Cart
Coatings for the marine industry
A short round-up of the latest trends concerning marine coatings, and the most optimum spraying methods
Two specific trends are relevant to today’s marine coatings industry.
1. The rise of high-performance coatings
The market for high-performance anti-corrosion coatings is booming. It is expected to grow at a CAGR of 4.8% between 2015 and 2023 to reach a value of US$18.22 billion. These innovative coatings provide a barrier against corrosion for substrates that are frequently subjected to the harsh corrosive conditions frequently experienced in marine environments. In terms of demand, epoxy coatings account for over 55% of the global high-performance anti-corrosion coatings market. However, acrylic coatings is the fastest-growing product segment.
Some of the latest products in this area use nanotechnology to create small protective particles that fill in all the microscopic surface imperfections and bond together. The result is a smooth finish over the tiny invisible holes and cracks that are present in even the cleanest, newest boats. The result is a smoother surface that prevents algal growth, and resists exhaust marks, oily streaks, glue residue and other dirt. They can also be used to protect upper deck surfaces from ultraviolet exposure and oxidization. Using these coatings reduces the need for cleaning, which saves maintenance time and costs.
2. Coatings for sub-zero conditions
In the harsh polar environments, temperatures can drop to well below -50°C. Special hull coatings are indispensable to improve a vessel’s performance in ice, maintain its speed, and also contribute to reducing fuel consumption and costs.
When applied to the hull, these special coatings reduce its roughness, reducing the chance of ice accumulation. Specialized coatings are also available which have significant resistance to ice abrasion and impact with icebergs. They are therefore beneficial to vessels such as icebreakers that are required to spend considerable time in ice-covered waters. Cruise ships are increasingly popular for Arctic and Antarctic voyages, so these also need to be coated with coatings for sub-zero temperatures.
The need for airless
By far the most important and efficient method for the application of heavy-duty marine coatings is airless spraying. It is used in around 99% of marine spray jobs. This is because of the chemistry of the paints, which are based on 100% volume solids, which requires high ratio pumps. Other reasons for airless are related to the large size of vessels, the vast areas to be painted, and the need to apply coatings at the correct thickness.
As the name implies, it is a technique of spray application which does not rely on the mixing of the paints with air to provide atomization. Instead, mixing is achieved by forcing the paint through a specially designed nozzle or ‘tip’ at very high pressures of around 175-245 bar.
This very high pressure is provided by a pump driven by an air motor. This pump unit requires a supply of compressed air (so the system as a whole is not airless). Pumps are available with compression ratios from 20:1 up to 60:1, which means that with an input air pressure to the motor of 5.6 bar, the maximum paint pressure at the gun would be 112 bar and 338 bar respectively. These are very high pressures, which means stringent safety precautions have to be put in place when using airless spray equipment.
A key component of an airless sprayer is the tip, which is usually made from tungsten carbide. It consists of an orifice, into the front of which is cut a V-groove or slot. Tips can be obtained with different orifice diameters and slot angles, and the tip must be chosen according to the properties of the paint, the required wet film thickness per coat and the shape and contours of the job.
Because of their small size there are often problems with the tips becoming blocked. In the past this necessitated taking the tip off the gun and cleaning it out, but now it is possible to use a reversible tip. This can be turned through 180° while still attached to the gun. This enables a burst of paint to force out any obstruction in the tip.
Tips will wear, especially when using abrasive paints such as zinc silicates or micaceous iron oxide pigmented materials. It is therefore important to check that wear is not excessive. High paint usage or poor atomization can often be due to a badly worn tip.
Graco’s airless sprayer for the marine industry
Graco’s King® airless sprayer product line has been in use for over 60 years. In that time it’s been the number one choice for many companies involved in protective coating applications. It’s appreciated for its dependability and durability to handle the toughest protective coatings. The King has recently been revamped to reduce icing potential and deliver low pulsation for improved performance.
For example, thermally isolated poppets are insulated from motor castings that can often drop below freezing temperatures. The newly designed poppets and external pilot lines virtually eliminate pilot valve freezing that can result in an instant stop.
Graco has also completely redesigned the poppets to improve reliability and sealing. There’s no internal sealing that can’t be visually inspected. The passages are also much larger making them more reliable and easier to service, troubleshoot and replace.
Customer feedback for a smoother changeover and no pressure drops has been incorporated in the King. Compared to NXT™ motors, a 145% higher intake/exhaust capacity in the air valve leads to a faster, smoother changeover, eliminating those annoying minor blemishes in the finish.
Graco’s powerful new air motor lets you use multiple guns with almost no perceivable pulsation. A new manifold has been designed to simplify the installation of multiple guns. With more powerful and efficient changeovers, the ability to spray with up to six guns is now possible.
The King airless sprayer incorporates the MaxLife® pump Lowers, which is designed for robustness and reliability in the most demanding jobs. It lasts up to six times longer than its predecessor. Key features include the exclusive MaxLife sleeve rod, long-life ceramic balls (optional) for maximum versatility no matter what’s being sprayed, and a standard 2-line outlet.
The King is available with an XL3400, XL6500 and XL10000 motor. Output per cycle varies between 180 cc and 430 cc; output at 60 cycles per min varies between 11 and 25.5 liters per minute. Maximum working pressure is 500 bar.
CONTACT YOUR MARINE SPECIALIST
Graco has a long-term commitment in delivering high-quality products for heavy-duty applications in very demanding environments such as those experienced in the marine industry. For more information on the products that Graco provides to the marine industry, Louis de Hillerin at louis.de.hillerin@graco.com.
Related Products
Related Articles
Graco: Highly active globally in the marine sector
Graco provides a wide range of products and services to the marine industry worldwide. Discover 5 examples of Graco products that are providing value for some of Graco’s marine customers.
On-board maintenance solutions for the maritime industry
Whether you’re a fleet owner or a ship chandler, keeping up-to-date with the latest developments in on-board maintenance is essential.
Graco strengthens its marine capabilities
It’s “all hands on deck” at Graco as the company further strengthens its position as a major global supplier of marine maintenance services. Louis de Hillerin, Manager Marine Division, explains more.
