Hunter’s paint job uses specialty products that will protect each ship from the harsh marine environments in which they will operate.
“The Blast & Paint (B&P) process is very intricate and is one of only a small number of trades involved in all stages of construction,” B&P Integrated Work Team Manager Simon said.
Blast & Paint preparation
The Hunter Class Frigate Program operates on a steel in, ship out methodology. This means that when the steel first arrives at the Osborne Naval Shipyard, the B&P team coordinates with subcontractor Eptec to make sure each piece receives a primer. The coating adds a layer of protection for the early stages of construction and, if needed, so it can be stored outside for a length of time.
Once the steel plates and profiles are fabricated into units, the segments are welded into blocks (with one to seven units making up a block and each frigate being comprised of 22 blocks). These blocks, some of the largest weighing hundreds of tonnes, are transported into Building 18 — the B&P chamber.
“Prior to being moved, each block is pressure washed to remove any contaminants like oil, grease and salt from its surface. It’s crucial blocks are as clean as possible before entering the B&P chamber. It could lead to big issues later on if they’re not addressed right away,” Simon said.
How to paint a frigate
Inside Building 18, blocks are blasted with steel grit — a process that creates specific anchoring patterns on smooth materials to maximise coating adhesion — to achieve a specified surface profile. Depending on the block’s size and its location on the ship, this process can take weeks to months and involves a combination of spray guns, rollers and brushes with a variety of different paint types, including anti-fouling that reduces marine life growth on the hull.
“Around 80% of the frigate’s paint has already been applied to the blocks when they leave B&P for final consolidation. After this, there’s still a lot of welding that takes place connecting blocks together to form the ship and the final paint is applied during outfitting,” Simon said.
B&P Coordinator Ben said that Hunter’s B&P process is done indoors compared to other shipbuilding programs.
“Traditionally, ships are built outside, and a one-time garnet blast product is used. The Hunter Class Frigate Program employs a steel grit recycled system in Building 18 and a steel shot and grit mix at the Surface Treatment Line. This minimises performance loss,” Ben said.
“Having the process take place in a controlled location at optimal times during construction reduces costs and is more efficient working within the schedule.”
The Blast & Paint craft
Both Simon and Ben agree that B&P is a highly skilled, niche trade that underpins the success of shipbuilding programs.
“Hunter’s build strategy means blocks are constructed in a certain order to streamline the consolidation sequence as much as possible,” Simon said.
“Each block comes in different shapes and sizes and have different requirements that all need to be considered from a B&P perspective.
“My team and I get involved early with the wider program teams to coordinate B&P activities. While we plan down to the finest details, we can adjust our work efforts when needed as well.”
Ben added, “Ocean environments will challenge these ships over their lifespans, making it all the more critical that this B&P process is done correctly the first time around.
“We use epoxy, polyurethane, waterborne acrylic and other paint types and depending on the application, multiple coats could be required for items in blocks like with tanks, bilges and in wet areas.
“Sometimes there are areas within blocks that are small, restricting spaces that a spray gun just can’t reach. In these situations, a fine brush with a steady hand is the best thing to get the job done.”
The first-of-class frigate, NUSHIP Hunter, is under construction and the build program is delivering a world-class anti-submarine warfare capability for the Royal Australian Navy.