Thermal
Spray Metalizing - Applications
Applications:
| • |
Steel
Infrastructure: Bridges, Walkways, Bridge
Bearings Railings, Piers |
| • |
Waterways,
Gates, Locks Repair of Galvanized Coatings |
| • |
Exterior
of Steel and Iron pipes |
| • |
Gas
Cylinders |
| • |
Boat
Trailers and other Marine equipment |
| • |
Tanks |
No
Volatile Organic Compounds
With Federal, State and local regulations limiting
VOCs,durable, cost effective coating selection
has become increasingly difficult. A
thermally sprayed coating of Plattzinc 85/15 has
NO VOCs.
The Federal Highway Administration commissioned
a test program in 1988 to investigate the performance
of "low VOC" coating systems for bridges.
Lab tests and long term natural field exposure
testing was done and evaluated after 6 months,
one, two, three and four years. Other natural
exposure evaluations were done after 16 months.
Among the coatings tested was Plattzinc 85/15.
Tables 1 & 2 show the results of some popular
systems with <340 g/l (low VOC).
The conclusions after 5 years of study were that
both zinc and 85/15 provided excellent long term
performance.. In terms of rusting and undercutting
at intentional scribes to the substrate, zinc
and 85/15 showed superior corrosion control and
performed better than a majority of the paint
systems tested. Based on this perfomance, the
report stated that the thermal sprayed coatings
appear to be the coating of choice on selected,
highly corrosion prone bridge structures prior
to erection or maintenance replacement.
Individual states have also conducted lab and
field testing on Plattzinc 85/1 5.Their results
favored field applied thermal spraying with 85/15
over other maintenance options. The factors making
a thermal spray coating attractive include;
| • |
Existing
paint is in poor condition. Bridge substructure
is in good condition. |
| • |
Bridge
substructure is in good condition. |
| • |
Bridge
deck is in good condition, new or recently
rehabilitated. |
| • |
Steel
is exposed to harsh salt spray or industrial
atmospheres. |
| • |
High
costs are anticipated for future maintenance
operation. |
Guidelines
for Thermal Spraying With Zinc and Zinc/Aluminum
| • |
Precleaning
with by solvent, steam or power washing to
remove dirt, grease and soluable salts may
be required. |
| • |
Blast
cleaning to white or near white (SSPC-SP5
or SSPC-SP10) with an angular grit to achieve
an anchor-tooth 2-4 mil profile. |
| • |
Moisture
cannot be present on the steel surface and
spraying should not take place when the steel
temperature is less than 5°F (3°C
above the dew point). |
| • |
One
layer or pass of the thermal spray coating
must be applied within 4
hours of blasting the surface. |
| • |
Spray
pattern should be in block form. The coating
should be applied in
multiple layers at right angles to the previous
layer (box pattern). |
| • |
The
sprayed coating should be visibly free of
lumps, blisters and loosely
adhering particle. |
| • |
Typical
coating thickness is from 4 mils to 20 mils,
depending upon the
environment, use of sealers, longevity to
be achieved and specifications. |
| • |
Jobsite
coating standards, quality control standards,
visual inspection and
adhesion conformance should be required. |
| • |
All
government regulations, health and safety
standards must be observed. |
Association
Specifications Related to Thermal Spraying
SSPC CS- Guide 23.00, June 1,1991,
Coating System Guide, Guide for Thermal Spray
Metallic Coating Systems;
Steel Structures Painting Council.
ASTM B833-93, Standard Specification
for Zinc Wire for Thermal Spray, American
Society for Testing and Materials.
ASTM A780-90, Standard Practice
for Repair of Damaged and Uncoated Areas of Hot
Dip Galvanized Coatings,
American Society for Testing and Materials.
ASTM C633, Standard Test
Method for Adhesion or Cohesive Strength for Flame
Sprayed Coatings, American Society
for Testing and Materials.
ANSI/AWS C2.20-9X, Specification
for Zinc ThermalSpray Coatings for Reinforced
Concrete, American Welding
Society.
ANSI/AWS A533-9X, Specification
for Alhy Wires, Cored Wire and Ceramic Rods for
Thermal Spraying, American
Welding Society.
ANSI/AWS C2.18.93, Guide
for the Protection of Steel With Thermal Spraying
Coating of Aluminum and Zinc, American
Welding Society
Mill 6712C, Military Specification,
Wire, Metallizing.
CSA Standard G189, Reaffirmed
1992, Sprayed Metal Coating for Atmospheric
Corrosion Protection, Canadian
Standards Association.
ISO 2063, Metalik and other inorganic
coatings - Thermal spraying. Zinc, aluminum and
their alloys, International
Standard, ANSI
E-mail:
thermalspraying@plattbros.com
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