Fasteners - hdgasa

Duplex coatings
Two different bus shelter types at the fabricators plant, prior to hot dip galvanizing.
process and special care needs to be
taken not to damage the paint in any
way. If the paint is damaged the area
must be sanded and re-sprayed.
The base coat was an epoxy
galvanizing primer called Epoxy
Adprime 1 Base. The paint is supplied
with a catalyst to initiate the
hardening process and ensure that it
dries correctly. A galvanizing primer is
essential as it bonds to the galvanized
steel unlike other paints. In addition,
it prevents the paint from peeling and
it also prevents water from penetrating
the paint and accumulating
underneath, forming bubbles.
The next coat was an intermediate
coat called Umeguard SX Base. This
paint is also supplied with a catalyst
to initiate the hardening process and
The totem pole type of bus stop installed at
one of the sites.
ensure the paint dries correctly. The
intermediate coat is an epoxy resin
coating. The colour chosen for this
coat was a light grey although it was
originally going to be a red-brown. The
darker colour was found to be
problematic when the sun shone on
the final coat, as the intermediate
colour would show through. This was
obviously unacceptable, therefore the
decision to change the intermediate
coat to the light grey was made.
The final coat consisted of two
different colours, one colour for the
totem pole assemblies and the other
colour for the rest of the bus shelter.
The first items to be sprayed were the
totem pole assemblies. These were
sprayed with a paint called Uny Marine
Base, supplied with a catalyst to
initiate the hardening process and
ensure the paint dried correctly. This is
a polyurethane finishing coat with
long lasting gloss retention. It is highly
durable and is resistant to chemical
damage.
After the totem pole assemblies were
painted, the rest of the assemblies
were also sprayed with Uny Marine
Base in a dark grey colour. The final
coat for the shelters, excluding the
totem pole assemblies, gave a stonechip
effect finish. This top coating is
beneficial in more than one way. It
hides any slight imperfections in the
paint that would normally be visible
if a smooth finish was used and it
gives a slightly thicker paint finish.
Exeo was impressed with the look
and asked for all the shelters to be
sprayed with this finish.
The paint was required to be a final
thickness of between 280 and 350
microns and was checked with a
digital paint thickness tester. If it was
found to be too thin, another coat was
applied. The average thickness of the
paint on the shelters throughout the
project was about 320 microns.
Once the spray painting was finished,
the shelters were left to stand for 48
hours in order for the paint to cure
and harden properly
Assembly
As specified by the architects, all nuts
and bolts used had to be high-tensile
and hot dip galvanized. Two different
sized nuts and bolts were used for the
assembly of the shelters, M12 and M16.
Galvazinc was used to repair the hot
dip galvanized coating prior to
painting.
Full shelter installation
The anchor bolt cages were also
manufactured by Arand Engineering.
M20 ready bar was cut to length and a
cage was made to hold them in place.
Two different types of cages were
made. The first type had four bolts in a
square formation, the other had only
two anchor bolts.
There was one cage with four anchor
bolts and two cages with two anchor
28 Hot Dip Galvanizing Today Volume 10 Issue 2 2013