AS 2699.3:2020 pdf free.Built-in components for masonry construction Part 3: Lintels and shelf angles (durability requirements).
3.1 Material selection
Materials for lintels shall be in accordance with Table 3.1.
Determination of the coating thickness of hot-dip galvanized lintels shall be in accordance with Appendix A.
NOTE 1 The method set out in Appendix A for hot-dip galvanized lintels may be used for site inspection of an individual article or for inspection of a batch lot, such as supplied to a distributor, or for house lots. It may also be used to demonstrate the galvanized coating thickness for alternative solutions.
NOTE 2 The methods set out in Clause E.2 and Clause E.3 for identifying 304 and 316 stainless steel lintels may be used for site inspection of an individual article or for inspection of a batch lot, such as supplied to a distributor, or for house lots. If there is any doubt, the stainless steel lintels should be assessed by examination of the supplier’s test report or a laboratory as described in Clause E.5.
Additional decorative coats may be applied to a lintel. The additional coating shall be compatible with the substrate material, but shall not be considered for durability calculations.
NOTE 3 Information on painting hot dip galvanized steel is available in AS/NZS 2312.2. Information on suitable top coats for inorganic zinc silicate coatings is available in AS 2312.1. Information on painting stainless steel can be obtained from paint suppliers.
C3.1 (Clause) The corrosivity of the atmospheric environment affects the durability of lintels used in masonry. Appendix D sets out methods that may be used to develop a reasonable estimation of the atmospheric exposure for lintels. If the location of the structure has been defined according to AS 4312—2008, then the required durability class for lintels may be determined using Appendix D, subject to the in-service conditions described in Clause 2.4.4 being met.
Galvanized (zinc) steel is resistant to mild alkaline conditions, such as exists in the mortar used in masonry construction. Uncured mortar does attack galvanized steel, although this attack slows once the mortar is cured, and experience has shown the durability is not significantly compromised. The coating types in AS 1397 include the “AZ” and ‘AM” coatings, which contain significant amounts of aluminium. These aluminium-rich products are susceptible to ongoing rapid corrosion in mortar due to their high aluminium content and are not suitable for use when lintels are embedded in fresh mortar.
Inorganic zinc silicate paints, as described in AS 2312.1, are considered an acceptable design solution in environments up to and including R3 when applied to suitably prepared surfaces.
Stainless steel grade 304 may exhibit rust spotting (tea staining) and crevice corrosion over time, specially in environments where the lintel is exposed to chlorides such as in marine locations and where it remains unwashed. If appearance is critical, the lintel may be coated, a smoother finish may be specified or grade 316/316L may be specified.AS 2699.3 pdf download.