Sapa Group

Aluminium extrusions
– perfectly suited to marine and offshore applications

In marine and offshore applications, aluminium is the ideal material to cope with heavy loads and hostile environments.
Just one third of the weight of steel, with far lower maintenance costs, it’s also 100 per cent recyclable. Most importantly,
it’s durable, strong and highly corrosion resistant.

The lightweight material that saves time and cost

By reducing weight, aluminium reduces transportation costs. It also saves time and cost in installation and decommissioning.
Further savings come because of the metal’s low maintenance qualities, and its resistance to corrosion, and because it
has a considerably longer lifetime than steel applications. Extremely versatile, aluminium adapts easily into any design, and
offers a smooth surface finish. So it’s well suited to many marine applications, and is used widely throughout the industry

Through pioneering research and development, aluminium specialist Sapa extrudes this remarkable metal specifically
to meet the demands of offshore and marine construction. Working with clients to create and supply machined, preassembled
and finished components to their precise requirements, its latest alloys offer even greater structural strength
for shipbuilders, all in accordance with established international marine society certifications. Aluminium also has a lower
environmental impact – for example, less painting or removal of old paint; fewer transported kilograms, and easier of
decommissioning and recycling.

Fire protection

Both aluminium and steel are non-combustible and do not burn. However, aluminium conducts heat more effectively than
steel, which assists in the dissipation of heat during a fire, and allows rapid boundary cooling of exposed structures. In areas
where special fire classes (such as A60) are required, Sapa applies protective materials, including mineral wool or ceramic
fibres. Even with the additional weight of the protective insulation, and any active fire suppression system that may be
required, the aluminium structure is still far lighter than steel.

5083 series – the new alloys for marine-grade extrusions

To meet the specific demands of the aggressive marine environment, Sapa is continuously developing new alloys. The
latest, the 5083 series, is highly resistant to corrosion in salt-water, so particularly suited to applications in the waterline
area. It also offers higher weldability and predictable post-weld strength, and extruded sections maintain their flatness.
They meet the stringent technical requirements for naval marine hull structure applications – with extrusions and panels
as required by DNV-GL and ABS.

For the production of the panels, Sapa uses Friction Stir Welding (FSW), a technique that uses a rotating tool to join flush
metal surfaces. The pressure and heat help to form a new, homogenous structure. Compared with melt welding, FSW
provides greater strength and less deformation. It also produces an entirely non-porous product, with sealed joints flush
with the flat surface.

In addition, FSW is an excellent technology for replicating products. Sapa friction stir welds and machines some of the
longest and widest aluminium panels in the world, and joins them into larger panels, maintaining superior tolerances
without sacrificing strength.

More about Sapa’s marine expertise

resources. In particular, the ability to produce large profiles and – through FSW – extruded panels, is making a huge difference to many marine businesses. For example, extruded decking profiles up to 320mm wide, structural profiles with a circumscribing circle diameter up to 290mm, and friction stir welded panels up to 18,000mm long x 3,500mm wide. These are major innovations that make the benefits of aluminium even more valuable in a highly challenging field.