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    Home > Coatings News > Paints and Coatings Market > Coating standard: technical standard for surface coating and testing of iron and steel products

    Coating standard: technical standard for surface coating and testing of iron and steel products

    • Last Update: 2020-04-03
    • Source: Internet
    • Author: User
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    Core tips: technical standards for surface coating and testing of iron and steel products: This standard is mainly applicable to the surface coating of iron and steel products Where there are no special requirements in the contract documents, the surface coating of the products shall comply with the provisions of this standard 1、 Surface preparation before painting All steel raw materials used for equipment manufacturing shall be derusted before painting And apply the maintenance primer (shop primer) within the specified time range 1 Before spray derusting, the thick rust layer shall be removed And remove grease and dirt After spraying or derusting, the steel surface must be cleaned of dust debris 2 For spray derusting steel surfaces, two derusting grades are specified his Paint knowledge | precautions for wall paint color selection Recommended introduction: when painting the wall, the owner sometimes has difficulty in choosing what color of the wall paint to paint In fact, there is no ugly color in the wall paint, only the disharmonious color matching The use of wall color contains the knowledge of health Too strong color will stimulate people's perception, make people have a sense of fidgety, affect people's mental health Grasp the basic principles of wall color and paint a colorful space 1、 Wall paint color selection notice 1 Light color is generally used for the top surface Light colors make people feel light, dark colors make people feel heavy Usually, the treatment of rooms is from top to bottom, from shallow to deep For example, the ceiling and walls of rooms are white and Home of coatings: technical standard for surface coating and testing of iron and steel products: this standard is mainly applicable to surface coating of iron and steel products Where there are no special requirements in the contract documents, the surface coating of the products shall comply with the provisions of this standard 1、 Surface treatment before painting all raw materials used for equipment manufacturing steel, surface derusting treatment is required before painting And apply the maintenance primer (shop primer) within the specified time range 1 Before spray derusting, the thick rust layer shall be removed And remove grease and dirt After spraying or derusting, the steel surface must be cleaned of dust debris 2 For spray derusting steel surfaces, two derusting grades are specified The text is described as follows: SA2 spray derusting thoroughly: there is no visible grease and dirt on the steel surface, and the scale, rust paint coating and other attachments have been basically removed, and the residues should be firmly attached SA2 is very thorough spray derusting The steel surface shall be free of grease, dirt, iron oxide paint layer and other attachments, and any residual trace shall be only spot or stripe like with slight stain 3 For manual power tool derusting steel surface, a derusting grade is specified, which is described as follows: ST3 is very thorough manual power tool derusting There is no visible grease and dirt on the steel surface, and there is no loose oxide skin or rust paint coating attachment After rust removal, the exposed part of the substrate surface shall have metallic luster 4 The term "attachment" may include welding slag, welding spatter, soluble salts, etc When the oxide skin, rust or paint layer can be peeled off from the steel surface with a metal putty scraper, it shall be deemed that the adhesion is not firm 5 The steel surface to be inspected shall be visually compared with the corresponding photos The photos should be close to the steel surface The assessment shall be conducted under the condition of good scattering sunlight or illumination equivalent to artificial lighting 6 The film thickness and coating selection during pretreatment are as follows: a) film (dry film) thickness: 15-25 μ M b) Coating varieties: inorganic zinc silicate (workshop) primer, epoxy primer, epoxy zinc rich primer, zinc phosphate primer, iron red epoxy resin primer, etc c) The primer used must be matched with the type of paint system or the type of paint suitable for the matched paint system primer 2、 Technical requirements 1 Before painting, it is allowed to paint only after reaching the specified derusting level standard 2 In light corrosive environment, when the conventional coating is to be applied, the surface rust removal level is SA2 3 When it is subject to chemical atmospheric corrosion, seawater corrosion, high temperature oxidation and inorganic zinc rich coating as primer, the surface rust removal level is SA2 4 Before painting, the surface roughness of steel must be controlled In addition to the control of angle speed of abrasive jet, the diameter of the particles of recycled abrasive shall not be greater than 1.2mm 5 After spray or spray derusting, the surface to be coated shall be coated with the first primer immediately after cleaning, and the interval shall not exceed 6h If the surface appears rusty again, it should be reprocessed, and painting can only be allowed after reaching the specified standard 6 For the parts or materials coated with workshop maintenance primer, which are re rusted due to welding, correction, scratch, exposure and other reasons, the second derusting must be carried out, and the derusting grade shall reach ST3 3、 Prepare before coating 1 All coatings used shall be provided with product qualification certificate and retested according to the coating product acceptance rules The coatings that do not conform to the product quality shall not be used 2 For the same coating system, primer, putty, intermediate paint, top coat and diluent must be used together 3 Before opening the paint barrel, the brand, variety, color, batch number, etc shall be confirmed and recorded If the mark is fuzzy, it should be checked carefully If there is skinning after opening the barrel, the skinning shall be carefully removed If it is found that the coating is out of date, it should be identified and confirmed that its quality is reliable before construction In case of deterioration of the paint, it should be discarded 4 Some pigments in the coating are easy to precipitate due to their high density, so it is necessary to use mechanical agitation to make the coating uniform Before adding the curing agent of two-component coating, it should be stirred evenly first, and then stirred evenly again after adding the curing agent 5 The mixture of two-component or three-component paint should be mixed according to the specified proportion The standard practice is as follows: ① the coating is evenly stirred; ② half of the curing agent is evenly stirred; ③ the rest of the curing agent is evenly stirred; ④ the diluent is added if necessary to evenly mix; ⑤ the curing pre reaction is carried out after a certain period of time according to the regulations; the use time shall not exceed the regulations The mixing use time of aging time is shortened with the rise of temperature, so it is necessary to pay attention to the manufacturer's instructions Construction in the sun must be avoided in high temperature seasons 6 The diluted coating can be used with the barrel open, without dilution, and habitual dilution must be avoided When diluent must be used, pay attention to confirm the correct diluent is used Excessive dilution will lead to the coating can not reach the specified thickness, reduce the drying and curing time, and cause sagging problems Diluent can be added in the following situations: ① when the temperature is low in winter, appropriate diluent can be added to reduce the viscosity of the coating; ② diluent should be added to manual or air spraying for easy construction; ③ appropriate diluent can be added to reduce the film thickness intentionally 7 Filtration in order to remove large particles, crusts or other foreign matters that are difficult to disperse from the coating, filtration must be carried out to ensure that the nozzle is not blocked The standard practice is poured into another empty barrel through the filter screen 80-120 mesh screen or filter shall be added at the suction port of paint pump during spraying Ensure that the strainer is clean Clean with solvent after use, so that it can be reused next time 4、 Painting 1 Air circulation must be maintained in the construction area There shall be no dust and other foreign matters flying during coating and curing During the coating construction, the paint film shall be uniform as far as possible and shall not be missed For edges, corners, seams, welds and other parts, painting shall be carried out first, and then large-scale painting 2 Putty shall be applied to the surface of machine products according to the process documents When applying putty, the primer shall be applied first, and the putty shall be applied after the primer is dry Puttying is generally carried out 1-2 times, each time the thickness is about 0.5-1mm, and the local maximum total thickness shall not exceed 5mm After the putty is dry, the surface shall be polished After polishing, the putty surface shall be flat, smooth, firm and free of cracks 3 The coating work shall be allowed to be carried out under climatic conditions Painting shall not be carried out in case of the following conditions A in general painting, the ambient temperature is below 5 ℃ or above 35 ℃ b When painting in the open air, there will be rain, snow, fog, frost and strong wind; C the surface temperature is lower than the dew point temperature plus 3 ℃; see the appendix reference for the dew point temperature value check d The relative humidity of the surrounding environment is more than 85%; 4 Defects such as pits, sand holes and air holes appear on the surface of the casting It must be filled with putty The putty layer shall not fall off or crack 5 Before coating, the surface treatment quality shall be checked Painting is not acceptable During coating construction, if there are sagging, wrinkling, blistering, cracking and peeling, pinhole and other defects Corresponding technical measures must be taken to repair 6 If the construction cannot be carried out according to the specified coating conditions due to the environment or other reasons, necessary technical measures shall be taken and the coating quality shall be ensured before construction, and the measures taken shall be recorded 7 The coating shall be applied in several times according to the coating interval specified in the coating product manual If the specified coating interval is exceeded, the surface of the previous coating shall be roughened as necessary 8 The wet coating shall be protected to prevent soiling and damage The soiled and damaged coating shall be repaired as required 9 At the junction of two different color coatings, the boundary must be clear, neat and standard 10 Assemble the coated parts on site, and paint the last finishing coat after the equipment installation and commissioning 11 Painting construction methods, whether brush painting or spraying, shall strictly comply with the operating procedures The film thickness shall meet the design requirements 12 The friction surface of A high strength bolt shall not be coated under any of the following conditions b Embedded in concrete or in contact with refractory c It is a close or relatively moving machined surface d Foundation bolt and its base plate e Seal the box and the inner surface of the valve f Stainless steel parts, plated parts, non-metallic parts and drawings shall indicate the parts not coated g Parts to be processed on site 5、 Secondary coating 1 Repair the rust return parts on the surface, the exposed parts of the joint and the damaged paint film in the installation process, and carry out the secondary coating 2 Before repair, the surface shall be cleaned and re derusted, then the surface shall be blown clean with clean compressed air, and the secondary coating repair shall be carried out according to the coating design requirements 3 The covering width of the repaired part to the surrounding coating shall not be less than 50mm If the damaged area is small, the repaired area shall be more than 1 times larger than the damaged area 4 After painting, the components shall be marked with original number, name, code, etc 6、 Coating inspection and acceptance 1 The appearance of the paint film shall meet the following requirements: no pinholes, bubbles, cracks, undercutting, color penetration, missing coating, sagging, local peeling and other defects are allowed for the paint film of primer, coating and finish paint; the surface of the finish paint shall be flat and even, and the paint film shall be full and consistent in color The inspection method can be observed by naked eye or magnifier after negotiation 2 Coating thickness test shall be carried out after each coating is dried After all coating is completed, the total thickness shall be tested Detection method: use the paint film thickness gauge to detect every 10 ㎡ (10 ㎡ if the paint film area is less than 10 ㎡), every 3-4m of the slender body, and every 3-5 points The average thickness of each point measured shall not be less than 90% of the total thickness of the specified coating and not more than 120% The minimum thickness of each measured point shall not be less than 70% of the total thickness of the specified coating 3 The coating quality can be tested to evaluate the resistance of the coating to the substrate The resistance of the coating to the substrate shall be evaluated according to the following methods: six test plates with the specification of 200 mm × 200 mm shall be selected and coated with the same coating system as the new product after surface treatment The resistance evaluation can be carried out after the paint film is dry, and the evaluation can be carried out by cross drawing or grid drawing after negotiation Fork drawing method: use a sharp blade or safety blade to draw a fork with an included angle of 60 ° on the surface of the test plate The knife mark shall be drawn to the steel plate, and then paste a professional pressure-sensitive adhesive tape with a width of 25 mm to make the adhesive tape close to the paint film, and then quickly pull it up by hand If the total width of the coating on both sides of the knife mark is not more than 2 mm, it is qualified Cross cut method: according to paint, varnish and paint
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