Abstract
This specification covers the basic requirements and associated test methods for water-based corrosion protective zinc/aluminum dispersion inorganic basecoats, and optional sealers and topcoats for fasteners. The basecoat can contain chrome (C) or be non-chrome (NC). These coatings are applied to ferrous parts by conventional dip-spin, dip-drain, or spray methods, which can be handled through a cleaning, coating, and baking operation, and which are not adversely affected by baking temperatures up to 330 °C. The coatings are classified into six grades (Grades 1 to 6) according to the required minimum basecoat thickness, and when tested, shall conform accordingly to appearance, adhesion, corrosion resistance, blister, thread fit, and hydrogen embrittlement requirements. The coating process does not induce the possibility of internal hydrogen embrittlement provided that the fasteners have not been cleaned or pre-treated with an acid or phosphate. Alkaline cleaning or vapor degreasing is required along with shot blasting to remove rust or scale. In this specification, units are presented in the metric scale.
Scope
1.1 This specification covers the basic requirements for water-based zinc/aluminum dispersion inorganic basecoats and optional sealers and topcoats for fasteners. The basecoat can contain chrome (C) or be non-chrome (NC).
1.2 These coatings are applied by conventional dip-spin, dip-drain, or spray methods to ferrous parts which can be handled through a cleaning, coating, and baking operation, and which are not adversely affected by baking temperatures up to 330 °C [626 °F].
1.3 The coating process does not induce the possibility of internal hydrogen embrittlement providing that the fasteners have not been cleaned or pre-treated with an acid or phosphate. Alkaline cleaning or vapor degreasing is required along with shot blasting to remove rust or scale.
1.4 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in non-conformance with the standard.
1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.
1.6 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
