1、9-65SSPC-Guide 14May 1, 1999Editorial Revisions November 1, 20041Joint standards may also be obtained from NACE International at http:/nace.org2 ASTM International, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959 or online at http:/www.astm.org1. Scope1.1 This guide describes one method for
2、repairing gal-vanized, organic, or inorganic zinc coatings using an organic zinc-rich coating. ASTM A 780 briey describes this and other alternative methods (metallizing and zinc-based solders) for repair of damaged and uncoated areas of hot-dip galvanized coatings.1.2 This method is intended to rep
3、air imperfections resulting from application, welding, cutting, drilling, grinding, abrading, or rough handling during transport or erection. It may also be used to repair imperfections in galvanizing, organic, or inor-ganic zinc coating that have occurred from weathering during storage or after ere
4、ction.1.3 This method can also be used to repair topcoated galvanizing, organic, or inorganic zinc coating.1.4 This guide is intended for use to supplement the coat-ing manufacturers printed instructions and literature. 2. Description2.1 This method consists of selecting organic zinc-rich coatings a
5、nd topcoats and preparing and applying the coatings to damaged galvanizing, organic or inorganic zinc coating.2.2 This method is intended for repairing localized imper-fections where the major portion of the existing zinc coating is intact.2.3 Organic zinc-rich coatings are suitable for repairing da
6、maged zinc coatings because they combine several favor-able properties. They can be readily applied by brush or spray under eld conditions to small and irregular shapes and are compatible with both zinc and steel substrates.3. Referenced Standards3.1 SSPC STANDARDS:PA 1 Shop, Field, and Maintenance
7、Painting of SteelPA 2 Measurement of Dry Coating Thickness with Magnetic GagesPA 3 A Guide to Safety in Paint Application Paint 5 Zinc Dust, Zinc Oxide, and Phenolic Varnish PaintPaint 20 Zinc-Rich Coating Type I Inorganic and Type IIOrganic Paint 29 Zinc Dust Sacricial Primer, Performance-BasedPS G
8、uide 12.00 Guide to Zinc-Rich Coating SystemsSP 1 Solvent CleaningSP 2 Hand Tool CleaningSP 3 Power Tool CleaningSP 11 Power Tool Cleaning to Bare MetalSP 15 Commercial Grade Power Tool Cleaning3.2 SSPC/NACE INTERNATIONAL STANDARDS:1SSPC-SP 5/NACE No. 1 White Metal Blast CleaningSSPC-SP 6/NACE No. 3
9、 Commercial Blast CleaningSSPC-SP 7/NACE No. 4 Brush-Off Blast CleaningSSPC-SP 10/NACE No. 2 Near-White Blast CleaningSSPC-SP 14/NACE No. 8 Industrial Blast CleaningSSPC-SP 12/NACE No. 5 Surface Preparation and Cleaning of Metals by Water-jetting Prior to Recoating3.3 ASTM INTERNATIONAL STANDARDS:2A
10、 780 Practice for Repair of Damaged and Uncoated Areas of Hot-Dip Galvanized Coatings4. Selecting Materials4.1 GENERAL: Compositions and performances of organic zinc-rich primers vary with regard to the individual resin system, the level of metallic zinc, the volatile organic compound (VOC) content,
11、 along with other formulation vari-ables. It is often desirable to require the zinc-rich coatings to meet performance criteria to verify that they can withstand the corrosion and weathering environments to which they will be subjected. Some performance tests are described in SSPC-Paint 20 and SSPC-P
12、aint 29. Coating selection can best be SSPC: The Society for Protective CoatingsTECHNOLOGY GUIDE NO. 14Guide for the Repair of Imperfections in Galvanized, Organic,or Inorganic Zinc-Coated Steel Using Organic Zinc-Rich Coatings9-66SSPC-Guide 14May 1, 1999Editorial Revisions November 1, 2004regulatio
13、ns. Organic zinc-rich coatings used for repair usually have a VOC level less than 500 g/L (4.2 lb/gal).4.5 TOPCOAT SELECTION: If a topcoat is to be applied over the zinc-rich primer, select the topcoat in accordance with SSPC-PS Guide 12.00 Topcoating will usually provide additional service life to
14、both zinc-rich primers and hot-dip galvanized coating. Topcoats must be formulated not only for environmental resistance, but also for compatibility with the organic zinc-rich coating, hot-dip galvanizing, or inorganic zinc coating. Generally, topcoating will be required in more severe environments,
15、 as recommended by the manufacturer.5. Procedures5.1 SURFACE PREPARATION5.1.1 Identify Damaged Areas: Visually identify dam-aged areas based on deterioration of the zinc, rusting of steel substrate, disbondment, or other defects of the zinc coating.5.1.2 Select Surface Preparation Methods: Suitable
16、methods include: Hand and power tools SSPC-SP 2, SSPC-SP 3, SSPC-SP 15, or SSPC-SP 11 Watterjetting SSPC-SP 12/NACE No. 5 Abrasive blast cleaning SSPC-SP 5/NACE No. 1, SSPC-SP 10/NACE No. 2, SSPC-SP 6/NACE No. 3, SSPC-SP 14/NACE No. 8, or SSPC-SP 7/NACE No. 4, depending upon the service environment.
17、Table 1 can be used as a general guideline for appropriate surface preparation for a variety of exposures. In all cases, the surface cleanliness should be at least as great as that recommended by the supplier of the primer.5.1.3 Surface Contaminants: Remove all grease, oil, corrosion by-products, di
18、rt, and other surface contaminants made from actual eld testing of candidate coatings in the environment in which the coatings are to be located.The paragraphs below describe some of the decisions to be made when selecting an organic zinc-rich repair primer. SSPC-PS Guide 12.00 provides general info
19、rmation on the description, selection, and application of zinc-rich coatings and the selection of topcoats.4.2 TYPE OF BINDER: Organic zinc-rich coating formula-tions are available with a variety of binders. The choice of a particular generic type of binder is up to the user. The most common binders
20、 for organic zinc-rich primers are two-compo-nent epoxy, epoxy ester, and moisture-curing polyurethane. 4.3 METALLIC ZINC LEVELS: Suppliers, applicators, and owners do not agree on the metallic zinc level (or loading) necessary for long-term protection of steel by organic zinc-rich coatings. The use
21、r can select any metallic zinc level found to provide the best performance, or conversely, not specify a zinc level. SSPC-Paint 20 denes three levels of zinc dust by weight present in the dried lm as follows:Level 1 equal to or greater than 85%Level 2 equal to or greater than 77% and less than 85%Le
22、vel 3 equal to or greater than 65% and less than 77%The above levels may be used to specify zinc loading of repair products meeting requirements of SSPC-Paints 5, 20, and 29 and ASTM A 780. The user may specify any percent-age of zinc loading (for example 95%) if desired.4.4 VOLATILE ORGANIC COMPOUN
23、D (VOC) CONTENT: The VOC content of organic zinc-rich coatings used for repair may vary widely. Each coating, after recommended thinning, must conform to published government regulations regarding VOC content. VOC information should be supplied on the label or the technical data sheet. Various gover
24、nmental agencies may have different VOC limits or use different methods of testing. The owner may modify the coating specication as necessary to specify a particular VOC content limit consistent with local TABLE 1RECOMMENDED MINIMUM SURFACE PREPARATIONService EnvironmentImmersionSplash/SpillageChemi
25、cal Fume, Neutral pHAtmospherictDry Abrasive BlastSP 10SP 10SP 6SP 7SSPC-SP 12/NACE No. 5, WaterjettingWJ 2WJ 2WJ 3WJ 4Hand or Power Tool CleaningNoneSP 11SP 11SP 29-67SSPC-Guide 14May 1, 1999Editorial Revisions November 1, 2004from the areas with imperfections and from the existing intact coating w
26、ithin a minimum of ve centimeters (two inches) of these areas by solvent cleaning or detergent washing (SSPC-SP 1), or other approved method.5.1.4 Topcoated Areas: If any of the areas to be repaired consist of topcoated galvanized steel or topcoated inorganic zinc, all loose topcoat in the damaged a
27、rea must be completely removed exposing an area of intact zinc coating surrounding the damaged area. 5.1.5 Weld Preparations: If the area to be repaired con-tains welds, all ux residue and weld spatter must be removed by blast cleaning or through mechanical means. See Section 4.4.1 of the SSPC Surfa
28、ce Preparation Commentary3regard-ing removal of weld spatter).5.2 REPAIRS WITH ZINC-RICH COATING5.2.1 Application: Apply the zinc-rich coating to the pre-pared surface by brush or spray according to the manufacturers recommendations and SSPC-PA 1. If a conict exists between SSPC-PA 1 and the manufac
29、turers printed recommendations, the latter should be followed. The patch of organic zinc-rich coating must extend a minimum of ve centimeters (two inches) over the undamaged zinc coated surface. specication should explicitly staten the extent of repair overlap, especially if more than ve centimeters
30、 (two inches) is required.5.2.2 Application Temperature: In general, solvent-borne organic zinc-rich coatings should be applied only at temperatures above 7C (45F) and relative humidities below 85%. Waterborne products may have other limitations. In all cases, consult the manufacturers literature fo
31、r temperature, humidity, and ventilation requirements, especially when the expected exposure is above 66C (150F).3SSPC Painting Manual, Volume 2, Systems and Specications5.2.3 Pot Life: Multiple component zinc-rich coatings must be applied within the pot life specied by the supplier, and the coating
32、 should be continuously agitated during application.5.2.4 Dry Film Thickness: The dry lm thickness of the organic zinc-rich coating should be that recommended by the manufacturer. Normally this is between 75 micrometers (3 mils) and 150 micrometers (6 mils). Dry lm thicknesses should be measured in
33、accordance with SSPC-PA 2.5.2.5 Safety: Observe all safe handling procedures de-scribed in the product material safety data sheet (MSDS) and SSPC-PA Guide 3.5.3 TOPCOATING: If a topcoat is specied, the application of the topcoat should be in accordance with SSPC-PS Guide 12.00 or the manufacturers p
34、rinted instructions.6. Disclaimer6.1 This guide is designed to describe, review, or analyze new or improved technology and does not meet the denition of a standard as dened by SSPC. A guide differs from a stan-dard in that it is not suitable for referencing in a specication or procurement document.6
35、.2 While every precaution is taken to ensure that all in-formation furnished in SSPC guides is as accurate, complete, and useful as possible, SSPC cannot assume responsibility nor incur any obligation resulting from the use of any materials, coatings, or methods described herein, or of the guide its
36、elf.6.3 This guide does not attempt to address problems concerning safety associated with its use. The user of this guide, as well as the user of all products or practices described herein, is responsible for instituting appropriate health and safety practices and for ensuring compliance with all governmental regulations.
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