When it comes to ensuring the longevity and durability of galvanized steel, the comparison between batch hot dip galvanized steel and pre-galvanized coatings reveals a clear winner. Batch galvanized steel, adhering to the Australian Standard AS/NZS 4680, surpasses any commercially available pre-galvanized coating, including those meeting AS 1397 specifications, in terms of durability. This superiority is acknowledged in AS/NZS 2312.2, which serves as the guideline for the durability and design of galvanized steel.

One of the key distinctions lies in the thickness of the coatings. For steel less than 1.5mm thick, the minimum batch galvanized coating thickness is typically 45 µm, whereas the thickest pre-galvanized coatings available commercially cap at a Z450 designation, equating to an average thickness of just 31 µm. This difference becomes crucial in environments where corrosion resistance is paramount.

While pre-galvanized materials may be suitable for applications in low corrosivity environments (C1 and C2 categories) due to their satisfactory durability, they fall short in more demanding conditions. The option to batch galvanize pre-galvanized materials without necessitating design or material changes offers a great solution. This process not only enhances durability but also ensures complete protection of cut edges, a common failure point in pre-galvanized materials.

For instance, these cable tray items initially featuring an 8 µm thick pre-galvanized coating saw an increase to 56 µm after batch galvanizing, significantly boosting their corrosion resistance without any additional requirements from the cable tray manufacturer. Although batch galvanizing might result in a somewhat rougher surface, the trade-off is a substantially longer lifespan and improved corrosion resistance. In a C3 environment, for example, these pre-galvanized coatings might offer around 6 years of protection, whereas batch galvanized coatings can extend this to 40 years.

Therefore, for applications requiring superior corrosion protection and adherence to Australian Standards, the choice is clear: batch hot dip galvanized steel is the optimal choice. This not only ensures compliance with AS/NZS 4680 but also guarantees a level of durability and longevity that pre-galvanized materials cannot match. For further insights into the durability of galvanized coatings, exploring our additional resources and expert analyses can provide valuable guidance.