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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Touch-up materials are required to meet a coating thickness of at least 2.
ASTM AZinc Dust in Paint | American Galvanizer’s Association
Where circumstances do not allow blast cleaning, it is permissible to power disk sand areas to be repaired to bright metal. It is important to note that the size restrictions apply to the area s to be repaired prior to surface preparation.
This is especially applicable for abrasive blast cleaned surfaces, where an appropriately sized blasting unit and hose should be utilized.
Brite Zinc is an organic zinc compound. For best results, thickness measurements for the metallized coating should be taken with either a magnetic or an electromagnetic gauge.
Apply the paint as recommended by the paint manufacturer in a single application employing multiple spray passes to achieve a dry film thickness to be agreed upon between the contracting parties. Zinc Spray Metallizing 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.
When ready to perform mechanical cleaning, check the surface preparation standard for clarity on the allowable tooling methods. 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.
Galv What does the cold galvanizing process consist of? 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.
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. Inspection of Cleaned Surfaces After surface preparation, the standards refer to points of inspection necessary to ensure proper adhesion of the repair material.
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. Historical Version s – view previous versions of standard.
Although some of the requirements within Ashm A are relatively straightforward, other requirements related to surface preparation often require clarification. 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 aztm or gas onto the surface to asttm coated.
Ensuring Conformance to ASTM A780
Anyone making use of this information assumes all liability arising from such use. Do not immediately apply repair materials over a freshly cleaned asrm. Within the text of this specification and where appropriate, SI units are shown in brackets.
Experience shows that in general organic zinc-rich systems are more tolerant of surface preparation.
To ensure that a smooth reconditioned coating can be effected, surface preparation shall extend into the undamaged galvanized coating. A listing of various manufacturers and products for the maintenance and repair of hot-dip galvanized structures is available for download. Galv Touch Up Methods Dr. The specification explains how to use the various repair methods as well as the required coating thickness for the repaired area.
The zinc used is nominally This material provides general information only and is not intended as a substitute for competent professional examination and verification as to suitability and applicability. 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.
The area being repaired needs to be preheated to approximately F C. Referenced Documents purchase separately The documents listed below a7800 referenced within the subject standard but are not provided as s780 of the standard.
Watch the Videos The main restriction in the specification for repairing newly galvanized material is the size of the atm which is outlined in the product galvanizing specifications: Inorganic binders are particularly suitable for paints applied in touch-up applications of undamaged hot-dip galvanized areas.
Authored by Alana Hochstein.
If replica tape is utilized, adtm readings are to be taken over each location and averaged to get one “measurement” of the profile of the surface. Brite Zinc meets and exceeds this percent. 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.
Similarly, contracting parties shall agree to the repair method to be used.