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Passion
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Despite its robust construction, the
Metco 16E wire flame spray gun weighs
only 2.5 kg, and thus is ideally suited
for mobile use – even for the nearly
140 metre high and 680 tonne heavy
spire of One World Trade Center.
T
he contract to corrosion protect the tower’s
spire was awarded to Drytec Trans-Canada by the
New York and New Jersey Port Authority, which
owned the building at the time. From the outset it was
clear to all involved that the sheer size of the workpiece
posed an enormous challenge. The original plan to gal-
vanize the high-strength steel was quickly dismissed, in
view of the immense size of the spire components, the
varying thicknesses and requirement for double dip-
ping. Painting was also not an option, as the binders in
the paint would have interfered with satellite communi-
cations. A pure zinc coating was chosen as this could
provide the required conductivity, as well as achieve the
required coating thickness of between 250 and 500 µm.
The search for a process
The next step was to find a process able to fulfil the coat-
ing thickness requirements and to accommodate the
spire’s highly complex geometry. Ultimately the Drytec
team presented flame spray technology to the building
owners and then spent nearly a year testing the equip-
ment.
Oerlikon Metco’s Key Account Manager was also
contacted at this time, because Drytec was confront-
ed with another challenge – the required coating bond
strength of 4.8 MPa. Drytec, moreover, had to submit
a process description to the New York City Inspector
precisely documenting each step of the coating process,
and describing the measures to prevent overspray, i.e.
excess spray not applied to the workpiece.
Metco solution fulfilled all requirements
Shortly afterwards, Oerlikon Metco presented the ca-
pabilities of the Metco 16E combustion spray gun
with zinc wire to the New York City Inspector at Drytec
headquarters – and won him over completely. An ad-
hesion strength of 8.3 MPa on all spire parts was actu-
ally achieved, thanks to the outstanding combination of
spray equipment and spray material. The required coat-
ing specifications, SSPC SP10 and SSPC-CS23, the
norm for thermal spraying (ISO 2063) and, of course, the
customer’s required coating thickness, could all thereby
be fulfilled.
“I don’t want to have to climb up
there with a can of paint
in a few years time to
touch up the structure!”
The City Inspector to Oerlikon Metco‘s
Key Account Manager.