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These recommendations cover anticorrosion protection of above-ground
and underground vertical welded carbon steel reservoirs designed for storing
petroleum products, pure and extra pure hydrocarbon fluids used as fuels
Requirements to the coating.
Corrosion- and petrol-resistance, fire-resistance; maintained continuity
during usage - these requirements are met by the coating obtained by cold
zincing by ZFES, produced by ZAO NPP VMP. ZFES composition is a two-package
material prepared by mixing the binder with zinc powder. According to
Specs, the mass ratio "binder (component A) to powder (component B)" in
ZFES No. 1 is 1:1. The coating was tested by Russian branch Institutes;
according to the branch standards the coating is certified and may be
used for protecting internal surfaces of fuel storage reservoirs. The
coating has Lloyd's Register certificate No. MATS/1515/1.
Properties of the ZVES coating. ZFES coating contains 89-90 mass
% of metal zinc. It is a conducting material; specific electric resistance,
depending on the ZFES composition, is 101-102 Ohm/m. Initial potential
to the chloride-silver electrode, depending on the content of zinc in
the dry coating, is 0.85 - 0.95 V. It is anodic towards steel and provides
cathode protection. The coating does not accumulate static electricity
and is non-sparking on impact. The coating's tension strength is identical
to that of the metal being protected, which ensures its maintained continuity
throughout the reservoir's stretching and compression along with temperature
drop during use. The coating is incombustible and belongs to the group
of materials that do not spread flame on the surface. It does not affect
clear petrol products contacting with it.
Recommended protection systems
Reservoir's internal surface: 4-5 layers of ZFES No. 1 with the
total coating thickness of 120-150 µm. Roofs and pontoons may be coated
with 4 layers of ZFES No. 1 with the total thickness of 100-120 µm.
Reservoir's external surface: Along the whole height and roof -
3 layers of ZFES # 1 + 1-2 layers of PAES composition (or ALUMOTAN composition).
The total coating thickness should be at least 120 µm. The coating colour
is silver. Compositions PAES (Specs 2312-013-12288779-99) and ALUMOTAN
supplied by ZAO NPP VMP complete with the composition ZVES. For the external
surface protection, compositions PAES and ALUMOTAN may be replaced by
enamels XB-16, XB-124, XB-124, XB-785, Vinicolor, Vinicor-62, that should
be applied in 2-3 layers. The net consumption of ZFES No. 1 is 0.16 kg/m2
per one layer (20-30 µm ), of PAES - 0.10 kg/m2 per one layer (10-20 µm
) and of ALUMOTAN - 0.12 kg/m2 per one coat (20-30 µm).
Application methods
1. Preparation of the paint.
Paint ZFES is a two-package material. The composition consists of ethyl-silicate
binder (component A) and zinc powder (component B). 2 composition brands
are manufactured - ZFES # 1 and ZFES # 2, which differ by mass ratio of
components A and B (1: 1 and 1: 1,5 correspondingly). Composition is prepared
immediately before using by mixing of components. Longevity of the paint
at temperature 200C isn't less than 8 hours. The paint is considered viable
if there is no film on its surface and no jelly-like lumps in it. Composition
is prepared as follows: Zinc powder is poured gradually into the pail
with the binder (not the other way!) at constant stirring. When all the
powder is poured, the mixture is stirred during 2-3 minutes and left till
intensive gassing stops (approximately 20-30 min.). Conditional viscosity
of the ready paint by viscosimeter V3-246 with nozzle diameter 4 mm at
200C is 18 - 35 sec.
2. Surface preparation.
Remove all surface defects (sharp edges, wire-edges, welding drops,
etc.);
Degrease the surface up to grade 1 as per State Standard 9.402-80;
Remove rust and oxides up to grade 2 as per State Standard 9.402-80
or Sa 2.5 according to ISO 8501-1:1988 by blast-cleaning. After mechanical
cleaning the dust should be removed from the surface. Presence of moisture
on the surface is not permissible. Time lag between the surface preparation
and paint first layer application shouldn't exceed 24 hours indoors or
6 hours outdoors.
3. Composition application.
When applying the paint it is necessary to take into account that ZFES
doesn't require additional use of solvent; it refers to the class of
quickly curing paint-&-varnish materials and requires permanent stirring
in order to prevent precipitation of zinc powder. Conditions of the
paint application:
ambient temperature from - 150C to +400C;
relative humidity - 30%-80%, optimal value - not less than 50%. If the
painting occurs at temperature below zero, the components should be kept
in the warm for 24 hours, then mix the components and use by small portions.
in order to prevent moisture condensation on the surface being painted
it is necessary to maintain metal surface temperature 30C higher than
the dew point temperature ZFES is applied by pneumatic and airless spraying,
by brush or by roller.
Technological conditions of application: Airless spraying:
spraying pressure: 10-20 MPa;
nozzle diameter: 0,33 - 0,53 mm (0,013 - 0,021 inches); Pneumatic
spraying:
compressed air pressure: 0,3 - 0,4 MPa;
nozzle diameter: 1,8 - 2,2 mm; Sharp edges, corners, welding seams and
other spots difficult to access should be painted with brush. When the
paint application is conducted by brush or by roller, it is not recommended
to pass one and the same spot repeatedly. ZFES is naturally cured. One
layer of the coating is cured up to "pull of" grade (slight touch by the
finger doesn't leave traces and isn't clammy) at the ambient temperature
at (20±2)0C and humidity (65±5) % within 30 minutes. But in
closed cavities and places difficult to access curing time can increase
approximately by 1,2. Before the coating contacts with aggressive medium
it should be kept intact not less than 7 days, maximum time of the exposure
is not limited. ZFES is repairable. Defect spots of the coating should
be removed, the surface should be cleaned till it shines, degreased and
re-painted. As a finishing composition PAES based on aluminium powder,
urethane- and acrylic-based enamels POLYTON, vinyl-epoxy, perchlorovinyl,
copolymer-vinyl-chloride, epoxy, epoxy-ether, urethane and melamine enamels.
The finishing layers application should be conducted not earlier than
24 hours after application of the last layer of ZFES. Composition PAES
is applied after 2 hours. Before the coating contacts with liquid medium
it should be kept intact not less than 7 days. In order to ensure high
quality of the work regular cleaning of the equipment and fulfilling all
rules of maintenance are necessary.
it is recommended to pass solvent through the paint sprayer for a few
minutes before starting the work;
after finishing work with the paint ZFES gear and equipment for preparation
and application of the composition should be washed with solvent; Solvents
for washing the equipment are: types P-6, P-7, P-60, marks 646, 648, white
spirit, xylol, toluene, solvent and their mixtures. Net consumption of
the paint ZVES according to its composition: ZFES #1 - 130-200 g/m3 for
one layer of dry coating with dry film thickness of 20 - 30 µm; ZFES #2
- 170-230 g/m3 for one layer of dry coating with dry film thickness of
30 - 40 µm
4. Coating Quality Control
After complete curing of the coating it is accepted according to the
following requirements: appearance, thickness, adhesion. The coating
should be firm enough to bear the pressing of the gear for coating thickness
estimation. Appearance is estimated visually. Coating thickness is estimated
by magnet thickness gauges. Adhesion is estimated by latticed cut test
(State Standard 15140-78). The coating spots damaged during the tests
are renewed up to the necessary total thickness.
| Quality criteria |
Inspection method |
Quality properties |
| Appearance |
Visual |
Coating surface – low-gloss, gray, without impurities |
| Thickness |
By portable thickness gauges |
According to the selected protection scheme |
| Adhesion |
By the lattice notch method |
1 point |
The coating may be used not earlier than 7 days after the painting.
The technology of applying the ZFES compound is detailed in the Application
Guideline.
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