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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Surface Preparation Always check for asm contaminants on the surface of the repair area just prior to mechanical cleaning. The zinc used is nominally A listing of various manufacturers and products for the maintenance and repair of hot-dip galvanized structures is available for download.
Xstm Zinc meets and exceeds this percent. Where circumstances do not allow blast cleaning, it is permissible to power disk sand areas to be repaired to bright metal. 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.
ASTM A780-Zinc Dust in Paint
The damage may be the result of welding or cutting flamein which case the coating will be damaged predominantly by burning. It is important to note that the size restrictions apply to the area s to be repaired prior to surface preparation. Zinc-Rich Paints Zinc-rich paint is applied to a clean, dry steel surface by either a brush or spray.
Touch-up and repair of galvanized steel is simple whether newly galvanized or in service for years. Finally, a visual inspection ast confirm the level of cleanliness must be carried out to ensure the standard is met. There is no ASTM specification which specifies a maximum allowable repair size for galvanized items already accepted and delivered.
Ensuring Conformance to ASTM A | American Galvanizer’s Association
The material used for repair shall have the specified coating thickness, shall provide barrier protection and preferably be anodic to steel, sstm application of the coating shall be possible under shop or field conditions.
Topics include proper materials to use while performing the process, wstm well as specifications to follow and proper application of the repair materials. 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. Inch-pound units and SI units are not necessarily exact equivalents. Topics will include proper equipment and materials to use while performing the process, explanation of the specifications to follow, and examples of best practice during application of the a708 materials.
Within the text of this specification and where appropriate, SI units are shown in brackets. Soldering is done with zinc-based alloys in either a stick or powder form.
Effective May 1st Each system shall be used independently of the other without combining values in any way. After surface preparation, the standards refer to points of inspection necessary to ensure proper adhesion of the repair material.
Ensuring Conformance to ASTM A780
Therefore, once in-field, any size of repairable z780 defect can be touched up. Galv Touch-Up and Repair Dr. Experience shows that in general organic zinc-rich systems are more tolerant of surface preparation. For less critical field exposure conditions, blast clean the awtm to near-white metal, in accordance with SSPC-SP10 1 to 2 mil 25 to 50 m anchor patternas a minimum.
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. Historical Version s – view previous versions of standard. Requirements concerning the renovation of uncoated areas remaining after initial hot-dip galvanizing are contained within the applicable material specification. The information provided herein is not intended as a representation or warranty on the part of the AGA.
When it comes to repairing galvanized steel in the field, there is no limitation to the size that can be repaired. 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 material provides general information only and is not intended as a substitute for competent professional examination and verification as to suitability and applicability. Most organic zinc-rich paints are not critical of climatic or atmospheric conditions for curing.
Brite Zinc is an organic zinc compound. This practice can also be used to repair hot-dip galvanized coatings damaged by excessively rough handling during shipping or erection. Zinc spray, or metallizing, is done by melting zinc powder or zinc wire in a flame or electric asfm and projecting the molten zinc droplets by air or gas onto the surface to be coated.
The material provided herein has been developed to provide accurate and authoritative information about after-fabrication hot-dip galvanized steel. 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.
The videos provide highly beneficial visual aids to those needing assistance with touch-up and repair, whether in the plant or the field. Anyone making use of this information assumes all liability arising from such use. Ensure a blotter test is performed prior to using a compressed air source in accordance with ASTM D 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.
The area being repaired needs to be preheated to approximately F C. ASTM A contains three acceptable methods of touch-up and repair of hot-dip galvanized steel: The method and extent of surface preparation shall be mutually agreeable to the contracting satm.
To ensure that a smooth reconditioned coating can be effected, surface preparation shall extend into the undamaged galvanized coating.
The repair coating thickness must meet the specification requirement for the material category of the part with a maximum thickness of 4 mils ? The specification explains how to use the various repair methods as well as the required coating thickness for the repaired area.
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. Hand tool cleaning with a stiff-bristle or nylon brush does not meet specification.
Although some of the requirements within ASTM A are relatively straightforward, other requirements related to surface preparation often require clarification. Paints containing aastm dust are classified as organic or inorganic, depending on the binder they contain. Zinc-rich paint is applied to a clean, dry steel surface by either a brush or spray.
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 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.
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: