New Standards in HDG from Galvanizers Association

Changes to AS/NZS 2312 on Hot Dip Galvanizing

The new Part 2 of the AS/NZS 2312 Standard on hot dip galvanizing (HDG) allows designers to more accurately estimate the durability of HDG coatings whilst providing detailed specification advice for duplex coatings, the effect of the steel chemistry and illustrating good design practice.

As such, it will serve as an essential aid for engineers, architects, specifiers and consultants for many years to come.

AS/NZS 2312, Guide to the protection of structural steel against atmospheric corrosion by the use of protective coatings, originated in 1967 as a guide for steel designers on methods for the corrosion protection of structural steel. The previous revision (2002) incorporated much information on the common methods of corrosion protection, including paint, HDG, thermal spray, powder coating and wrapping systems.

Unfortunately the complexity of designing and specifying protective paint systems meant that much of the useful HDG information was lost in the detail of the other systems.

During the process of reviewing the old Standard it was recognised that steel designers would benefit by separating it into product-specific sections to avoid confusion. The revised Standard was released in December 2014 in two parts, covering paint systems and HDG with both using the same definitions from AS 4312 for corrosivity categories in Australia, but now clearly recognising that the design process and durability of the two products are very different.

Designers wishing to specify batch galvanizing need only use two Standards; one covering the design and durability of HDG steel (AS/NZS 2312.2) and the other dealing with the manufacturing process and tolerances (AS/NZS 4680).