This standard specifies the technical requirements for coating and testing of hydropower products and their components.
This standard is mainly applied to the surface coating of steel products. Where there is no special requirement in the contract documents, the surface coating of the products shall comply with the provisions of this standard.
First, the surface treatment before painting
All steel raw materials used in equipment manufacturing require surface rust removal before painting. And paint the primer (shop primer) within the specified time range.
1. Before the rust is sprayed, the thick rust layer should be removed. And remove grease and dirt. After spraying or descaling, the surface of the steel must remove dust and debris.
2. Two rust-removing grades are specified for the surface of blast-derusting steel. Its text is described as follows:
Sa2 is thoroughly sprayed to remove rust: There is no visible grease and dirt on the steel surface, and attachments such as oxide scale, rust, and paint coating have been substantially removed, and their residue should be firmly attached.
Sa21/2 sprays rust very thoroughly. There are no visible grease, dirt, iron oxides, or paint deposits on the surface of the steel. Any traces of residue should be only slight dots with stripes or stripes.
3. For the derusting steel surfaces of manual and power tools, there is a derusting rating, which is described as follows:
St3 is a very thorough hand and power tool for rust removal. There is no visible grease and dirt on the steel surface, and there are no loose deposits of scale, rust, and paint coating. The exposed surface of the substrate after derusting should have a metallic luster.
4. The term "attachment" may include welding slag, welding spatter, soluble salts, and the like. When the scale, rust, or paint layer can be peeled from the surface of the steel with a metal blade, it should be regarded as not firmly attached
5. The surface of the steel to be inspected should be visually compared with the corresponding photograph. Photos should be close to the steel surface. The assessment should be conducted under well-scattered daylight or under artificial lighting conditions with equivalent illumination.
6. The thickness of the paint film and the coating selection during pretreatment are as follows:
a) Paint film (dry film) thickness: 15 to 25 μm.
b) Coating types: Inorganic zinc silicate (workshop) primer, epoxy primer, epoxy zinc-rich primer, zinc phosphate primer, iron red epoxy grease primer, etc.
c) The primer used must be of the type in the product's supporting paint system or of paint suitable for the primer in the matching paint system.
Second, technical requirements
1. Before painting, paint must be allowed after it meets the required derusting grade standards.
2. In the mildly corrosive environment, the surface derusting rating standard is Sa2 when preparing to apply conventional paint.
3. When the atmospheric corrosion of chemical industry, seawater erosion, high temperature oxidation and inorganic zinc-rich coatings are used as primers, the surface derusting rating standard is Sa21/2.
4. The surface roughness of steel before painting must be controlled. In addition to controlling the angle and speed of abrasive blasting, the diameter of the pellets used for recycling should not exceed 1.2 mm.
5. After spraying or blasting, the surface of the material to be coated shall be rust-removed, and the first layer of primer shall be applied immediately after cleaning. The interval time shall not exceed 6 hours. If the surface is rusted again, it should be re-processed, and the paint should be allowed to reach the specified standard.
6. The coated parts or materials coated with workshop maintenance primer shall cause secondary rust removal due to welding, rectification, abrasions, exposure to sunlight, etc., and must be re-rusted. The grade after derusting shall reach St3.
Third, preparation before painting
1. The paint used shall have a product certificate, which shall be re-inspected according to the acceptance rules for paint products. Coatings that do not meet the product quality must not be used.
2, the same coating system, the choice of primer, putty, intermediate paint, topcoat, thinner, etc. must be used in conjunction.
3, before the paint open bucket to confirm its brand, variety, color, batch number, etc., and record. If the logo is ambiguous, it should be carefully checked. If there is a skinning phenomenon after opening the barrel, the crust should be carefully removed. If the paint is found to be out of date, it should be identified and confirmed to be reliable in quality. In case of paint deterioration, it should be discarded.
4. Some pigments in the paint are dense and easy to precipitate. Mechanical stirring is required to make the paint uniform. Before adding the curing agent, the two-component coating should be uniformly stirred, and after adding the curing agent, stir it evenly.
5, mixed mature two-component or three-component paint to be mixed according to the specified ratio. The normative approach is as follows:
1 Stir the paint evenly;
2 Pour in half the hardener and stir well;
3 Pour in the remaining curing agent and mix well.
4 Then add diluent if necessary and stir well;
5 according to the provisions of a certain time for aging pre-reaction;
Note that the use time should not exceed the regulations. The maturation time and the mixed use time decrease as the temperature increases, so pay attention to the manufacturer's instructions. The hot season must avoid construction in the sun.
6, dilution
Paints can usually be used on drums without dilution, and customary dilutions must be avoided. When you must use thinner, be sure to use the correct diluent. Excessive dilution can cause the paint to reach the specified thickness, reduce drying and curing time, and cause sag problems. Thinners can be added in the following situations:
1 In the winter when the temperature is low, an appropriate amount of diluent can be added to reduce the viscosity of the coating.
2 manual or air spray need to add thinner for easy construction;
3 deliberately reduce the film thickness can add appropriate amount of diluent.
7, filter
In order to remove large particles, crusts, or other foreign materials that are difficult to disperse in the paint, it is necessary to filter so that the nozzles are not blocked. The normative approach is to pass the filter into another empty bucket. When spraying, add a 80-120 mesh sieve or filter at the suction port of the paint pump. Keep the filter clean. After use, wash with solvent for reuse.
Fourth, coating
1. The construction area must maintain air circulation. No dust and other foreign materials should fly during painting and curing. During the coating construction process, it is necessary to ensure the uniformity of the paint film and not to miss the paint. For edges, corners, crevices, welds and other parts to be painted, and then a large area of ​​painting.
2. The surface of the machine product needs to be puttyed and should be processed according to the process document. When the putty is scraped, the primer should be applied first, and the primer should be dried before the scraping operation. Putty putty is usually performed 1~2 times, each time the thickness is about 0.5~1mm, and the local maximum total thickness may not exceed 5mm. After the putty is dried, the surface must be polished. The polished putty surface should be flat, smooth, firm, and free of cracks.
3. The painting work should be carried out under permissible weather conditions. Do not paint when the following conditions occur
a. In general painting, the ambient temperature is below 5 degrees Celsius or above 35 degrees Celsius.
b. In the open-air coating, there is rain, snow, fog, frost, and strong winds;
c. The surface temperature is less than the dew point temperature plus 3 degrees Celsius; check the dew point temperature value in the Appendix for reference.
d. The relative humidity in the surrounding environment is above 85 percent;
4. Defects such as pits, sand holes and air holes appear on the casting surface. Must be filled with putty. Under the putty layer must not fall off or crack.
5. Before coating, check the surface treatment quality. Unsatisfactory coating cannot be performed. In the process of painting, sagging, wrinkling, blistering, cracking, pinholes and other defects occur. Must take appropriate technical measures to repair.
6. When the construction cannot be carried out according to the specified painting conditions due to the environment or other reasons, it is necessary to take necessary technical measures and confirm that the quality of the painting can be guaranteed before construction. Records shall be kept of the measures taken.
7. Coatings by grade coating must be performed according to the coating interval specified in the coating product specification. If the specified coating interval is exceeded, the front coat surface must be roughened.
8. The coating that is not dry should be protected to prevent contamination and damage. The coating that has been contaminated and damaged should be repaired as required.
9, the junction of two different colors of paint film, the boundary must be clear, neat and standardized.
10. Coating parts assembled on site, and the last coat of paint shall be applied after the equipment is installed and tested.
11. The method of painting construction shall strictly follow the operating rules whether it is applied by brush or spraying. The thickness of the coating should meet the design requirements.
12, the following conditions are not painted
a. High-strength bolt friction surface.
b. buried concrete or contact with the refractory material.
c. Machined surfaces that are close-packed or have relative motion.
d. Anchor bolts and their bottom plates.
e. Sealed box and body surface.
f. Stainless steel parts, plated parts, non-metallic parts and parts not indicated on the drawings.
g. The site to be processed on site.
Fifth, second coating
1. The surface of the surface where the rust is returned and the joints exposed and the damaged lacquer film during the installation should be repaired.
2. Before the repair, clean the surface, re-rust, and clean the surface with clean compressed air, and perform the secondary coating repair according to the coating design requirements.
3. The covering width of the repaired part should not be less than 50mm. When the damaged area is small, the repaired area should be more than 1 times larger than the damaged area.
4. After the painting is complete, make a clear mark on the components according to the original number, name, and code number.
Six, coating testing and inspection
1. The appearance of the paint film shall meet the following requirements: No defects such as pinholes, air bubbles, cracks, bite bottoms, bleeding, missing paint, sagging, local peeling, etc. shall be allowed on the primer, intermediate paint, and topcoat paint film; Should be even and uniform, full paint film, uniform color. The inspection method can be negotiated with the naked eye or with a magnifying glass.
2. The coating thickness should be tested after each coating is dried. After the entire coating is completed, the total thickness is checked again. The detection method is: using a film thickness gauge to detect, every 10m2 (the area of ​​the film is less than 10m2 is measured by 10m2) as a place, and the slender body is every 3 to 4M long as a place, each place measures 3 to 5 point. The average value of the thickness of each point measured at each location shall not be less than 90% of the total thickness of the specified coating and not more than 120%. The minimum of each measured point thickness shall not be less than 70% of the total thickness of the specified coating.
3, testing the quality of coating can be carried out coating resistance evaluation of the substrate
The resistance assessment of the coating release from the substrate was carried out according to the following method: Six test plates with a size of 200 mm×200 mm were selected and after surface treatment, the same coating system as the new product was applied. The resistance evaluation is carried out after the paint film is dried. The evaluation can be carried out by using the cross-cut method or cross-cut method.
Fork method: Use a sharp blade or a safety blade to draw a fork with an included angle of 60° on the surface of the test board. The tool mark should be drawn to the steel plate. Then stick a professional pressure-sensitive tape with a width of 25mm to make the tape tightly against the paint film. , and then quickly torn by hand, if the total width of the coating on both sides of the knife mark is not more than 2mm is qualified.
Cross-cutting method: According to the relevant provisions of "the test of the paint and varnish paint film" (GB/T9286) to assess. The assessment result should not be less than the level 2 requirements.
This standard is mainly applied to the surface coating of steel products. Where there is no special requirement in the contract documents, the surface coating of the products shall comply with the provisions of this standard.
First, the surface treatment before painting
All steel raw materials used in equipment manufacturing require surface rust removal before painting. And paint the primer (shop primer) within the specified time range.
1. Before the rust is sprayed, the thick rust layer should be removed. And remove grease and dirt. After spraying or descaling, the surface of the steel must remove dust and debris.
2. Two rust-removing grades are specified for the surface of blast-derusting steel. Its text is described as follows:
Sa2 is thoroughly sprayed to remove rust: There is no visible grease and dirt on the steel surface, and attachments such as oxide scale, rust, and paint coating have been substantially removed, and their residue should be firmly attached.
Sa21/2 sprays rust very thoroughly. There are no visible grease, dirt, iron oxides, or paint deposits on the surface of the steel. Any traces of residue should be only slight dots with stripes or stripes.
3. For the derusting steel surfaces of manual and power tools, there is a derusting rating, which is described as follows:
St3 is a very thorough hand and power tool for rust removal. There is no visible grease and dirt on the steel surface, and there are no loose deposits of scale, rust, and paint coating. The exposed surface of the substrate after derusting should have a metallic luster.
4. The term "attachment" may include welding slag, welding spatter, soluble salts, and the like. When the scale, rust, or paint layer can be peeled from the surface of the steel with a metal blade, it should be regarded as not firmly attached
5. The surface of the steel to be inspected should be visually compared with the corresponding photograph. Photos should be close to the steel surface. The assessment should be conducted under well-scattered daylight or under artificial lighting conditions with equivalent illumination.
6. The thickness of the paint film and the coating selection during pretreatment are as follows:
a) Paint film (dry film) thickness: 15 to 25 μm.
b) Coating types: Inorganic zinc silicate (workshop) primer, epoxy primer, epoxy zinc-rich primer, zinc phosphate primer, iron red epoxy grease primer, etc.
c) The primer used must be of the type in the product's supporting paint system or of paint suitable for the primer in the matching paint system.
Second, technical requirements
1. Before painting, paint must be allowed after it meets the required derusting grade standards.
2. In the mildly corrosive environment, the surface derusting rating standard is Sa2 when preparing to apply conventional paint.
3. When the atmospheric corrosion of chemical industry, seawater erosion, high temperature oxidation and inorganic zinc-rich coatings are used as primers, the surface derusting rating standard is Sa21/2.
4. The surface roughness of steel before painting must be controlled. In addition to controlling the angle and speed of abrasive blasting, the diameter of the pellets used for recycling should not exceed 1.2 mm.
5. After spraying or blasting, the surface of the material to be coated shall be rust-removed, and the first layer of primer shall be applied immediately after cleaning. The interval time shall not exceed 6 hours. If the surface is rusted again, it should be re-processed, and the paint should be allowed to reach the specified standard.
6. The coated parts or materials coated with workshop maintenance primer shall cause secondary rust removal due to welding, rectification, abrasions, exposure to sunlight, etc., and must be re-rusted. The grade after derusting shall reach St3.
Third, preparation before painting
1. The paint used shall have a product certificate, which shall be re-inspected according to the acceptance rules for paint products. Coatings that do not meet the product quality must not be used.
2, the same coating system, the choice of primer, putty, intermediate paint, topcoat, thinner, etc. must be used in conjunction.
3, before the paint open bucket to confirm its brand, variety, color, batch number, etc., and record. If the logo is ambiguous, it should be carefully checked. If there is a skinning phenomenon after opening the barrel, the crust should be carefully removed. If the paint is found to be out of date, it should be identified and confirmed to be reliable in quality. In case of paint deterioration, it should be discarded.
4. Some pigments in the paint are dense and easy to precipitate. Mechanical stirring is required to make the paint uniform. Before adding the curing agent, the two-component coating should be uniformly stirred, and after adding the curing agent, stir it evenly.
5, mixed mature two-component or three-component paint to be mixed according to the specified ratio. The normative approach is as follows:
1 Stir the paint evenly;
2 Pour in half the hardener and stir well;
3 Pour in the remaining curing agent and mix well.
4 Then add diluent if necessary and stir well;
5 according to the provisions of a certain time for aging pre-reaction;
Note that the use time should not exceed the regulations. The maturation time and the mixed use time decrease as the temperature increases, so pay attention to the manufacturer's instructions. The hot season must avoid construction in the sun.
6, dilution
Paints can usually be used on drums without dilution, and customary dilutions must be avoided. When you must use thinner, be sure to use the correct diluent. Excessive dilution can cause the paint to reach the specified thickness, reduce drying and curing time, and cause sag problems. Thinners can be added in the following situations:
1 In the winter when the temperature is low, an appropriate amount of diluent can be added to reduce the viscosity of the coating.
2 manual or air spray need to add thinner for easy construction;
3 deliberately reduce the film thickness can add appropriate amount of diluent.
7, filter
In order to remove large particles, crusts, or other foreign materials that are difficult to disperse in the paint, it is necessary to filter so that the nozzles are not blocked. The normative approach is to pass the filter into another empty bucket. When spraying, add a 80-120 mesh sieve or filter at the suction port of the paint pump. Keep the filter clean. After use, wash with solvent for reuse.
Fourth, coating
1. The construction area must maintain air circulation. No dust and other foreign materials should fly during painting and curing. During the coating construction process, it is necessary to ensure the uniformity of the paint film and not to miss the paint. For edges, corners, crevices, welds and other parts to be painted, and then a large area of ​​painting.
2. The surface of the machine product needs to be puttyed and should be processed according to the process document. When the putty is scraped, the primer should be applied first, and the primer should be dried before the scraping operation. Putty putty is usually performed 1~2 times, each time the thickness is about 0.5~1mm, and the local maximum total thickness may not exceed 5mm. After the putty is dried, the surface must be polished. The polished putty surface should be flat, smooth, firm, and free of cracks.
3. The painting work should be carried out under permissible weather conditions. Do not paint when the following conditions occur
a. In general painting, the ambient temperature is below 5 degrees Celsius or above 35 degrees Celsius.
b. In the open-air coating, there is rain, snow, fog, frost, and strong winds;
c. The surface temperature is less than the dew point temperature plus 3 degrees Celsius; check the dew point temperature value in the Appendix for reference.
d. The relative humidity in the surrounding environment is above 85 percent;
4. Defects such as pits, sand holes and air holes appear on the casting surface. Must be filled with putty. Under the putty layer must not fall off or crack.
5. Before coating, check the surface treatment quality. Unsatisfactory coating cannot be performed. In the process of painting, sagging, wrinkling, blistering, cracking, pinholes and other defects occur. Must take appropriate technical measures to repair.
6. When the construction cannot be carried out according to the specified painting conditions due to the environment or other reasons, it is necessary to take necessary technical measures and confirm that the quality of the painting can be guaranteed before construction. Records shall be kept of the measures taken.
7. Coatings by grade coating must be performed according to the coating interval specified in the coating product specification. If the specified coating interval is exceeded, the front coat surface must be roughened.
8. The coating that is not dry should be protected to prevent contamination and damage. The coating that has been contaminated and damaged should be repaired as required.
9, the junction of two different colors of paint film, the boundary must be clear, neat and standardized.
10. Coating parts assembled on site, and the last coat of paint shall be applied after the equipment is installed and tested.
11. The method of painting construction shall strictly follow the operating rules whether it is applied by brush or spraying. The thickness of the coating should meet the design requirements.
12, the following conditions are not painted
a. High-strength bolt friction surface.
b. buried concrete or contact with the refractory material.
c. Machined surfaces that are close-packed or have relative motion.
d. Anchor bolts and their bottom plates.
e. Sealed box and body surface.
f. Stainless steel parts, plated parts, non-metallic parts and parts not indicated on the drawings.
g. The site to be processed on site.
Fifth, second coating
1. The surface of the surface where the rust is returned and the joints exposed and the damaged lacquer film during the installation should be repaired.
2. Before the repair, clean the surface, re-rust, and clean the surface with clean compressed air, and perform the secondary coating repair according to the coating design requirements.
3. The covering width of the repaired part should not be less than 50mm. When the damaged area is small, the repaired area should be more than 1 times larger than the damaged area.
4. After the painting is complete, make a clear mark on the components according to the original number, name, and code number.
Six, coating testing and inspection
1. The appearance of the paint film shall meet the following requirements: No defects such as pinholes, air bubbles, cracks, bite bottoms, bleeding, missing paint, sagging, local peeling, etc. shall be allowed on the primer, intermediate paint, and topcoat paint film; Should be even and uniform, full paint film, uniform color. The inspection method can be negotiated with the naked eye or with a magnifying glass.
2. The coating thickness should be tested after each coating is dried. After the entire coating is completed, the total thickness is checked again. The detection method is: using a film thickness gauge to detect, every 10m2 (the area of ​​the film is less than 10m2 is measured by 10m2) as a place, and the slender body is every 3 to 4M long as a place, each place measures 3 to 5 point. The average value of the thickness of each point measured at each location shall not be less than 90% of the total thickness of the specified coating and not more than 120%. The minimum of each measured point thickness shall not be less than 70% of the total thickness of the specified coating.
3, testing the quality of coating can be carried out coating resistance evaluation of the substrate
The resistance assessment of the coating release from the substrate was carried out according to the following method: Six test plates with a size of 200 mm×200 mm were selected and after surface treatment, the same coating system as the new product was applied. The resistance evaluation is carried out after the paint film is dried. The evaluation can be carried out by using the cross-cut method or cross-cut method.
Fork method: Use a sharp blade or a safety blade to draw a fork with an included angle of 60° on the surface of the test board. The tool mark should be drawn to the steel plate. Then stick a professional pressure-sensitive tape with a width of 25mm to make the tape tightly against the paint film. , and then quickly torn by hand, if the total width of the coating on both sides of the knife mark is not more than 2mm is qualified.
Cross-cutting method: According to the relevant provisions of "the test of the paint and varnish paint film" (GB/T9286) to assess. The assessment result should not be less than the level 2 requirements.