PAINTING PROCEDURES FOR BUTTERFLY VALVES
Painting is a very important process when making the high quality of the butterfly valves. It can protect the valves against the corrosion in the bad working condition.
1. In order to ensure the paint quality of the valve and meet customer requirements, so this regulation is specially formulated.
2. Scope of application: Suitable for valves manufactured by our factory.
3. Process description:
3.1. Storage and identification of paint: Paint should be stored in a cool, dry and ventilated indoor warehouse that away from heat sources and direct sunlight. Paint management personnel should ensure that the paint is used within the validity period and marked so as not to be mixed.
3.2. Paint tools: Painters must clean the paint tools such as brushes and paint guns when dumping the remaining paint in the bucket and changing the type of paint or at the end of each working day.
3.3.1. if the standard is not specified in the order/contract, after completing the pressure test of the valve, use an air gun to flush the water in the valve cavity and send the valve to the paint areas. The painter uses cleaning tools such as brushes, oil cotton, spray guns and gasoline to clean the oil, grease and other dirt on the valves.
3.3.2. the painted surface of the valve must be inspected before painting. The rust, oxide scale, burrs, iron filings, sticky sand, scars, welding slag, etc. that affect the quality of the painting must be removed. The painting can be applied only after inspection.
3.3.3. the uneven surface, such as casting defects, pores, etc., should be polished, putty and other surface treat
3.3.4 The parts of the valve that do not need to be painted should be protected by painters to avoid being painted
3.3.5. When the paint is opened, the painter should carefully read the instruction manual
3.4. Primer paint:
3.4.1 The material for the first layer: epoxy zinc-rich rust inhibitor
The material for the Second layer: epoxy cloud iron rust inhibitor
3.4.2. According to the construction requirements before painting, the quality of the paint should be checked. Unqualified or deteriorated paint cannot be used.
3.4.3. Before painting, select and determine the appropriate painting tool according to the paint operation requirements. Use a paint brush to paint. The direction of painting should be first up and down, then left and right. Paint should not be too much to prevent Dripping. The painting distance should not be too large to prevent the paint film from being too thin.
3.4.4. Special attention should be paid to the surface roughness, edges, corners and protrusions, which should be pre-coated.
3.4.5. On the back of the flanges of the valve, the bottom of the valve must be painted evenly.
3.4.6. The end flange shall be evenly coated with a brush dipped in epoxy zinc-rich rust inhibitor.
3.4.7. The first layer of primer is applied by hand, and the second layer of primer can be sprayed.
3.4.8. Use emery cloth (sandpaper) to repair the primer that needs to be trimmed smooth and smooth.
3.5. Topcoat (third layer):
3.5.1 The color standard is blue, or customized as per the requirements of clients.
3.5.2. After the paint is completely dry, spray it with a spray gun with a No. 9 nozzle. It should move back and forth in parallel when spraying, covering half of the previous movement each time to ensure that the thickness of the paint film in each part is uniform.
3.5.3 Spraying should be carried out according to the amount used during the operation, and the thickness of the paint film is often measured using a Film measuring meter. When the thickness of the paint film does not meet the requirements, it must be repainted.
3.5.4. After brushing the paint, wipe the sealing surfaces of the flanges at both ends of the valve, and apply the butter evenly to the sealing surface with a brush to prevent rust, then spray the soft film anti-rust paint to the valve body
cavity, and then according to The size of the valve is covered with plastic or wood to protect the valve.
4. Paint thickness:
4.1. The thickness of the first layer of epoxy zinc-rich rust inhibitor dry film is 40um.
4.2. The second layer of epoxy cloud iron rust inhibitor has a dry film thickness of 40um.
4.3. The dry film thickness of topcoat is 40um.
5. Paint interval time:
5.1. The first layer of epoxy zinc-rich rust inhibitor paint should be dried before the second layer of epoxy cloud iron rust inhibitor paint is applied, and the second layer of paint should be dried before the third layer of paint can be applied. The paint interval time can be done as per the list in the table below.
5.2. Table 1: Paint interval time:
6. Customer requirements: When the customer specifies the paint and paint process, the paint color, paint method, and thickness of the paint layer shall be in accordance with the customer requirements.
7.1. Inspectors shall conduct sampling inspection of valve product paint quality according to Standard “GB/T2828 general inspection level II’’, by 1.5AQL normal one-time sampling.
7.2. The inspector shall make a record according to the “Valve Paint Record Report”.