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Steel performs in African coastal conditions

The use of aluminium-zinc coated steel as a practical cladding material is gaining popularity along the coast of Africa.

Bounded by three oceans and the Mediterranean Sea, Africa has a vast coastline of 26 000km. Its deep rivers and natural ports have been historically important trading hubs and remain as vibrant nodes of urban settlement and business.

The populations of this vast coastline are blessed with abundant natural materials for building, but increasingly, as new infrastructure development booms, the use of metal as a practical, durable cladding material is taking off.

The Safal Group is the sole licensee of aluminium zinc coating technology in Africa and sells its coated steel sheeting along 12 000km of this coastline, down the eastern seaboard from Djibouti to South Africa in the extreme south, and up westward to Luanda in Angola.

All coated steels are not the same

Steel plays a huge role in development, but it does have an inherent weakness – when used unprotected and exposed to the environment, it rusts and corrodes. To extend the service life of steel, it is generally protected with a corrosion-inhibiting coating.
The two most commonly used coatings to protect steel are:

  • Aluminium zinc coating (AZ) – aluminium and zinc.
  • Galvanised coating (GI) – zinc.

The addition of aluminium to zinc in the coating alloy extends the service life of a steel roof by up to four times that of galvanised steel.


Comparison between AZ and GI coatings:

AZ coating

GI coating

Superior corrosion resistance:

Aluminium offers barrier protection.

*AZ 150 after 240 hours of salt spray testing – no signs of deterioration

Medium corrosion resistance:

Zinc offers sacrificial protection.

*Z275 after 240 hours of salt spray testing – signs of red dust appear.

Excellent heat reflectivity:

Roofing applications: Creates a cooler internal temperature in summer and a warmer temperature in winter due to reflection

Moderate heat reflectivity:

Due to low reflection values, the head loss is greater, creating a hotter internal temperature in summer and a colder temperature in winter

Heat resistance:

AZ can reach temperatures of up to 315°C before discolouration

Heat resistance:

GI can reach temperatures of up to 480°C.

Product can be used up to 400°C before discolouration

Source: BIEC International Inc., licensors for aluminium-zinc coating technology used by Safal Steel and other Safal Group coating mills in Africa

Made for Africa’s coastline

Aluminium zinc coating technology, developed in the 1960s in North America, enabled coated steel to deliver a service life of decades, even in aggressive coastal conditions. This development revolutionised the metal cladding industry, and is today the most widely used coating technology worldwide.

In Africa this coated steel is branded ZincAL and its factory colour-coated derivative is called ColorPlus, produced in Africa at three coating mills owned by the Safal Group.

The thicker the coating, the longer is the resistance to corrosion and the longer the life of the protected steel substrate, and a coating of 54 microns on ZincAL Ultima gives it corrosion-proof performance credentials which are suitable for coastal areas where only aluminium sheeting was previously specified.