After nearly two decades, the standard for galvanized coatings has been rewritten to match the design requirement of today.
Laser-cut steels and faster fabrication lines are revolutionising how we build. But the Standards governing corrosion protection haven’t kept pace. Now, AS/NZS 4680 – the benchmark hot dip galvanized coatings on fabricated iron and steel articles – has undergone a top-to-bottom rewrite.
Whether you’re designing structural steel, specifying galvanized rebar, or working with next-gen low-reactivity alloys – the new Standard codifies best practice for engineers to fabricators and galvanizers.
AS/NZS 4680 is referenced in over 60 Australian Standards, from electrical and structural work to plumbing, water, fire safety and residential housing, said Peter Golding, CEO of the Galvanizers Association of Australia (GAA).
“It’s critical that engineers are aware of any changes to Standards,” he said. “But it’s also critical that we keep those Standards relevant to modern design.”
An essential rewrite
AS/NZS 4680 hasn’t undergone an update in almost two decades. And any guideline that hasn’t transformed within that time frame becomes tired, Golding said.
“People’s interpretations of words change over time,” he added.
On top of that, global galvanizing Standards, which local Standards are historically aligned with, have been revised twice in that time. So to maintain both international alignment and local relevance, the Standard required a rethink.
“We needed to realign the Standard to the extent that we could to improve clarity, reduce misunderstanding and meet our international obligations,” Golding said.
Across the manufacturing industry Australia has a strong history in standardisation which has over time helped to ensure quality and safety in design and fabrication processing, said Monique English, Engagement Manager at Standards Australia.
“The importance of standardisation is central to the industry’s commitment to safety and quality,” she said.
“Innovation regarding the hot-dip galvanized (zinc) coatings on fabricated ferrous articles relies on the safe application of standards, and particularly their technical application.”
Measurable results
Among the most impactful updates to the Standard is the introduction of a mandatory acceptance inspection method, bringing a new level of objectivity to compliance.
“It involves documented statistical sampling that is clear to the users as to what constitutes acceptance,” Golding said.
“How you go about measuring the coating thickness of the galvanized steel to determine whether it meets the Standard is absolutely clear and has a defined step-by-step process so anyone can do it.”
In the previous Standard, coating thickness could be measured using several vague or inconsistent methods. The revised approach removes doubt, enabling verifiable, repeatable testing.
“But it’s critical that the fabricator provides the galvanizer with steel test certificates to understand the nature of the steel they’re galvanizing which will reduce conflict after the event,” he said.
For engineers designing to AS/NZS 5131, it’s not essentially an additional requirement. “But it is an additional requirement to provide that information to the users,” Golding added.
Accounting for modern steels
The rise of ultra-low reactive steels, such as laser plate steels, introduced a new challenge. These materials, prized for their precision and processability, have special chemistries which make them less reactive in the galvanizing process.
The new Standard addresses this via adjusted coating thickness requirements for these modern materials.
“The vast majority of uses for those steels are what we’d call ancillary elements, so they’re not critical to the corrosion protection,” Golding said.
“But because their coating thickness is naturally lower, we needed to define the coating thickness requirement for those products related to the steel they are supplied to.”
The new galvanized coating thickness requirement is relatively easy to achieve through blasting the steel, referenced in a new appendix in the Standard.
“This provides an equivalent durability to normal steels for ultra low-reactive steels, or a thicker coating on any steel if increased durability is desired,” he said.
Another change around the coating thickness for all steels is clarification of the appearance requirements.
“There’s no technical change but we’ve essentially made it really clear what the appearance requirements are for acceptance inspection,” he added.
Rebar gets clearer guidance
A new appendix for galvanized rebar has also been included in the updated Standard, closing the gap between AS/NZS 4680 and the rebar Standard AS/NZS 4671. While the latter defines performance expectations, it previously lacked guidance on proving conformance for galvanized steel. The new appendix offers practical advice on specifying galvanized rebar with confidence.
“While AS/NZS 4671 allows galvanized rebar it doesn’t provide any information on what would be required to show conformance to that Standard,” Golding said. “So we’ve included a simple appendix which takes the requirements from AS/NZS 4671 and shows how a specifier can govern the steel they’re purchasing.”
Clearer roles for designers and galvanizers
Another major shift in the new Standard is the removal of design and durability requirements from AS/NZS 4680. These are now housed entirely within AS/NZS 2312.2, a design and durability Standard that provides essential guidance for preparing components – including information on venting, draining, heat effects, the impact of steel chemistry on coating thickness, and duplex coatings.
While AS/NZS 4680 outlines the galvanizing process, it does not function as a design guide, underlining the importance of using the appropriate Standards in tandem.
“A designer of steel to be galvanized could just look at that Standard and say, ‘These are the things I need to know about,’” Golding said. “Whereas the galvanizer uses AS/NZS 4680 to make sure that their parts will meet the design requirements given to them.”
This distinction between the engineer’s role in material selection and the galvanizer’s role in applying the protective layer helps clarify responsibilities, ensuring each party focuses on what they do best.
For an introduction to the new Standard, read the Galvanizers Association of Australia Advisory Note, available here.
