ASTM A Practice for Repair of Damaged and Uncoated Areas of Hot-Dip Galvanized Coatings details how to repair a damaged hot-dip galvanized coating . 2. Referenced Documents. ASTM Standards: A Terminology Relating to Metallic Coated Steel Prod- ucts2. D Specification for Zinc Dust Pigment3. ASTM Designation: A (American Standard Testing Method). Standard Practice for Repair of Damaged and Uncoated Areas of Hot-Dip Galvanized Coatings.
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Zinc-rich paint is applied to a clean, dry steel surface by either a brush or spray. Zinc-Rich Paints Zinc-rich paint is applied to a clean, dry steel surface by either a brush or spray.
Inspection of Cleaned Surfaces After surface preparation, the standards refer to points of inspection necessary to ensure proper adhesion of the repair material. For best results, thickness measurements for the metallized coating should be taken with either a magnetic or an electromagnetic gauge.
Effective May 1st It is important to note that the size restrictions apply to the area s to be repaired prior to surface preparation. ASTM does not give any warranty express or implied or make any representation that the contents of this abstract are accurate, complete or up to date.
ASTM A contains three acceptable methods of touch-up and repair of hot-dip galvanized s780 As noted before, the cathodic protection of the coating will provide some protection to uncoated areas, but the best practice for longevity is to touch-up any bare areas. Most organic zinc-rich paints atsm not critical of climatic or atmospheric conditions for curing.
Repairing HDG Steel
Galv Touch-Up and Repair Dr. The material used for repair shall have the specified coating thickness, shall provide barrier protection and preferably be anodic to steel, and application of the coating shall be possible under shop or field conditions.
Brite Zinc meets and exceeds this percent.
Experience shows that in general organic zinc-rich systems are more tolerant of surface preparation. The videos provide highly beneficial visual aids to those needing assistance with touch-up and repair, whether in the plant or the field. The practice is the same, but there are more restrictions to the allowable repairs on a new product than one that has been in service. Zinc spray, or metallizing, is done by melting zinc powder or zinc wire in a flame or electric arc and projecting the molten zinc droplets by air or gas onto the surface to be coated.
It is informational only and not an official part of the standard; the full text of the standard itself must be referred to for its use and application. August 1, Authored by Alana Hochstein.
ASTM A780-Zinc Dust in Paint
To ensure that a smooth reconditioned coating can be effected, surface preparation shall extend into the undamaged galvanized coating. However, do not clean aa780 beyond the area of repair.
After surface preparation, the standards refer to points of inspection necessary to ensure proper adhesion of the repair material. In order to ensure strict adherence to the specification ASTM A when performing repairs at the galvanizing plant, the galvanizer should be well versed in the equipment, materials and surface preparation standards required of each repair method.
This abstract is a brief summary of the referenced standard. The touch-up and repair of hot-dip galvanized steel coatings is important to maintain uniform barrier and cathodic protection as well as ensure longevity. This material provides general information only and is not intended as a substitute for competent professional examination and verification as to suitability and applicability.
Corrosion resistance and service performance are very dependent on the properties of the paint system, the extent of surface preparation, and skills of individual applicators.
This practice describes methods a7780 may be used to repair damaged hot-dip galvanized coatings on hardware, structural shapes, and other products fabricated prior to hot-dip galvanizing, and uncoated areas remaining after initial hot-dip galvanizing. Where circumstances do not allow blast cleaning, it is permissible to power disk sand areas to be repaired to bright metal.
The main restriction in the specification for repairing newly galvanized material is the size of the area which is outlined in the product galvanizing specifications:. The zinc used is nominally The material provided herein has been developed to provide accurate and authoritative information about after-fabrication hot-dip galvanized steel.
Do not average the readings, as this requirement was removed from the specifications in Brite Zinc is an organic zinc compound. Authored by Alana Hochstein. Correct for the additional tape thickness i. Where such contaminants are found, the surface preparation standards associated with all repair materials require the removal of visible dirt, oil and grease deposits using a solvent cleaning method such as SSPC-SP1 Solvent Cleaning.
Requirements concerning the astj of uncoated areas remaining after initial hot-dip galvanizing are contained within the applicable material specification. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. This is especially applicable for abrasive blast cleaned surfaces, where an appropriately sized blasting unit and hose should be utilized.
Maximum Allowable Repair Size The practice for repairing the galvanized coating in-field is the same as the practice for repair at the galvanizing facility, but there are more restrictions to the allowable repair size while at the galvanizing facility. Link to Active This link will always route to the current Active version of the standard. For all surface preparation methods, cleaning must extend satm the surrounding, undamaged galvanized coating.
Surface profiling for abrasive blast cleaned surfaces may be performed using any method listed within ASTM D visual comparator, surface profile depth micrometer, or replica tape.
ASTM AZinc Dust in Paint | American Galvanizer’s Association
Historical Version s – view previous versions of standard. At the galvanizing facility, the maximum allowable repair size for iron and steel products per ASTM A is no more than 1 inch [2. Topics will include proper equipment and materials to use while performing the process, explanation of the specifications to follow, and examples of best practice zstm application of the repair materials.