Untreated (black) steel grating
Untreated steel grating for applications where custom finishing is required. Suitable for painting, coating, or other site-specific treatments.
Mill-finish welded grating supplied without galvanizing or shop coating — ready for your site-applied paint, epoxy, polyurethane, or other protective treatment. Untreated grating is the right choice when you need a specific coating system applied after installation, or when the grating will be incorporated into a structure with its own corrosion protection plan.
Why choose untreated grating?
- Custom coating compatibility — apply your specified paint system, powder coat, or specialty epoxy without risk of adhesion issues over galvanizing.
- Duplex systems — some projects galvanize on-site or apply a duplex system (zinc + organic topcoat) as part of a single specification.
- Weld-in-place installation — field-welded grating connections require bare steel at weld points; ordering untreated avoids grinding off galvanizing.
- Indoor or low-corrosion environments — dry interior platforms where corrosion risk is minimal and a shop primer is sufficient.
- Cost optimization — removing the galvanizing step reduces lead time and unit cost when an alternative protection method is already budgeted.
Specifications
| Parameter | Details |
|---|---|
| Surface finish | Mill-finish raw steel (no coating) |
| Material | Carbon steel Q235B / A36 / S235JR |
| Construction | Welded (press-welded) or press-locked — same as welded bar grating |
| Bearing bar | 20–65 mm height, 3–5 mm thickness (same range as galvanized) |
| Pitches | s₁ = 12.5–40 mm, s₂ = 25–101.6 mm |
| Panel size | Up to 1,000 × 6,000 mm (custom available) |
| Tolerances | Per NAAMM MBG 531, EN ISO 24637, or YB/T 4001.1 |
| For RFQ | Grating geometry, panel sizes, intended coating system |
Handling and storage
Untreated steel will develop surface rust if exposed to moisture. We recommend applying a temporary shop primer or protective oil for transit, and storing panels under cover until your on-site coating process begins. See Materials & Finishes for a full comparison of finish options.
When untreated grating is acceptable
Data centers
Short-duration construction walkways inside dry halls prior to owner coating systems.
Power generation
Indoor BOP mezzanines that receive a field paint system after structural completion.
Oil & gas
Temporary offshore access during hook-up when a later paint cycle is planned.
Also see
Corrosion and fire-paint coordination
Mill scale is not a durable finish. If the site is not dry, default to galvanized welded grating. Coordinate intumescent or epoxy systems with the coating supplier.
Frequently asked questions
Is untreated suitable outdoors?
Generally no unless a site coating is applied immediately and maintained.
Can untreated be painted in the shop?
Yes when the paint system is qualified for shop application and transport.
Does untreated cost less?
Material saving exists, but lifecycle corrosion risk often favors galvanizing.
Welded or press-locked untreated?
Both can be supplied mill finish—state which fabrication type.
Storage requirements?
Keep dry to avoid flash rust before coating.
Blasting before paint?
Many specs require Sa 2½ or commercial blast—state surface prep class.
Need a quotation?
Send product type, spacing, material, finish, panel size, quantity, and drawings.