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 Paints Zinc-rich paint is applied to a clean, dry steel surface by either a brush or spray.
The repair coating thickness must meet the specification requirement for the material category of the part with a maximum thickness of 4 mils ? Zinc-rich paint is applied to a clean, dry steel surface by either a astk or spray. Touch-up and repair of galvanized steel is simple whether newly galvanized or in service for years.
ASTM AZinc Dust in Paint | American Galvanizer’s Association
The method and extent of surface preparation shall be mutually agreeable to the contracting parties. 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.
Most organic zinc-rich paints are not critical of climatic or atmospheric conditions for curing. 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.
A listing of various manufacturers and products for the maintenance and repair of hot-dip galvanized structures is available for download. Soldering is done with zinc-based alloys in either a stick or powder form.
Ensuring Conformance to ASTM A780
Appropriate grinding tools include reciprocating sanders, orbital sanders, or grinding astk that utilize abrasive cloths, discs, wheels or flaps. This practice describes the use of three types of material that possess the required properties for repair of damaged galvanized coatings, namely: 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.
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. 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.
The six-part video series will provide highly beneficial visual aids to those needing assistance with meeting the requirements of ASTM A Requirements concerning the renovation of uncoated areas remaining after initial hot-dip galvanizing are contained within the applicable material specification. 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.
Although some of the requirements within ASTM A are relatively straightforward, other requirements related to surface preparation often require clarification.
To ensure that a smooth reconditioned coating can be effected, surface preparation shall extend into the undamaged galvanized aa780. The specification explains how to use the various repair methods as well as the required coating thickness for the repaired area.
The material provided herein has been developed to provide accurate and authoritative information about after-fabrication hot-dip galvanized steel.
The zinc coating is difficult to damage, and field fabrication that requires removal of the coating should be minimized as much as possible. Contact Us Order Status. Brite Zinc is an organic zinc compound.
ASTM A780-Zinc Dust in Paint
Experience shows that in general organic zinc-rich systems are more tolerant of surface preparation. Do not immediately apply repair materials over a freshly cleaned surface. The damage may be the result of welding or cutting flamein which case the coating will be damaged predominantly by burning.
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.
Repairing HDG Steel | American Galvanizer’s Association
Link to Active This link will always route to the current Active version of the standard. 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. Inspection of Cleaned Surfaces After surface preparation, the standards refer to points of inspection necessary to ensure proper adhesion of the repair material.
It is a70 responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
Effective May 1st The videos provide highly beneficial visual aids to those needing assistance with touch-up and repair, whether in the plant or the field. When ready to perform mechanical cleaning, check the surface preparation standard for clarity on the allowable tooling methods.
Zinc-based solder products closely match the surrounding zinc and blend in well with the existing coating appearance. However, do not clean excessively beyond the area of repair. August 1, Authored by Alana Hochstein.