Epoxy Polyamide Paints (Primer, Intermediate, and Topcoat)

Epoxy Polyamide Paint Application

PAINT SPECIFICATION NO. 22 – Epoxy Polyamide Paints (Primer, Intermediate, and Topcoat)

1. Scope
1.1 This specification covers three types of two-component epoxy polyamide coatings—primer, intermediate, and topcoat —for use on steel surfaces. The information described herein shall be used as a control for evaluation of proposed coating systems. See SSPC-PS 13.01, “Epoxy Polyamide Painting System,” for specifications covering system requirements, including surface preparation, application, and thickness.

1.2 These coatings, when applied over properly prepared steel surfaces, are suitable for exposures in environmental zones 2A (frequently wet by fresh water), 2B (frequently wet by salt water), 3A (chemical, acidic), 3B (chemical, neutral), 3C (chemical, alkaline), 3D (chemical, solvents); but not for potable water tanks. They are intended for brush or spray ap­plication over steel prepared in accordance with SSPC-SP 6, “Commercial Blast Cleaning,” or SSPC-SP 8, “Pickling.” The performance will be improved by a better degree of surface preparation. They are suitable for shop, field, or maintenance coatings and are to be applied in accordance with SSPC-PA 1, “Shop, Field, and Maintenance Painting of Steel.” If the primed part of the structure is to be exposed to the weather, it should be topcoated as soon as practical.

2. Description
2.1 The coatings supplied under this specification are two-part products composed of a base component and a cur­ing agent component. When the two components are mixed in the proper proportions the coatings are capable of curing at temperatures as low as 50°F (10°C) and fully curing in seven days.
2.2 The primer contains approximately 65% by volume of nonvolatile film-forming solids (pigment and binder). The theoretical spreading rate for a 2.5 mil (63 micrometers) dry film thickness is 420 square feet/U.S. gallon (10.2 square meters/liter).
2.3 The intermediate contains approximately 65% by volume of nonvolatile film-forming solids (pigment and binder). The theoretical spreading rate for a 2.5 mil (64 micrometers) dry film thickness is 420 square feet/U.S. gallon (10.2 square meters/liter).
2.4 The topcoat contains approximately 60% by volume of nonvolatile film-forming solids (pigment and binder). The theoretical spreading rate for 2.5 mil (63 micrometers) dry film thickness is 380 square feet/U.S. gallon (9.5 square meters/ liter).

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.
3.2 If there is a conflict between the requirements of any of the cited referenced standards and this specification, the requirements of this specification shall prevail.

3.3 SSPC STANDARDS AND JOINT STANDARDS:

3.4 ASTM INTERNATIONAL STANDARDS:
B 117 Method of Salt Spray (Fog) Testing
D 209 Specification for Lampblack Pigment
D 263 Specification for Chrome Oxide Green Pigment
D 331 (Withdrawn) Specification for 2-Ethoxyethyl Acetate (95% Grade)
D 476 Classification for Dry Pigmentary Titanium Dioxide Products
D 522 Test Methods for Mandrel Bend Test of Attached Organic Coatings
D 562 Test Method for Consistency of Paints
D 605 Measuring Krebs Unit (KU) Viscosity Using a Stormer-type Viscometer
D 607 Specification for Magnesium Silicate Pigment (Talc)
D 610 Specification for Wet Ground Mica Pigments
D 714 Test Method for Evaluating Degree of Rusting on Painted Steel Surfaces
D 1153 Test Method for Evaluating Degree of Blistering of Paints
D 1210 Specification for Methyl Isobutyl Ketone
D 1310 Test Methods for Fineness of Dispersion of Pigment-Vehicle Systems by Hegman-type Gage
D 1475 Test Method for Flash Point and Fire Point of Liquids by Tag Open-Cup Apparatus
D 1544 Test Method for Density of Liquid Coatings, Inks, and Related Products
D 1640 Test Method for Color of Transparent Liquids by Bubble Time Method
D 1652 Test Methods for Drying, Curing, or Film Formation of Organic Coatings at Room Temperature
D 1654 Test Methods for Epoxy Content of Epoxy Resins
D 2369 Test Method for Evaluation of Painted or Coated Specimens Subjected to Corrosive Environments
D 2541 Test Method for Volatile Content of Coatings
D 3722 Specification for Natural Red and Brown Iron Oxide Pigments

3.5 AMERICAN NATIONAL STANDARDS INSTITUTE (ANSI) STANDARD:
Z129.1 Hazardous Industrial Chemicals – Precautionary Labeling

4. Composition
4.1 Ingredients and proportions of the reference formula­tions shall be as specified in Table 1.
4.2 Each component of these paints based on the speci­fied ingredients shall be uniform, stable in storage, and free from grit and coarse particles.
4.3 The base component of each coating shall contain an epoxy resin together with anti-corrosion pigments, color pigments, mineral fillers, gellant, leveling agent, and volatile solvents. The epoxy resin shall be a di-epoxide condensation product of biphenol A and epichlorohydrin with terminal epoxide group.
4.4 The curing agent component of each coating shall contain a liquid type polyamide resin and volatile solvent. The
polyamide resin shall be a condensation product of dimerized fatty acids and polyamines.
4.5 Each coating shall conform to the composition (analysis) requirements of Table 2.

5. Properties
5.1 The epoxy resin shall meet the requirements of Table 3.
5.2 The undiluted polyamide resin shall meet the require­ments of Table 4.
5.3 Coatings supplied under this specification shall be com­parable in performance to the reference formulations of Table 1. They need not be composed of the quantities and types of ingredients given in Table 1. However, if substitutions of other ingredients are made, the coatings shall meet the performance requirements of this specification; and, when incorporated into a painting system, the performance requirements of SSPC-PS 13.01, “Epoxy Polyamide Painting System.”
5.4 After combining the base and curing agent compo­nents, the primer, intermediate, and topcoat shall conform to the requirements of Table 5 and Sections 5.5 through 5.9.
5.5 POT LIFE: Determine pot life of the individual coatings as follows. Thoroughly mix a one-pint sample of the finished coating and let stand at 77 ± 3°F (25 ± 2°C) for eight hours. At the end of this time there shall be no evidence of gelation. The coatings shall be in a free-flowing condition and brushable without thinning. NOTE: When mixing larger volumes, more heat will develop with a resultant shortening of the pot life.
5.6 SOLVENT RESISTANCE: The development of solvent (methyl ethyl ketone) resistance is required as an indication of satisfactory cure and subsequent chemical resistance. Apply the individual coating (primer, intermediate, topcoat) by spray or brush to a clean test panel so that a dry film thickness of two to three mils (51- 76 micrometers) per coat is obtained. Air dry the panel for five days at 77 ± 3°F (25 ± 2°C) and relative humidity of 40%- 50%. Following the curing period, saturate a small cottonball with methyl ethyl ketone and place on the test panel under a watch glass for 30 minutes. After a ten-minute recovery period, determine the pencil hardness of the coating. The minimum allowable rating is “7B.”

Determine pencil hardness as follows: Using a series of drawing leads (either wood clinched or secured in a mechanical holder), expose approximately 1/4 inch (6 mm) of lead. With a rotary motion square the point of the lead against No. 400 grit paper. Hold the lead at approximately 45° and push forward against the film using a pressure just short of breaking the lead. If penetration is not made, repeat using the next harder lead until penetration is made. Rate the film by indicating the hardest lead that does not penetrate.

5.7 TEST PANELS: Test panels shall be carbon steel— minimum size 4 x 8 x 1/8 inch (10.2 x 20.3 x 0.31 cm)—unless otherwise specified. They shall be blast cleaned in accordance with SSPC-SP 10, “Near-White Blast Cleaning.” Air drying and test conditions shall be at 77 ± 3°F (25 ± 2°C), and 40%-50% relative humidity.
5.8 ELCOMETER ADHESION TEST: Prepare test panels as in Section 5.7 using 1 /4 inch (6 mm) thick steel plate. Apply coatings at 2.0 to 3.0 mils (51 to 76 micrometers) dry film thick­ness per coat in accordance with the following schedule.

COATING SUBSTRATE DRYING TIMES

Primer Steel – 5 days
Topcoat Primer – 5 days
Intermediate Primer – 72 hours

The adhesion of the prime coat to the substrate, inter-coat adhesion, or cohesion of any coat of the painting system shall be determined by the adhesion tester (1,000 pounds, 156 kg). Prepare test panels as described above. Lightly sand the coat­ing surface and aluminum dolly, and apply a quick set adhesive containing alpha cyanoacrylate. Allow the adhesive to cure overnight. Scribe the coating and adhesive around the dolly prior to testing. Make a minimum of three trials and report the average. An average of 400 pounds per square inch (280,000 kg/square meter) is considered acceptable.

5.9 SALT SPRAY RESISTANCE (PRIMER ONLY): Pre­pare at least two test panels as in Section 5.7 and apply one prime coat at 2.5 to 3.0 mils (64 to 76 micrometers) dry film thickness. Air dry five days. Protect the backs and edges. Scribe the panels as per ASTM D 1654 to base metal and exposure for 500 hours at five percent salt spray in accordance with ASTM B 117. During the test, the panels shall be inclined at an angle of 15 degrees off the vertical. At the end of the test period, the primer shall have a minimum rust grade rating of “8.” Blistering shall be no more than Blister Size No. 4, few. Photographic standards SSPC-VIS 2, “Standard Method of Evaluating Degree of Rusting on Painted Steel Surfaces,” or ASTM D 610 may be used for rusting, and ASTM D 714 may be used for blistering.

6. Labeling
6.1 Technical data shall be provided for at least all data elements categorized as “essential” in SSPC-Guide 13.
6.2 Refer to ANSI Z129.1, “Hazardous Industrial Chemicals — Precautionary Labeling.”

6.3 MARKING OF CONTAINERS: Each container of each component shall be legibly marked with the following information:

Name: Epoxy Polyamide Coating (Specify Which: Primer, Intermediate, or Topcoat)
Specification: SSPC-Paint 22
Component:
Color:
Lot Number:
Stock Number:
Date of Manufacture:
Quantity of Paint in Container:
Information and Warnings as may be required by
Federal and State Laws:
Manufacturer’s Name and Address:

6.3 DIRECTIONS FOR USE: The manufacturer shall sup­ply complete instructions covering uses, surface preparation, mixing, thinning, application method, application conditions, pot life, wet and dry film thicknesses, temperature and humidity limitations, drying time, etc., with each container of paint.

6.4 The following are guidelines for the instructions required:
Mixing and Thinning: Each coating component should be stirred to a smooth homogenous mixture. Then the proper amount of base and curing agent components, as recom­mended by the manufacturer, should be added together and mixed thoroughly. After allowing to stand for 30 minutes at 77 ± 3 °F (25 ± 2°C), the coating may be thinned up to 12% by volume of the total coating for spraying. The coating should be applied within the manufacturer’s pot life limitations.
Coating Thickness: The protective coatings are usually applied by spray to a dry film thickness of two to three mils (51-76 micrometers) per coat with total dry thickness seven to nine mils (178-229 micrometers), as measured in accordance with SSPC-PA 2, “Measurement of Dry Coating Thickness with Magnetic Gages.”
Cure Time Between Coats: Under normal conditions, each coat should be air dried a minimum of four hours, but no more than 72 hours between application coats. In very hot weather with surfaces exposed to direct sunlight, it may be necessary to limit the intercoat drying period to 24 hours or less. Long drying time between coats may cause poor intercoat adhesion. These coatings shall not be applied at temperatures below 50°F(10°C).

7. Inspection
7.1 All materials (coatings) supplied under this specifi­cation are subject to timely inspection by the purchaser or his authorized representative. The purchaser shall have the right to reject any materials supplied which are found to be defective under this specification (see Note 9.1.) In case of dispute, unless otherwise specified, the arbitration or settle­ment procedure established in the procurement documents shall be followed. If no arbitration procedure is established, then a procedure mutually agreeable to purchaser, material supplier, and contractor shall be used.

7.2 Samples of paints may be requested by the purchaser and shall be supplied upon request along with the manufac­turer’s 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.
7.3 Unless otherwise specified, the sampling shall be in accordance with ASTM D 3925.

8. Disclaimer
8.1 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.
8.2 This 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.

9. Notes
Notes are not requirements of this specification.
9.1 The procurement documents should establish the responsibility for samples, testing, and any required affidavit certifying full compliance with the specification.
9.2 ASTM and Federal Standard Test Methods listed as “canceled” or “withdrawn” are no longer maintained, but are still available as historical documents.
PAINT SPECIFICATION NO. 22 – Epoxy Polyamide Paints (Primer, Intermediate, and Topcoat)