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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The practice for repairing the galvanized coating in-field is the same as the practice for repair at the galvanizing facility, but atsm are more restrictions to the allowable repair size while at the galvanizing facility. Do not immediately apply repair materials over a freshly cleaned surface. For power tool cleaned surfaces, a surface profile depth micrometer is the appropriate method for confirming profile, unless otherwise agreed.
This abstract is a brief summary of the referenced standard.
Repairing HDG Steel | American Galvanizer’s Association
Link to Active This link will always route astn the current Active version of the standard. ASTM A contains three acceptable methods of touch-up and repair of hot-dip galvanized steel: This practice can also be used to repair hot-dip galvanized coatings damaged by excessively rough handling during shipping or erection.
Appropriate grinding tools include reciprocating sanders, orbital sanders, or grinding devices that utilize abrasive cloths, discs, wheels or flaps.
Zinc-Rich Paints Zinc-rich paint is applied to a clean, dry steel surface by either a brush or spray. The videos provide highly beneficial visual aids to those needing assistance with touch-up and repair, whether in the plant or the field. Effective May 1st Requirements concerning the renovation of uncoated areas remaining after initial hot-dip galvanizing are contained within the applicable material specification. 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 astk application.
Correct for the additional tape thickness i. Soldering is done with zinc-based alloys in either a stick or powder form. The specification explains how to use the various repair methods as well as the required coating thickness for the repaired area. Astmm Documents purchase separately The documents listed below are referenced within the subject standard but are not provided as part of the standard. 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.
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.
Ensuring Conformance to ASTM A780
This practice describes methods that 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. Brite Zinc meets and exceeds a78 percent. Inspector Listing – Non-U. Topics include proper materials to use while performing the process, as well as specifications to follow and proper application of the repair materials.
Touch-up materials are required to meet a coating thickness of at least 2. The area being repaired needs to be preheated to approximately F C. As noted before, asgm 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.
At the galvanizing facility, the maximum allowable repair size for iron and steel products per ASTM A is no more than 1 inch [2. astk
Each system shall be used independently of the other without combining values in any way. Historical A7780 s – view previous versions of standard. 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.
For less critical field exposure conditions, blast clean the surface to near-white metal, in accordance with SSPC-SP10 1 to 2 mil 25 to 50 m anchor patternas a minimum. When it comes to repairing galvanized steel in the field, there is no limitation to the size that can be repaired. The method and extent of surface preparation shall be mutually agreeable to the contracting parties. To ensure that a smooth reconditioned coating can be effected, surface preparation shall extend into the undamaged galvanized coating.
Similarly, contracting parties shall agree to the repair method to be used. Galv Touch Astk Methods Dr. Watch the Videos 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: Touch-up and repair of galvanized steel is simple whether newly galvanized or in service for years.
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:. Contact Us Order Status. August 1, Authored ast, Alana Hochstein. Although some of the requirements within ASTM A are relatively straightforward, other requirements related to surface preparation often require clarification. The zinc coating is difficult to damage, and field fabrication that requires removal of the coating should be minimized as much as possible.
However, do not clean excessively beyond the area of repair. Anyone making use of this information assumes all liability arising from such use. The damage may be the result of welding or cutting flamein which case the coating will be damaged predominantly by burning.
ASTM AZinc Dust in Paint | American Galvanizer’s Association
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. 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.
The material provided herein has been developed to provide accurate and authoritative information about after-fabrication hot-dip galvanized steel. There is no ASTM specification which specifies a maximum allowable repair size for galvanized items already accepted and delivered. Topics will include proper equipment and materials to use while performing the process, explanation of z780 specifications to follow, and examples of best practice during application of the repair materials.
Within the text of this specification and where appropriate, SI units are shown in brackets. Brite Zinc is an organic zinc compound.
When ready to perform mechanical cleaning, check the surface preparation standard for clarity on the allowable tooling methods.
Paints containing zinc dust are classified as organic or inorganic, depending on the binder they contain.
Finally, a visual inspection to confirm the level of cleanliness must be carried out to ensure the standard is met. For best results, thickness measurements for the metallized coating should be taken with either a magnetic or an 7a80 gauge.