ASTM A780 PDF

Brite Zinc meets and exceeds this percent. 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. Experience shows that in general organic zinc-rich systems are more tolerant of surface preparation. Most organic zinc-rich paints are not critical of climatic or atmospheric conditions for curing.

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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. Touch-up and repair of galvanized steel is simple whether newly galvanized or in service for years. 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.

The videos provide highly beneficial visual aids to those needing assistance with touch-up and repair, whether in the plant or the field. Topics include proper materials to use while performing the process, as well as specifications to follow and proper application of the repair materials.

The zinc coating is difficult to damage, and field fabrication that requires removal of the coating should be minimized as much as possible. 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. A listing of various manufacturers and products for the maintenance and repair of hot-dip galvanized structures is available for download.

The specification explains how to use the various repair methods as well as the required coating thickness for the repaired area. Touch-up materials are required to meet a coating thickness of at least 2. ASTM A contains three acceptable methods of touch-up and repair of hot-dip galvanized steel: Zinc-Based Solders Zinc-Based Solder Soldering is done with zinc-based alloys in either a stick or powder form. The area being repaired needs to be preheated to approximately F C. The repair coating thickness must meet the specification requirement for the material category of the part with a maximum thickness of 4 mils ?

Zinc-based solder products closely match the surrounding zinc and blend in well with the existing coating appearance. Paints containing zinc dust are classified as organic or inorganic, depending on the binder they contain. Inorganic binders are particularly suitable for paints applied in touch-up applications of undamaged hot-dip galvanized areas. Metallizing Zinc Spray Zinc Spray Metallizing 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.

The zinc used is nominally For best results, thickness measurements for the metallized coating should be taken with either a magnetic or an electromagnetic gauge.

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ASTM A780-Zinc Dust in Paint

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. Touch-up and repair of galvanized steel is simple whether newly galvanized or in service for years. 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. The videos provide highly beneficial visual aids to those needing assistance with touch-up and repair, whether in the plant or the field. Topics include proper materials to use while performing the process, as well as specifications to follow and proper application of the repair materials. The zinc coating is difficult to damage, and field fabrication that requires removal of the coating should be minimized as much as possible.

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Terminology 3. Materials 4. The most common types of solders are zinc- cadmium, zinc-tin-lead, and zinc-tin-copper alloys. No further reproductions authorized.

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ASTM A780 - Repair of Damaged and Uncoated Areas of Hot-Dip Galvanized Coatings

More A The damage may be the result of welding or cutting flame , in which case the coating will be damaged predominantly by burning. 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. This practice describes the use of three types of material that possess the required properties for repair of damaged galvanized coatings, namely: 1 zinc-based solders which includes low melting point zinc alloy repair rods or powders, 2 paints containing zinc dust, and 3 sprayed zinc metallizing.

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