Standard · Metallic coatings and cathodic protection
ASTM A780/A780M
Touch-up and repair of bare or damaged spots on hot-dip galvanized steel.
ASTM A780/A780M gives the ways to repair galvanizing damaged by welding, cutting or handling, and areas the zinc did not cover. The current edition is A780/A780M-20.
Three repair methods
- Zinc-based solder: a low-melting zinc alloy rod or powder, worked onto the preheated area.
- Zinc-rich paint: a paint with a high zinc content in the dry film, organic or inorganic.
- Sprayed zinc: thermal spraying of zinc wire or powder (metallizing).
What the inspector checks
The repair must reach the specified thickness and should protect the steel as zinc does. A zinc-rich paint repair is applied thicker than the galvanizing around it. The galvanizing specification, such as ASTM A123, sets how large an area may be repaired.
2 practice items in the members area mention ASTM A780/A780M (CIP 2: 2).
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This page describes the subject of ASTM A780/A780M in our own words; it does not reproduce the standard. For the full text, buy the current edition from ASTM International. Checked on 2026-10-14; errors go in the corrections log. CoatMentor is an independent study aid. It is not affiliated with ISO, AMPP, SSPC, NACE International, ASTM or FROSIO.