Saving weight can be a priority on board commercial ships and naval vessels. The designers of cruise ships, ferries, offshore support vessels and tugs often face weight constraints, but for military vessels, weight minimisation is always an important objective.
However, there has often been a compromise between lightweight coatings and cost. Now, two of the specially formulated lightweight coatings from AkzoNobel’s International® range have gained US Navy approval. These coatings are designed to combine all of the best features for exterior and interior decks with dramatic weight savings. The coatings offer an innovative new option both for commercial ships and Navies.
Both products, which can be used during new construction or at maintenance and repair, exceed the requirements set out in US Navy Military Specification standards and have recently been granted approval for their respective applications.
Intershield 5150LWT is a low solar-absorbing, high durability, lightweight, epoxy non-skid deck coating resistant to fuel and chemical damage from aircraft and vehicles. Together with the appropriate primer, the system has excellent anti-corrosive performance. It is the first approved non-skid coating that can be used for both ‘General’ deck areas and ‘Landing’ deck areas on board aircraft carriers. Since Intershield 5150LWT systems can be applied as an anti-corrosive epoxy non-skid deck coating in general areas, landing and run-out area coating system, it has the benefits of easier one coating type system maintenance and less complex sea stores management on-board.
Intershield 5150LWT is a low absorption coating which results in less heat from the sun passing through decks to spaces below. This cuts the load on air-conditioning units and saves energy. It also creates improved working conditions for ships’ crews and a better operating environment for sensitive electronic equipment.
The most important characteristic of Intershield 5150LWT, however, is its light weight. It offers a 25% saving in weight over existing non-skid coating Intershield 6GV and is 60% lighter than the requirement set out in the MIL-PRF-24667 standard. Intershield 5150LWT has a low volatile organic compound (VOC) rating and was granted US Navy approval to MIL-PRF-24667 Type I and Type II; Composition G and Composition L categories in November 2015.
It is therefore approved as a standard- and high-durability rollable deck coating and can be applied as an abrasive deck system in all areas that receive a non-skid deck coating.
Intershield 5150LWT is coloured dark grey (FS Color 36076) and is packaged in a six-gallon kit. It has a spread rate of one US gallon per 20-30 square feet and a drying time of 12 hours at 73ᵒF (23ᵒC)
Intershield 7100LWT is an ultra-lightweight self-levelling epoxy underlayment, with zero VOC, which can be used with or without primers as a primary interior coating either at new construction or for levelling uneven decks during maintenance and repair. Principal applications for this coating include the underlayment for non-skid exterior decks, and internally for mess areas, berthing spaces, passage-ways, galleys and wet areas including showers and heads.
Intershield 7100LWT can reduce weight by almost 60%. It has received US Navy approval to the MIL-PRF-3135 Type III, Class 2, Grade B standard with a content weight less than one pound per square foot at a thickness of one quarter inch, or 0.5kg per 100 square centimetres at a thickness of 64 millimetres. The coating requires little secondary surface preparation and can be top-coated with a range of products including tiles and carpet.
The shiny coating is applied with squeegees or notched trowels directly to metal surfaces and does not require a primer. In addition to its zero VOC content, benefits include long-term corrosion protection, resistance to fuel and chemicals, self-levelling properties for easy application, suitability for shipboard areas subject to water, and no over-coating requirement.
Weight savings are important for ship designers over a range of commercial and naval vessels. Cruise vessels, Ro-Ro’s, fast ferries, offshore support vessels and tugs are amongst the merchant ships and workboats in which structural weight can be a design constraint. Less weight in a ship structure can facilitate the carriage of more cargo and/or reduce through-the-water resistance, adding speed, saving fuel and reducing CO2 and other emissions, including particulate matter, or a combination of both.
In a military context, lighter decks save structural weight, adding to speed, reducing fuel consumption and potentially enabling the carriage of more armament. The use of Intershield 5150LWT non-skid coating on the entire flight deck of an aircraft carrier, for example, would save 22 tons, equivalent to one additional aircraft or significant volumes of additional munitions.
The fact that both of these products have successfully completed the rigorous US Navy approval process demonstrates that their formulation is both robust and fit-for-purpose.