Specification of steel surface preparation before application of paint
Some standard content:
1 General Provisions
Petroleum and Natural Gas Industry Standard of the People's Republic of China Specification for Surface Pretreatment of Steel Materials before Painting
Approval Department: China National Petroleum Corporation Date of Approval: 1997-12-28
Effective Date: 1998-06-01
SY/T 0407-1997
Replaces SYJ4007—1986
1.0.1 This specification is formulated to ensure the quality of pretreatment of steel surfaces before painting and to improve the adhesion and quality of coatings. 1.0.2 This specification is applicable to the pretreatment of steel surfaces before painting. 1.0.3 In addition to complying with this specification, the pretreatment of steel surfaces before painting shall also comply with the provisions of the relevant mandatory standards currently in force in the country. 2 Basic Provisions
2.0.1 The quality level and assessment of steel surface pretreatment before painting shall comply with the provisions of "Rust Level and Rust Removal Level of Steel Surface Before Painting" GB/T8923.
2.0.2 The minimum quality requirements for surface pretreatment (rust removal quality level and surface roughness) shall be specified in the technical standards or design documents of the relevant coatings.
2.0.3 The cleaning agents, abrasives, etc. used in surface pretreatment shall have a certificate of conformity and a factory quality certificate. 2.0.4 The equipment used for surface pretreatment shall meet the process requirements of this specification and have safe and reliable performance. 2.0.5 The relevant industrial hygiene and environmental protection involved in the surface pretreatment process shall be implemented in accordance with the relevant national mandatory standards such as "Industrial Enterprise Design Hygiene Standard" TJ36, "Painting Operation Safety Regulations for Pre-painting Process Safety" GB7692 and "Painting Operation Safety Regulations for Pre-painting Process Ventilation and Purification" GB7693. 3 Cleaning
3.1 Scope of application
3.1.1 This chapter applies to cleaning the surface of steel materials with solvents, emulsions or alkaline cleaning agents to remove all visible oil, grease, dust, lubricants and other soluble dirt on the steel surface. 3.2 Surface treatment before and after cleaning
3.2.1 Before cleaning, use a rigid fiber brush or wire brush to remove loose materials (excluding oil and grease) on the steel surface. 3.2.2 After cleaning, use appropriate methods (such as brushing, blowing with clean and dry compressed air or vacuuming) to remove dust and other dirt on the steel surface before painting. 3.3 Cleaning method
3.3.1 Before cleaning, scrape off the thicker oil or grease attached to the steel surface. 3.3.2 The oil or grease left on the steel surface can be removed by any of the following cleaning methods: 1. Scrub the steel surface with a rag or brush soaked in solvent. When scrubbing for the last time, use a clean solvent, rag or brush. 2. Spray the steel surface with solvent. When spraying for the last time, use a clean solvent. 3. Completely immerse the steel surface in the solvent tank. The amount of dirt contained in the solvent used for the last soaking should not have an adverse effect on the coating work.
Use the vapor of a stable chlorinated hydrocarbon solvent to remove grease. 4
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5. Emulsified cleaning agents or alkaline cleaning agents can be used instead of the solvents used in the above methods, but after cleaning, fresh water or steam must be used to remove harmful residues on the steel surface.
6. Use a decontaminant or detergent together with steam for steam cleaning. After cleaning, use steam or fresh water to wash to remove harmful residues on the steel surface.
3.3.3 The applicable scope and precautions of various cleaning methods can be referred to Table 3.3.3. Table 3.3.3 The applicable scope and precautions of various cleaning methods Cleaning method
Solvents (such as industrial gasoline, solvent gasoline, coal tar, turpentine, perchloroethylene, trichloroethylene, etc.)
Alkaline cleaning agent (trisodium phosphate, etc.)
Steam cleaning (can be used with detergent or alkaline cleaning agent)
3.4 Safety measures
Scope of application
Remove oil, grease, soluble dirt and soluble coating
Precautions
If the old coating needs to be retained, a non-toxic cleaning agent should be used. Solvents that are damaged; Solvents and rags should be changed frequently, and the solvent used for the last rinse must be clean. After cleaning, rinse with water, preferably pressurized hot water to remove saponifiable coating oil, grease and detergent; After rinsing, the pH value of the steel surface should not be greater than the pH value of the rinse water; The steel surface should be passivated; If other dirt needs to be retained, remove oil, grease and other dirt. Remove oil, grease and other dirt. When the pressure and temperature are sufficient, they can also be removed. 3.4.1 Solvent cleaning operations shall not be carried out before safety measures are taken. The old coating should be cleaned with a solvent that is not destructive to the coating. After cleaning, the residue should be rinsed off the steel surface. The old coating can be eroded or damaged during cleaning. After cleaning, the residue should be rinsed off the steel surface. 3.4.2 The storage and handling of solvents shall be carried out in accordance with relevant national or industry regulations. 3.4.3 The construction site must be equipped with ventilation devices to ensure that the concentration of solvents in the air is lower than the minimum value that can cause poisoning or fire and explosion. The concentration of organic solvent vapor should comply with the relevant provisions of the current national standard "Industrial Enterprise Design Hygiene Standard" TJ36. 3.4.4 When using acid or alkaline cleaning agents, workers must wear safety goggles, rubber gloves, safety protective clothing, and gas masks when necessary.
4 Tool rust removal
4.1 Surface treatment before and after tool rust removal
4.1.1 Before rust removal of tools, the visible oil, grease and dirt on the surface of steel should be removed by the methods specified in Chapter 3 of this specification or other methods adopted by the design:
4.1.2 After rust removal of tools, dust on the surface of steel should be removed by appropriate methods before painting. 4.1.31 After rust removal of tools, if it is found that the surface of steel does not meet the corresponding quality requirements of Article 3.3.3 of GB/T8923 before painting, it should be cleaned again.
4.2 Tool rust removal methods
4.2.1. Tool rust removal can be divided into two methods: manual and power tool rust removal. The rust removal grade should correspond to St2 and St3 in GB/T8923--1988, and its quality should meet the requirements of Table 4.2.1. 834
Quality level
St. Thorough manual and
power tool rust removal
Very thorough manual and power tool rust removal
Table 4,2.1 Quality levels and quality requirements for manual and power tool rust removal Quality requirements
SY/T 0407—1997
The steel surface should be free of visible grease and dirt, and free of loosely attached scale, rust and paint coatings.
The steel surface should be free of visible grease and dirt, and free of loosely attached scale, rust and paint coatings. Rust removal should be more thorough than St2, and the surface of the exposed part of the substrate should have a metallic luster. 4.2.2 Manual tool rust removal should be carried out according to the following procedures: 1 Use impact manual tools to remove the layered rust and welding spatter on the steel surface. 2 Use a wire brush, coarse sandpaper, spatula or similar hand tool to brush, grind or scrape off all loose oxide scale, loose rust and loose old coating on the steel surface.
4.2.3 Rust removal with power tools should be carried out according to the following procedures: 1 Use a power-driven rotary or impact rust removal tool, such as a rotary wire brush, grinding wheel, etc., to remove the layered rust and welding spatter as well as loose oxide scale, loose rust and loose old coating on the steel surface. 2 On the steel surface, where the power tool cannot reach, use hand tools for additional cleaning. 3 When using tools to remove rust, the steel surface should not be damaged, and the steel surface should not be polished too smooth. 4.3 Safety measures
4.3.1 If there is a risk of fire and explosion, safety precautions should be taken before starting work. If the component has been filled with flammable substances before, they should be removed to a concentration below the dangerous concentration; if the component to be rusted is close to flammable substances or gases, non-sparking tools should be used.
4.3.2 In places where there is dust hazard, the operator should wear a filtered air dust collector. 4.3.3 If the rust removal work is harmful to the eyes, the operator should wear goggles. 4.3.4 Hand-held power tools for rust removal must comply with the provisions of "Safety of Hand-held Power Tools Part 1: General Requirements" GB3883.1. Pneumatic or hydraulic grinding tools must comply with the provisions of "Safety Rules for Abrasive Tools" GB2494. 5 Blasting (blasting) rust removal
5.1 Surface treatment before and after blasting (blasting) rust removal 5.1.1 Before blasting (blasting) rust removal, the visible oil, grease and scale on the surface of the steel should be removed by the methods specified in Chapter 3 of this specification or other methods adopted by the design.
5.1.2 After blasting (blasting) rust removal, before painting, the loose rust and dust on the surface of the workpiece should be removed by blowing with dry, oil-free air, sucking with a vacuum cleaner or brushing with a brush.
5.1.3 If wet spraying is used, after spraying, it should be rinsed with fresh water mixed with sufficient corrosion inhibitor, or rust prevention treatment should be performed after rinsing with fresh water. After rinsing, if there is still residue on the surface, it should be cleaned with a brush. 5.1.4 After spraying (blasting) rust removal, necessary treatment should be carried out on the defects revealed on the steel surface in accordance with regulations. 5.1.5 The steel surface after spraying (blasting) rust removal should be painted before it is contaminated. If the steel surface has been contaminated before painting, it should be cleaned again.
5.2 Spraying (blasting) rust removal method
5.2.1 The quality requirements of each quality grade of spraying (blasting) rust removal shall comply with the provisions of Table 5.2.1. The four quality grades shall correspond to Sa1, Sa2, Sa3 and Sa3 in GB/T8923--1988 respectively. 5.2.2 Any of the following spraying (blasting) methods may be used: 1 Open dry blasting: Use compressed air to spray clean and dry metal or non-metal abrasives through the nozzle. 2 Closed circulation blasting: Use a closed circulation abrasive system to spray metal or non-metal abrasives through the nozzle with compressed air. 835
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3 Closed circulation blasting: Use a closed circulation abrasive system to blast metal abrasives with a centrifugal impeller. 4 Wet blasting: Use compressed air to spray non-metallic abrasives mixed with water through the nozzle. A sufficient amount of corrosion inhibitor should be added to the spraying water. Otherwise, it should be rinsed with fresh water after spraying and rust prevention treatment should be performed. Table 5.2.1 Quality grades and quality requirements for blasting (blasting) rust removal Quality grade Sa 1 Mild blasting or blasting rust removal Sa 2 Thorough blasting or blasting rust removal Sa 2V Very good spraying
or blasting rust removal
Sa3 Make the steel surface clean
Steel surface should be free of visible grease and dirt, and no loosely attached oxide scale, rust and paint coating.
Steel surface should be free of visible grease and dirt, and oxide scale, rust and paint coating have been basically removed, and their residues should be firmly attached.
Steel surface should be free of visible grease, dirt, oxide scale, rust and paint coating, and any remaining traces should only be slight spots or stripes.
Steel surface should be free of grease, dirt, oxide scale, rust and paint coating, and the surface should show a uniform metallic color.
5.2.3 The compressed air used for spraying rust removal should be dry and oil-free. 5.2.4 The blasting (blasting) rust removal operation should not cause any damage to the partially or fully completed workpiece. 5.2.5 When the surface temperature of the steel is 3°C below the dew point, dry blasting operation should not be carried out. 5.3 Abrasives for blasting (blasting) rust removal
5.3.1 The abrasives should be selected according to the steel grade, type, original rust degree, type of coating, rust removal method and surface roughness required for coating.
5.3.2 For blasting (blasting) rust removal, metal abrasives such as cast steel shot, cast iron shot, cast steel sand, cast iron sand and steel wire segments can be used. Commonly used metal abrasives should meet the following requirements:
*- Cast steel shot should meet the requirements of "Cast Steel Shot" GB/*6484; cast steel sand should meet the requirements of "Cast Steel Sand" GB/*6485; - Cast iron shot should meet the requirements of "Cast Iron Shot" GB/*6486; - Cast iron sand should meet the requirements of "Cast Iron Sand" GB/*6487; - Steel wire segments can refer to the requirements of Appendix A of this specification. Note: GB/*6484~GB/*6487 are all original national standards that have been downgraded to industry standards but have not yet been converted. 5.3.3 For blasting (blasting) rust removal, natural mineral abrasives such as quartz sand and burning stone and artificial mineral non-metallic abrasives such as slag and furnace slag can also be used. The physical properties of commonly used non-metallic abrasives can be referred to Table 5.3.3. Table 5.3.3 Physical properties of commonly used non-metallic abrasives Abrasive type
Natural abrasive
Mineral sand
Garnet
Uniform quartz
(Diesel)
Cube
Bulk density
(kg/m)
Mass of free silicon
Dust content
Abrasive type
By-product abrasive
(Slag)
Steel slag||t t||Nickel slag
Alumina
Glass ball
(Mohs)
Bulk density
(kg/m2)
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Free silicon mass
Dust content
Natural mineral abrasives must be purified before use to remove salts and impurities, and artificial mineral abrasives must be clean and dry, without slag inclusions, sand, gravel, organic matter and other impurities. 5.3.4 The types and uses of metal abrasives suitable for various spraying (blasting) rust removal operations can be selected according to Table 5.3.4. Table 5.3.4
Types of metal abrasives suitable for various blasting (blasting) rust removal operations and their uses Name
Assembled new steel
Heat-treated steel
Heavy steel plate
Corroded steel
Welding oxide scale
Dressing workpiece
Maintaining coating
Abrasive type
Size range?
0.6～1.4 (shot)
0.6～1.4 (shot)
0.4~1. 0 (sand)
0.4～1.0 (sand)
0.8~1.4 (shot)
0. 4~ 1. 0 (sand)
0. 6~~0.8 (shot)
0. 4～0. 7 (sand)
0.1~1.2 (sand)
Note: ① For the circulating abrasive system, the size range of the abrasive refers to the size range of the mixed abrasive formed during operation. 5.3.5
Hardness (HRC)
The types and uses of non-metallic abrasives suitable for use in various blasting (blasting) rust removal operations can be selected by referring to Table 5.3.5. Types and uses of non-metallic abrasives used in various blasting (blasting) rust removal operations Table 5.3.5
New steel
Assembled new steel
Heat-treated steel
Heavy steel plate
Corroded steel
Welding oxide scale
Finished workpiece
Bulk density (kg/m)
≥1600
Note: ① Coarse: Abrasives that cannot pass through a sieve with an aperture of 850μm. Size range
Medium?
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②Medium: Abrasives that cannot pass through a sieve with an aperture of 355μm, but can pass through a sieve with an aperture of 710μm. ③Fine: Abrasives that can pass through a sieve with an aperture of 300μm. 5.3.6
Based on the requirements of the coating system for the anchor pattern depth on the steel surface, the abrasive for spraying (casting) can be selected by referring to Table 5, 3.6. Table 5.3.6bZxz.net
Representative anchor depths produced by commonly used abrasives Abrasives
Ranshi pills
Heavy mineral sand
Corresponding sieve size
0.60~0.71
0.71~0.81
0. 81 ~~0. 97
0. 97~1.20
0.31~0.40
0.40~0.73
1. 46 ~1.67
96±10
Typical anchor depth (μm)
63±10
71±12. 5
116±12.5
86±10
116±12.5
165±20
89±10
101±12.5
116±12,5
152±17.5
86±10
129±22.5
68±10
73±10
66±10
Note: ① The typical anchor depth in the above table is the maximum and average surface roughness expected to be achieved under good spraying (blasting) conditions (impeller or nozzle). The anchor depth produced by a certain abrasive in the table refers to the anchor depth produced by the mixed abrasive when the abrasive has become a stable mixed abrasive in the circulating abrasive jet rust removal machine. If new abrasive is used, the anchor pattern depth will increase significantly. ② The hardness of the steel shot in the table is HRC40-50, and the hardness of the steel sand is HRC55-60. 5.4 Selection of the quality grade of blasting (blasting) rust removal 5.4.1 The quality grade of blasting (blasting) rust removal should be selected according to the use environment of the steel, the protective coating used for the steel, the coating system and the rust removal process method.
5.4.2 The quality grade of spray (blast) rust removal selected under various environmental conditions can be determined according to Table 5.4.2. Table 5.4.2 Typical uses of various spray (blast) rust removal quality grades Rust removal quality grade
Sa3 Spray or blast rust removal that makes the steel surface clean Sa 2X Very thorough spray or blast rust removal Sa 2 Thorough spray or blast rust removal
Sa 1 Mild spray or blast rust removal
Typical uses
The use environment is highly corrosive and requires the steel to have an extremely clean surface to extend the service life of the coating
The use environment is highly corrosive and conventional coatings can achieve the best anti-corrosion effect for steel When steel is exposed to a moderately corrosive environment, conventional coatings can achieve an anti-corrosion effect When steel is exposed to a conventional environment, conventional coatings can achieve an anti-corrosion effect The film thickness and anchor pattern depth of common coatings can be determined by referring to Table 5.4,3. 5.4.3
Drying oil and alkyd
Phenolic and epoxy resin
Oxidized rubber
Ethylene
Silicone and silicone acrylate
Modified epoxy (high temperature resistant coating)
Epoxy phenolic
Polyurethane
Poly film lining
Inorganic zinc-rich
5.5 Safety measures
Two-component
One-component
Epoxy phenolic
Modified Epoxy
Solvent-based
Common coating primer dry film thickness and anchor pattern depth comparison table Primer dry film thickness
50.8~76.2
50.8~76.2
50.8~101.6
25.4~50.8
25.4~50.8
50.8~101.6
50.8~101.6
25.4~50.8
50. 8 ~~76. 2
25.4~50.8
76.2~127. 0
50.8~~101.6
25. 4 ~~78. 1
SY/T 0407--1997
Anchor pattern depth
19.05~~25.4| |tt||25. 4~36.75
25.4~~31.75
25.4~31.75
19,05~25.4
25.4~31.75
25.4~31.75
25.4~31.75
25. 4~31. 75
50.8101.6
25.4~31.75
10. 5~31. 75
19.05~~25. 4
5.5.1 If there is a risk of fire and explosion, complete protection should be taken before starting work. If the component has been previously filled with flammable materials, they should be removed to a concentration below the dangerous concentration. 5.5.2 Nozzle operators exposed to blasting dust should wear protective masks connected to a clean compressed air source. 5.5.3 Other workers exposed to blasting dust should wear filtered air dust collectors. Adequate protection should be provided for personnel engaged in blasting to avoid the hazards of flying dust. 5.5.4 People near the blasting site should wear goggles. 5.5.5 The spray pipe should be grounded.
6 Pickling
6.1 Scope of application and quality requirements
6.1.1 This chapter applies to the pickling treatment of steel surfaces. 6.1.2 Chemical and electrolytic methods can be used for pickling treatment. After pickling, the steel surface should be free of visible scale, rust and old coating. 6.1.3 The corrosion degree of the steel surface should meet the specified coating requirements. 6.1.4 The color uniformity of the steel surface after pickling is allowed to be affected by the steel grade, original rust degree, shape, rolling or processing marks and corrosion method.
6.2 Surface treatment before pickling
6.2.1 Use the methods specified in Chapter 3 of this specification to remove most of the oil, grease, lubricant and other contaminants (excluding scale, oxide and rust) on the steel surface.
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6.2.2 It is advisable to use tool derusting method or spray (blasting) derusting method (only required to reach Sa1 level) to remove most of the oxide scale, rust and old coating on the surface to shorten the time of pickling and derusting. 6.3 Pickling method and requirements
6.3.1 Immerse the steel surface in sulfuric acid, hydrochloric acid or phosphoric acid solution at room temperature. Sufficient corrosion inhibitor should be added to the pickling solution to reduce corrosion to the base metal. After all the oxide scale and rust are completely removed, rinse with fresh water and then passivate. 6.3.2 Immerse the steel surface in a sulfuric acid solution at a temperature of 60°C or above and a concentration of 5% to 10% (by weight). Sufficient corrosion inhibitors should be added to the pickling solution until all scales and rust are removed and then rinsed with fresh water. Finally, soak the steel surface in a phosphoric acid solution at about 80°C containing 0.3% to 0.5% iron phosphate and a concentration of 1% to 2% (by weight) for 1 to 5 minutes. 6.3.3 Immerse the steel surface in a sulfuric acid solution at a temperature of 75 to 80°C and a volume fraction of 5%. Sufficient corrosion inhibitors should be added to the pickling solution until all scales and rust are removed and then rinsed with hot water at 75 to 80°C for 2 minutes; finally, soak in a passivation solution at a temperature of 85°C or above for more than 2 minutes. The passivation solution should contain 0.75% sodium dichromate or about 0.5% orthophosphoric acid. 6.3.4 Place the steel in an acid or alkaline electrolytic cell for electrolysis. If the workpiece is used as the cathode during electrolysis, appropriate treatment should be done to prevent or reduce the occurrence of hydrogen embrittlement. If electrolysis is carried out in an alkaline solution, it must be fully rinsed with hot water after electrolysis, and then immersed in a dilute phosphoric acid or dilute dichromate solution until all the alkali traces remaining on the surface are removed. 6.3.5 The pickling treatment should meet the following requirements: 1 The content of dissolved iron in the sulfuric acid tank should not exceed 6%, and the content of dissolved iron in the hydrochloric acid tank should not exceed 10%. 2 Pure fresh water or distilled water must be used as a solution or rinse liquid. During the rinse process, clean water should be continuously injected into the rinse tank so that the total amount of acid and soluble salt carried per liter of water does not exceed 2g. 3 The steel removed from the pickling tank should be suspended above the tank for a short time to drain most of the pickling solution. Harmful pickling residues, unreacted acids or alkalis, metal deposits and other harmful contaminants must be removed after pickling. 4
The pickled steel should not be stacked up so that the surfaces are in contact with each other, and should be overlapped after the surfaces are completely dry. 5
6 Painting must be done before visible rust appears. 6.4 Safety measures
6.4.1 Adequate ventilation facilities should be provided to ensure the health of the workers and the concentration of hydrogen should be limited to below the explosion limit.
6.4.2 Operators should wear goggles.
6.4.3 Workers must wear rubber aprons, rubber boots and rubber gloves. 6.4.4 The discharge of waste liquid generated during pickling and electrolysis should comply with the relevant national standards in force. 6.4.5 The handling and storage of chemicals used in pickling and electrolysis should comply with the relevant national regulations in force. 6.4.6 Concentrated acid must be poured slowly into water or dilute acid, and it should be stirred while pouring. Appendix A
Wire segment
A.1 Appearance and specifications
A.1.1 The wire segment should be cylindrical, and the length of the cylinder is approximately the diameter of the wire. The mass of defective particles in the finished product shall not exceed 10% of the inspected amount. Defective particles refer to cracked, overly twisted and overly irregular particles. A.1.2 The specifications of the steel wire segment shall comply with the provisions of Table A.1.2. 840
Nominal diameter
Allowable
Standard value of diameter
Technical requirements
Table A.1.2 Specifications of steel wire segment
(Length = nominal diameter)
Allowable length deviation
(Measure 20 particles to obtain the average value)
The chemical composition of the steel wire segment shall comply with the provisions of Table A.2.1. Table A.2.1
0.45~~0.75
0.60~1.20
Chemical composition of steel wire segments
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Total mass of every 200 particles
The tensile strength of the steel wire before cutting and the hardness of the steel wire after cutting shall comply with the provisions of Table A.2,2. A.2.2
Table A.2.2 Tensile strength of steel wire and hardness of steel wire segment Nominal diameter
Tensile strength of steel wire (Pa)
1 634×106~1 875×106
1 675×106~1 924×106
1 710×105 ~1 972×106
1 758×106~2 020×106
1 800×105 -- 2 075×106
1 827×106 ~2 103×108
1 868X106 -~ 2 144×105
1896×106~2.165×106
1 951×106 -2 205×106
Allowable deviation
Minimum hardness of wire segment (HRC)
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