631-3B Hull Ablative Coating System.pdf

MOC-631-3B

September 2000

SUPERSEDING

AMC-631-3A

JUNE 1991

NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION (NOAA)

MARINE OPERATIONS CENTER

STANDARD SPECIFICATION MOC-631-3B

UNDERWATER BODY ABLATIVE COATING SYSTEM

1. SCOPE. This specification contains the general requirements for application of an ablative coating system on the underwater body of NOAA steel ships and boats, using sandblasting or ultra-high pressure water blasting procedures for surface preparation.

2. REFERENCES.

a. Steel Structures Painting Council Surface Preparation Specification No. 10 (SSPC-SP 10-85), "Near White Blast Cleaning"

b. Steel Structures Painting Council Paint Application Specification No. 2 (SSPC-PA-2), "Measurement of Dry Paint Thickness with Magnetic Gages"

3. REQUIREMENTS.

3.1 General Requirements.

3.1.1 The ablative anti-foulant coating system shall be a

copper-based tributyltin-free system. Two systems currently authorized for use by this specification are the International FP Epoxy/BRA Antifoulant (International Paint Co.) and the Devran 234QC Epoxy/ABC-AF #3 Antifoulant (Devoe Marine Coatings).

3.1.2 The underwater body is defined as the entire

underwater hull plating and all appendages up to the upper boottopping limit. Included are all rudders, struts, skegs, bilge keels, sea chest strainer plates, sea chests, domes, propulsion shafting, fairwaters, rope guards, and the bow thruster tunnel.

3.1.3 Boottopping lines shall be carefully cut in. The

boottopping shall be same as existing unless otherwise specified.

3.1.4 All paint materials shall be applied using spray

equipment, except sea chest strainer plates shall be coated by dipping. After the last coat of anti-fouling paint has been applied, the underwater body draft marks shall be repainted, with brushes, using a high grade white gloss marine paint.

3.1.5 All coating thicknesses are stated in dry film

thickness (DFT). All dry film thickness determinations shall be performed in accordance with reference 2.b.

3.1.6 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 temperature of the surface to be painted shall be at least 5 degrees Fahrenheit above the dew point at the jobsite. The dewpoint 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. In no instance shall the air or surface temperature be less than 35 degrees Fahrenheit.

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

d. In the event the Contractor desires or must proceed with painting when the existing weather conditions do not meet the above specified conditions, the Contractor shall erect a cover over the surfaces to be painted and shall heat the surfaces and the surrounding air to establish the required conditions.

The conditions shall be maintained until the paint has fully cured.

3.1.7 Bilge blocks shall be shifted to allow all their

contact areas to be prepared and painted. The Dockmaster shall be consulted to determine the sequence of shifting blocks. Keel blocks need not be shifted unless otherwise specified.

3.1.8 Comply with the manufacturers' printed

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

3.1.9 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.

3.1.10 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. The final coat of anti-fouling paint shall be allowed to cure a minimum of 24 hours prior to undocking the ship.

3.1.11 Comply with and enforce all safety and environmental

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

3.2 Surface Preparation.

3.2.1 Whenever the detail specifications requires the

underwater body be coated with a "complete system", the entire underwater body is to be prepared as follows:

a. Prior to any sandblasting, all sea chests strainer plates shall be removed and all hull openings, transducers, anodes, waster pieces, bearings, stern tube openings, bow thrusters, fiberglass covers (over shafts and domes) and propellers shall be plugged, covered, and otherwise protected from damage or contamination during surface preparation and coating application.

b. Sandblast all steel surfaces to near white blasted surfaces in accordance with reference 2.a.

c. After sandblasting, surfaces shall be brushed with clean brushes, blown off with compressed air, or cleaned by vacuum to remove all traces of blast products and dust.

3.2.2 Whenever the detail specifications require the

existing coating system on the underwater body to be coated with a "maintenance system", the underwater body shall be prepared as follows:

a. Prepare the entire underwater body (except fiberglass surfaces and transducers) with a high pressure wash, using a controlled close high pressure water wash spray at a pressure of not less than 3000 psi, to clean the surface to a condition acceptable to the paint manufacturer's on-site representative. If salt water is used for an initial high pressure water wash, the water wash shall be followed with a final high pressure fresh water wash.

b. After the water washed surfaces have been allowed to sit for 24 hours, the COTR will designate areas to be sandblasted. The detail specifications will state the amount (in square feet) that will be required to be sandblasted. Prepare designated areas by sandblasting using the same procedure required above for the "complete system".

3.2.3 Regardless of whether a "complete system" or a

"maintenance system" is required, all fiberglass surfaces shall be prepared as follows:

a. Use wooden or plastic scrapers, mechanically prepare to a bare clean surface, exercising care not to gouge, scratch, or otherwise damage the fiberglass.

b. Using a hand or finishing sander with fine grit paper, remove all remaining marine growth, loose paint, and dirt.

Wipe the surfaces with a damp soft cloth to remove all dust and residue.

3.2.4 Ultra High-Pressure Water Blasting (UHPWB) may be

used in lieu of sandblasting when indicated in the detailed specifications. UHPWB can only be used on steel surfaces that have been sandblasted previously (prior to installation or during previous drydockings) with sufficient profile to ensure coating adhesion. The requirements for UHPWB include:

a. Degree: HB 2 ½ Light

b. Water Pressure: Between 36,000 and 40,000 psi

3.3 Coating Systems. After surface preparation, apply either a complete system or a maintenance system (as specified in the detail specifications) as follows.

3.3.1. Complete System. When a "complete system" is

required by the detail specifications, apply one of the two following 5-coat coating systems after completing surface preparation. The first coat is to be applied as soon as practical after surface preparation and before any rusting occurs. In no case shall the surfaces be allowed to remain overnight without coating.

a. International System.

1. Two coats, 5.0-6.0 mils DFT each, International FP series epoxy. First coat shall be FPD052 (off-white) and second color shall be FPK705 (gray).

2. Three coats, 4.0-5.0 mils DFT each, International BRA500 series ablative antifoulant. The first and third coats shall be BRA570 red and the second coat shall be BRA572 black, except in the boottopping all three coats shall be BRA572 black.

b. Devoe System.

1. Two coats, 5.0-6.0 mils DFT each, Devran 234 epoxy. The first coat may be any color, but second coat shall be gray.

2. Three coats, 4.0-5.0 mils DFT each, Devoe ABC 3 ablative antifoulant. The first and third coats shall be red and the second coat shall be black, except in the boottopping all three coats shall be black.

3.3.2 Maintenance System. Whenever a "maintenance system"

is required by the detail specifications, apply the following coating system after completion of surface preparation. The coating materials shall be provided by the same manufacturer as the existing system.

a. To all sandblasted areas, apply a complete 5-coat coating system same as specified above for the "complete system".

The first coat is to be applied as soon as practical after surface preparation and before any rusting occurs. In no case shall the surfaces be allowed to remain overnight without coating.

b. To all prepared surfaces that are not sandblasted, apply two new coats, 4.0-5.0 DFT each, of the same ablative antifoulant as existing (last three coats of one of the complete systems specified above). The first new coat shall be black and the second new coat shall be red, except in the boottopping both new coats shall be black.

4. QUALITY ASSURANCE.

4.1 Certification and Records.

4.1.1 Provide the on-site services of a manufacturer's

representative for the coating system being applied. The representative shall be on-site during all mixing and application of paint, and shall conduct or witness all inspections. All surface preparation and other aspects of the coating system application shall be acceptable to the paint manufacturer's representative.

4.1.2. Prior to commencing the surface preparation:

a. Provide the COTR with a detail "Paint Plan" which clearly outlines the complete painting timetable and procedures, including methods for conducting and documenting inspections.

The "Paint Plan" shall be approved by the manufacturer's representative before submitting it to the COTR. Attach copies of all applicable manufacturers' printed recommendations, instructions and product data sheets to the "Paint Plan.

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

4.1.3 Provide the COTR with the following information:

a. Number of gallons of each type paint used.

b. Certification by the Contractor's paint foreman and the paint manufacturer's representative that the conditions specified in 3.1.6 were maintained during application and curing of the paint. If measured, the wet-bulb temperature at the jobsite and the 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.

e. A copy of paint manufacturer's representative service report which outlines all inspections, observations, and recommendations provided by the representative.

4.2 Inspections.

4.2.1 Prior to any sandblasting or UHPWB, conduct an

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

4.2.2 After completion of surface preparation, the paint

manufacturer's representative shall inspect the surfaces before the first coat of paint is applied. The COTR shall be notified of the inspection and allowed an opportunity to witness the inspection.

4.2.3 Prior to applying each coat of paint, verify to the

COTR and the paint manufacturer's representative that the conditions exist as prescribed in paragraph 3.1.6.

4.2.4 After each coat of paint is applied and prior to the

next coat, take DFT readings in accordance with reference 2.b.

The paint manufacturer's representative shall witness the measurements. The COTR shall be notified of the inspection and allowed an opportunity to witness the inspections. Provide magnetic gages, calibrated immediately before taking the measurements in presence of the paint manufacturer's representative.

END OF SPECIFICATION