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These recommendations cover anticorrosion protection of the metal
structures (MS) in the system of Ministry of transport: systems of a contact
network, as well as bridge metal structures and a rolling stock with zinc-rich
compositions (ZRC) produced by "Fine Metal Powders"(FMP).
Zinc-rich compositions produced by FMP are recommended for anti-corrosion
protection of metal structures in the system of the Ministry of transport:
for steel metal structures of railway contact systems devices
under welding of railway rolling stock metal structures
ZINOL-SV composition is used under contact welding of the carriage body
metal structures
Cold Zincing Method, it's Advantages.
Cold zincing method is based on using zinc-rich compositions, which main
component is ultra-fine zinc powder with specific properties produced
by Fine Metal Powders Co. Zinc rich compositions are applied to the previously
prepared metal surface by traditional paint-&-varnish methods. After curing
coatings with zinc content up to 96% are obtained. Cold zincing method
summarizes advantages of traditional methods of anti-corrosion protection
- both zincing and paint-&-varnish coatings; it provides complex steel
protection - combining protective (cathode) mechanism similar to that
of zinc metal coatings (hot-dip galvanizing) and a barrier mechanism similar
to that of traditional paint-&-varnish materials. Due to all this coating
obtained by cold zincing method surpass other types of coatings by stability
towards corrosion, terms of service life, maintainability and simplicity
of application. Advantages of cold zincing method and zinc-rich compositions:
Process is environmentally friendly;
Simplicity and convenience of application by traditional paint-&-varnish
methods (spraying,, roller or brush);
Universality of using - not only in shop, but also in field conditions
at ambient temperature from -150°C up to +400°C and relative humidity
up to 90%;
Zinc-rich compositions can be used as independent coatings, as primers
in complex systems in combination with paint-&-varnish finishing materials
of different assignment and for maintenance of zinc metal coatings;
Maintainability: damaged surfaces are easily recovered using the same
composition;
Economical efficiency: long-termed coatings service life reduces maintenance
expenses.
Advantages of cold zincing compared to hot-dip galvanizing.
Longer service life at equal zinc content;
Aptitude for large-dimensions structures;
Compatibility with decorative coatings application.
Advantages of cold zincing compared to paint-&-varnish materials:
Protective (cathode) mechanism of steel protection;
Conductivity;
Absence of under-film corrosion;
Service life is longer by 2-4 times;
Coatings prevent fire spreading on the surface.
2. Recommended protection systems in atmospheric conditions: Standard
systems for MS protection of different application are given in the table.
Selection of the optimum scheme including type of paint-&-varnish materials,
the number of layers and thickness of the coating should be made taking
into account weather conditions of the particular regions, characteristics
of the medium where the metal structures are used; also conditions of
paint-&-varnish materials application and their technical and economical
efficiency.
| Projects |
Primer |
Preferable finishing enamel* |
Total thickness, µm |
Expected service life**, years, not less |
| Name of the primer |
No. of layers |
Thickness, µm |
| 1 |
2 |
3 |
4 |
5 |
6 |
7 |
| Bridge MS |
ZINOTAN |
2 |
80-120 |
ALUMOTAN |
150-170 |
10 |
ZFES # 1
ZFES # 2 |
2 |
80-120 |
Vinycolor |
150-170 |
10 |
| ZINOL |
2 |
80-120 |
ALPOL |
150-170 |
10 |
| Contact network supports |
ZINOL |
2 |
80-120 |
ALPOL |
100-150 |
not less than 15 |
| Maintenance of hot-galvanized articles |
ZINOL |
2 |
80-120 |
ALPOL |
|
|
| Rolling-stock |
ZINOL-SV |
1 |
30-40 |
Under contact welding |
30-40 |
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*Compatibility with mentioned finishing materials was tested by independent
expert organizations, possibility of application of other finishing materials
should be checked with DFMP specialists; ** Service life periods mentioned
in the table refer to the coatings applied according to the tested application
method to degreased surface, blast-cleaned from the rust and oxides up
to Sa 2 ? as per ISO 8501-1:1988, up to roughness grade Rz ~ 20% of total
thickness of the coating. Deterioration of surface preparation quality
will lead to reducing of service life of the coating.
Application technology
Application of the coating includes following consequent operations:
Surface preparation: removing of dirt, old paint, degreasing, removal
of rust and oxides;
Application of zinc-rich primer: preparation of zinc-rich composition;
Application of finishing layers: preparation of the composition (enamel),
application of the required number of layers, curing, quality control
and acceptance of the system of coatings. 3.1. Surface preparation:
There shouldn't be scales, rust, old paints remnants, organic contamination
(oil, grease), flux remnants, welding drops, wire- and sharp edges;
Removing of oxides is conducted by blast cleaning up to grade Sa 2 -
Sa 2,5 according to the international standard ISO 8501-1:1988. At maintenance
and composition application in field conditions the surface can be prepared
mechanically up to grade St 2.5 - St 3 according to ISO 8501-1:1988. In
this case service life of the coating will be reduced, especially in medium-
and high-aggressive conditions;
At maintenance of hot-galvanized articles it is necessary to remove
scaling off rust (mechanically), degrease the surface, form the necessary
roughness and apply the composition;
Degreasing of the elements of the structure is conducted before blast-cleaning,
at cleaning manually or mechanically after the cleaning;
Zinc-rich composition application should be conducted not later than
6 hours after surface preparation outdoors or not later than 24 hours
indoors. 3.2. Zinc-rich composition application: Before starting
painting it is necessary to fix the ambient conditions (temperature and
relative humidity) and check absence of contaminations and corrosion on
the steel surface. While applying the paint it is necessary to stir the
composition periodically to avoid zinc powder sedimentation. Zinc-rich
compositions are applied by spraying (pneumatic or airless), by brush
or by roller in a few layers with natural interlayer curing. Application
of every next layer is possible after the previous one is fully cured.
Curing time depends on ambient temperature and relative humidity and varies
from 20 to 90 minutes. When the padding of the surface being painted is
finished it is necessary to estimate the coating quality by the following
characteristics:
Appearance - visually;
Thickness - by thickness gauges;
Adhesion - by lattice cut test. Damaged spots of the coating should
be re-painted.
Zinc-rich composition consumption for one-layer coating:
| Zinc-rich composition |
Thickness of one layer, µm |
Net consumption for on layer*, g/m2 |
| ZFES # 1 |
20-30 |
160 |
| ZFES # 2 |
30-40 |
200 |
| ZINOL |
30-40 |
260 |
| ZINOTAN |
30-40 |
240 |
Actual consumption is defined by method and conditions of application,
also by the roughness and the type of the painted surface.
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