement.

Fouling was reported to be up to ½ m long, and giving off odorous and aggressive gases, turning the white lead oxide pigmented paint on the topside darker on a sailing ship anchored in the Indian Ocean.

Lord Nelson reportedly employed copper plates attached to the ship’s hull to prevent fouling, greatly increasing his ships maneuverability in combat. Steel ships cannot use copperplates due to the galvanic corrosion induced by such bi-metallic couples.

By 1870 there were more than 300 anti-fouling paint registered. Most of the formulations used biocides to kill organisms through a leaching process.

In about 1910 pine gum rosin was reported to be used to make a slowly water soluble antifouling.

R. Mallet a 19th century paint expert noted – “The necessary balance between adhesion and slow diffusion or washing away through the water of the poisonous soap is too delicate for practice. Either the soap adheres firmly and does not wash away enough to keep off fouling, or it washes away so fast as soon to be gone.”

Later the antifouling paints evolved and used vinyl or chlorinated paint filled with copper and biocides. Some of the biocides used were persistent and accumulated in the

water. It was not until 1974 with the evolution of the at that time regarded more environmentally friendly TBT-copolymer systems that we were provided with a real predictable long term anti-fouling performance. Due to the fine and predictable delivery mechanism in this technology the need for biocides was reduced and those used were in general biodegradable. Due to concerns of TBT adhesion to silt, and lasting problems (real or perceived) the TBT-copolymer AF came under scrutiny by environmental groups, and this biocide is now practically banned. In its place has come a re-introduction of the pine rosin systems, under a new name, and some different “new generation” antifouling paints. In brief the present situation in relation to anti fouling paints from a ship owners point of view can be summarized as – less predictable, more complicated and more expensive than has been the case since 1974.

We all want the ships to look nice as when they were new all the time. The ships float, however, in a very corrosive electrolyte – the seawater. That means that good corrosion control systems have to be employed. Corrosion onboard ships Corrosion, as it occurs onboard ships, is an electrochemical reaction. The reaction require four prerequisites to be satisfied to progress:

• an anode, • a cathode, • an electron pathway • an electrolyte (ionic pathway).

Electrolyte Anode Cathode

If any one of those four prerequisites is missing corrosion will to occur.

Corrosion does occur onboard ships. Here the coating is broken down, but there has not been much loss of metal. The strength of this structure is still sound – Action is, however, needed to continuously preserve the structure, and the only solution in this case is a complete new coating? The picture below shows a coating that is still generally intact, but with corrosion attacking the steel on edges, etc., where the coating is broken. This tank could possibly be spot repaired.

If the coating in this tank is left as it is it will continue to degrade and end up like the previous, or the next, picture. The most cost effective strategy is using in cyclic coating maintenance repairs that expand the service life of the existing coating. Getting to it early enough saves structure and money.

Some tanks on some ships does in fact not look good! – This is a tank with general rusting. The ship structure still OK, but there is loss of metal evident, and eventually the structure can be weakened. The Regulatory Environment

- IACS ESP - IMO A798 - SOLAS Reg 3-2, Part A-1 - > 15 year GOOD in ballast/cargo since 2002 Bulk ship failures in the late 80’s lead the International Association of Classification

Societies (IACS) to create the Enhanced Survey Programme for ballast tanks. The ESP mandated that all ballast tanks had to be coated with a “hard” coating, and that the condition of the coating while the ship is in service must be “reasonable”.

A short while after that International Maritime Organization (IMO), a United Nations body, created Recommendation A798 in an attempt to bring the standard of work on new construction stage in line with what IACS would later require when the ships are in service. This recommendation was made mandatory in July of 1998 by incorporation into IMO’s Safety Of Life At Sea (SOLAS) in Part A-1, as Regulation 3-2.

In 2002 the IACS ESP was tightened again and the present requirements on coating condition in ballast tanks on tanker ships is quite stringent, and discussions of incorporating cargo tanks under the ESP started. Corrosion prevention or mitigation The most common methods to prevent corrosion is by;

1. Preventing access of the electrolyte 2. Reversing the flow of electrons 3. Corrosion resistant alloys 4. Corrosion allowance

The first method involves applying a layer onto the steel that prevents an electrolyte to move at the steel surface, this layer is called a coating. The second method is commonly known as cathodic protection; anodes, or impressed current. The third method above is the use of alloys that does not corrode in these environments. Method four allows the corrosion to proceed and incorporate enough structural material in the design to last for the intended service life.

• Corrosion allowance It is possible to build ships with such a thick steel that even with free corrosion taking place the ship would have enough strength left to perform its designed service life. It is generally agreed today that this is no longer a cost efficient way to build and operate ships. There is still today, however, always a certain corrosion allowance incorporated into the structural strength calculations. This means that even with defects in the anti corrosive systems there are not any structural problems occurring that for a relatively long time, which gives the owner time to plan the correct action.

• Cathodic protection The use of anodes and/or impressed current protection systems is common onboard ships. Anodes prevent the galvanic corrosion driven by the brass propeller. Anodes and “impressed current protection” systems provide protection on spots where the coating is damaged on the general under water hull areas. The inorganic zinc coatings are hybrid systems in that they have a dual function - they provide cathodic protection as anodes and as the initially porous coating is filled with corrosion products it becomes more like conventional a coating.

• Coatings Coatings are barriers and they are most common method by which corrosion protection is obtained. Barriers hear means that they do not allow ions to penetrate the coating and get to the steel, and it does not permit movement of any existing ions at the steel surface.

Pre-striping of blasted tank before 1st coat – a proper job!

Proper striping before 2nd coat!

Most important parts of the ship to protect

• Ballast tank protection Reasons:

1. Corrosion protection 2. Satisfying regulatory requirements (SOLAS, IACS, IMO..)

Good references – DNV Guide #8, TSCF Guidelines for Selection and Application of Ballast Tank Coatings. Ballast tanks were coated using several different product types in the past: Bitumen

products, Hot applied coal tar, Sheep fat, Coal tar epoxies, drying vegetable oils, etc. The most common coating used on new ships in the 60’s and the 70’s anup to the late 80’s was the coal tar epoxy (CTE). In the late 80’s and early 90’s the trend was towards the use of “hydro carbon modified”, light color, epoxy products. In recent years the trend is more towards use of more pure epoxy products. The main reasons to coat these spaces are corrosion control, and to satisfy the regulatory bodies. The structural integrity of the ballast tanks often decides the ships life.

Early and uncontrolled corrosion leads to a reduced life. IACS mandated in the late 90’s in the Enhanced Survey Programme (ESP) that all ballast tanks on tanker ships had to be coated with a hard coating, and have a certain quality. IMO in their A798 recommended, and later SOLAS in Part 1, Regulation 3-2 mandated, that the ballast tanks

had to be blasted and that a light color hard coating must be used. The coating system applied as per the manufacturer’s recommendations, and maintained as per an agreed maintenance scheme, must perform for a time period as stated by the owner. It mandates further that all specifications and application procedures and other required documentation is in place, and that as per IMO A798 it shall be verified by the flag state control agent.

IACS in 2001 tightened the requirement further to require a “good” coating condition in all ballast tanks after 15 years of service – before 15 years “fair” is acceptable. Ships are now in fact being rejected for cargo because of the coating in the ballast tanks not meeting IACS “good” requirements as interpreted by the class surveyor, even if the structure is entirely sound. In fact there has been a case when only one tank fell below “good” and the ship was rejected - the condition of the coating in ballast tanks now has a direct influence on the bottom line. The picture to the right was taken inside a newly coated tank. It always looks nice before that tank has been used. The picture below is more interesting in that is shows a tank after 5 years in service. The coating showed no defects after 5 years, which tells us that it is possible to apply coatings for a long performance in these spaces.

To further reduce cost without lowering the performance expectation the use of true 100% solids, fast cure, products will become more common in the future. For that to be successful, however, the coating manufacturer’s representatives and the applicators much evolve somewhat. The process must be adopted to fit the product – not the other way around. There are, however, great (not the least time) savings possible.

This condition is no longer acceptable! → → → → → → → → → → → → →

• Underwater hull Reasons to coat: 1. Anti corrosive properties 2. Drag / fouling control In the 60’s and 60’s the underwater hull areas in the US were coated with vinyl anti corrosive

systems, when they were coated with chlorinated rubber systems in Europe. Later Coal Tar Epoxy with a Vinyl tar tie coat became the anti corrosive paint work horse systems worldwide for ship under water hull at new construction stage, as the vinyl tar systems became the dominating products worldwide for underwater hull touch-up in dry dock.

In US the trend soon changed over to epoxy systems also for dry dock repairs. Now basically the rest of the have more or less followed the US. The main reasons to coat the underwater hull is for corrosion and fouling prevention. Antifouling alternatives after IMO AF treaty comes into force:

- Ablative (CDP) systems - Hybrid Ablative/Hydrolyzing systems - Hydrolyzing systems - Foul release systems - Other systems -

Hull AF Alternatives (post IMO AF Treaty)

►Ablative systems - Soluble part rosin based (invented about 1910) - Different insoluble co-resins and amounts - Water sensitive, high absorption, thick active zone - Leach layer and need for hard washing - Sensitive to increased pH – rosin solubility change - Cost about 50% above TBT-based systems - Predictable performance for 36 months – questionable for slow ships in water waters.

►Hybrid Ablative/Hydrolyzing systems

- Soluble part rosin based, reduced amount

- Co-resin (part) hydrolyzing and not hydrophilic - Less water sensitive and less water absorption = less active zone - Leach layer and need for good washing - Somewhat sensitive to increased pH due to the rosin - Cost about 75% above TBT-based systems - Predictable performance for more than 36 months, maybe even 60 months.

►Hydrolyzing systems

- Hydrolyzing matrix (Cu-acrylate, Si-acrylate, Zn-acrylate, etc) - In general hydrophobic resins - Little water absorption = thin active zone - Thin leach layer = only normal washing necessary - Insensitive to pH change (CP driven) - Cost about 200-300% above TBT-based systems - Predictable for 60 months (Zn-acylates maybe excluded)

►Foul release systems

- None reactive low energy surface systems (Silicone, Fluoro polymer. etc.) - Strongly hydrophobic - Virtually no water absorption = no active zone and lo leach layer - Insensitive to pH change (CP driven) - Sensitive to mechanical contact - Cost about 400-600% above TBT-based systems. - Predictable for fast ships in all waters for 10 years, medium speed ships in moderate

temperature and works for “normal” speed ships in colder waters

►Other systems - Smooth “brush-able” hard coats (repeated under water scrubbing) - “Electrolytic systems” - Water glass / Cu metal based - “Wall paper” / Cu metal based (Cu impregnated adhesive plastic sheets)

Ship in dry dock in Bahrain.

Consequences for AF none performance - 94,000 ships w.w. / 50% of which are coastal - 100 mic (0.1 mm) increase in roughness = 1% increase in fuel consumption - Moderately fouled hull reported decrease speed by 20% - Severely fouled hull reported increase fuel consumption by 40% - If average fouling increase drag to reduce speed by 10% we need about 5,000 more ships

to do the same work. - Increased fuel consumption = increased green house gas emissions - Shipping today is extremely energy efficient, will that remain so..?

• Topsides Reasons to coat: 1. Anticorrosive properties 2. Appearance 3. Repetitive T/U due to contact and “Panama black” In the past the topside areas were coated using single component alkyd systems. This was the

marine standard for many years. During the latest 10-15 years, however, there has been a change - the industry has pretty much converted to the use of better performing epoxy and polyurethane systems. The main reason for coating the topsides is cosmetics – the rate of corrosion on topside areas is in fact not that elevated on most of the ships. For owners that want to limit maintenance cost to a minimum the topside system typically incorporate a zinc silicate primer.

Competitor of SNTG, and a SNTG ship in dock.

• Main deck, deck areas, and superstructures

Main reasons to coat: 1. Anticorrosive properties 2. Appearance 3. None skid 4. Abrasion / exposure resistance 5. Mixed metal areas 6. Repetitive repairs due to contact damage

Also on these areas the alkyd and chlorinated rubber (and vinyl in the US) coating types dominated for a long time. But in the last 10-15 years coatings based on epoxy and polyurethane systems taken dominating position. The main reasons to coat these areas is to control corrosion on supports and structure, and to provide an appealing first impression of the ship. Zinc silicate primers have been used, and are used by some owners, to get the most cost effective performance.

Above, a picture of a typical main deck of a modern chemical tanker ship in nice weather. Below is a picture of the deck of a chemical tanker in less good weather.

• Internal dry spaces 1. Appearance 2. Comfort

3. Easy to clean Engine room and storage spaces are coated mainly for cosmetic reasons. To give a good

working environment to the ship’s crew.

• Cargo Tank Coating 1. Corrosion protection 2. Satisfying regulatory requirements (IACS, FDA, EPA …) 3. Protection of cargo from tank, and tank from cargo 4. Easy of cleaning

This is a very large topic in itself, and it is sufficient here to note that the choice of coating is

dictated by the service requirements, and that the regulatory bodies (IACS, etc.) has incorporated coated cargo tanks in under a similar ESP as is in place for ballast tanks.

Coated and stainless steel cargo tank!

The most common alternatives are: 1. Zinc silicates (ethyl and water based): pH limited 2. PE systems: Limited in strong solvents, basically CPP trade 3. Novolac/PE hybrid systems: More resistant to solvents, chemical trade 4. Novolac systems, Resistant to strong solvents, upscale chemical trade 5. Stainless steels (304L, 316L, 316LN, 316 LNMo, 318LN, etc.) 6. Other (Siloxirane, Polyurethane, etc.), different limits.

Selection of coating systems and cost aspects

As these picture show all coatings are not alike! To choose the right paint for the right area is not an easy task! Much of the information that would help the owner choose is hidden from them. Even the MSDS sheets are sometimes incomplete.

This aluminum flake reinforced pure epoxy is looking good after 5 years in service with

no signs of coating cracks or blisters.

But, this “modified epoxy” is cracking in the corners after 5 years and will not last as

long as the product above.

This is an example of a pure epoxy after 5 years that is also showing coating cracks in

corners. This shows how hard it is in fact to choose the right paint – the data in the product data sheet does not provide the necessary information to be able to predict if such cracks will or will not appear – or how long it will take.

These are all different coatings tested for abrasion resistance and the result in these tests

is also quite different from one coating to another. Coatings that supposed to be equal!

Some coatings were damaged extensively in the test, yet some just on the surface. This

test is designed to indicate the coating performance expectation in bulk cargo holds.

Another aspect that further complicates things is the fact that the coatings have different

physical and resistance characteristics when applied under different conditions. A coating applied under colder conditions retains more solvent after application, making the coating initially more “flexible” and less abrasion resistant, but later as the solvent do leave the film the coating becomes hard, stressed, brittle and more abrasion resistant. So, not only is it important to choose the right paint, but also to know it’s application requirements based on the service conditions it shall resist, for a long time.

Cost of corrosion protection

The data shown in this presentation is an approximation of reality. It is an attempt to show examples on how to evaluate the system choices rather than providing “true” cost numbers. Prices vary from location to location, and by time, and one cannot give an exact cost yet generic picture that will be overall accurate.

• Underwater Hull Anticorrosive Alternatives - Up to 5 years service: 2/3 coats VT or Chlorinated Rubber AC - 5-10 years service: 1 coat PE + 1 coat TieC - 10+ years service: 2 coats PE + 1 coat TieC

• Hull AC cost (Surface preparation $10, and 1$/coat in work, plus paint cost) - Up to 5 years service: 16$/m2 – 3.2 $/m2/year - 5-10 years service: 14.5 $/m2 – 1.45 $/m2/year - 10+ years service (use 15 years as median): 16$/m2 – 1.07 $/m2/year

02468

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Up to 5 years 10 years 15+ years

System Design

UW HULL COATING COST

Series1Series2

• Cost for AF systems Involve paint, off-hire ($15k/day over 5k m2 = $3/m2/day), hull cleaning ($4/m2 ablative and $2 hydrolyzing), surface preparation ($10/m2), application ($2/m2), dry dock time, etc.

- Ablative systems (36 months): $50/m2 - $15.2/m2/year - Hybrid systems (60 months): $50/m2 - $10/m2/year - Hydrolyzing systems (60 months): $75/m2 - $15/m2/year - Foul release systems (120 months): $116/m2 - $11.6/m2/year - Other systems: Not known!

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CDP CDP/HYD HYDROLYS Foul release

Types of AF

Antifouling Options after TBT-ban

Series1Series2

• Topside Coating Alternatives - Up to 5 years service: 3/4 coats Alkyd or Chlorinated Rubber - 5-10 years service: 2 coats PE + PU - 10+ years (15) service: 1 coat Zn + 1 coat PE + PU

• Topside Coating Cost (Surface preparation $10, and 1$/coat in work, plus paint cost, including one topcoat annually for cosmetics)

- Up to 5 years service: $17/m2 plus $8.75 in m&r- $4.75/m2/year - 5-10 years service (use 8 as median): $16/m2 plus $16 in m&r - $4.0/m2/year - 10+ years service (use 15 years as median): $19/m2 plus $30 for m&r - $3.2/m2/year

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Topside System Cost

Up to 5 years10 years15+ years

• Exposed Decks Coating Alternatives - Up to 5 years service: 3/4 coats Alkyd or Chlorinated Rubber - 5-10 years service (use 8 years as median): 2 coats PE + PU - 10+ years (15 as median) service: 1 coat Zn + 1 coat PE + PU

• Exposed Decks Coating Cost (Surface preparation $10, and 1$/coat in work, plus paint

cost, assume 25 years life and recoating at service life intervals, plus 1 topcoat annually for cosmetics for alkyds, but each 3 years for polyurethane)

- Up to 5 years service: $17/m2 plus $8.75 in m&r- $4.75/m2/year - 5-10 years service: $16/m2 plus $4 in m&r - $2.5/m2/year - 10+ years service (use 15 years as median): $19/m2 plus $6 for m&r - $1.75/m2/year

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Deck Coating System Cost

Up to 5 years10 years15+ years

• Ballast Tank Coating Alternatives

- Up to 5 years service: p/t (or HB), 2 x ME - 5-10 years service: Sa 2 and s/s of shop primer, 2 x ME or PE - 10-15 years service: Sa 2 ½ and s/s of shop primer, 2 x PE - 15-20 years service: Full Sa 2 ½, 3 x PE

• Ballast Tank Coating Alternative Cost (25 year ship life) (Surface preparation NB $20 for

up to 5 years, $25 for 10 and 15 years and $30 for 20 years, for m&r $35/m2 for 10 years, and 1$/coat in work each time, maintenance repairs over 25 years (cyclic each 5 years 5%), plus paint cost)

- Up to 5 years service: cost for 25 years ship life $113/m2 - $5.65/m2/year - 5-10 years service: cost for 25 years ship life $118/m2 - $5.9/m2/year - 10-15 years service: cost for 25 years ship life $78/m2 - $3.9/m2/year - 15-20 years service: cost for 25 years ship life $46/m2 - $2.3/m2/year

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Up to 5 years 5-10 years 10-15 years 15-20 years

System Choice At NB

Ballast tank Coating Cost For 25 Years Life

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• Blue series = Total added cost over 25 years time • Red series = Initial CAPEX • White series = Cost / year • Cargo Tank Coating Alternative Cost (10 coating life) - Zinc silicates (ethyl and water based): $45/m2 - $4.5/m2/year - PE systems: $50/m2 - $5.0/m2/year - Novalac/PE hybrid systems: $55/m2 - $5.5/m2/year - Novalac systems: $55/m2 - $5.5/m2/year - Other systems: Too little data.

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Systems

cargo Tank Coating Cost

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Action for ships in service

- Inspection - Consider performance intent - Planning (next DD..etc.) - Action

Whether the problem is in a cargo tank, ballast or other coated areas does not matter that much we must still have good data to work with. SNTG inspect all cargo tanks twice and all ballast tanks once per year, and reports are filed. It is important that the type and extent of the failure is well documented – preferably with pictures, and in some cases samples collected. The designed performance criteria, how long the coating must last, must then be identified, as well as how long can we go before we have to act. The next step is to plan the action, in the next dry dock, or do we have to employ a riding squad? Only when we know why, where and for how long can we define the most cost effective action. Special Application – Propeller / Rudder

- In past used epoxy products - AF systems - Now testing Silicone based systems - Reduce “adhesion” of water to propeller (drag) - Reduce amount of energy required for each turn (or each ton of water pushed away) - Reduced amount of “body of water” being pulled around by the propeller - Of total drag a fouled propeller has the same affect as a fouled hull!

• Experience With Propeller Coatings - Increased speed – 1 kn (or 5-8%) - Reduced vibration expected not verified yet - Reduced m&r expected not verified yet - Reduced fuel consumption

Badly fouled ship hull

Propeller and rudder coated with Intersleek on M/T Stolt Hikawa.