Select Marine Coatings

By August 19, 2016 Article, Technology No Comments
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^ Coating Hulls & Other Marine Assets Slashes Corrosion, Fouling, & Osmotic Blistering

Image Courtesy of DOGMAge at http://www.shutterstock.com/pic-376362088/stock-photo-men-painting-ship-hull.html?src=il7y6vmxdELkQsxf4ffClw-1-0

In the Interest of Healthy Hulls & Marine Assets

Marine coatings save the owners and operators of marine assets such as ships, rigs, marine platforms, and other coastal and marine structures from tons of financial and procedural hassles.

Corrosion, fouling, and osmotic blistering are the chief culprits who conspire to shorten the useful life of marine assets. Their havoc they wreck on ship hulls is far worse.

Marine corrosion alone causes 30% of marine assets to fail. Serious fouling can mount a ship’s fuel use by as much as 40% even as mild fouling drops speeds by 10-18%. And for every 25 micron escalation in hull roughness, the engine has to deliver 2-3% more power.

Left unchecked, these culprits will bring down the performance of ships and force a drydocking more frequently than the average 2.5 to 4 years. A ship with a drydock need is a huge expense indeed. Neither does it earn revenues when sitting idle.

Diligently designed marine coatings are therefore in high demand. This is why research firm MarketsandMarkets expects the global marine coatings market to clock an impressive $10.4 billion by 2019.

Top Marine Coatings

Quality low-friction coatings must be cost-effective, bond strongly with the base material and protect it from corrosion. They must resist wear, low temperatures, high pressure, and changes in temperature.

Hempel, AkzoNobel, PPG Protective & Marine Coatings, and Sherwin-Williams are among the top global brands in this market. Developing a coating is a tedious job that takes 1-5 years as lab technicians and chemical engineers pore over the blending proportions of 15-20 elements.

Drydocking is a Time Consuming, Complex, & Expensive Process Image Courtesy of Templar52 at https://en.wikipedia.org/wiki/File:Dry_docking.8.JPG

Drydocking is a Time Consuming, Complex, & Expensive Process
Image Courtesy of Templar52 at https://en.wikipedia.org/wiki/File:Dry_docking.8.JPG

Then come the extensive trials and numerous third party approvals and certifications needed to confirm the coating’s utility and safety. This can again take several months, even a year.

Hempadur Multi-Strength GF 35870 is Hempel’s amine-adduct-cured, glassflake-reinforced, pure epoxy coating. Hard and resistant to abrasion and impact, it withstands seawater, aliaphatic hydrocarbons, gasoline, and mineral oils.

Lloyds Register recognizes it as an abrasion-resistant ice coating. Ships in the Arctic have to brave bone-chilling 580F below zero (-500C) cold. Hulls need to break ice, displace it, and overcome hull-ice friction before they can move through such icy waters.

There was no marine coating to shield hulls against ice till the mid-1970s. Now, the coefficient of friction between hull and ice for uncoated hulls is 0.2 to 0.3 while that for a low-friction coating hull is 0.05 to 0.17.

Sherwin-Williams’ Heat-Flex Hi-Temp 3500 minimizes hidden corrosion under insulation (CUI) to a bare minimum. CUI is the external corrosion that results from water accumulating between the insulation (coating) and the metal surface.

Effective from -800F to 3500F (-620C to 1770C), personnel can apply it directly on substrates at up to 3500F (1770C) thereby eliminating the downtime for coating / recoating.

An omni-purpose, single-component water-based, acrylic, spray applied insulative coating, its composite silica and ceramic microspheres optimize thermal insulation properties.

It is easy to repair and prevents condensation on cold surfaces. This precludes the accumulation of condensed water vapor from promoting corrosion.

Fouling & Corrosion are Sworn Enemies of Fast Attack Crafts Image Courtesy of the British Royal Navy at https://en.wikipedia.org/wiki/File:Royal_Navy_MTB_5.jpg

Fouling & Corrosion are Sworn Enemies of Fast Attack Crafts
Image Courtesy of the British Royal Navy at https://en.wikipedia.org/wiki/File:Royal_Navy_MTB_5.jpg

Solvents inside coatings absorb heat from the surface and evaporate. When applied at low temperatures and high humidity, coatings do not dry completely and therefore do not adhere properly. This gives a wrinkled and ineffective coating.

But apply coatings on too hot a surface that they react with it. They also dry quickly making it near-impossible to complete other finishing operations in time.

SIGMA SAILADVANCE is a series of four anti-fouling coatings by PPG Protective & Marine Coatings that can cut fuel use by up to 7%. Less fouling means less idle time, low friction, and linear polishing that transform into energy savings and low total operational costs.

This series uses Controlled Surface-Active Polymers (CSP) that lubricate the hull-water interface while also smoothening the hull. This respectively lowers friction and prevents fouling. The four coatings of the series are SIGMASAILADVANCE: RX, GX, MX, and DX.

The Green Push

International Maritime Organization’s (IMO’s) Convention on the Control of Harmful Antifouling Systems for Ships 2008 bans the use of organotin compounds such as tributyltin (TBT) and triphenyltin (TPT) in antifouling paints because these pollute water.

That apart, fuel use considerations mean the industry is hard pressed to develop effective antifouling coatings with minimal volatile organic compounds (VOCs) and harmful biocides but with a higher percentage of solids.

Companies are investing heavily in research and development even as international regulations seek to cut or eliminate the following toxic elements in coatings:

  • volatile organic compounds (VOCs)
  • lead / chromate in anticorrosive pigments
  • coal tar and asbestos
  • isocyanates and aromatic amines based hardeners
  • organotin-based biocides

Finally

The necessity to have eco-friendly coatings that cut fuel use while minimizing corrosion and fouling will trigger the development of numerous complex blends of marine coatings in the near future.

To know more on what affects the health of ships and other marine assets, visit our blog.

Contact Kemplon Engineering for sublime marine fabrication services, marine pipe fitting, and large scale custom metal fabrication.