Gusto+paint+specifications

GT291 SM G 05 400 V1 Page 13 6. SURFACE PREPARATION6.1 GENERALUnless indicated otherwise, all fabrication and assembly shall be completed beforesurface preparation begins. All hot-works shall be completed in all areas intended to becoated, as well as in the adjacent areas. The steel work shall be confirmed finishedbefore any surface preparation starts.Surface preparation method and grade shall be selected in accordance with the gradesreported in the applicable paint system of this specification (section 13).As general rule, all surfaces to be coated shall be cleaned to the specified preparationgrade to obtain a surface that meets the requirements defined in the appropriate paintsystem Sheet.6.2 PRE-CLEANING OF SURFACESPrior to any surface preparation (abrasive blasting, power tooling, water-jetting, etc.), anyoil, grease, welding fumes residue, and other fatty materials, shall be removed byappropriate solvents in accordance with standard SSPC-SP 1 Solvent Cleaning.Petroleum, kerosene, diesel oil or other fatty solvents shall not be used.All bolt-holes shall be solvent cleaned prior to abrasive blasting.No acid washes or other cleaning solutions or solvents shall be used on steel surfacesafter they are abrasive blasted. This includes inhibitive washes intended to preventrusting.Fresh water used for washing and rinsing shall have a chlorides-content not higher than25 ppm.All welding areas and appurtenances shall be given special attention for removal ofwelding flux in crevices. When electrodes are used with basic coating or shielding, thewelded area shall be free from alkaline residues by rinsing with warm water prior toblasting.After abrasive blasting or power tool cleaning and prior to coat, all surfaces shall beexamined for traces or smudges of oil or grease. If any exist, they shall be removed bysolvent washing and the area re-cleaned as originally provided.All metal surfaces to be coated which do not require abrasive blasting or power toolcleaning shall be thoroughly cleaned and/or degreased with a high-pressure water orsteam cleaning unit to remove all mud, oil, grease, or other foreign matter.GT291 SM G 05 400 V1 Page 14 6.3 ABRASIVE BLAST CLEANING6.3.1 GeneralAbrasive blast cleaning shall always be performed according to the SSPC standardreported in the paint system sheet of this specification.After abrasive blasting all metal shall be free of rust, grease, dirt, water-soluble salts,corrosion products, oxides, paint, and any other foreign matter according to the specifiedstandard requirements. Final appearance shall be checked and conform to VisualStandard for Abrasive Blast Cleaned Steel SSPC-VIS 1.At completion of abrasive blast cleaning the surface shall be dust-free prior to theapplication of the primer coat. This can be accomplished by using an industrial vacuumcleaner together with a stiff brush. Surface cleanliness shall be checked and conform toClass 1 of standard ISO 8502-3.The maximum acceptable water-soluble salts contamination on abrasive blasted surfacesbefore application of any primer shall be as follows:• 3 μg/cm2 for stainless steel surfaces• 3 μg/cm2 for the immersed areas (permanent or intermittent),• 5 μg/cm2 for areas exposed to environment.Extraction of contaminants from surface shall be done according to standard ISO 8502-6and quantitative determination of water-soluble salts shall be performed according tostandard ISO 8502-9.6.3.2 Equipment for Abrasive Blast CleaningThe compressed air supply used for abrasive blasting shall be clean, free of water andoil.Adequate separators and traps shall be provided and these shall be kept emptied ofwater and oil. Accumulations of water and oil shall be removed from the air receiver byregular purging. Control of the compressed air cleanness shall be done according tostandard ASTM D-4285.In no circumstance compressed air temperature shall be more than 100°C and pressurelower than 650 kPa measured at the nozzles.Where air operated equipment is used, the operator's hood or head gear shall beventilated by clean cool air served through a regulator filter to prevent blasting residuesfrom being inhaled by the operator.6.3.3 AbrasivesAll abrasive materials used for blast cleaning shall be dry and clean and shall be testedfor water-soluble salts content. Conductivity measured according to standard ASTM D-4940, shall not exceed 250 μS/cm.Non-metallic abrasives shall meet the requirements of standard I SO 11126 Parts 1÷8.Tests and controls shall be done according to standard ISO 11127 Part 1÷7.Metallic abrasives shall meet the requirements of standard ISO 11124 Parts 1÷4. TestsGT291 SM G 05 400 V1 Page 15 and controls shall be done according to standard ISO 11125 Part 1÷7.Abrasive type and size shall be selected in order to assure the profile and roughness ofsubstrate for the applicable paint system. Surface profile/roughness shall be measuredaccording to standard NACE RP0287. For safety and health reason in no circumstancethe use of silica abrasive shall be allowed.6.3.4 Techniques & RestrictionsBlast cleaning shall not be conducted when the surfaces are less than 3°C above dewpoint or when the relative humidity of the air is above 85%.To prevent dust and abrasive contamination, abrasive blasting shall not be done in openareas close to painting operations or wet-coated surfaces. Where rectification has beennecessary on abrasive blast cleaned surfaces, the dressed areas shall be re-blasted andthen freed of spent abrasives to provide adequate profile.Blasting shall continue a minimum of 100 mm into any adjacent coated areas. The edgesof old paint are to be feathered, and a check is to be made for compatibility of new paintover old paint to ensure that new paint does not soften and lift old paint particularly at thefeathered edges.Any surfaces not primed and/or wetted by rain or moisture shall be re-blasted prior tocoating.All cleaned surfaces shall be primed before rust bloom occurs.6.4 POWER TOOL CLEANINGPower tool cleaning shall be done in certain instances (e.g. difficult-to-reach-areas, repairand touch-ups, erection weld), and shall conform to standards SSPC-SP 3 or SSPC-SP11 according to the requirements of paint system sheet of this specification.Surfaces which can’t be abrasive blasted due to e.g. their location, shall be cleaned by“scotch-brite” and/or power tool (e.g. needle gun) cleaning, only after PURCHASERapproval.On completion of power tool cleaning the surface shall be dust-free prior to theapplication of the primer coat. This can be accomplished by using an industrial vacuumcleaner together with a stiff brush. Surface cleanliness shall be checked and conform toClass 1 of standard ISO 8502-3.GT291 SM G 05 400 V1 Page 16 6.5 WATER JETTINGWhen appropriate and specifically required by this specification or recommended byPAI NT MANUFACTURER, cleaning by water jetting shall be performed according tostandard SSPC-SP 12.Since water jetting does not produce a surface profile of the magnitude currentlyrecognized by the coating industry, in no circumstance will it be accepted as analternative to abrasive blast cleaning.According to standard SSPC-SP 12 the following definitions and pressure ranges forwater jetting are adopted in this specification:• Low-Pressure Water Cleaning (LP WC): Water cleaning performed at pressures less than 34 MPa (5,000 psig).• High-Pressure Water Cleaning (HP WC): Water cleaning performed at pressures from 34 to 70 MPa (5,000 to 10,000 psig).• Non-visible Contamination (NV): Non-visible contamination is the presence of organic matter, such as very thin films of oil and grease, and/or soluble ionicmaterials such as chlorides, ferrous salts, and sulphates that remain on thesubstrate after cleaning.• Visible Surface Cleanliness (VC): Visible surface cleanliness is the visible condition of the substrate, when viewed without magnification, after cleaning.6.6 SURFACE PREPARATION OF HOT DIP GALVANIZED STEELAll steel surfaces hot dip galvanised, before being coated with the paint system providedin the relevant sheet shall be cleaned as follow:• cleaning and degreasing according to standard SSPC-SP 1;• all galvanising irregularities (zinc high spots, etc.) shall be removed by power tooling taking care that the zinc layer is not completely removed;• galvanized surface shall be roughened by abrasive sweep or brush blasting according to ASTM D 2092 or, alternatively to other method reported in thestandard ASTM D 2092, approved by PURCHASER.Damage to galvanising layer due to steel works and welding shall be cleaned by abrasiveblasting according to standard SSPC-SP 10 or by power tooling according to standardSSPC-SP 11 and that touched-up with Zinc Rich Primer.6.7 SURFACE PREPARATION OF SHOP PRIMED STEELAll shop-primed surfaces shall be cleaned by high-pressure fresh water washing (approx20 MPa) and, by simultaneous scrubbing with stiff brush, if necessary, to remove zincsalt, chalk marks and other contaminants.In case of unknown shop-primer, all steel surfaces shall be 100% abrasive blast cleanedaccording to standard SSPC-SP 10 before the application of the 1st coat of any paintsystem.。