4.4 Basic coating requirements
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Statutory Documents - IMO Publications and Documents - Resolutions - Maritime Safety Committee - Resolution MSC.244(83) - Adoption of Performance Standard for Protective Coatings for Void Spaces on Bulk Carriers and Oil Tankers - (Adopted on 5 October 2007) - Annex - Performance Standard for Protective Coatings for Void Spaces on Bulk Carriers and Oil Tankers - 4 Coating Standard - 4.4 Basic coating requirements

4.4 Basic coating requirements

  4.4.1 The requirements for protective coating systems, which should be applied at ship construction to void spaces in bulk carriers and oil tankers meeting the standard specified in paragraph 4.1, are listed in table 1.

  4.4.2 Coating manufacturers should provide a specification of the protective coating system to satisfy the requirements of table 1.

  4.4.3 The Administration or an organization recognized by the Administration should verify the Technical Data Sheet and Statement of Compliance or Type Approval Certificate for the protective coating system.

  4.4.4 The shipyard should apply the protective coating in accordance with the verified Technical Data Sheet and its own verified application procedures.

Table 1 Basic coating system requirements for void spaces in bulk carriers and oil tankers

  Characteristic Requirement

1Design of coating system

.1 Selection of the coating system The selection of the coating system should be considered by the parties involved with respect to the service conditions and planned maintenance. The following aspects, among other things should be considered:
   

.1 location of space relative to heated surfaces;

.2 required surface conditions;

.3 required surface cleanliness and dryness;

.4 relative humidity;

.5 access and maintenance; and

.6 mechanical ventilation.

    Coating manufacturers should have products with documented satisfactory performance records and technical data sheets. The manufacturers should also be capable of rendering adequate technical assistance. Performance records, Technical Data Sheet and technical assistance (if given) should be recorded in the Coating Technical File.
    Coatings for application underneath sun-heated decks or on bulkheads forming boundaries of heated spaces should be able to withstand repeated heating and/or cooling without becoming brittle.
.2 Coating type Epoxy-based systems.
    Other coating systems with performance according to the test procedure in annex 1.
    When a multi-coat system is applied, contrasting colour is recommended for each coat.
    The top coat should be of a light colour in order to facilitate in-service inspection.
.3 Coating pre-qualification test Epoxy-based systems tested prior to the date of adoption 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 may be accepted;
    or any coating system which meets the requirements in table 1.1.3 of the Performance standard for protective coating for dedicated seawater ballast tanks in all types of ships and double-side skin spaces of bulk carriers (resolution MSC.215(82)), is accepted and may be applied in accordance with this Standard;
    or which have documented field exposure for 5 years with a final coating condition of not less than “GOOD” may also be accepted.
    For other systems, including epoxy-based systems tested after the adoption of this Standard, testing according to the procedure in annex 1 to this Standard should be required.
.4 Job specification There should be a minimum of one stripe coat and one spray coat. The stripe coat should be applied on thermally cut free edges and small holes only.
    Surface contaminants such as rust, grease, dust, salt, oil, etc., should be removed prior to painting with proper methods according to the paint manufacturer’s recommendation. Abrasive inclusions embedded in the coating should be removed. Job specifications should include the dry-to-recoat times and walk-on time given by the manufacturer.
.5 NDFT (nominal total dry film thickness)footnote NDFT 200 µm with a 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 should be taken to avoid increasing the thickness in an exaggerated way. Wet film thickness should be regularly checked during application.
    Thinner should be limited to those types and quantities recommended by the manufacturer.

2 PSP (Primary surface preparation)

.1 Blasting and profilefootnote footnote Sa 2˝; with profiles between 30-75 µm.
    Blasting should 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 should be carried out at the end of the surface preparation and before the application of the primer, in accordance with the manufacturer’s recommendations.
.2 Water soluble sale limit equivalent to NaClfootnote ≤ 50 mg/m2 of sodium chloride.
.3 Shop primer Zinc containing inhibitor free zinc silicate based or equivalent.
    Compatibility with main coating system should be confirmed by the coating manufacturer.

3 SSP (Secondary surface preparation)

.1 Steel condition The steel surface should 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 contaminantfootnote.
    Edges to be smooth, subject to one pass grinding or at least equivalent process before paintingfootnote.
.2 Surface treatmentfootnote For damaged shop primer:
    Sa 2 or St 3 on damaged shop primer and welds;
    For intact shop primer:
    Sa 2 removing at least 70% of intact shop primer, which has not passed a pre-qualification certified by test procedures in table 1.1.3.
    If the complete coating system comprising epoxy-based main coating and shop primer has passed a pre-qualification certified by test procedures in table 1.1.3 intact shop primer may be retained provided the same epoxy coating system is used. The retained shop primer should be cleaned by sweep blasting, high pressure water washing or other methods in accordance with the manufacturer’s recommendation.
    If a zinc silicate shop primer has passed the pre-qualification test of table 1.1.3 as part of an epoxy coating system, it may be used in combination with other epoxy coatings certified under table 1.1.3, provided that the compatibility has been confirmed by the manufacturer by the test in accordance with paragraph 1.7 of appendix 1 to annex 1 of the Performance standard for protective coatings for dedicated seawater ballast tanks in all types of ships and double-side skin spaces of bulk carriers, without wave movement.
.3 Surface treatment after erectionfootnote St 3 or better or Sa 2 where practicable on butts and damages.
    Coating in overlap to be feathered.
.4 Profile requirementsfootnote In case of full or partial blasting 30-75 µm, otherwise as recommended by the coating manufacturer.
.5 Dustfootnote Dust quantity rating “2” for dust size class “3”, “4” and “5”.
.6 Water soluble salts limit equivalent to NaCl after blasting/ grindingfootnote ≤ 100 mg/m2 of sodium chloride.
.7 Oil contamination No oil contamination.

4 Miscellaneous

4
.1 Ventilation 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.
.2 Environmental conditions Coating should be applied under controlled humidity and surface conditions, in accordance with the manufacturer's specifications. In addition, coating should 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.

.3 Testing of coatingfootnote Destructive testing should be avoided.
    Dry film thickness should be measured after each coat for quality control purposes and the total dry film thickness should be confirmed after completion of final coat, using appropriate thickness gauges.
.4 Repair Any defective areas, e.g. pin-holes, bubbles, voids, etc. should be marked up and appropriate repairs effected. All such repairs should be re-checked and documented.
Parent topic: 4 Coating Standard
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