Engineers Amazed at Underwater Painting

A diver hand paints Alocit in the splash zone to the legs of a gas platform.

By Cathy Frost, General Manager at Alocit International Ltd

A simple demonstration at oil and gas exhibitions around the world often holds corrosion control engineers transfixed. It involves a person dipping a brush into a paint can at the bottom of a tank of water and then coating a metal object that is also under water.

It’s an eye catching demonstration that shows off the qualities of Alocit, a unique coating that has been used to solve corrosion issues in adverse conditions over wet surfaces and even under water for more than 30 years.

In 1968 Swiss chemists developed the range of high build, zero VOC coatings with outstanding adhesive and protective qualities that could even be used in splash zones or sub-sea. The coating was specifically designed for sub-sea use, is resistant to microbial induced corrosion and accelerated low water corrosion and coating for welding repairs. These days it is also being used effectively by divers applying the product under water.

Alocit International in the UK acquired the Swiss technology in 1991 and by 1995 had gone on to develop tropical grades for temperate water and in 1997 relocated toll manufacture to Manchester in the UK  where the coating has been produced under licence by a trusted team at WSL in Manchester UK for more than 20 years.

Alocit can be easily applied under water with a pumped brush.

In 1999 the first anti fouling trial was held in Portsmouth in the UK which first revealed the product’s marine growth retardant qualities. Research and trials in various environments around the world have been under way since then in a bid to re-inforce those anti fouling properties. It also has remarkable adhesion qualities, something that was verified by a third party inspection of the product which had been painted and cured underwater and showed a pull off test over 16MPa.

That adhesion is evident when applied on damp or oily metal and concrete, on dry or wet surfaces, splash zones, underwater and on areas of constant condensation. It also has excellent abrasion qualities and protects against corrosion on steel and is suitable as a sealant and adhesive for concrete. With more than 500 listed case histories covering industries as diverse as oil and gas, power, mining, sewage and shipping it is being used in aggressive environments in every corner of the world.

Long life and ability to succeed in difficult circumstances has made it the coating of choice for protecting challenging substrates such as sweating pipes on refineries in the tropics and dripping wet bridges in northern hemisphere winters.

The coating is not just for wet surfaces. It can be applied to concrete, steel and many other substrates – in the dry, in the wet or on oil-soaked concrete. The list of potential applications is as long as that of its satisfied customers, which includes some of the best-known companies in the world.

Coated Petronas Twin Towers gas line jointing flanges suffering from corrosion due to failure of the original coating.

Testimonials and case histories show that coating applications from 1968 at a Swiss waste water treatment plant are still intact well into the 21st century – despite a lifetime of exposure to aggressive waste products.

Other case studies include:

  • Use by the Royal Netherlands/UK and US Navies as well as the Australia Submarine Corp, and approved by the Royal Navy Institute of Naval Medicine. It went through vigorous and expensive trials with the US Navy.
  • Significant use on the Panama Canal.
  • A massive floating dock in Western Australia used for dry docking submarines and other vessels.
  • Being used offshore in the splash zone of a gas platform in an environmentally sensitive area.
  • An application in Swiss rail tunnels to coat over oily concrete.
  • Pile coating in regions as geographically diverse as New York Harbour, the Middle East and Taiwan where the product has proven its durability and ease of use in all environments.
  • On single buoy moorings where water jetting for surface preparation allows coating on wet surfaces.
A demonstration at the Australian Oil & Gas Expo of Alocit being applied under water.

The product also has UK environmental approval for bund coating.

Along with high performance the coatings are easy to use and environmentally safe. With no volatile organic compounds or heavy metals, they are as effective and safe underwater as they are on dry land. The product can be applied almost anywhere: floors, walls, bunds, tanks, bilges, tunnels, marine structures, sheet and round piles, under-decking, lock gates, bridges and water treatment plants. It resists hydrostatic pressure, bonds to fresh and pre-formed concrete and can encapsulate PCBs and other contaminants in old concrete.

The coating is available in a range of colours. Black, white and grey are available as standard, but other colours matching to international standards: US FED-STD-595, RAL, BS 36, BS 3800 are also available. Great resistance makes it ideal for salt water applications, sewage, petrol/gasoline, oil, a range of acids at various concentrations, sodium and potassium hydroxide solutions and more.

The Petronas Twin Towers in Malaysia were experiencing coating failure in gas line jointing flanges.

The coating can be applied using brush, roller or spray. Plural component or airless pumps can be used for spraying above water or power-brushing over large areas. It can also be applied underwater by brush straight from the container (as shown in video). It is safe to use in delicate ecosystems. It has no solvents or heavy metals and, once cured, is completely non-toxic (BS 6920), presenting no threat to marine life.

While the coating has a long and successful track record research and development is ongoing. Work is under way to enable its use in repairs using remotely operated vehicles, a project which follows on from work done in Europe on underground pipe repairs. A hand held dual unit applicator is also being developed for small sub-sea repairs and boat users.  Developments like these will add significantly to the product’s impact over the next 30 years.

Note: The opinions, beliefs, and viewpoints expressed in this article do not necessarily reflect the opinions of Subsea World News.

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