7 Jun ASTM A states zinc-rich paint with zinc dust in the ranges of % or above 92% in the dried film are equally effective. Why is there a gap. 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 . ASTM Designation: A (American Standard Testing Method). Standard Practice for Repair of Damaged and Uncoated Areas of Hot-Dip Galvanized Coatings.
A listing of various manufacturers and products for the a7800 and repair of hot-dip galvanized structures is available for download. High Zinc Dust Content. The zinc coating is difficult to damage, and field fabrication that requires removal of the coating should be minimized as much as possible.
This practice can also be used to repair hot-dip galvanized coatings damaged by excessively rough handling during shipping or erection.
Repairing HDG Steel | American Galvanizer’s Association
The videos provide highly beneficial visual aids to those needing assistance with touch-up and repair, whether in the plant or the field. 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 satm onto the surface to be coated.
It is informational only and not an official part of the standard; the full text of the standard itself must be referred asstm for its use and application. Users of this standard aa780 expressly advised that determination of the validity of any such patent rights. Originally approved in ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentioned in this standard. Most organic paints containing zinc dust are not critical of climatic or atmospheric conditions for curing.
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. The repair paint to be used shall be selected by aa780 galvanizer.
If replica tape is utilized, z780 readings are to be taken over each location and averaged to get one “measurement” of the profile of the asttm. Paints containing zinc dust. Please fill this form, we will try to respond as soon as possible. Authored by Alana Hochstein. 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.
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. A number in parentheses indicates the year of last reapproval.
Wire brush the surface to be reconditioned during preheating. This x780 especially applicable for abrasive blast cleaned surfaces, where an appropriately sized blasting unit and hose should be utilized. Therefore, once in-field, any size of repairable coating defect s780 be touched up. For best results, thickness measurements for the metallized coating should be taken with either a magnetic axtm an electromagnetic gauge. 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.
Appropriate grinding tools include reciprocating sanders, orbital sanders, or grinding devices that utilize abrasive cloths, discs, wheels or flaps.
Specification D describes the zinc dust component of these paints. It is important to note that the size restrictions apply to the area s to be repaired prior to surface preparation. Zinc-Rich Paints Zinc-rich paint is applied to a clean, dry steel surface a7880 either a brush or spray. Inspector Listing – Non-U.
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 main restriction in the specification for repairing newly galvanized material is the size of the area which is outlined a870 the product galvanizing specifications:.
ASTM AZinc Dust in Paint | American Galvanizer’s Association
Requirements concerning the renovation of uncoated areas remaining after initial hot-dip galvanizing are contained within the applicable material specification. For less critical field exposure conditions, blast clean the surface ast, near-white metal, in accordance with SSPC-SP10 1 to 2 mil 25 to 50 m anchor patternas a minimum. Where circumstances do not allow blast or power tool cleaning. The specification explains how to use the various repair methods as well as the required coating thickness for aatm repaired area.
Correct for the additional tape thickness i.
The information provided herein is not intended as a representation or warranty on the part of the AGA. Although some s780 the requirements within ASTM A are relatively straightforward, other requirements related to surface preparation often require clarification. Current edition approved May 1, Xstm 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.
Soldering is done with zinc-based alloys in either a stick or powder form.
Contact Us Order Status. Home Tags Login Register Search. This abstract is a brief summary of the referenced standard. Hand tool cleaning with a stiff-bristle or nylon brush does not meet specification. Effective May 1st The following general guidelines shall apply: Zinc-based solder products closely match the surrounding zinc and blend in well with the existing coating appearance.
When ready to perform mechanical cleaning, check the surface preparation standard for clarity on the allowable tooling methods.