«Two complementary techniques for metal protection»


Known as the DUPLEX SYSTEM (GALVANIZED + POWDER COATED), the combination of two corrosion protection systems that complement each other:

  • Galvanised coating
  • Paint coating

The system consists of hot-dip galvanising the steel before applying a layer of powder coating.


Galvanised coating

Hot-dip galvanising is a corrosion protection procedure for materials and items made of iron or steel, which consists of dipping them into a bath of molten zinc. During this process, protective zinc coatings and zinc alloys are formed on these materials, which adhere perfectly to the base substrate through metallurgical bonding.

Paint coating

In the powder coating process, powder paint is especially developed to provide high corrosion and UV resistance as well as great mechanical strength.

The duplex system is generally used where more effective corrosion protection is required.

The most common examples are in building, urban furniture, road equipment, and chemical and electrical industries.

DT = K (DZn + DP)

DT = Total duration of galvanising + powder coating
DZn = Duration of galvanised coating
DP =Paint duration
K = A constant

The synergistic effect, the value of the constant K, can be quantified between 1.3 and 2.5 depending on the paint system and the environmental conditions to which the system is exposed.

Applicable standards

Industrial application of powder organic coatings to hot dip galvanized or sherardized steel articles [duplex systems]. Specifications, recommendations and guidelines.

Process applied based on European quality mark QUALISTEELCOAT

Paints and varnishes. Corrosion protection of steel structures by protective paint systems. Part 5: Protective paint systems. (ISO 12944-5:2019).

Hot dip galvanized coatings on iron and steel articles. Specifications and test methods. (ISO 1461:2009)

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