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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This is especially applicable for abrasive blast cleaned surfaces, where an appropriately sized blasting unit and hose should be utilized.
The area being repaired needs to be preheated to approximately F C. Inorganic binders are particularly suitable for paints applied in touch-up applications of undamaged hot-dip galvanized areas. The six-part video series will provide highly beneficial visual aids to those needing assistance with meeting the requirements of ASTM A Galv Touch-Up and Repair Dr.
Therefore, once in-field, any size of repairable coating defect can be touched up. Referenced Documents purchase separately The documents listed below are referenced within the subject standard but are not provided as part of the standard. Do not immediately apply repair materials over a freshly cleaned surface. To ensure that a smooth reconditioned coating can be effected, surface preparation shall extend into the undamaged galvanized coating.
However, do not clean excessively beyond the area of repair. If replica tape is utilized, two readings are to be taken over each location and averaged to get one “measurement” of the profile of the surface. Finally, a visual inspection to confirm the level of cleanliness must be carried out to ensure the standard is met.
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. Contact Us Order Status. The videos provide highly beneficial visual aids to those needing assistance with touch-up and repair, whether in the plant or the field.
Inch-pound units and SI units are not necessarily exact equivalents. Surface Preparation Always check for visible contaminants on the surface of the repair area just prior to mechanical cleaning. The zinc coating is difficult to damage, and field fabrication that requires removal of the coating should be minimized as much as possible.
Repairing HDG Steel | American Galvanizer’s Association
Touch-up materials are required to meet a coating thickness of at least 2. 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. Experience shows that in general organic zinc-rich systems are more tolerant of surface preparation.
This practice can also be used to repair hot-dip galvanized coatings damaged by excessively rough handling during shipping or erection. Requirements concerning the renovation of uncoated areas remaining after initial hot-dip galvanizing are contained within the applicable material specification.
Galv Touch Up Methods Dr. Where blast or power tool cleaning cannot be performed, hand tool cleaning per SSPC-SP2 Hand Tool Cleaning allows the use of wire brushing, scraping, chipping and sanding. Always check for visible contaminants on the surface of the repair area just prior to mechanical cleaning.
ASTM A780-Zinc Dust in Paint
Topics include proper materials to use while performing the process, as well as specifications to follow and proper application of the repair materials. 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.
August 1, Authored by Alana Hochstein. 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.
Within the text of this specification and where appropriate, SI units are shown in brackets. The specification explains how to use the various repair methods as well as the required coating thickness for the repaired area.
At the galvanizing facility, the maximum allowable repair size for iron and steel products per ASTM A is no more than 1 inch [2. ASTM A contains three acceptable methods of touch-up and repair of hot-dip galvanized steel: For best results, thickness measurements for the metallized coating should be taken with either a magnetic or an electromagnetic gauge. Hand tool cleaning with a stiff-bristle or nylon brush a7880 not meet specification.
Correct for the additional tape thickness i.
The method and extent of surface preparation shall be mutually agreeable to the contracting a70. Where circumstances do not allow blast cleaning, it is permissible to power disk sand areas to be repaired to bright metal. For power tool cleaned surfaces, a surface profile depth micrometer is the appropriate method for confirming profile, unless otherwise agreed.
ASTM AZinc Dust in Paint | American Galvanizer’s Association
Galv What does the cold galvanizing process consist of? Authored by Alana Q780. 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. Paints containing zinc dust are classified as organic or inorganic, depending on the binder they contain.
For all ast preparation methods, cleaning must extend into the surrounding, undamaged galvanized coating. Touch-up and repair of galvanized steel is simple whether newly galvanized or in service for years.
Soldering is done with zinc-based alloys in either a stick or powder form. After surface preparation, the standards refer to points of inspection necessary to ensure proper adhesion of the repair material. Inspector Listing – Non-U. 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.