Peter Golding, CEO, Galvanizers Association of Australia
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 who needed advice on methods for the corrosion protection of structural steel. The last revision (2002) incorporated much information on the common methods of corrosion protection, including paint, hot dip galvanizing, thermal spray, powder coating and wrapping systems. Unfortunately the complexity of designing and specifying protective paint systems meant that much of the useful information on hot dip galvanizing was lost in the detail of the other systems.
During the review process, 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; with Part 1 covering paint systems and Part 2 covering hot dip galvanizing (HDG). Both new parts use the same definitions from AS 4312 for corrosivity categories in Australia and Table 14 of NZS 3404.1:2009, but now clearly recognise that the design process and durability of the two products are very different.
Designers wishing to specify HDG 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).