ASTM A780 PDF

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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Repairing HDG Steel

Galv Touch-Up and Repair Dr. 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. Authored by Alana Hochstein. Zinc-Rich Paints Zinc-rich paint is applied to a clean, dry steel surface by either a brush or spray.

Although the hot-dip galvanized coating is very resistant to damage, small voids or defects in the coating can occur during the galvanizing process or due to improper handling of the steel after galvanizing. 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.

At the galvanizing facility, the maximum allowable repair size for iron and steel products per ASTM A is no more than 1 inch [2. The zinc used is nominally Referenced Documents purchase separately The documents listed below are referenced within the subject standard but are not provided as part of the standard.

In order to ensure strict adherence to the specification ASTM A z780 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.

Hand tool cleaning with a stiff-bristle or nylon brush does not meet specification. Historical Version s – view previous versions of standard. Correct for the additional tape thickness i. Call for more information.

Ensuring Conformance to ASTM A | American Galvanizer’s Association

Effective May 1st Experience shows that in general organic zinc-rich systems are more tolerant of surface preparation. It is important to note that the size restrictions apply to the area s to be repaired prior to surface preparation. To ensure that a smooth reconditioned coating can be effected, surface preparation shall extend into the undamaged galvanized coating. Contact Us Order Status. The area being repaired needs to be preheated to approximately F C.

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For all a7880 preparation methods, cleaning must extend into the surrounding, undamaged galvanized coating. The videos provide highly beneficial visual aids to those needing assistance with touch-up and repair, whether in the plant or the field.

Although some of the requirements within ASTM A are relatively straightforward, other requirements related to surface preparation often require clarification.

Ensuring Conformance to ASTM A780

Anyone making use of this information assumes all liability arising from such use. Where circumstances do not allow blast cleaning, it is permissible to power disk sand areas to be repaired to bright metal. The six-part video series will provide highly beneficial visual aids to those needing assistance with meeting the requirements of ASTM A 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.

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.

Topics include proper materials a80 use while performing the process, as well as specifications to follow and proper application of the repair materials. For best results, thickness measurements for the metallized coating should be taken with either a magnetic or an electromagnetic gauge.

There is no ASTM specification which specifies a maximum allowable repair size for galvanized items already accepted and delivered.

Repairing HDG Steel | American Galvanizer’s Association

Do not average the readings, as this requirement was removed from the specifications in Paints containing zinc dust are classified as organic or inorganic, depending on the binder they contain. 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: 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 repair materials.

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Zinc-based solder products closely match the surrounding zinc and blend in well with the existing coating appearance. For power tool cleaned surfaces, a surface profile depth micrometer is the appropriate method for confirming profile, unless otherwise agreed.

Link to Active This link will always route to the current Active version of the standard. Zinc-rich paint is applied to a clean, dry steel surface by either a brush or spray. This material provides general information only and is not intended as zstm substitute for competent professional examination and verification as to suitability and applicability.

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. Surface Preparation Always check for visible contaminants on the surface of the repair area just prior to mechanical cleaning. Most organic zinc-rich paints are not critical of climatic or atmospheric conditions for curing. This practice describes the use of three types of material that possess the required properties for repair of damaged galvanized coatings, namely: Touch-up and repair of galvanized steel is simple whether newly ast, or in service for years.

Ensure a blotter test is performed prior to using a compressed air source in accordance with ASTM D The touch-up and repair of hot-dip galvanized steel coatings is important to maintain uniform barrier and cathodic aztm as well as ensure longevity. Do not immediately apply repair materials over a freshly cleaned surface. Any dust or loose residue from cleaning must be brushed away using a stiff-bristle brush or blown off using clean, dry air.