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Construction
Forgebar grating is constructed of Load Bearing Bars in
various depths and thicknesses with lateral restraint provided by
6mm square twisted Cross Bars forge welded to the upper edges of
the Load Bearing Bars. This process produces a product of
one piece construction with a high strength to weight ratio which
meets the requirements of Australian Standard 1657 - 1992 and
British Standard 4592 - 1970.
Material
The Load Bearing Bars in Forgebar gratings are manufactured from
steel that complies to the following equivalent standards:
AS 1594-H250
AS 3679-250
Forgebar Product Coding
| A |
S |
30 |
32
/ S |
| Cross
bar stitching |
Optional
if serrated load bars are required |
Load
bar pitchings |
Load
bar depth / Nominal thickness |
Plain
Serrated
Forgebar serrated grating has been tested by a recognised NATA
laboratory for its co-efficient of friction and was found to be
equal or slightly better than similar local products.
More importantly, because of the unique method of manufacture, the
loss of load carrying capacity due to these serrations averages
less than 8%.
Design Criteria
The figures shown in all safe load tables have been calculated in
accordance with the following data:
- Loading Code AS 1170-1 load combination 1.25 x Dead
Load and 1.5x Live Load.
- Steel Structures Code AS4100-1990.
- Mass calculated with grating in an untreated and
unedged condition.
- Minimum yield strength of steel 260 MPa.
- Load calculated in accordance with an allowable
bending stress 171.6 MPa (0.66Fy).
- Load Bars are assumed simply supported and unserrated.
- Spans have been based on maximum of 5mm deflection
which is a limiting deflection for pedestrian comfort.
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Finishes
Forgebar grating is available in a
choice of three finishes:
1. Hot Dipped Galvanised
The hot dip
galvanising process produces a durable, abrasion resistant coating
of metallic zinc and zinc-iron alloy layers metallurgically bonded
to the steel base, at a bath temperature of 450C. Hot dip
galvanising conforms to the equivalent following standards:
Australian Standard AS/NZS 4680:1999
British Standard BS729 - 1971
American Standard ASTM-A123-73
2. Black Bitumen
Dipped
An economical paint finish which is best suited to indoor
installations, or mining applications in a dry climate.
Note: there is no pre-treatment of steel before
dipping. This finish is not recommended in corrosive areas.
3. Untreated (No surface treatment/protection)
Normally supplied on stock mats or panels to customers who wish to
perform their own fabrication on grating.
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