One Coat Zinc-Rich Painting System Specification
PAINTING SYSTEM NO. 12.01 – One Coat Zinc-Rich Painting System
1. Scope
1.1 This specification covers a one-coat zinc-rich painting system to be used on carbon steel in mild to moderately severe environments and corrosive marine atmospheric environments (see Note 10.1).
1.2 Zinc-rich coatings, both topcoated and untopcoated, have been used successfully in a wide variety of environmental zones. For a detailed breakdown of applicability of various types of zinc-rich coatings in different environmental zones, refer to SSPC-Guide 12.00. Consult the coating manufacturer for specific exposure recommendations.
1.3 This specification does not pertain to weldable prefabrication zinc-rich primers, which are typically applied at thicknesses less than 25 micrometers (1 mil). Further information regarding these and other zinc-rich primers can be found in SSPC-PS Guide 12.00.
2. Description
2.1 This painting system consists of abrasive blast cleaning and one coat of zinc-rich coating.
2.2 This specification describes the application and field performance requirements for a one-coat zinc-rich system and should be used with SSPC-Paint 20 or SSPC-Paint 29 and with other SSPC specifications covering surface preparation, application, thickness, and inspection. SSPC-Paint 20 and SSPC-Paint 29 define the minimum compositional and performance requirements for zinc-rich coatings. If topcoating will be required, refer to SSPC-PS Guide 8.00 and to Note 10.2 of this specification.
3. Referenced Standards
3.1 The latest issue, revision, or amendment of the referenced standards in effect on the date of invitation to bid shall govern, unless otherwise specified. Standards marked with an asterisk (*) are referenced only in the Notes, which are not requirements of this specification.
3.2 If there is a conflict between the requirements of any of the cited referenced standards and this specification, the requirements of this painting system specification shall prevail.
3.3 SSPC STANDARDS AND JOINT STANDARDS:
* Guide 14
PA 1 PA 2 Paint 20 Paint 29 PS Guide 12.00 PS Guide 8.00
* SP8 SP 5/NACE No. 1 SP 6/NACE No. 3 SP 10/NACE No. 2
* SP 12/NACE No. 5
Guide for Repair of Imperfections in Galvanized or Inorganic Zinc- Coated Steel Using Organic Zinc- Rich Coatings Shop, Field, and Maintenance Painting of Steel Measurement of Dry Coating Thickness with Magnetic-Rich Primers (Type I– Inorganic, and Type II–Organic) Zinc Dust Sacrificial Primer, Performance-Based Guide for Selecting Zinc-Rich Painting Systems Guide to Topcoating Zinc-Rich Primers Pickling White Metal Blast Cleaning Commercial Blast Cleaning Near-White Blast Cleaning Surface Preparation and Cleaning of Steel and Other Hard Materials by High- and Ultrahigh-Pressure Waterjetting Prior to Recoating
3.4 ASTM INTERNATIONAL STANDARDS:
* D 3925 Standard Practice for Sampling Liquid Paints and Related Pigmented Coatings
D 4417 Standard Test Methods for Field Measurement of Surface Profile of Blast Cleaned Steel
4. Surface Preparation
4.1 DEGREE OF CLEANING: The minimum surface preparation shall be SSPC-SP 6 for new steel and SSPC-SP 10 for previously painted or pitted steel. If specified in the procurement documents or by the coating manufacturer, higher 1 ASTM International, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959.
Degrees of blast cleaning (SSPC-SP 5 or SSPC-SP 10) shall be substituted (see Notes 10.3 and 10.4).
4.2 PROFILE HEIGHT: The profile height shall be within the range of 40 to 90 micrometers (1.5 to 3.5 mils) or as recommended by the manufacturer of the primer. Profile shall be measured in accordance with ASTM D 4417.
5. Coatings
5.1 COATING: The coating in this painting system shall be in accordance with SSPC-Paint 20 or SSPC-Paint 29.
6. Coating Application
6.1 COATING APPLICATION: The coating shall be applied in accordance with SSPC-PA 1 (see Notes 10.5 and 10.6).
6.2 TOUCH-UP COATING:Touch-up coating shall be done in accordance with SSPC-PA 1 and in particular with the section thereof entitled “Field Painting.” Unless otherwise specified, touch-up coating shall be done in the field with a compatible zinc-rich coating (see Note 10.7).
6.3 NUMBER OF COATS:This coating system shall consist of one coat.
6.4 DRY FILM THICKNESS (DFT): The dry film thickness shall be a minimum of 64 micrometers (2.5 mils) or as specified by the manufacturer of the primer. DFT shall be measured in accordance with SSPC-PA 2. Refer to manufacturerʼs data sheet for maximum allowable dry film thickness (see Note 10.8).
6.4.1 Low Dry Film Thickness: Low dry film thickness shall be repaired based upon the written recommendations of the zinc-rich coating manufacturer.
6.4.2 Excessive Dry Film Thickness: Excess thickness above the maximum acceptable levels shall be repaired according to the recommendations of the coating manufacturer. This may require the removal of excessive thickness only, or complete removal and reapplication of the coating (see Note 10.9).
6.5 REPAIR: In the event of mudcracking or loss of adhesion, the defective zinc-rich coating shall be suitably removed and the affected area shall be recoated.
7. Field Performance
7.1 Upon request of the purchaser, the coating supplier shall furnish case histories of satisfactory service in an environment similar to that intended. The names and addresses of previous users who can give information regarding coating service performance must be included. The specifier shall determine the applicability of this data for his specific use.
7.2 Additionally, or in lieu of suitable in-service field exposure or application histories as described above, the coating supplier and the user may establish a criterion of performance agreeable to all parties.
8. Inspection
8.1 All work and materials supplied under this specification are subject to timely inspection by the purchaser or his authorized representative. The contractor shall correct such work or replace such material as is found defective under this specification. In case of dispute, unless otherwise specified, the arbitration or settlement procedure established in the procurement documents shall be followed.If no arbitration or settlement procedure is established, then a procedure mutually agreeable to purchaser, material supplier, and contractor shall be used.
8.2 Samples of paints under this painting system may be requested by the purchaser and shall be supplied upon request along with the manufacturerʼs name and identification for the materials. Samples may be requested at the time the purchase order is placed or may be taken from unopened containers at the job site (see Note 10.10).
8.3 Unless otherwise specified, the sampling shall be in accordance with ASTM D 3925.
9. Disclaimer
9.1 While every precaution is taken to ensure that all information furnished in SSPC standards and specifications 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 specified herein, or of the specification or standard itself.
9.2 This painting system specification does not attempt to address problems concerning safety associated with its use. The user of this specification, 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.
10. Notes
Notes are not requirements of this specification.
10.1 MANUFACTURERʼS LITERATURE: This painting system specification is intended to be supplemented by the coating manufacturer’s instructions and literature. If the manufacturer’s literature or recommendations are to become part of the requirements of a procurement document, they must be submitted as part of the design or bidding document. The date of the manufacturer’s literature and the number of sheets should be listed. In the event of a conflict between the manufacturer’s written instructions and this specification, the specifier, or other appropriate authorities, shall be notified to provide clarification.
10.2 TOPCOATING: Although not required by this specification, suitable topcoating may provide additional service life. Topcoats must be formulated not only for environmental resistance, but also for suitable application (to minimize pinholing, bubbling, etc.) over a zinc-rich primer. Topcoating will be required in service environments with pH below 5 or above 10. The following is a guide:
10.2.1 Immersion: For aqueous immersion service, the zinc-rich coating may be topcoated with a suitable topcoat. Zinc-rich coatings are satisfactory for many non-aqueous immersion services provided trace zinc contamination is not important. If contamination can occur, a suitable resistant topcoat may be employed.
10.2.2 Splash/Spillage: When coatings for appearance and protection of process equipment and structural materials are within a process area and exposed to process fumes and frequent splash and spillage of process chemicals, resistant topcoats may provide additional service life.
10.2.3 Chemical Fume: Coatings that are exposed to moderate and high concentrations of corrosive fumes and weather, but no splash or spillage, may be topcoated to provide additional service life.
10.2.4 Atmospheric: Coatings primarily for appearance in yard areas and service buildings (exposure to non-corrosive fumes and weathering only) may be topcoated to provide additional service life, but a zinc-rich primer alone is sufficient to provide long-term protection.
10.3 DEGREE OF BLAST CLEANING:While blast cleaning to white metal is always preferred, this surface preparation is often difficult and expensive to achieve. A near-white metal blast cleaning, or in some cases, a commercial blast cleaning, will often provide a satisfactory surface for these coatings. Although this specification is written for blast cleaned surfaces, under certain conditions pickling can be used for Type IC (solvent base inorganic) and Type II (organic) zinc-rich primers if agreed upon by the contracting parties. The pickling procedures shall be in accordance with paragraph 5.2.1 of SSPC-SP 8. Specifically, this requires adequate rinsing of all pickling residues with 60°C (140°F) hot water and prohibits subsequent phosphoric acid or dichromate immersion.
The degree of deviation from the ideal that zinc-rich coatings will tolerate without serious loss of their properties varies considerably from coating to coating. Therefore, adequate instructions from the manufacturer are essential and must be closely followed to ensure maximum performance.
A general guideline for surface preparation under various exposures is as follows:
Recommended Exposure Minimum Surface Preparation
Immersion–continuous immersion or condensation
SSPC-SP 5
Splash/Spillage–Frequent condensation, splash, spray, spillage, and high fume concentrations
SSPC-SP 5
Chemical Fume–Relatively high fume concentrations, no splash
SSPC-SP 10
Atmospheric–Non-corrosive fume concentrations and outside
SSPC-SP 6
Marine Atmospheric
SSPC-SP 10
10.4 WET ABRASIVE BLAST CLEANING: Under certain circumstances, wet abrasive blast cleaning or waterjetting (SSPC-SP 12/NACE No. 5) may be an alternative to dry abrasive blast cleaning.
10.5 APPLICATION METHOD: Zinc-rich coatings are preferably applied by spray due to advantages of this method, but some may be roller coated or brushed to force paint into surface irregularities. Normally, inorganic zinc-rich coatings should not be applied by brush or roller. During application, frequent mixing of the coating is essential to ensure uniform pigment suspension. For spray application, use of a continuously agitated pot is recommended. The coating manufacturerʼs recommendations should be followed.
10.6 MIXING: The painting system coating should be mixed in accordance with the manufacturer’s written instructions. Generally, the mixing procedure of a multi-package zinc-rich coating is as follows: stir the fluid vehicle until homogeneous and then pour it into the mixing container. Sift in the zinc dust in small quantities, mixing it in thoroughly. Mix until the dust is well dispersed. Pass the mixture through a 30-mesh screen to remove any lumps. When spraying, it is also good practice to use a 30-mesh in-line screen at the coating intake.
10.7 Refer to SSPC-Guide 14 “Guide for Repair of Imperfections in Galvanized or Inorganic Zinc Coated Steel Using Organic Zinc-Rich Coatings” for additional information about touch-up coating.
10.8 It is generally recommended that zinc-rich coatings not be applied at dry film thicknesses greater than 125 micrometers (5 mils) per coat because of their tendency to mudcrack at film thicknesses greater than 125 micrometers (5 mils). Refer to manufacturer’s data sheet for dry film thickness limits.
10.9 The amount of zinc-rich coating that is excessive is highly dependent on the formulation, the environment, the requirements for use, and the curing conditions. Based on a survey of suppliers, specifiers, and applicators, the most common value for maximum acceptable DFT is 125 to 150 micrometers (5 to 6 mils). For some zinc-rich coatings, the maximum DFT may be as low as 90 micrometers (3.5 mils), while for certain organic zinc-rich coatings, a maximum DFT of 250 micrometers (10 mils) is acceptable.
10.10 The procurement documents should establish the responsibility for samples, testing, and any required affidavit certifying full compliance with the specification.
10.11 FAYING SURFACES: Certain zinc-rich primers, when untopcoated, provide sufficient friction to allow their use on faying surfaces of high-tensile bolt connections. The coating manufacturer should be consulted regarding the suitability of the zinc-rich primer for this purpose and should submit test data and parameters for use of this painting system.
PAINTING SYSTEM NO. 12.01 – One Coat Zinc-Rich Painting System
