01st December 2020
The ISO 12944-2 is a British standard that specifies the corrosion protection of steel structures by protective paint systems. It offers guidance for classifying the principal environments to which steel structures are exposed and the corrosivity of these environments.
The ISO 12944-2 is in place to offer guidelines for protecting steel structures such as fences, posts, gates and other components. Unprotected steel in the atmosphere, water and soil are subject to corrosion which can cause damage. To avoid this corrosion, steel structures are usually protected to withstand corrosion stresses. There are different ways of protecting steel structures, but ISO 12944-2 looks at protection via paint systems and covers.
Atmospheric corrosion can occur on metal fences and railings. It is a process that takes place in a film of moisture on the metal surface. The guide uses a corrosion chart to measure and classify corrosion, ranging from C1-C5. The corrosion rate is increased by increased humidity, condensation, and an increase in the amount of pollution in the atmosphere. Structures in the open air are also exposed to climatic parameters and pollutants such as aerosols. This is why outdoor fences are at particular risk of being corroded.
The ISO 12944-2 has been designed to provide information for those who work with steel structures and protective paint systems. This includes owners of structures, consultants, planners, inspectors, companies carrying out the work and manufacturers of coating materials. The standard has been written to give this information in the form of a series of instructions.
The ISO 12944-2 classifies atmospheric-corrosivity categories based on mass loss by standard specimens. It describes natural atmospheric environments that steel structures may be exposed to and gives guidance on the estimation of how corrosive they are.
The standard also provides details on special corrosion stresses that can increase the corrosion rate or put pressure on the performance of the protective paint system. In addition, it describes different categories of environment for structures in water or soil.
Metal fences are exposed to the elements and can therefore be easily corroded. Therefore, measures should be taken to prevent this from happening and prolong the fence’s life. Paint protective systems and powder coatings give extra protection against corrosion and rusting. The metal is covered with a polyester or epoxy powder with a powder coating, which is then heated to fuse a protective layer. This offers protection against rusting and degradation. The ISO 12944-2 is important for manufacturers to follow as it ensures that any fencing produced meets British guidelines in materials used, processes carried out and health and safety requirements.
All Zaun posts/panels/gates and painted auxiliary components (for example, clamp-bars, slide bolts etc.) benefit from a protective zinc layer and electrostatically applied polyester powder coating to BS1722 p16. Care is taken with pre-treatment to ensure sound adhesion between the zinc and paint layers. In a UK C1 environment, as defined in ISO 12944 p2, this should ensure a useful life expectancy of the fence of at least 15-20 years. Life expectancy in all environments can be extended by maintaining the fencing with regular washing. Useful life will be reduced if the fencing is damaged. Any coating damage should be repaired to reduce the effect on useful life.
Enhanced painting systems such as marine coatings are also available for improved life expectancy in C2-C5M environments.