1, Scope of Application.

This document specifies the requirements for surface treatment, coating process, coating quality inspection and acceptance of new steel buoys before painting in china.

2, Requirement.

1) Surface treatment before painting.

a, The surface of the new buoy steel should be shot blast pretreatment, the rust removal grade should reach the Sa2.5 grade requirements in GB8923-1989, and the surface roughness should reach 40-75 microns; after the pretreatment is qualified, the first anti-rust primer should be coated within 4 hours.

b, For buoy maintenance, the fouling marine organisms should be removed in time after the buoy comes out of water, and then shot blasting should be used for pretreatment. Surface treatment is carried out by hand tools, etc., and the rust removal quality should meet the grade requirements of St3 in GB8923-1989. After the pretreatment is qualified, the anti-rust primer should be applied within 4 hours.

c, When repairing a small area, power tools or hand tools can generally be used for surface treatment. The rust removal quality should meet the requirements of the St2 level of GB8923-1989, and the edges should be smooth. After the pretreatment is qualified, the anti-rust primer should be painted as soon as possible.

2)Coating process requirements

a, Before painting, check whether the variety and color of the paint used meet the requirements of this article, check the quality and shelf life of the paint, and the paint beyond the shelf life should not be used.

b, The paint should be fully stirred before use. If necessary, use 60-80 mesh screen to filter; spraying must be filtered. When using two-component paint, the proportion of each component should meet the technical requirements of the product and must be used up within the specified time. The surface to be coated must be clean, dry and free from contamination.

3) Coating construction environment requirements.

a, Painting construction should generally be carried out under environmental conditions of temperature 5 to 30 °C and relative humidity below 85%.

b, When it is raining, foggy, or the buoy float  is covered with water vapor, frost and snow, it should not be painted; it should not be painted in windy weather and a lot of dust.

c, The temperature of the steel plate is higher than 40°C and should not be painted; it should not be painted under the hot sun.

The temperature is below 5 °C, generally can not be painted, such as due to special needs must be painted should meet the following requirements:

The weather is clear, the temperature of the steel plate is higher than the dew point of 3 °C, and the temperature is not lower than the minimum temperature specified for the drying of the paint;

Epoxy coatings are coated with low-temperature curable coatings;

If the paint is too viscous and not easy to brush, it can be added less than 5% diluent, or it can be heated in a water bath (pay attention to opening the barrel lid), and it is strictly forbidden to use open flame or electric fire to heat directly;

The coating test must be carried out on site before it can be carried out.

d, Avoid being polluted by surrounding dust or splashed by water during coating construction and before the coating is dried.

e, No open flames are allowed around during coating construction.

f, There should be good ventilation when painting.

4) Coating method.

 Coating should be use high pressure airless spray as much as possible. In certain cases, brushing and compressed air spraying are also possible.

5) Coating craft.

a, For the parts that are difficult to reach by spraying and the parts where the coating film thickness is difficult to guarantee, such as welding seams, frame edges and other areas, before the formal coating, it is necessary to pre-coat 1-2 coats by brushing, and wait for it to dry slightly before applying Large area painting.

b, When brushing, the upper and lower directions and the left and right directions should be crossed. For corner seams, edges, and surface protrusions, the coating thickness must be guaranteed to avoid paint accumulation and sagging or the coating is too thin.

c, When using high pressure airless spraying, prevent static sparks from causing fires and explosions.

d, Before high-pressure airless spraying, check whether the paint pump, hose, and spray gun are in good condition. Select the nozzle according to the paint performance and paint film requirements, and the nozzle pressure should meet the specified requirements.

e, When spraying, the spray gun and the surface to be coated should be kept vertical and moved in parallel, and the distance between the spray muzzle and the working surface should be 300-500mm.

f, After the spray pump reaches the predetermined pressure after normal operation, the spraying operation can be started. The speed of the gun movement should be uniform.

g, The application interval must be guaranteed when rescuing. The next coating cannot be performed until the front paint has dried. When a cured coating exceeds the coating interval, the surface must be brushed before the next coat can be applied.

h, When two different types of coatings are at the junction, they must be overlapped according to the principle of coating matching to avoid bottom bite and color bleeding.

6) Management requirements for painting construction.

a, When the buoy is painted in the factory, the construction unit should make it clear that the special person is responsible, carefully organize the implementation, and ensure the quality of the coating and the safety of the personnel.

b, Before painting, the construction unit should estimate the amount of paint required and formulate a detailed construction plan according to the actual situation of the coating area, construction method, substrate and other actual conditions of each part of the buoy and with reference to the previous construction data.  

c, It is strictly forbidden to apply anti-fouling paint directly to bare metal surfaces.

7), Film Thickness Management

a, During the construction process, the thickness of the wet film should be measured and controlled at any time (in accordance with the determination of the thickness of the film of GB/T13452.2-1992 color paint and varnish), and strive to be uniform and flat to achieve the specified dry film thickness.

b, The dry film thickness is determined according to the GB/T13452.2-1992 method, and the determination must be carried out after the coating is completely dried.

c, The number of measurement points, 5 points per 1 square meter, and the parts that are really difficult to measure, such as welding and rivets, may not be measured.

d, More than 85% of the measurement points are not lower than the specified film thickness value, and the thickness of the remaining measurement points is not less than 85% of the specified film thickness value, otherwise it will be recoiled or recoiled.