631-4.pdf

AMC-631-4

DECEMBER 1992

NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION (NOAA)

ATLANTIC MARINE CENTER

STANDARD SPECIFICATION AMC-631-4

COATING SYSTEMS FOR ALUMINUM SURFACES

1. SCOPE. This specification contains the general requirements for surface preparation and application of the coating systems most frequently used on aluminum surfaces of NOAA ships and boats.

2. REFERENCES.

None

3. REQUIREMENTS.

3.1 General Requirements.

3.1.1 Comply with the manufacturers' printed

recommendations and instructions for all aspects of handling, mixing, and application of the paint materials.

3.1.2 All paint shall be delivered to the jobsite in

original, unopened containers with labels intact. All containers shall remain unopened until required for use. Each container of paint shall be clearly marked or labelled to show paint identification, date of manufacture, batch number, analysis of contents, identification of all toxic substances, and special instructions.

3.1.3 Paint shall be used before its shelf life has

expired. If a paint has no stated shelf life or is more than one year old, the manufacturer must certify in writing that the paint is suitable for use.

3.1.4 All coating thicknesses are stated in dry film

thickness (DFT). All dry film thickness measurements shall be taken with a non-magnetic thickness gage. At the option of the contractor, thickness may be taken using a wet film thickness gauge to check wet thickness and converted to dry film thickness readings using the paint manufacturer's printed literature.

3.1.5 Coatings shall be applied only when the following

conditions are maintained:

a. Apply paint only to dry surfaces and when there is no chance of precipitation until after the paint has cured. The surface temperature shall be at least five degrees Fahrenheit above the dew point. The dew point can be presumed to be satisfactory if a thin, clearly defined film of water applied to the cleaned surface with a damp cloth evaporates within 15 minutes. Otherwise, the dew point shall be measured prior to painting by taking the dry-bulb temperature of the surface and the wet-bulb temperature at the jobsite.

b. The air temperature and surface temperature must both be a minimum of 45 degrees Fahrenheit at all times, unless a lower temperature is specifically authorized by the paint manufacturer's printed instructions.

c. Painting is permitted only when the humidity is less than 95 percent.

d. When paint must be applied in damp or cold weather, the aluminum must be painted under cover and the surrounding air and the surface heated to establish the required conditions. The steel shall remain under cover or be protected until dry or until weather conditions permit its exposure.

3.1.6 Each coat of paint shall be in a proper state of cure

or dryness before the application of the succeeding coat. Paint shall be considered dry for recoating when an additional coat can be applied without the development of any detrimental film irregularities, such as lifting, wrinkling, or loss of adhesion of the undercoat. The time interval between coating applications shall be in compliance with the manufacturer's printed instructions.

3.1.7 All paint materials shall be furnished by the

Contractor and shall be applied using spray equipment, unless otherwise specified. When applying touch-up coatings to small areas disturbed by other work, brushes and rollers may be used.

3.1.8 Paint shall be used before its shelf life has

expired. If a paint has no stated shelf life or is more than one year old, the manufacturer must certify in writing that the paint is suitable for use.

3.1.9 Comply with and enforce all safety and environmental

protection regulations relative to removal, disposal, mixing, and application of paints and other materials.

3.1.10 Mask, tape, cover, and otherwise protect all

equipment, machinery, cables, piping, insulation, glass, furnishings, and other government materials from damage, overspray and contamination. Remove and reinstall parts and loose gear as necessary to avoid damage.

3.1.11 Plug, wrap, blank, cover, or mask all openings as

needed to prevent entry of blast materials into the ship or boat and to confine blast materials inside the compartment being sandblasted. Install industrial foam filter materials on the intake and exhaust of ventilation systems which will be in use.

Renew filter materials when air flow becomes restricted.

3.1.12 When surface preparation and coating of a

compartment or surface is specified, included shall be all plating, frames, longitudinals, beams, stiffeners, brackets, baffles, and other structural members. Aluminum ladders in tanks, voids, and cofferdams are also to be included.

3.1.13 Surface preparation and paint application of shell

plating and frames below the Load Waterline shall be accomplished only while the ship or boat is hauled out of the water, unless otherwise and specifically authorized.

3.1.14 Where colors are not specified in this

specification, the color for coatings shall be as specified in other procurement documents or specifications. Where colors are not specified elsewhere, the colors shall be selected by the COTR or other NOAA representative responsible for acceptance of the work.

3.2 Surface Preparation.

3.2.1 Unless otherwise specified , aluminum surfaces shall

be prepared by light abrasive blasting using 80-grit aluminum oxide or garnet to remove all existing coatings, corrosion products, and other foreign products and to produce a 1.0 to 1.25 mil anchor profile. Use the minimum blasting pressure which will remove the existing coatings. As the coating removal nears bare metal, use a light sandsweeping motion to avoid damage to the soft aluminum. Under no circumstance is any metal abrasive grit, other than aluminum oxide, be used. Also, reclaimed aluminum oxide or garnet abrasive grits which have been used on other metals shall not be used.

3.2.2 When "power tool" cleaning is specified by other

procurement documents or specifications, aluminum surfaces shall be prepared by using stainless steel wire brushes, scouring pads or aluminum oxide abrasive sanding pads with power wire brushes or orbital sanders. Extreme care must be taken to prevent damage to the aluminum surface while insuring that all corrosive products, existing coatings, and other foreign materials are removed.

3.2.3 If oil or grease products are present, the aluminum

surface shall be wiped and cleaned with a degreaser recommended by the paint manufacturer prior to any blasting or power tool preparations.

3.2.4 After surface preparation, surfaces shall be brushed

with clean stiff bristle brushes, blown off with compressed air, or cleaned by vacuum to remove all traces of blast products and dust.

3.2.5 Whenever sandblasting or spray painting is specified

for surface preparation of exterior steel surfaces at a Government facility, or when applicable regulations and laws prohibit release of blast materials and paint into the atmosphere, the surfaces shall be enclosed in a cover adequate to contain the blast materials and paint.

3.2.6 Cleaning and painting shall be so scheduled that

detrimental amounts of dust or other contaminants do not fall on wet, newly-painted surfaces.

3.2.7 In order to prevent degradation or contamination of

the prepared surfaces, the first coat of paint shall be applied as soon as possible after the surfaces have been prepared. The first coat shall always be applied within four hours after surface preparation is completed. Succeeding coats shall be applied before contamination of the under surface occurs.

3.3 Coating Systems. Following acceptance of the surface

preparation by the COTR, apply the coating system specified in the procurement document or detail specification and defined below.

3.3.1 System ALUM-1: (Exterior surfaces)

a. Coat one: Apply 2.0 to 4.0 mils DFT, of polyamide-epoxy, MIL-P-24441, formula 150 (green).

d. Coat two: Apply 2.0 to 4.0 mils DFT, of polyamide-epoxy, MIL-P-24441, formula 151 (haze grey).

c. Coat three: While the previous coat is still tacky, apply 2.0 to 3.0 mils DFT, of 30-percent modified silicone alkyd high gloss marine paint, using one of the products listed in Appendix A.

e. Coat four: Apply 2.0 to 3.0 mils DFT of 30-percent modified silicone alkyd high gloss marine paint same as previous coat.

3.3.2 System ALUM-2: (Interior surfaces)

a. Coat one: Apply 2.0 to 4.0 mils DFT polyamide-epoxy, MIL-P-24441, formula 150 (green).

b. Coat two: Apply 2.0 to 3.0 mils DFT latex fire-retardant paint, DOD-C-24596, Type I.

c. Coat three: Same as coat two.

3.3.3 System ALUM-3: (Deck non-skid)

a. Coat one: Apply 2.0 to 4.0 mils DFT of polyamide-epoxy, MIL-P-24441, formula 150 (green).

b. Coat two: Same as coat one.

c. Coat three: While the previous coat is still tacky, apply 2.0 to 3.0 mils DFT of 30-percent modified silicone alkyd high gloss marine paint, using one of the products listed in Appendix A.

d. Coat four: Immediately after applying coat three, spread a coat of #40-mesh garnet over the coating while it is still wet. Completely cover the coating and allow the coating to dry for eight hours. Then, sweep off and vacuum up the excess garnet.

e. Coat five: Same as coat three.

4. QUALITY ASSURANCE.

4.1 Certification and Records.

4.1.1 Whenever the surfaces to be prepared and coated exceeds a total surface area of 10 square-feet, comply with the following prior to commencing the surface preparation:

a. Prepare and submit to the COTR a detail "Paint Plan" which clearly outlines the complete painting timetable and procedures, including methods for conducting and documenting inspections. Also to be included shall be copies of all applicable manufacturers' printed recommendations, instructions and product data sheets.

b. The Contractor's paint foreman shall meet with the COTR to discuss and review the "Paint Plan".

4.1.2 Provide to the COTR the following information:

a. Number of gallons of each type paint used.

b. Certification by the Contractor's paint foreman that the conditions specified in 3.1.5 were maintained during application and curing of the paint. If measured, wet-bulb temperature at the jobsite and dry-bulb temperature of the surface immediately before applying each coat of paint.

c. Date and time of starting and completing each coat of paint.

d. Complete set of all DFT measurements taken.

4.2 Inspections.

4.2.1 Prior to any sandblasting or painting, conduct an

inspection with the COTR of all protective coverings and masking to insure that the protection is adequate.

4.2.2 After completion of surface preparation, the COTR or other person designated by the COTR shall inspect the surfaces before the first coat of paint is applied.

4.2.3 Prior to applying each coat of paint, verify to the COTR or other person specified by the COTR that the conditions exist as prescribed in paragraph 3.1.5.

4.2.4 After each coat of paint is applied and prior to the next coat, take DFT readings. The COTR or other person specified by the COTR shall be permitted to witness the measurements. Provide thickness gages, calibrated immediately before taking the measurements in presence of the COTR or other person specified by the COTR.

4.2.5 In the event the COTR or other person specified by the

COTR is unable to witness the required inspections and measurements, the Contractor shall nonetheless conduct and document the inspections and measurements to verify compliance with the requirements of this specification.

APPENDIX A

30-PERCENT MODIFIED SILICONE ALKYD PAINTS

Product Manufacturer

Gloss Silicone Alkyd(series) Devoe Marine Coatings SA-22 Silicone Alkyd Porter Coatings CMB000 Silicone Alkyd International Paint Silalx 300 International Paint 21-W-9 Silicone Alkyd Valspar 434U-1000 Silicone Alkyd Hempel's Marine Paints Series 5539 Glidden Coatings and Resins 40-E Silicone Alkyd Farboil HM-70 Carboline Silicoguard 600 Seaguard

END OF SPECIFICATION