1、SSPC-PS Guide 12.00March 1, 20071SSPC: The Society for Protective CoatingsCOATING SYSTEM GUIDE 12.00Guide to Zinc-Rich Coating Systems1. Scope1.1 This guide provides general information on the descrip-tion, selection, and application of zinc-rich coatings as well as the selection and application (in
2、cluding surface preparation) of topcoats.1.2 Zinc-rich coatings as referenced in this Guide are broadly defined as coatings containing high levels of zinc such as SSPC-Paint 20 or SSPC-Paint 29.1.3 Zinc-rich coatings are classified as follows:Type IA Inorganic - post-cured, water-borne, alkali silic
3、atesType IB Inorganic - self-cured, water-borne,alkali silicatesType IC Inorganic - self-cured, solvent-borne, alkyl silicatesType IIA Organic - thermoplastic binders Type IIB Organic - thermoset binders1.4 Zinc-rich coatings, both topcoated and untopcoated, have been used successfully in a wide var
4、iety of environmental zones. For a detailed breakdown of applicability of various types of zinc-rich coatings in different environmental zones, see Table 1. 2. DescriptionThe guide describes two types of zinc-rich coatings; how to select zinc rich coating systems for either topcoated or untopcoated
5、service; and requirements for surface preparation, application, and inspection and repair of zinc rich coatings.3. Referenced Standards3.1 SSPC STANDARDS AND JOINT STANDARDS:Guide 9 Guide for Atmospheric Testing of Coatings in the FieldGuide 15 Field Methods for Retrieval and Analysis of Soluble Sal
6、ts on Steel and other Nonporous SubstratesPA 1 Shop, Field, and Maintenance Painting of SteelPA 2 Measurement of Dry Coating Thick-ness With Magnetic GagesPaint 20 Zinc-Rich Coatings (Type I - Inorganic and Type II - Organic)Paint 271Basic Zinc Chromate-Vinyl Butyral Wash PrimerPaint 29 Zinc Dust Sa
7、crificial Primer, Performance-BasedPaint 30 Weld-Through Inorganic Zinc PrimerPS 12.01 One-Coat Zinc-Rich Painting SystemPS Guide 22.00 Guide for Selecting One-Coat Preconstruction or Prefabrication Painting SystemsSP 1 Solvent CleaningSP 5/NACE No. 1 White Metal Blast CleaningSP 6/NACE No. 3 Commer
8、cial Blast CleaningSP 10/NACE No. 2 Near-White Blast CleaningSP 12/NACE No. 5 Surface Preparation and Cleaning of Metals by Waterjetting Prior to Recoating3.2 ASTM INTERNATIONAL STANDARDS2:D 520 Standard Specification for Zinc Dust PigmentD 3359 Test Methods for Measuring Adhesion by Tape TestD 3363
9、 Standard Test Method for Film Hardness by Pencil TestD 4541 Test Method for Pull-Off Strength of Coatings Using Portable Adhesion TestersD 4752 Test Method for Measuring MEK Resistance of Ethyl Silicate (Inorganic) Zinc-Rich Primers by Solvent Rub1This paint contains chromate pigments. Users are ur
10、ged to follow all health, safety, and environmental requirements in applying, handling, or disposing of these materials.2ASTM International 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959. Standards are available online at http:/www.astm.org.SSPC-PS Guide 12.00March 1, 20072Environmental Zon
11、es IA IB IC IIA IIBUntopcoated Topcoated Untopcoated Topcoated Untopcoated Topcoated Untopcoated Topcoated Untopcoated Topcoated1A Interior, Normally DryR-SP 10 R-SP 10 R-SP 10 R-SP 10 R-SP 6 R-SP 6 R-SP 6 R-SP 6 R-SP6 R-SP 61B Exterior, Normally DryR-SP 10 R-SP 10 R-SP 10 R-SP 10 R-SP 6 R-SP 6 R-SP
12、 6 R-SP 6 R-SP 6 R-SP 62A Frequently Wet, Fresh WaterR-SP 10 R-SP 10 R-SP 10 R-SP 10 R-SP 10 R-SP 10 R-SP 10 R-SP 10 R-SP 10 R-SP 102B Frequently Wet, Salt WaterR-SP 10 R-SP 10 R-SP 10 R-SP 10 R-SP 10 R-SP 10 NR R-SP 10 NR R-SP 102C Fresh Water ImmersionQ-SP 5 Q-SP 5 Q-SP 5 Q-SP 5 Q-SP 10 Q-SP 10 NR
13、 Q-SP 10 Q-SP 10 Q-SP 102D Salt Water ImmersionQ-SP 10 Q-SP 10 Q-SP 10 Q-SP 10 Q-SP 10 Q-SP 10 NR Q-SP 10 NR Q-SP 103A Chemical Exposure, Acidic (pH 2 to 5)NR Q-SP 10 NR Q-SP 10 NR Q-SP 10 NR Q-SP 6 NR Q-SP 63B Chemical Exposure, Neutral (pH 5 to 10)R-SP 10 R-SP 10 R-SP 10 R-SP 10 R-SP 6 R-SP 6 R-SP
14、 6 R-SP 6 R-SP 6 R-SP 63C Chemical Exposure, Alkaline (pH 10 to 12)NR R-SP 10 NR R-SP 10 NR R-SP 6 NR R-SP 6 NR R-SP 63D Chemical Exposure, SolventR-SP 10 Q-SP 10 R-SP 10 Q-SP 10 R-SP 6 Q-SP 6 NR NR NR Q-SP 63E Chemical Exposure, SevereNR NR NR NR NR NR NR NR NR NRBINDER TYPES:IA = Inorganic; post-c
15、ured, waterborne alkali silicatesIB = Inorgenic; self-cured, waterborne alkali silicatesIC = Inorganic; self-cured, solvent-borne alkyl silicatesIIA = Organic; thermoplastic binders (e.g., phenoxy)IIB = Organic; thermoset binders (e.g., epoxy polyamide, moisture-cured polyurethane)RECOMMENDED USAGE:
16、R = RecommendNR = Not RecommendedQ = Some products recommended, others not recommended. (See Sections 5.2, 5.3, 5.4, and 5.5.)RECOMMENDED SURFACE PREPARATION:The number refers to the minimum SSPC blast cleaning surface preparations as follows:SP 5 = SSPC-SP 5, White Metal Blast CleaningSP 6 = SSPC-S
17、P 6, Commercial Blast CleaningSP 10 = SSPC-SP 10, Near-White Blast CleaningNOTE: For pitted old steel, the blast cleaning requirement should be the next higher degree of cleanliness.i.e., the SP 10 shown above should be SP 5, the SP 6 shown above should be SP 10.Note: This table provides general gui
18、delines only. Its use should be limited to determination of generic suitability and minimum surface preparation requirements. There are substantial differences in performance between the various types of zinc-rich coatings in a given environment. These recommendations provide minimum acceptable surf
19、ace preparation, primer, and topcoating requirements for the designated environmental zones. However, recommendations do not imply equivalent system performance. For specifi c conditions, the coating manufacturer should be consulted.TABLE 1Guidelines for Surface Preparation and Topcoatingof Zinc-Ric
20、h Primers in Various EnvironmentsZINC-RICH BINDER TYPESSSPC-PS Guide 12.00March 1, 20074. Types of Zinc-Rich Coatings4.1.1 A zinc-rich coating is an anticorrosive coating for iron and steel incorporating zinc dust in a concentration sufficient to enable the zinc metal in the dried film to corrode pr
21、eferentially to the ferrous substrate, i.e., to give galvanic protection. Note that SSPC-Paint 20 and SSPC-Paint 29 require 65% minimum zinc loading in the dry film. Galvanic action is not universally accepted as the primary method by which these coatings protect the substrate.4.1.2 Some zinc-rich c
22、oatings are used as prefabrication primers or shop primers, where they are applied to freshly blast cleaned steel plates and sections. The prefabrication primers, often at a lesser thickness, are intended to protect the steel throughout the fabrication period until the final painting system can be a
23、pplied to the finished structure. At that juncture, the pre-fabrication primer may be incorporated into the final system or removed. SSPC-PS Guide 22.00 and SSPC-Paint 0 discuss the use of zinc-rich coatings as prefabrication primers.4.1.3 Zinc-rich coatings may be used as a one-coat system or may b
24、e overcoated with one or more other coat-ings. The use of untopcoated zinc-rich systems is discussed in Section 5. and the use of topcoated systems is discussed in Section 5.4.4.2 VEHICLES FOR ZINC-RICH COATINGS: Zinc-rich coatings are available in a number of different commercial types. These coati
25、ngs may be categorized as having inorganic (Type I) or organic (Type II) vehicles. 4.2.1 Inorganic Vehicles: Type I inorganic vehicles include post-cured water-borne alkali silicates (IA); self-cured, water-borne alkali silicates (IB); and self-cured, solvent-borne alkyl silicates (IC). The vehicles
26、 of Types IA and IB may include the alkali metals (commonly sodium, lithium, and potassium), while IC vehicles are alkyl silicates (most commonly ethyl silicates). Type IA vehicles are post-cured with a separate wash solution, usually mildly acidic in nature, applied as an aftercoat. Type IB vehicle
27、s are chemically similar to Type IA vehicles, except they are formulated to self-cure upon exposure to moisture and carbon dioxide in the air. Type IC vehicles self-cure upon exposure to atmospheric moisture.4.2.2 Organic Vehicles: Type II vehicles include those with thermoplastic binders (IIA) and
28、thermoset binders (IIB). Type II thermoplastic vehicles include polymers of chlorinated rubber, styrene, vinyl, and other organic materials that soften upon exposure to heat. Type IIB thermoset vehicles do not soften upon heating, and include polymers of epoxy, polyure-thane, polyester, silicone, an
29、d other chemically cross-linked materials.4.3 PIGMENTATION FOR ZINC-RICH COATINGS: The major pigment component in these coatings is zinc dust of the type described in ASTM D 520. Zinc-rich coatings are successfully formulated with zinc dust levels ranging from 65 to 95 percent by weight in the dried
30、 film. 4.4 NUMBER OF COMPONENTS: Inorganic and organic zinc-rich coatings are supplied as a single- or multi-compo-nent package. Many multi-component packages separate the zinc pigment and vehicle and provide directions for mixture immediately prior to application. Multi-component coatings have a li
31、mited pot life after mixing. Because pot life will vary with vehicle/resin type, the manufacturers product data sheets should always be consulted.5. Selection of Coating System5.1 CLASSIFYING EXPOSURE ZONES: Successful corrosion protection utilizing a zinc-rich coating system is dependent upon the a
32、nticipated service in environmental exposure zones. Guidelines for the use of organic and inor-ganic zinc-rich coatings, either topcoated or untopcoated, are presented below based on the following SSPC classifications of exposure:1A Interior, Normally Dry1B Exterior, Normally Dry2A Frequently Wet-Fr
33、esh Water2B Frequently Wet-Salt Water2C Fresh Water Immersion2D Salt Water ImmersionA Atmospheric Chemical Exposures (pH 2 to 5)B Atmospheric Chemical Exposures (pH 5 to 10)C Atmospheric Chemical Exposures (pH 10 to 12)D Chemical Exposure, SolventsE Chemical Exposure, Severe5.2 GUIDELINES FOR USAGE:
34、 The untopcoated and topcoated inorganic and organic zinc-rich coatings are categorized as suitable (recommended), unsuitable (not recommended), or questionable for the exposure environments listed in Section 5.1. Questionable means that some products may perform satisfactorily, while other products
35、 may not, or that the environmental description is too variable to assure satisfactory coating system performance. Guidelines for the use of topcoated and untopcoated zinc-rich coatings in various environments are presented below and in Table 1.5.3 USE OF UNTOPCOATED ZINC-RICH COATINGS5.3.1 Untopcoa
36、ted Inorganic Zinc-Rich Coatings: These coatings may be suitable for use in the following envi-ronmental zones: 1A, 1B, 2A, 2B, 3B, and 3D. These coatings are not recommended for the following environmental zones: A, C, and E. These coatings are questionable for use in environmental zones 2C and 2D.
37、 These coatings are suit-able for application to uninsulated hot equipment with service temperatures up to 400 C (750 F).SSPC-PS Guide 12.00March 1, 200745.3.2 Untopcoated Organic Zinc-Rich Coatings: These coatings may be suitable for use in the following environmental zones: 1A, 1B, 2A, and 3B. The
38、se coatings are not recom-mended for the following environmental zones: 2B, 2D, 3A, C, D, and E. These coatings are questionable for use in environmental zone 2C.5.3.3 A one-coat zinc-rich coating system is described in SSPC-PS 12.01.5.4 USE OF TOPCOATED ZINC-RICH COATING SYSTEMS: Zinc-rich primers
39、are topcoated to provide extended exterior durability in severe exposures; to improve color, gloss, and other appearance properties; and to provide resistance to specific conditions such as highly acidic or highly alkaline environments.5.4.1 Topcoated Inorganic Zinc-Rich Coating Systems: These syste
40、ms may be suitable for use in the following environ-mental zones: 1A, 1B, 2A, 2B, 3B, and 3C. These systems are not recommended for environmental zone E. Some topcoated inorganic zinc-rich systems have demonstrated suitability for use in environmental zones 2C, 2D, A, and D. These systems are suitab
41、le for application to uninsulated hot equipment with service temperatures up to 400 C (750 F) when used with heat resistant topcoats.5.4.2 Topcoated Organic Zinc-Rich Coating Systems: These systems may be suitable for use in the following environ-mental zones: 1A, 1B, 2A, 2B, 3B, and 3C. These syste
42、ms are not recommended for environmental zone E. Some topcoated organic zinc-rich systems have demonstrated suitability for use in environmental zones 2C, 2D, A, and D.5.5 VARIATIONS IN FORMULATION: These guidelines are based on the general characteristics of the different types of zinc-rich coating
43、 systems and exposure environments. Substantial formulation differences exist among zinc-rich coat-ings. The ability of a topcoated system to perform adequately is strongly dependent on the generic type and formulation of the topcoat (see Section 7.4). Therefore, the recommendations of the coating m
44、anufacturer regarding the use of a zinc-rich coating (organic or inorganic, topcoated or untopcoated) in a given environment should be solicited. This is particularly critical when considering use of a zinc-rich system in a ques-tionable category.5.6 COATING HISTORY: Documented information with auth
45、enticated data detailing the history and exposure of the coating in terms of service life under specific conditions may be considered when preparing specifications for major proj-ects. Details relative to surface preparation and application of coating should be supplied. SSPC-Guide 9 lists the type
46、of data to be submitted. Additionally, or in lieu of suitable in-service field exposure or application histories as described above, the coating supplier, the coating applicator, and the user may establish a criterion of performance agreeable to all parties. 6. Selection of Primer6.1 PRIMER: The pri
47、mer should be in accordance with SSPC-Paint 20 or SSPC-Paint 29.6.1.1 Zinc-rich coatings are particularly useful for protecting steel surfaces in moist corrosive environments. These coat-ings are very resistant to high humidity and salt air, lasting many years. They galvanically prevent rust undercu
48、tting at small breaks in the coating system, often filling the breaks with protective deposits of zinc oxidation products, greatly extending coating life. Unless topcoated, they are unsuitable for acidic or alkaline service outside the pH range from about 5 to 10. Variations in properties of these c
49、oatings depend largely on the vehicle, whether inorganic or organic. The choice of the best coating for a specific end use should be made by a comparison of properties with the requirements of the service. Application and surface preparation constraints may limit the choice. The degree of corrosion protection desired may be a prime consideration. Zinc-rich coatings are characterized by their abrasion resistance, toughness of film, and galvanic action of the zinc. 6.1.1.1 For SSPC-Paint 29, the long-term corrosion resis-tance is assured by more rigorous performance tes
