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Characteristic/ Reference standards
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Requirement
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1
Design of coating system
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| .1
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Selection of the coating
system
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The selection of the coating system
shall be considered by the parties involved with respect to the service
conditions and planned maintenance. The following aspects, among other
things shall be considered :
.1 location of space
relative to heated surfaces;
.2 frequency of
ballasting and deballasting operations;
.3 required
surface conditions;
.4 required surface
cleanliness and dryness; and
.5 supplementary
cathodic protections, if any (where coating is supplemented by cathodic
protection, the coating shall be compatible with the cathodic protection
system).
Coating manufacturers shall have products with documented
satisfactory performance records and technical data sheets. The
manufacturers shall also be capable of rendering adequate technical
assistance. Performance records, technical data sheet and technical a
ssistance (if given) shall be recorded in the Coating Technical File.
Coatings for application underneath sun-heated decks or on
bulkheads forming boundaries of heated spaces shall be able to withstand
repeated heating and/or cooling without becoming brittle.
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| .2
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Coating type
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Epoxy-based systems.
Other coating systems with performance according to the test
procedure in annex 1.
A multi-coat system with each
coat of contrasting colour is recommended.
The top coat
shall be of a light colour in order to facilitate in-service inspection.
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| .3
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Coating pre-qualification test
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Epoxy-based systems tested prior to
the date of entry into force of this Standard in a laboratory by a method
corresponding to the test procedure in annex 1 or equivalent, which as a minimum meets the
requirements for rusting and blistering; or which have documented field
exposure for 5 years with a final coating condition of not less than “GOOD”
may be accepted.
For all other systems, testing according to
the procedure in annex 1, or equivalent, is required.
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| .4
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Job specification
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There shall be a minimum of two stripe
coats and two spray coats, except that the second stripe coat, by way of
welded seams only, may be reduced in scope where it is proven that the NDFT
can be met by the coats applied, in order to avoid unnecessary
over-thickness. Any reduction in scope of the second stripe coat shall be
fully detailed in the CTF.
Stripe coats shall be applied by
brush or roller. Roller to be used for scallops, ratholes, etc., only.
Each main coating layer shall be appropriately cured before
application of the next coat, in accordance with coating manufacturer’s
recommendations. Surface contaminants such as rust, grease, dust, salt, oil,
etc., shall be removed prior to painting with proper method according to the
paint manufacturer’s recommendation. Abrasive inclusions embedded in the
coating shall be removed. Job specifications shall include the dry-to-recoat
times and walk-on time given by the manufacturer.
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| .5
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NDFT (nominal total dry film
thickness)footnote
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NDFT 320 μm with 90/10 rule for
epoxy-based coatings; other systems to coating manufacturer’s
specifications.
Maximum total dry film thickness according
to manufacturer’s detailed specifications.
Care shall be
taken to avoid increasing the thickness in an exaggerated way. Wet film
thickness shall be regularly checked during application.
Thinner shall be limited to those types and quantities
recommended by the manufacturer.
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2PSP (Primary surface preparation)
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| .1
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Blasting and profilefootnote
footnote
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Sa 2˝; with profiles between 30-75 μm
Blasting shall not be carried out when:
.1 the relative humidity is above 85%; or
.2 the surface temperature of steel is less than 3°C
above the dew point.
Checking of the steel surface cleanliness and
roughness profile shall be carried out at the end of the surface preparation
and before the application of the primer, in accordance with the
manufacturer’s recommendations.
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| .2
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Water soluble salt limit equivalent to
NaClfootnote
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≤ 50 mg/m2 of sodium
chloride.
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| .3
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Shop primer
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Zinc containing inhibitor free zinc
silicate based or equivalent.
Compatibility with main
coating system shall be confirmed by the coating manufacturer.
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3 Secondary surface preparation
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| .1
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Steel conditionfootnote
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The steel surface shall be prepared
so that the coating selected can achieve an even distribution at the
required NDFT and have an adequate adhesion by removing sharp edges,
grinding weld beads and removing weld spatter and any other surface
contaminant.
Edges shall be treated to a rounded radius of
minimum 2 mm, or subjected to three pass grinding or at least equivalent
process before painting.
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| .2
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Surface
treatmentfootnote
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Sa 2˝ on
damaged shop primer and welds.
Sa 2 removing at least 70% of
intact shop primer, which has not passed a prequalification certified by
test procedures in 1.3.
If the complete coating system
comprising epoxy-based main coating and shop primer has passed a
pre-qualification certified by test procedures in 1.3, intact shop primer
may be retained provided the same epoxy coating system is used. The retained
shop primer shall be cleaned by sweep blasting, high-pressure water washing
or equivalent method.
If a zinc silicate shop primer has
passed the pre-qualification test of 1.3 as part of an epoxy coating system,
it may be used in combination with other epoxy coatings certified under 1.3,
provided that the compatibility has been confirmed by the manufacturer by
the test in accordance with 1.7 of appendix
1 to annex 1 without wave movement.
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| .3
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Surface
treatment after erectionfootnote
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Butts St 3
or better or Sa 2˝ where practicable. Small damages up to 2% of total area:
St 3. Contiguous damages over 25 m2 or over 2% of the total area
of the tank, Sa 2˝ shall be applied.
Coating in overlap
shall be feathered.
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| .4
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Profile
requirementsfootnote
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In case of
full or partial blasting 30-75 μm, otherwise as recommended by the coating
manufacturer.
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| .5
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Dustfootnote
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Dust
quantity rating “1” for dust size class “3”, “4” or “5”. Lower dust size
classes to be removed if visible on the surface to be coated without
magnification.
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| .6
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Water
soluble salts limit equivalent to NaCl after blasting/ grindingfootnote
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≤ 50
mg/m2 of sodium chloride.
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| .7
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Oil
contamination
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No oil
contamination.
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4 Miscellaneous
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| .1
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Ventilation
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Adequate
ventilation is necessary for the proper drying and curing of coating.
Ventilation should be maintained throughout the application process and for
a period after application is completed, as recommended by the coating
manufacturer.
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| .2
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Environmental conditions
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Coating
shall be applied under controlled humidity and surface conditions, in
accordance with the manufacturer’s specifications. In addition, coating
shall not be applied when:
.1 the relative humidity is
above 85%; or
.2 the surface temperature is
less than 3°C above the dew point.
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| .3
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Testing of
coatingfootnote
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Destructive
testing shall be avoided.
Dry film thickness shall be
measured after each coat for quality control purpose and the total dry film
thickness shall be confirmed after completion of final coat, using
appropriate thickness gauges (see annex
3).
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| .4
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Repair
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Any
defective areas, e.g., pin-holes, bubbles, voids, etc., shall be marked up
and appropriate repairs effected. All such repairs shall be re-checked and
documented.
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