Corpus sync: neutrality remakes, note hygiene, datasheet relocation, transformer-split cross-refs
---
title: Shop Painting and Galvanizing of Steel
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## The three families are distinguished as follows, and the choice among them is the central decision of this standard: {note}
−- **Shop prime painting** -- a thin film of primer (zinc-rich, alkyd, epoxy, or urethane) applied over a prepared steel surface, providing barrier and/or sacrificial protection for interior or protected exposures, or a base for later field topcoats.
−- **Hot-dip (batch) galvanizing** -- immersion of the fabricated assembly in molten zinc per ASTM A123, producing a metallurgically bonded zinc coating that provides both barrier and cathodic protection for exterior and corrosive exposures.
−- **Duplex system** -- a paint or powder topcoat applied over a hot-dip galvanized base, used where color, appearance, or aggressive exposure demands more than galvanizing alone.
+- **Shop prime painting** — a thin film of primer (zinc-rich, alkyd, epoxy, or urethane) applied over a prepared steel surface, providing barrier and/or sacrificial protection for interior or protected exposures, or a base for later field topcoats.
+- **Hot-dip (batch) galvanizing** — immersion of the fabricated assembly in molten zinc per ASTM A123, producing a metallurgically bonded zinc coating that provides both barrier and cathodic protection for exterior and corrosive exposures.
+- **Duplex system** — a paint or powder topcoat applied over a hot-dip galvanized base, used where color, appearance, or aggressive exposure demands more than galvanizing alone.
## This standard applies to building structural frames, open-web steel joists, miscellaneous metals (stairs, railings, lintels, embeds), ornamental ironwork, and similar steel assemblies that receive their primary corrosion protection in a fabrication shop. {note}
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## This standard governs only the corrosion-protection coating. The base steel, its fabrication, and its erection are governed elsewhere: {note}
−- Structural frame erection, connections, camber, and AISC tolerances -- [[sync/structural-steel-framing]].
−- Miscellaneous-metals member selection and fabrication tolerances -- [[sync/miscellaneous-metals]] and [[sync/metal-fabrications]].
−- Welding processes, weld inspection, and NDT -- [[sync/welding-requirements]].
−- Field-applied architectural and high-performance topcoats (final colors, gloss, specialty finishes) -- [[sync/high-performance-coatings]].
−- Abatement of existing lead-based paint before recoating -- [[sync/hazardous-material-abatement]].
+- Structural frame erection, connections, camber, and AISC tolerances — [[sync/structural-steel-framing]].
+- Miscellaneous-metals member selection and fabrication tolerances — [[sync/miscellaneous-metals]] and [[sync/metal-fabrications]].
+- Welding processes, weld inspection, and NDT — [[sync/welding-requirements]].
+- Field-applied architectural and high-performance topcoats (final colors, gloss, specialty finishes) — [[sync/high-performance-coatings]].
+- Abatement of existing lead-based paint before recoating — [[sync/hazardous-material-abatement]].
## The following are outside the scope of this standard. {note}
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## The default systems for typical commercial construction are SSPC-SP 6 commercial blast plus an alkyd or epoxy primer at 1.5 mils DFT for interior framing, and ASTM A123 hot-dip galvanizing for exterior miscellaneous metals (railings, lintels, embeds). The selections below depart from those defaults only where exposure or appearance demands it. {note}
+## The corrosion-protection system shall be specified for each steel scope, departing from the default interior and exterior systems only where exposure or appearance demands it.
+
```datasheet
label: Corrosion-protection system
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```
+## The exposure category shall be classified for each steel scope, and it shall govern the corrosion-protection system selected for that scope.
+
```datasheet
label: Exposure category
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## Inorganic zinc-rich primers (silicate binder) provide the strongest bare-steel cathodic protection and qualify many slip-critical connections, but require near-white blast preparation and accept only epoxy or urethane topcoats. Organic zinc-rich primers (epoxy binder) trade a small amount of cathodic performance for easier topcoat compatibility. Alkyd red-oxide primers are the economical choice for interior, protected steel. Epoxy and urethane primers serve intermediate barrier roles where zinc is not required. {note}
+## The shop primer generic type shall be specified, matched to the cathodic protection, surface preparation, and topcoat compatibility required for the application.
+
```datasheet
label: Shop primer generic type
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```
−## Alkyd topcoats shall not be applied over inorganic zinc-rich primers. {note}
+## Alkyd topcoats shall not be applied over inorganic zinc-rich primers.
## Alkyd films saponify over the alkaline zinc-silicate surface, causing adhesion failure; only epoxy or urethane topcoats are compatible over zinc-rich primers. Because this is a boundary on what is permitted rather than an action, it is stated here as rationale; the corresponding obligation appears as a clause in the Topcoat Systems section. {note}
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```
−## Surfaces left uncoated in the shop must be identified so the applicator does not over-paint connection and weld areas. {note}
+## Surfaces left uncoated in the shop must be identified so the applicator does not over-paint connection and weld areas.
## Standard practice leaves slip-critical faying surfaces, bolt holes, and a band around field welds bare; the specification must state this explicitly to avoid both bare steel where coating is required and over-painting where it is not, each of which generates RFIs. {note}
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## Galvanized surfaces shall be prepared in accordance with ASTM D6386 before painting, or ASTM D7803 before powder coating. {note}
−## Painting directly over fresh galvanizing -- particularly over wet-storage stain (white rust) -- causes rapid delamination. ASTM D6386 requires sweep blasting, weathering, or chemical passivation to provide a sound surface for the topcoat; omitting this preparation is the most common cause of duplex-system failure. {note}
+## Painting directly over fresh galvanizing — particularly over wet-storage stain (white rust) — causes rapid delamination. ASTM D6386 requires sweep blasting, weathering, or chemical passivation to provide a sound surface for the topcoat; omitting this preparation is the most common cause of duplex-system failure. {note}
### Galvanized surfaces to be painted shall be prepared in accordance with ASTM D6386 by sweep blast, weathering, or chemical treatment.
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## Damaged galvanizing, cut edges, copes, and field welds shall be repaired in accordance with ASTM A780. {note}
−## Repair of bare areas is frequently omitted from specifications, leaving cut edges and field-weld zones unprotected after erection. ASTM A780 defines acceptable methods -- zinc-rich paint, zinc solder (zinc-based alloy), or thermal-spray zinc -- and the repaired film thickness must at least match the parent coating. {note}
+## Repair of bare areas is frequently omitted from specifications, leaving cut edges and field-weld zones unprotected after erection. ASTM A780 defines acceptable methods — zinc-rich paint, zinc solder (zinc-based alloy), or thermal-spray zinc — and the repaired film thickness must at least match the parent coating. {note}
### Bare areas not exceeding 1 in.² (25 cm²) shall be repaired with zinc-rich paint per ASTM A780 Method A to a dry film thickness of not less than 3.0 mils.
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# Delivery, Storage, and Handling {toc}
−## Coated and galvanized steel shall be handled and stored to prevent coating damage and wet-storage staining. {note}
+## Coated and galvanized steel shall be handled and stored to prevent coating damage and wet-storage staining.
### Coated members shall be handled with padded slings or other non-marring devices to avoid abrading the coating.
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# Warranty {toc}
−## The Contractor shall warrant the shop-applied coating systems against defective materials and workmanship for the specified period. {note}
+## The Contractor shall warrant the shop-applied coating systems against defective materials and workmanship for the specified period.
### The Contractor shall warrant shop coatings and galvanizing against peeling, blistering, and corrosion attributable to defective materials or workmanship for the specified warranty period from the date of Substantial Completion.
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default: 1 year
```