+---
+title: Shop Painting and Galvanizing of Steel
+category: Structural / Steel & Metal Fabrications
+toc_depth: 3
+description: >
+ When to use: Shop-applied corrosion protection for structural steel and miscellaneous metals
+ fabricated off-site, including shop prime painting (zinc-rich, alkyd, epoxy, or urethane primers),
+ hot-dip galvanizing of fabricated assemblies (ASTM A123) and hardware (ASTM A153), duplex
+ galvanize-plus-paint systems, and repair of damaged galvanized coatings (ASTM A780), for building
+ frames, joists, stairs, railings, lintels, embeds, and ornamental ironwork across commercial,
+ institutional, industrial, and infrastructure projects.
+ Not intended for: field-applied architectural and high-performance topcoat systems
+ ([[sync/high-performance-coatings]]); steel erection, connections, and AISC tolerances
+ ([[sync/structural-steel-framing]]); miscellaneous-metals and fabrication tolerances
+ ([[sync/miscellaneous-metals]], [[sync/metal-fabrications]]); welding processes and weld
+ inspection ([[sync/welding-requirements]]); lead-paint abatement before recoating
+ ([[sync/hazardous-material-abatement]]); galvanized reinforcing bar (ASTM A767); continuously
+ galvanized sheet, pipe, or wire (different ASTM scope); and thermal-spray metallizing as a primary
+ system.
+---
+
+# Scope {toc}
+
+## This standard covers shop-applied corrosion-protection systems for structural steel and miscellaneous metals fabricated off-site before field erection. {note}
+
+## Three primary system families are addressed: shop prime painting, hot-dip (batch) galvanizing, and duplex systems that combine galvanizing with a paint topcoat. {note}
+
+## 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.
+
+## 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}
+
+## Coordination with the work of related standards. {note}
+
+## 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]].
+
+## The following are outside the scope of this standard. {note}
+
+- Galvanized reinforcing bar for concrete, which is governed by ASTM A767, not by structural-steel galvanizing.
+- Continuously galvanized sheet, pipe, or wire products (ASTM A653 and similar), which are mill-line products with thinner coatings and a different ASTM scope than batch-galvanized fabrications.
+- Thermal-spray (metallized) zinc or aluminum and cold-galvanizing compound used as a primary protective system; where metallizing is required, reference SSPC-CS 23.00.
+
+# Referenced Standards {toc}
+
+## Materials, surface preparation, application, and inspection shall comply with the latest adopted edition of each of the following unless a specific edition is cited. {note}
+
+## Where referenced standards conflict, the more stringent requirement shall govern unless the Engineer of Record directs otherwise in writing.
+
+## The publishing body for the SSPC-SP and SSPC-PA designations is now AMPP (the Association for Materials Protection and Performance), formed by the 2021 merger of SSPC and NACE International; the legacy SSPC designations remain in active use on current project specifications and are retained here. {note}
+
+| Standard | Title |
+|----------|-------|
+| ASTM A123/A123M-24 | Zinc (Hot-Dip Galvanized) Coatings on Iron and Steel Products |
+| ASTM A153/A153M | Zinc Coating (Hot-Dip) on Iron and Steel Hardware |
+| ASTM A385/A385M | Practice for Providing High-Quality Zinc Coatings (Hot-Dip) |
+| ASTM A780/A780M | Repair of Damaged and Uncoated Areas of Hot-Dip Galvanized Coatings |
+| ASTM A90/A90M | Weight (Mass) of Coating on Iron and Steel Articles with Zinc or Zinc-Alloy Coatings |
+| ASTM D6386 | Preparation of Hot-Dip Galvanized Surfaces for Painting |
+| ASTM D7803 | Preparation of Hot-Dip Galvanized Surfaces for Powder Coating |
+| ASTM E376 | Measuring Coating Thickness by Magnetic-Field or Eddy-Current Testing |
+| SSPC-SP 1 (AMPP) | Solvent Cleaning |
+| SSPC-SP 6 / NACE No. 3 (AMPP) | Commercial Blast Cleaning |
+| SSPC-SP 10 / NACE No. 2 (AMPP) | Near-White Metal Blast Cleaning |
+| SSPC Paint 20 | Zinc-Rich Coating, Type I (Inorganic) and Type II (Organic) |
+| SSPC-PA 1 (AMPP) | Shop, Field, and Maintenance Painting of Steel |
+| SSPC-PA 2 (AMPP) | Determining Conformance to Dry Coating Thickness Requirements |
+| AISC 303 | Code of Standard Practice for Steel Buildings and Bridges |
+| AISC 360 | Specification for Structural Steel Buildings |
+| ASME B18.2.2 | Nuts for General Applications (over-tapping of galvanized nuts) |
+| ASTM A563 | Carbon and Alloy Steel Nuts |
+
+# Submittals {toc}
+
+## Action Submittals {note}
+
+### The Contractor shall submit the following action submittals before any shop coating work begins:
+
+- Product data sheets for each primer, topcoat, and repair coating, including generic type, volume solids, recommended dry film thickness (DFT), and zinc content where applicable.
+- A coating system schedule identifying the system assigned to each steel category (interior frame, exterior miscellaneous metals, slip-critical connections, etc.).
+- Manufacturer's surface-preparation and application instructions for each coating.
+- For zinc-rich primers used at slip-critical connections, the certified Class B slip-coefficient test report for the specific product.
+- For galvanizing, the name and location of the galvanizing facility and confirmation of compliance with ASTM A123 or A153.
+
+```datasheet
+label: Action submittals required
+type: checkbox
+options:
+ - Coating product data sheets
+ - Coating system schedule by steel category
+ - Surface-preparation and application instructions
+ - Class B slip-coefficient test report (slip-critical primers)
+ - Galvanizer identification and compliance statement
+default:
+ - Coating product data sheets
+ - Coating system schedule by steel category
+ - Surface-preparation and application instructions
+```
+
+## Informational Submittals {note}
+
+### The Contractor shall submit the following informational submittals:
+
+- Applicator and galvanizer qualification records demonstrating the required experience.
+- Mill certificates or steel chemistry data where reactive-steel control under ASTM A385 is required.
+- Inspection and test reports for surface-preparation cleanliness, anchor profile, and dry film thickness.
+- Galvanized coating-thickness inspection records per ASTM A123 Section 8.
+
+```datasheet
+label: Informational submittals required
+type: checkbox
+options:
+ - Applicator and galvanizer qualifications
+ - Steel chemistry / mill certificates (reactive-steel control)
+ - Surface-prep and DFT inspection reports
+ - Galvanized coating-thickness records
+default:
+ - Applicator and galvanizer qualifications
+ - Surface-prep and DFT inspection reports
+ - Galvanized coating-thickness records
+```
+
+## Closeout Submittals {note}
+
+### The Contractor shall submit the following closeout submittals before final acceptance:
+
+- Repair records for damaged galvanizing and field welds touched up per ASTM A780.
+- Final DFT and visual-inspection reports for the completed coating systems.
+- Coating manufacturer's warranty documentation where a warranty is required.
+
+```datasheet
+label: Closeout submittals required
+type: checkbox
+options:
+ - ASTM A780 repair records
+ - Final DFT and visual inspection reports
+ - Coating warranty documentation
+default:
+ - ASTM A780 repair records
+ - Final DFT and visual inspection reports
+```
+
+# Quality Assurance {toc}
+
+## Applicator and galvanizer qualifications establish that the firms performing the work have demonstrated competence in the specified systems. {note}
+
+### The shop-painting applicator shall have not less than three years of documented experience applying the specified primer and topcoat systems on comparable structural and miscellaneous-metal work.
+
+### The galvanizing facility shall regularly perform batch hot-dip galvanizing of fabricated assemblies in conformance with ASTM A123 and shall maintain coating-thickness inspection records.
+
+### Coating manufacturers shall be limited to those who regularly produce the specified generic coating types and can furnish the required product data and test reports.
+
+## Inspection governs how compliance with surface-preparation and thickness requirements is verified. {note}
+
+### Surface-preparation cleanliness shall be verified against the specified SSPC visual standard before any primer is applied.
+
+### Surface anchor profile shall be measured and shall fall within the coating manufacturer's recommended range for the specified primer.
+
+### Dry film thickness of shop-applied paint shall be measured with a magnetic gauge in accordance with SSPC-PA 2, taking five spot readings per unit area.
+
+### Galvanized coating thickness shall be verified by magnetic gauge per ASTM A123, with the stripping method of ASTM A90 used as the referee method in case of dispute.
+
+### Galvanized assemblies shall be visually inspected per ASTM A123 Section 8 for finish, adhesion, and bare areas.
+
+## Mock-ups and pre-application conditioning. {note}
+
+### Where directed for architecturally exposed work, the applicator shall prepare a representative sample assembly demonstrating the specified surface preparation, color, and finish for acceptance before production coating.
+
+### For duplex systems, the galvanized surface shall be prepared and a sample topcoat applied and accepted before production topcoating proceeds.
+
+# System Selection {toc}
+
+## The protective system is selected from the exposure category, the required service life, and the project budget. {note}
+
+## 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}
+
+```datasheet
+label: Corrosion-protection system
+type: radio
+options:
+ - Shop prime paint only (interior / protected steel)
+ - Shop prime + field topcoat (base coat under field finish)
+ - Hot-dip galvanize per ASTM A123 (exterior / structural)
+ - Duplex (galvanize + paint topcoat)
+default: Hot-dip galvanize per ASTM A123 (exterior / structural)
+```
+
+```datasheet
+label: Exposure category
+type: radio
+options:
+ - Interior, conditioned and dry
+ - Interior, humid or intermittently wet
+ - Exterior, atmospheric
+ - Exterior, marine or industrial / corrosive
+default: Exterior, atmospheric
+```
+
+## Primer generic type determines compatibility, performance tier, and surface-preparation level. {note}
+
+## 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}
+
+```datasheet
+label: Shop primer generic type
+type: select
+options:
+ - Alkyd red-oxide (interior / protected)
+ - Inorganic zinc-rich (SSPC Paint 20, Type I)
+ - Organic zinc-rich epoxy (SSPC Paint 20, Type II)
+ - Epoxy primer (barrier)
+ - Urethane primer (barrier)
+default: Alkyd red-oxide (interior / protected)
+```
+
+## Alkyd topcoats shall not be applied over inorganic zinc-rich primers. {note}
+
+## 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}
+
+# Surface Preparation {toc}
+
+## Surface preparation level is the single largest determinant of coating service life and is matched to the primer generic type. {note}
+
+## Standard shop prime systems require SSPC-SP 6 commercial blast cleaning, which removes all visible oil, grease, rust, and mill scale with no more than 33% staining per unit area. Inorganic zinc-rich primers and high-performance systems require the higher SSPC-SP 10 near-white blast, which limits staining to 5% per unit area. {note}
+
+### Contaminated steel shall be solvent cleaned in accordance with SSPC-SP 1 to remove oil and grease before abrasive blasting.
+
+### Steel to receive standard shop prime systems shall be abrasive blast cleaned to SSPC-SP 6 commercial blast cleaning.
+
+### Steel to receive inorganic zinc-rich primer or a high-performance topcoat system shall be abrasive blast cleaned to SSPC-SP 10 near-white metal blast cleaning.
+
+### The abrasive shall be selected and graded to produce the anchor profile required by the primer manufacturer.
+
+### Primer shall be applied within the manufacturer's maximum allowable time after blasting and before any visible rust bloom forms.
+
+```datasheet
+label: Surface preparation standard (shop paint)
+type: radio
+options:
+ - SSPC-SP 1 (solvent clean, pre-blast only)
+ - SSPC-SP 6 / NACE No. 3 (commercial blast)
+ - SSPC-SP 10 / NACE No. 2 (near-white blast)
+default: SSPC-SP 6 / NACE No. 3 (commercial blast)
+```
+
+```datasheet
+label: Surface anchor profile
+type: range
+unit: mils
+min: 1.0
+max: 3.5
+step: 0.5
+default: 2.0
+```
+
+# Shop Prime Painting {toc}
+
+## Shop prime painting shall be applied in accordance with SSPC-PA 1 covering surface preparation, mixing, thinning limits, application conditions, and inspection. {note}
+
+### Primer shall be mixed and thinned only within the limits of the manufacturer's product data sheet.
+
+### Primer shall not be applied when the steel surface temperature is within 5 °F (3 °C) of the dew point or when ambient conditions fall outside the manufacturer's limits.
+
+### Each coat shall be applied to achieve a continuous film free of runs, sags, holidays, and dry spray.
+
+## Dry film thickness is specified by primer type and is the governing acceptance parameter for shop paint. {note}
+
+## Alkyd red-oxide primers are specified at 1.0 to 2.0 mils DFT, with 1.5 mils the typical default. Zinc-rich primers, whether inorganic or organic, are specified at 3.0 mils DFT to satisfy the SSPC Paint 20 requirement of a minimum 65% metallic zinc by weight in the dry film. {note}
+
+### Alkyd red-oxide shop primer shall achieve a dry film thickness within the specified range.
+
+### Zinc-rich shop primer shall achieve a dry film thickness of not less than 3.0 mils.
+
+### Zinc-rich primer shall contain not less than 65% metallic zinc by weight in the dry film in accordance with SSPC Paint 20.
+
+### No single DFT reading shall fall below 80% of the specified minimum, in accordance with SSPC-PA 2.
+
+```datasheet
+label: Alkyd primer dry film thickness
+type: range
+unit: mils
+min: 1.0
+max: 2.0
+step: 0.5
+default: 1.5
+```
+
+```datasheet
+label: Zinc-rich primer dry film thickness
+type: range
+unit: mils
+min: 2.5
+max: 4.0
+step: 0.5
+default: 3.0
+```
+
+```datasheet
+label: Minimum metallic zinc in dry film (zinc-rich primer)
+type: range
+unit: "% by weight"
+min: 65
+max: 90
+step: 1
+default: 65
+```
+
+## Surfaces left uncoated in the shop must be identified so the applicator does not over-paint connection and weld areas. {note}
+
+## 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}
+
+### Faying surfaces of slip-critical connections shall be left uncoated unless a qualified Class B coating is specified for those surfaces.
+
+### A band not less than 2 in. (50 mm) on each side of field welds shall be left unprimed, and weld areas to be galvanized shall be left free of pre-weld primer.
+
+### Surfaces to be embedded in concrete shall be left unprimed unless otherwise directed.
+
+```datasheet
+label: Leave uncoated in shop
+type: checkbox
+options:
+ - Slip-critical faying surfaces
+ - Bolt holes
+ - 2 in. band at field welds
+ - Surfaces embedded in concrete
+default:
+ - Slip-critical faying surfaces
+ - 2 in. band at field welds
+ - Surfaces embedded in concrete
+```
+
+# Topcoat Systems {toc}
+
+## Shop-applied topcoats over a compatible primer extend service life and provide intermediate finish where a field finish is not the final coat. {note}
+
+### Topcoats over zinc-rich primer shall be epoxy or urethane; alkyd topcoats shall not be used over zinc-rich primer.
+
+### The topcoat dry film thickness shall meet the manufacturer's published minimum for the specified system.
+
+### Topcoat shall be applied only after the primer has cured and after the primer surface has been verified clean and dry.
+
+```datasheet
+label: Shop topcoat system
+type: select
+options:
+ - None (primer only; field finish to follow)
+ - Epoxy topcoat
+ - Polyurethane topcoat
+ - Acrylic topcoat
+default: None (primer only; field finish to follow)
+```
+
+```datasheet
+label: Topcoat dry film thickness
+type: range
+unit: mils
+min: 2.0
+max: 5.0
+step: 0.5
+default: 3.0
+```
+
+# Hot-Dip Galvanizing {toc}
+
+## Hot-dip galvanizing of fabricated assemblies shall conform to ASTM A123, and hardware items shall conform to ASTM A153. {note}
+
+## ASTM A123 governs batch galvanizing of fabricated structural shapes, plates, and bars; ASTM A153 governs fasteners and miscellaneous hardware that are centrifuged (spun) after dipping. The two standards have different thickness tables and different handling, and citing A123 for hardware (or substituting continuously galvanized A653 sheet for batch-galvanized fabrications) is a common and consequential error. {note}
+
+### Fabricated assemblies shall be hot-dip galvanized after fabrication in accordance with ASTM A123.
+
+### Bolts, nuts, washers, rods, and miscellaneous hardware shall be hot-dip galvanized in accordance with ASTM A153 and centrifuged.
+
+### Continuously galvanized sheet product shall not be substituted for batch hot-dip galvanizing of fabrications.
+
+```datasheet
+label: Galvanizing specification
+type: radio
+options:
+ - ASTM A123 (fabricated assemblies)
+ - ASTM A153 (hardware / fasteners)
+ - Both A123 and A153 (assemblies with hardware)
+default: ASTM A123 (fabricated assemblies)
+```
+
+## Minimum average coating thickness is set by the ASTM A123 material category, which depends on steel thickness. {note}
+
+## Per ASTM A123/A123M-24 Table 1, structural shapes and plates 3/16 in. and thicker require a minimum average coating of 85 µm (3.4 mils); material from 1/8 in. to less than 3/16 in. requires 65 µm; material thinner than 1/8 in. requires 45 µm. ASTM A153 Class C fasteners 3/8 in. diameter and larger require a minimum average of 43 µm (1.7 mils), and Class D fasteners smaller than 3/8 in. require 25 µm (1.0 mil). {note}
+
+### Galvanized coating on structural shapes and plates 3/16 in. and thicker shall achieve a minimum average thickness of 85 µm (3.4 mils).
+
+### Galvanized coating on material from 1/8 in. to less than 3/16 in. shall achieve a minimum average thickness of 65 µm.
+
+### Galvanized coating on material thinner than 1/8 in. shall achieve a minimum average thickness of 45 µm.
+
+### Galvanized hardware shall achieve the minimum average thickness for its ASTM A153 class.
+
+```datasheet
+label: Minimum average galvanized coating thickness (structural ≥ 3/16 in.)
+type: range
+unit: µm
+min: 45
+max: 100
+step: 5
+default: 85
+```
+
+```datasheet
+label: ASTM A153 hardware class
+type: select
+options:
+ - Class C (fasteners ≥ 3/8 in. dia., 43 µm min.)
+ - Class D (fasteners < 3/8 in. dia., 25 µm min.)
+default: Class C (fasteners ≥ 3/8 in. dia., 43 µm min.)
+```
+
+## Galvanized nuts shall be over-tapped after galvanizing in accordance with ASME B18.2.2 or ASTM A563 to accommodate the coating on the bolt threads. {note}
+
+## Over-tapping is required because the zinc coating thickens the bolt threads; nuts tapped to standard dimensions before galvanizing will not run onto a galvanized bolt. This obligation is stated as a clause below. {note}
+
+### Galvanized nuts shall be tapped oversize after galvanizing in accordance with ASME B18.2.2 or ASTM A563.
+
+## Design for galvanizing must provide for venting, drainage, and steel chemistry control per ASTM A385. {note}
+
+## Welded assemblies with trapped air or sealed hollow sections can blow out explosively during immersion in the molten bath; ASTM A385 requires that all surfaces be welded and that vent and drain holes be provided. Steel chemistry also governs coating quality: silicon in the Sandelin range (roughly 0.04% to 0.15%) produces thick, dull-gray, brittle coatings, so reactive-steel control is required where appearance or bend-after-galvanize behavior matters. {note}
+
+### Hollow and enclosed assemblies shall be provided with vent and drain holes sized and located in accordance with ASTM A385.
+
+### Where appearance or post-galvanize forming is critical, steel chemistry shall be controlled to limit silicon to not more than 0.04% or to the 0.15% to 0.25% range, and phosphorus to not more than 0.05%, in accordance with ASTM A385.
+
+### Mill certificates shall be reviewed for silicon and phosphorus content on members requiring reactive-steel control.
+
+```datasheet
+label: Reactive-steel chemistry control (ASTM A385)
+type: radio
+options:
+ - Not required (standard structural)
+ - Required (AESS or post-galvanize forming)
+default: Not required (standard structural)
+```
+
+```datasheet
+label: Vent and drain holes for hollow sections
+type: radio
+options:
+ - Required per ASTM A385
+ - Not applicable (no enclosed sections)
+default: Required per ASTM A385
+```
+
+# Duplex Systems {toc}
+
+## A duplex system applies a paint or powder topcoat over hot-dip galvanizing where color, appearance, or aggressive exposure demands more than galvanizing alone. {note}
+
+## The duplex system service life is synergistic: industry data places it at 1.5 to 2.3 times the sum of the individual galvanizing and paint service lives. Realizing that synergy depends entirely on correct surface preparation of the galvanized surface before topcoating. {note}
+
+## 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}
+
+### Galvanized surfaces to be painted shall be prepared in accordance with ASTM D6386 by sweep blast, weathering, or chemical treatment.
+
+### Galvanized surfaces to be powder coated shall be prepared in accordance with ASTM D7803.
+
+### Wet-storage stain (white rust) shall be removed before any topcoat is applied.
+
+### The duplex topcoat shall achieve a dry film thickness of not less than 2.0 mils over the prepared galvanized surface.
+
+```datasheet
+label: Duplex surface preparation
+type: radio
+options:
+ - ASTM D6386 (for paint topcoat)
+ - ASTM D7803 (for powder coat topcoat)
+default: ASTM D6386 (for paint topcoat)
+```
+
+```datasheet
+label: Duplex topcoat type
+type: select
+options:
+ - Epoxy
+ - Polyurethane
+ - Powder coat
+default: Polyurethane
+```
+
+```datasheet
+label: Duplex topcoat dry film thickness
+type: range
+unit: mils
+min: 2.0
+max: 5.0
+step: 0.5
+default: 3.0
+```
+
+# Slip-Critical Connections {toc}
+
+## Faying surfaces of slip-critical (friction-type) bolted connections require a defined surface condition so the connection develops its design slip resistance. {note}
+
+## The slip resistance of a connection depends on the faying-surface coating. AISC 303 defines Class B faying surfaces with a mean slip coefficient of not less than 0.50. Inorganic zinc-rich primers at 3 mils DFT typically qualify as Class B, but only the specific product's certified test report establishes that; not all zinc-rich primers qualify. Galvanized faying surfaces are not Class B as deposited and must be conditioned. {note}
+
+### The faying-surface class for slip-critical connections shall be as specified, and the coating shall be verified by certified test report to meet the specified class.
+
+### Inorganic zinc-rich primer used as a Class B faying-surface coating shall be supported by a certified slip-coefficient test report for the specific product at the applied thickness.
+
+### Galvanized faying surfaces shall be hand wire brushed or otherwise conditioned to achieve a Class B slip coefficient in accordance with AISC 360 commentary.
+
+### Faying surfaces shall not receive any coating other than the qualified slip-critical coating.
+
+```datasheet
+label: Faying-surface condition (slip-critical)
+type: radio
+options:
+ - Uncoated (clean mill scale or blast-cleaned, Class A)
+ - Inorganic zinc-rich primer, Class B (certified)
+ - Galvanized and conditioned, Class B
+default: Inorganic zinc-rich primer, Class B (certified)
+```
+
+```datasheet
+label: Required mean slip coefficient
+type: range
+unit: ""
+min: 0.30
+max: 0.55
+step: 0.05
+default: 0.50
+```
+
+# Repair of Damaged Coatings {toc}
+
+## 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}
+
+### 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.
+
+### Bare areas exceeding 1 in.² (25 cm²) shall be repaired by thermal-spray zinc or zinc solder per ASTM A780.
+
+### Repair coating dry film thickness shall be not less than the specified minimum thickness of the parent galvanized coating.
+
+### Field welds and cut edges on galvanized members shall be touched up after erection in accordance with ASTM A780.
+
+```datasheet
+label: Galvanizing repair method (ASTM A780)
+type: radio
+options:
+ - Zinc-rich paint (Method A, areas ≤ 1 in.²)
+ - Zinc solder (areas > 1 in.²)
+ - Thermal-spray zinc (areas > 1 in.²)
+default: Zinc-rich paint (Method A, areas ≤ 1 in.²)
+```
+
+```datasheet
+label: Repair coating dry film thickness
+type: range
+unit: mils
+min: 3.0
+max: 6.0
+step: 0.5
+default: 3.0
+```
+
+# Sequencing and Coordination {toc}
+
+## The sequence of welding, galvanizing, and painting must be coordinated and shown on the structural drawings before shop drawings are issued. {note}
+
+## Galvanize-after-weld is strongly preferred over weld-after-galvanize because welding through a galvanized coating burns off the zinc and generates fume; the structural engineer must flag members to be galvanized so that hole sizing, vent requirements, and camber can be addressed before fabrication. Where galvanizing and shop prime are both specified on a single assembly, the precedence and the boundaries must be explicit, or the fabricator cannot proceed without an RFI. {note}
+
+### Members to be galvanized shall be identified on the structural drawings, including any vent-hole, hole-size, and camber implications.
+
+### Assemblies shall be galvanized after welding wherever the design permits.
+
+### Where both galvanizing and shop prime apply to the same assembly, the drawings shall state which surfaces receive each system and the order of application.
+
+### Areas to be field welded shall be left free of any coating that would interfere with welding or be damaged by it.
+
+```datasheet
+label: Welding / galvanizing sequence
+type: radio
+options:
+ - Galvanize after weld (preferred)
+ - Weld after galvanize (repair required at welds)
+default: Galvanize after weld (preferred)
+```
+
+### The specific members to be galvanized, and the locations of vent and drain holes on enclosed sections, are shown on the structural drawings. [[drawing: galvanized member schedule]] {note}
+
+# Delivery, Storage, and Handling {toc}
+
+## Coated and galvanized steel shall be handled and stored to prevent coating damage and wet-storage staining. {note}
+
+### Coated members shall be handled with padded slings or other non-marring devices to avoid abrading the coating.
+
+### Galvanized members shall be stored off the ground, separated, and stacked to allow air circulation and prevent wet-storage staining.
+
+### Members shall not be stored in standing water or in continuous contact that traps moisture between surfaces.
+
+### Damage to shop coatings during shipping, handling, or erection shall be repaired to match the original system before final acceptance.
+
+```datasheet
+label: Galvanized storage protection
+type: checkbox
+options:
+ - Stored off ground on dunnage
+ - Spaced for air circulation
+ - Protected from standing water
+default:
+ - Stored off ground on dunnage
+ - Spaced for air circulation
+ - Protected from standing water
+```
+
+# 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 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.
+
+### Coating defects discovered within the warranty period shall be repaired to match the original system at no cost to the Owner.
+
+```datasheet
+label: Coating warranty period
+type: select
+options:
+ - 1 year
+ - 2 years
+ - 5 years
+default: 1 year
+```