Challenges and Opportunities in the Chemical Tank Coatings ... · • MarineLine 784 (and enhanced)...

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Challenges and Opportunities in the Chemical Tank Coatings Market

Tanker Shipping & Trade Conference, Awards & Exhibition

Alan Walker – Safinah Group

Alan.walker@safinah‐group.com

Agenda

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• The Chemical Market and its effect on tank coatings

• Drivers that have resulted in the new generation of low cargo absorption type epoxy tank linings

• The inherent risks with the new generation

• What can Owners influence and best practices

• Summary

Agenda

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• Summary

The Chemical Tanker MarketChanges that are effecting the coatings (1 of 2)

• The growth in seaborne trade has resulted in larger ships

o More complex to painto More flexing = more stress in the coating = more

potential to cracko Stainless steel is no longer an option

• Increased carriage of methanol in coated tanks.4

The Chemical Tanker MarketChanges that are effecting the coatings (2 of 2)

• Supply/demand• Significant surpluses of chemicals in the USA and ME• Deficits in Asia/China• Increased voyage time means increased cargo carriage time• A requirement to carry different cargoes back to back e.g. veg oils and

caustic from Asia 5

Agenda

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• Summary

The drivers effecting the tank coating

• A greater number of cargoes carried in coated tanks• A requirement for less restrictions between cargoes• Faster (and lower cost) cleaning• Tighter cargo specifications and improved analytical techniques to detect cargo contamination

• More methanol and other high specification cargoes are being carried

• Tank cleaning restrictions – e.g. washing with methanol prior to wall wash test

• The mandatory sea water flush immediately after discharge of toxic and low flash cargoes

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“Older” technology coatings• Phenolic Epoxy type

• Broadest chemical carriage capabilities but:

• ‐ Absorb and retain cargoes

• ‐ Relatively long cleaning times

• ‐ Difficulty passing wall wash test without a methanol wash

• Zinc Silicate

• Excellent resistance to pure and pH neutral chemicals but:

• ‐ the relatively rough and porous surfaces are difficult to clean after carrying certain cargoes such as oils prior to pure chemicals

• Stainless Steel

• Does not absorb or retain cargoes but:

• ‐ Too expensive for larger ship

• ‐ Smaller ships cannot compete on longer voyages 8

This means

• Phenolic epoxy coatings are now only suitable for CPP cargoes and easy chems not for the carriage of high purity chemicals

• A new generation of coatings was required

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The New Generation of Coatings

• Low absorption coatings

• MarineLine 784 (and enhanced) ‐ Siloxirane

• Interline 9001 ‐ Bi‐modal

• Jotun Tankguard Flexline ‐ Solvoxirane

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Benefits• Low cargo absorption• Extended chemical resistance• Reduced sequencing restrictions• Shorter recovery periods after aggressive

cargoes• Easy clean benefits

• These are new and more complicated technologies that were and are:

• Developed and tested in the same way

• Applied in the same way

• Operated in the same way (or more aggressively)

Defined as coatings that require a high temperature cure as part of the application procedure

Agenda

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• Summary

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• Highly cross linked structures with high internal stresses• More sensitive to poorer surface preparation• Relatively short overcoating intervals between coats• Stricter humidity and temperature controls during application• High dry film thickness will increase internal stress• Heat curing ‐ Hot air or hot water?o Hot air can result in variable steel temperatures – e.g. hotter areas in way of heat inlets

o Hot water means the coating is cured in an immersed state that can effect the coating when it is dried out – such as increased internal stress and/or more brittle films

Inherent risks

As a result cargo tank coating premature failures are increasing

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Failures investigations in general show:

• Not cargo related (according to manufacturers resistance lists)

• Application appears according to guidelines

• Tank cleaning processes appear OK

What is found:

• Grit inclusion

• Blistering to the steel substrate

• Intercoat blistering and delamination

• Cracking on welds

• Surface micro‐cracking

Agenda

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• Summary

What can Owners/Operators influence to mitigate tank coating failures

Tank coating parameters• Vessel design• Paint specification and product selection• Application management• Paint chemistry/formulation• Correct (and caring) operation (cargo carriage/cleaning etc)

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Paint specification and product selection• Move away from generic requests• Move to a risk based functional specification approach when selecting the paint technology, the paint specification and the products based on known application and operational parameters

• A functional specification to be developed against weighted parameters such as:

o The main cargoes to be carriedo Application conditions/limitations of shipyardo Cargo sequencing requirement and cargo carriage times o Venting conditions/humidity etc whilst in service o Etc

• Do not base selection on paint suppliers sales pitches and price – develop a risk based matrix to select the best coating for the Vessel 18

Application management

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• The new generation of tank coatings are not the same as previous tank coatings

• They have high internal stresses due to the heavy cross linking making them susceptible to cracking, blistering and delamination

• The current coating failure rates shows that leaving the coating supervision to the shipyards and paint companies has not worked

• The cost of dedicated tank coating application experts to manage the process is a worthwhile cost

Application management ‐ focus areas

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• Abrasive blasting – use new non recycled angular grit ‐ a rounded steel profiles leads to poor adhesion to the steel and premature coating failure

• Cleaning – ensure all surfaces are properly vacuum cleaned just prior to painting ‐ grit inclusions under the paint will lead to blistering and corrosion

• Overcoating intervals ‐ exceeding the over coating interval can lead to intercoat blistering and delamination

• Localised “hot” spots within the tank during application can cause localised blistering/delamination due to exceeding overcoating intervals in these areas

• Dry film thickness (DFT) ‐ increased DFT increases the internal stresses in all coatings. Less DFT can be better than too much!

• Properly manage the heat curing process

Application – what can go wrong – sister ships after 8 years

• Sister ships ‐ What was the same or different?

• Specification • Coating • Operation• Application

Ship A Ship B

• Surface profile 40µ

• DFT 400 ‐ 550µ

• Grit contamination and corrosion under the paint

• The result: poor adhesion to the steel, blistering and corrosion

• Major failure

Ship A Ship B

Surface profile >75µDFT 270 ‐ 450µClean surfacesExcellent adhesionResult: very minor localised blistering and corrosion

Differences?

Correct (and caring) operation ‐ examples

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• Minimise mandatory water flushing after the carriage of water miscible/hydrolysable cargoes such as methanol

• Gas free and mop out as soon as possible – in practice how quickly can this be done in all tanks with vessel man power

• Ventilate with dry air after water miscible cargoes• Ventilate from the tank bottom to remove solvents (all solvents are heavier than air)

• Inert gas from diesel burners has high humidity after water scrubbing –take care when inerting with this type of inert gas after the carriage of water miscible cargoes

• Do not/try not to over heat cargoes such as PFAD and store for prolonged periods of time (e.g. due to delayed berthing)

Correct (and caring) operation ‐ examples

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• Do not over clean and keep cleaning temperatures as low as possible –experiment with shorter cleaning periods and lower temperatures rather than just following historic procedures

• To be competitive paint companies have pushed the CRG as far as possible – Owners can dial this back

• Train operators about tank coating care e.g. venting from tank bottoms; using dry air for water miscible cargoes

• Train the crew how to maintain the coatings correctly

Crew maintenance

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• Crew maintenance standards are generally limited:• Accessibility• Inadequate surface preparation• Incorrect coats/DFTs• Insufficient time between coats• Insufficient time to load cargo• No post or hot cure

• As a result crew maintenance in my experience lasts 3 – 6 months• Far better to:• Do less crew painting but to a better standard e.g. damages on tank tops to control pitting.

• Use specialist tank coating maintenance products• Plan major maintenance at scheduled dry dockings

• May 2019• Tank top ‐ full cosmetic coat• Looks good• From a distance

• August 2019• The cosmetic coat has extensive corrosion and delamination

• In addition, there is an increased risk of cargo contamination and cargo pump damage from paint flakes



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Paint chemistry/formulation

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• If the risk of developing cargo tank coatings becomes greater than the reward they will not be developed

• Collaboration is the way forward• Major chemical/product tank operators should work with the paint companies to develop and properly test new products in the field

• Laboratory testing and (relatively) small scale test patching does not mean the coating will be suitable for full in service performance over the expected coating lifetime

• Without collaboration it is impossible to build track record without taking high risks

Agenda

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• Summary

Summary (1 of 2)

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• Changes in the chemical tank market are having an effect on the cargo tank coatings

• These along with new regulations and tighter cargo specifications and improved testing have made previous tank coatings unusable for chemical carriage

• The new low absorption generation of tank linings are different• There are inherent risks with these new tank linings and premature failures are on the increase

Summary (2 of 2)

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• In the short term Owners/Operators can take actions to mitigate tank coating failures

o Move from generic specifications to functional specificationso Utilise experts to prepare functional specifications, train the operators/

crew, and for application management

• In the longer term Owners/Operators should collaborate with paint manufacturers to improve existing and develop new products

Thank you

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Challenges and Opportunities in the Chemical Tank Coatings ... · • MarineLine 784 (and enhanced)...

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Transcript of Challenges and Opportunities in the Chemical Tank Coatings ... · • MarineLine 784 (and enhanced)...