| |
Design Basics | Standards Update | AS/NZS 4680: 2006 Specification | Galvanized Reinforcement | Design Specification and Inspection | Bolting | Welding
AS/NZS
4680: 2006
Hot-dip galvanized (zinc) coatings on
fabricated ferrous articles
Standard Specification for Hot-Dip Galvanized Coatings
to be used in conjunction with the Australian / New Zealand
Standard 4680 and is designed for simple insertion into
specifiers' overall materials specifications.
SCOPE
This specification covers the after fabrication galvanized
coating applied to general steel articles, structural sections,
angles, channels, beams, columns, fabricated steel assemblies,
castings, threaded fasteners, steel reinforcement and other
steel components.
This specification does not apply to the galvanized coating
on semi-finished products such as wire, tube or sheet galvanized
in continuous, semi-continuous or specialised plants.
GALVANIZING
All articles to be galvanized shall be handled in such
a manner as to avoid any mechanical damage and to minimise
distortion.
Design features that may lead to difficulties during galvanizing
should be pointed out prior to dipping.
Galvanizing parameters such as galvanizing temperature,
time of immersion and withdrawal speed shall be employed
to suit the requirements of the article.
The composition of the zinc in the galvanizing bath shall
not be less that 98.0% zinc.
COATING REQUIREMENTS
Thickness
The thickness of the galvanized coating shall conform with
Table 1 and Table 2 in AS/NZS 4680:
TABLE 1.
|
REQUIREMENTS FOR COATING THICKNESS AND
MASS FOR ARTICLES THAT ARE NOT CENTRIFUGED
|
Article Thickness
mm |
Local coating thickness
Microns
|
Average coating thickness
Microns
|
Average coating
mass
g/m2
|
| 1.5mm or less |
35
|
45
|
320
|
| Over 1.5 to 3mm |
45
|
55
|
390
|
| Over 3 to 6mm |
55
|
70
|
500
|
| Over 6mm |
70
|
85
|
600
|
|
TABLE 2.
|
REQUIREMENTS FOR COATING THICKNESS AND
MASS FOR ARTICLES THAT ARE CENTRIFUGED
|
Article Thickness
(incl. castings)
mm |
Local coating thickness
Microns
|
Average coating thickness
Microns
|
Average coating
mass
g/m2
|
| Less than 8mm |
25
|
35
|
250
|
| 8mm and over |
40
|
55
|
390
|
|
The thickness of the galvanized coating shall first be
tested by the purchaser/designer at the galvanizer's works,
using an approved magnetic measuring device. In the event
of any dispute, an independent test shall be carried out
in accordance with AS/NZS 4680, Appendix G.
Surface Finish
The galvanized coating shall be continuous, adherent, as
smooth and evenly distributed as possible, and free from
any defect that is detrimental to the stated end use of
the coated article. On silicon killed steels, the coating
may be dull grey, provided the coating is sound and continuous.
The integrity of the coating shall be determined by
visual inspection and coating thickness measurements.
Where slip factors are required to enable high strength
friction grip bolting, where shown, these shall be obtained
after galvanizing by suitable mechanical treatment of
the faying surfaces.
Where a paint finish is to be applied to the galvanized
coating, this should be advised at the time of order
and all spikes shall be removed and all edges shall be
free from lumps and runs.
Adhesion
The galvanized coating shall be sufficiently adherent
to withstand normal handling during transport and erection.
|
