CHIEF CHEMIST DEPT. PAGE No. 1 of 7 SPECIFICATION FOR PAINTING ON GALVANIZED SURFACES BY WET or ELECTROSTATIC POWDER PAINTING 1. SCOPE This specification covers the requirements for painting of steel surfaces hot dipped or electrolytically galvanized. Galvanized steel shall be protected by paint (duplex system) except for threaded items such as nuts and bolts which will be chromated according to the instructions of the laboratory of materials. Painting on galvanized surfaces may be problematic and a test patch is recommended in order to assure a proper adhesion of the primer on the prepared surface. In each project it's recommended to enable a patch test before the work. The project manager will choose the painting system according to the environment and to the kind of galvanized layer. 2. SURFACE PREPARATION 2.1. On hot dip Galvanized items 2.1.1. Solvent cleaning Cleaning all surfaces from dirt, dust, oil, grease using a suitable solvent to SSPC SP-1. Approved Chemitaas products: Ardox 6-551, BC-70 or similar products of other manufacturers. App.2-1
CHIEF CHEMIST DEPT. PAGE No. 2 of 7 2.1.2. Surface treatment By one of the following methods: A. Brush-off blast cleaning According to SSPC-SP-7 specification. Will be performed only by authorized workers. Authorization shall be granted after ability to perform roughening of the zinc coating and remove no more than 10 microns of the zinc layer. The zinc layer thickness shall be examined before and after blasting. B. Chemical treatment Submerging the item in a phosphating bath type ZINC-PHOSPHATE conforming to BS. 3189-1991standard. 2.2 On electrolytically galvanized items 2.2.1 Solvent cleaning According to par. 2.1.1. 2.2.2 Surface treatment By one of the following methods: A. Mechanical The surface shall be roughened to a degree suitable for the specified paint system. Approved surface cleaning media are listed in par. 7.4. B. Chemical treatment according to par. 2.1.2B. App.2-2
CHIEF CHEMIST DEPT. PAGE No. 3 of 7 3. PAINTING ENVIRONMENT SUBSTRATE PAINTING SYSTEM THICKNESS MICRON REMARKS 3.1 Internal location 3.1.1 Hot dip or external in a galvanizing dry environment zinc layer thickness over 80 micron 3.1.1.1 Liquid paints Epoxy polyamide modified special for galvanizes surfaces / two component aliphatic polyurethane. 40 50 Total 90 3.1.1.2 Electrostatic power painting with pure polyester Total See par. 4.1 for products see par. 6.1 and 6.2 remarks See par. 4.2 for manufacturers and 3.1.2 Electrolyticaly galvanizing 20-40 micron zinc layer thickness 3.1.2.1 Liquid paints Epoxy polyamide modified special for galvanized surfaces 70 See par. 4.1 for products Two component aliphatic polyurethane. Total 120 50 See par. 6.1, 6.2 Remarks. ` 3.1.2.2 Electrostatic painting with pure polyester Total 80 80 See par. 4.2 for App.2-3
CHIEF CHEMIST DEPT. PAGE No. 4 of 7 ENVIRONMENT SUBSTRATE PAINTING SYSTEM THICKNESS MICRON REMARKS 3.2 External location marine or industrial fume environment 3.2.1 Hot dip galvanizing zinc layer thickness over 80 micron 3.2.1.1 Liquid paint epoxy polyamide modified special for galvanized surfaces 70 See par. 4.1 for Two component Aliphatic Polyurethane 50 See par. 6.1 and 6.2 Remarks 3.2.1.2 Electrostatic painting External location marine or industrial fume environment 3.2.2 Electrolitically galvanizing 20-40 micron zinc layer thickness Prime: Epoxy. Top: pure polyester Total 3.2.2.1 Epoxy polyamide modified special for galvanized surfaces. 120 100 See par. 4.2 for manufacturer. See par. 4 for manufacturers and Two component aliphatic polyurethane 50 Total 3.2.2.2 Electrostatic painting Prime: Epoxy. Top: pure polyester Total 150 120 See par. 4.2 for manufacturers. App.2-4
CHIEF CHEMIST DEPT. PAGE No. 5 of 7 4. Paint products 4.1 Wet painting procedure above galvanized surface Manufacturer Tambour Nirlat Carboline Sherwin williams Ameron Sigma International Freitag Primer Epitamarin Uniseal brown code 842-xx or Epogal code 644-xx Epoxy Primer 524 Rust Bond Penetrating Primer Duraplate 235 Amercoat TC 71 Sigmacover 522 Or Sigmacover 280 Interguard 269 Vigor EP 201C Top Tamaglass PU (Aliphatic) Unicryl Carboline 134 ACROLOM 218 Amercoat 450 S Sigmadur 520 Interthane 990 Vigor PU 239 4.2 Electrostatic painting Manufacturer Tambour Nirlat - Univercol David Powders Product name Polyester Shamir Polyester Unilac Polyester Remarks 185-xxx series 7000 App.2-5
CHIEF CHEMIST DEPT. PAGE No. 6 of 7 5. Technical Requirement for electrostatic painting Laboratory tests will be carried out on panels measuring 100 x 150 x 0.7 mm. 5.1 Thickness of Coating At least 80 Microns. The test to be according to SSPC-PA1/1982. 5.2 Adhesion Pull-off according to ASTM D 4541-85. Test dolly 20 mm. Using Acrylic Adhesive (DP-805, Scotch-weld or equivalent). Minimum 1000 psi. 5.3 Hardness Hardness of coating to scratching: 4000 gr. According to ISO R 1518. 5.4 Impact According to ASTM D-2794: 25 Kg/cm. Will not be every cracking of the coating, nor any detachment from the substrate. 5.5 Extensibility ISO-1520-Erichsen Cupping: 6 mm without cracks or detachments. 5.6 Permeability A coated panel will be partially submerged in pressure cooker containing distilled water to a level of at least 25 mm. Cooking at least for two hours after the appearance of steam. After cooling of the cooker and the panel, the coating should be examined: no bubbles should appear on the surface. (They are acceptable only near the edges). 5.7 Resistance to Salt Spray Fog: Three panels will be placed in al salt water chamber for 1000 hours after being cross-cut in the center of the plate with an X, 50-70 mm long. After drying for 24 hours at room temperature, adhesion to the cross-cut will be examined. Spread of rust along the lines and separation of the coating must not exceed 2 mm. There must be no bubbles or rust spots on the surface remote from the cut and the edges of the plate. CHIEF CHEMIST DEPT. PAGE No.7 of 7 App.2-6
6. Quality assurance Is based on the authorization of the process and manufacturer that shall be granted after ability to supply panels that will conform the requirements specified in par.5. During the fabrication only thickness off the coating will be checked. There are not permitted measurements under the specified thickness in par.5.1. REMARKS 1. Damaged hot dip galvanized surfaces must be repaired by applying at least two coats of organic zinc rich coatings to give a minimum dry film thickness of micron. Approved products: Z.R.C I.E.C - distributor carmel handasa catalog no. 35067 ZINGA - distributor m.b.l catalog no. 35067. ZINC-GLAD 5 - distributor Chemital catalog no.35067. GLAVITE 90 E - distributor tambour catalog no.35067 2. In the painting system will be involved only paints from the same manufacturer 3. Every two successive coats must be colour contrasted. 4. I.E.C. will approve only paint products that permit over coating with the paints specified in par 4.1.1. The result of adhesion test performed after over coating according to Israeli Standard 785/27 will be at least level 1. 5. Surface profile producing media recommended: non-woven abrasive wheels and discs such as: 3 M Scotch-Brite clean strip discs and wheels. Coated abrasive discs (sending pads) as: Flap wheels such as: Grind 0 Flex Wheels from Merit Corporation Needle guns consisting of a bundle of wire needles which can impact the surface. Prepared: Y. Casapu Revised by Shay Litani (June 2012) Approved: Dr. E. Sutskover App.2-7