1 Aug In order to ensure strict adherence to the specification ASTM A when performing repairs at the galvanizing plant, the galvanizer should be. 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.
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To ensure that a smooth reconditioned coating astm a780 be effected, surface preparation shall extend into the undamaged galvanized coating.
After surface preparation, the standards refer to points of inspection necessary to ensure proper adhesion of the repair material.
Surface Preparation Always check for visible contaminants on the surface of the adtm area just prior to mechanical cleaning. Soldering astm a780 done with zinc-based alloys in either a stick or powder form. Link to Active This link will always route to the current Astm a780 version of the standard.
Repairing HDG Steel
Contact Us Order Status. August 1, Authored by Alana Hochstein. This practice describes the use of three types a708 material that possess the required properties for repair of damaged galvanized coatings, namely: The specification explains astm a780 to use the various repair methods as well as the required coating thickness for the repaired area.
Corrosion astm a780 and service performance astm a780 very dependent on the properties of the paint system, the extent of surface preparation, and skills of individual applicators.
Inspection of Cleaned Surfaces After astm a780 preparation, the standards refer to points of inspection necessary to ensure proper adhesion of the repair aa780. Historical Version s – view previous versions of standard. Inorganic binders are particularly suitable for paints applied in touch-up applications of undamaged hot-dip galvanized areas. 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.
This practice can also be used to repair hot-dip galvanized awtm damaged by excessively astm a780 handling during shipping or erection. a7780
Finally, a visual astm a780 to confirm the level of cleanliness must be carried out astm a780 ensure the standard is met. Do not average the readings, as this requirement was removed from the specifications in The a70 is the same, but there are more restrictions to the allowable repairs on a new astm a780 than one that has been in service.
Most organic zinc-rich paints are not critical of climatic or aastm conditions for curing. If replica tape is utilized, two readings are to be taken over each astm a780 and averaged to get one “measurement” of the profile of the surface. For less critical field exposure conditions, blast clean the surface to near-white metal, in accordance with SSPC-SP10 1 a7880 2 mil 25 to 50 m anchor patternas a minimum.
It is informational only and not an official part of the standard; the full text of the standard itself must astm a780 referred to for its use and application. However, do astm a780 clean excessively beyond the area of repair. In order to ensure strict adherence to the specification ASTM A when performing repairs at the galvanizing plant, the galvanizer astm a780 be well versed in the equipment, materials and surface preparation standards required of each repair method.
ASTM A780-Zinc Dust in Paint
The damage may be the result of welding or astm a780 flamein which case the coating will be damaged predominantly by burning. Ensure a blotter test is astm a780 prior to using a compressed air source in accordance with ASTM D The zinc used is nominally Call for more information. Zinc-rich paint is applied to a clean, dry steel surface by either a brush or spray.
The method and extent of surface preparation shall be mutually agreeable to the contracting parties. The main restriction astm a780 the specification for repairing newly galvanized material is the size astm a780 the area which is outlined in the product galvanizing specifications:. It is important to note that the size restrictions apply to the astm a780 s to be repaired prior to surface preparation.
Within the text of this specification and where appropriate, SI units are shown in brackets. ASTM does not give any warranty express or implied or make any representation that the contents of this abstract are accurate, complete or up to date.
Do not astm a780 apply repair materials over a freshly cleaned surface. Therefore, once in-field, any size of repairable coating defect can be touched up.
Touch-up astm a780 are required to meet a coating thickness of at least 2. The practice for repairing x780 galvanized coating in-field is the same as the practice for astm a780 at the galvanizing facility, but there are more restrictions to the allowable repair size while astm a780 the galvanizing facility. Any dust or loose residue from cleaning must be brushed away using a stiff-bristle brush or blown off aatm clean, dry air.
For all surface preparation methods, cleaning must extend into the surrounding, undamaged galvanized coating. Each system shall be used independently of the other without combining values in any way.
Repairing HDG Steel | American Galvanizer’s Association
Appropriate grinding tools include reciprocating sanders, orbital sanders, or grinding devices that astm a780 abrasive cloths, discs, wheels or flaps. Correct for the additional tape thickness i. Always check for visible contaminants on the surface of the repair area just prior to mechanical cleaning.
The area being repaired needs to be preheated to approximately F C. Surface profiling for abrasive blast cleaned surfaces may be performed using any method listed within ASTM D visual comparator, surface profile astm a780 micrometer, awtm replica tape.
A listing of various manufacturers and products for astm a780 maintenance and s780 of hot-dip galvanized structures is available for download.
This practice describes methods that may be used to repair damaged hot-dip galvanized coatings on hardware, astm a780 shapes, and other products fabricated prior astn hot-dip galvanizing, and uncoated areas remaining after initial hot-dip galvanizing. Effective May 1st Similarly, contracting parties shall agree to the repair method to be used. Apply the paint as recommended by the paint manufacturer in a single application employing multiple spray passes to achieve a astm a780 film thickness to be agreed upon between the contracting parties.