Durability in Corrosive Environments

Installation of galvanised steel sections that may be subject to excessive exposure to chlorides (salt) are at risk of detrimental corrosion attack (rust). Such environments may include coastal areas near rough seas or in close proximity to breaking surf, areas inland from the coast that are regularly subject to high winds, areas located within 100 metres of calm waters, and other harsh corrosive environments in general, such as chemical plants or areas subject to acidic spray (brick cleaning).

A few basic principles to follow in such circumstance to minimise the risk of corrosion:

• Wall and ceiling framing should be lined as soon as possible after installation
• Corner beads and set bead finishing sections in general have minimal galvanised coating, and such sections should be installed and immediately finished with setting compound (within 24 hours)
• Exposed finishing sections such as reveal beads, metal access panels and EzyJamb door frames should be coated in an anti-corrosion primer immediately after installation if the building envelope in not sealed
• Even though hardware such as RocYork door hinges are made from stainless steel, they are specifically designed for internal use only. Install such hardware only once the building envelope has been completely sealed from the external environment
• Where it is not possible to install lining materials on framing or finish the set beads for an extended period, a suitable protective coating should be applied to the exposed sections
• Protective coatings should consist of a two-pack process, such as zinc phosphate primer and high build topcoat (epoxy, fluoropolymer, polyurethane, etc). Seek professional advice from a protective coatings supplier
• Where a protective coating has not been applied to the framing sections and an extended period has passed before lining occurs, all framing sections should be carefully inspected before lining to determine if corrosion has occurred
• Remove moisture from sections before lining
• Do not store materials on site for extended periods
• Inspect all sections prior to installation and do not install if corrosion is present. Applying paint to corroded surfaces may not stop the corrosive process and may result in latent defects
• After cutting galvanised steel sections, ensure that all swarf and cutting dust is removed from the section to be installed
• If in doubt, seek professional advice from a qualified Corrosion Engineer

For installation of galvanised framing at indoor swimming pools, indoor feature fountains or other indoor aquatic environments, please contact Studco for specific advice.

Studco products are manufactured from coated steel in compliance to AS 1397:2021 Continuous hot-dip metallic coated steel sheet and strip – Coatings of zinc and zinc alloyed with aluminium and magnesium.

Further suggested reading:

AS 4312:2019 Atmospheric corrosivity zones in Australia – Published by Standards Australia

ISO 14713-1:2017 – Zinc coatings – Guidelines and recommendations for the protection against corrosion of iron and steel in structures – Part 1: General principles of design
and corrosion resistance – Published by the International Organization for Standardization

Durability Design of Steel Framing in Residential & Low-Rise Construction
– https://www.nash.asn.au/wp-content/uploads/2022/04/Durability-design-of-steel-framing-in-residential-and-low-rise-construction-Final-ASEC-2014_1411525018.pdf

Corrosion: effect of coating thickness – Bluescope CTB – 4 Technical Bulletin
– https://cdn.dcs.bluescope.com.au/download/corrosion-technical-bulletin-ctb-04-coating-thickness

Durability of Cold-Formed Steel Framing Members
– http://www.steelframing.org/PDF/sustainability/TN-D001-07.pdf

Tips to Select the Right Coating for Your Application
– https://www.aicoatings.com.au/tips-to-select-the-right-coating-for-your-application/

NASH Fact File 2 – Durability
– https://www.steel.org.au/getattachment/8a1c26ed-ca38-4246-a1ff-ecfb0e4330db/NASH_2007FactsheetsNo2-Durability.pdf

Durability & Liability
– https://www.steel.org.au/getattachment/f6e179b7-0ac4-4405-94c9-d85e3b3f5193/Durability-and-liability_CM_Nov_2008.pdf

If you have any questions regarding the risk of corrosion or require additional information, please contact Studco’s Technical Team on 1300 255 255.