Hot-Dip Galvanized Flat Bar (S235-GALV, Q235B)
Hot-dip galvanized flat bar with a zinc coating of 30 to 700 g/m² total on both surfaces, for earthing strips, cable trays, fencing and outdoor frames. Supplied 10 mm to 200 mm wide and 3 mm to 60 mm thick, cut to length or punched and drilled before dipping.
Product Overview
Galvanized flat bar starts as hot-rolled flat bar that is pickled, fluxed and immersed in molten zinc, so a zinc-iron alloy layer bonds metallurgically to the whole surface, including the cut ends and the drilled holes. That is the practical difference from a painted strip: the coating protects by sacrificial action, so a scratched or cut edge does not become the start of a rust line.
Coating weight is specified rather than assumed. We quote 30 g/m² for light indoor duty up to 700 g/m² for severe coastal and industrial atmospheres, with the figure given as the total on both surfaces; as a working guide, 100 g/m² corresponds to roughly 7 µm of coating on each face. A 70 µm high-build coating, about 500 g/m² total, is a standard production option for buried earthing conductors and coastal work.
Because galvanized flat bar is used above all for earthing and for cable and pipe support, we normally deliver it cut to length and punched or drilled to your drawing so the finished part arrives fully coated and ready to install, with no bare steel to touch up on site.
Specifications & Size Range
Standard width and thickness combinations available galvanized, with the coating weight chosen per order. Punched, drilled and cut-to-length processing is carried out before dipping so that every cut edge is coated. Coating mass test reports travel with each lot.
| Product form | Common sizes (mm) | Coating (g/m²) | Standard length | Typical use |
|---|---|---|---|---|
| Light strip | 20×3, 25×3.5, 25×4, 30×3.5, 30×4 | 30 – 275 | 6 m, or cut to order | Cable tray edges, small brackets, signage frames, fencing ties |
| Standard earthing strip | 40×4, 50×4.5, 50×5, 60×5.5, 60×6 | 275 – 500 | 6 m, punched to drawing | Substation earthing grids, lightning conductors, cable racks |
| High-build coating | 50×6, 60×6, 80×8, 100×8 | up to 700 (about 70 µm) | 6 m, cut to order | Buried earthing, coastal and chemical plant service |
| Heavy section | 100×10, 120×10, 150×12, 200×16 | 275 – 500 | 6 m / 12 m, cut to order | Guard-rail frames, gantry reinforcement, structural brackets |
| Processed bar | Any size above | as specified | to drawing | Members supplied punched, drilled and cut to the fabrication drawing |
Tolerances
Zinc coating to GB/T 13912, ISO 1461, ASTM A123 and JIS H8641, quoted as coating mass in g/m² total on both surfaces, with about 7 µm of coating per 100 g/m². Coating adhesion is checked by bend test to GB/T 13912. Base bar dimensions and straightness follow GB/T 702, and the coating weight is verified on a sample basis for each lot.
Steel Grades & International Equivalents
All grades below are supplied with a mill test certificate. The right-hand column shows the material type and the Chinese standard the grade is produced to; the middle columns give the nearest recognised equivalent in other national standards. Exact equivalence for a specific project should be confirmed on the enquiry.
| GB (China) | ASTM / AISI (US) | EN (Europe) | JIS (Japan) | DIN (Germany) | Type / Standard |
|---|---|---|---|---|---|
| Q235B + hot-dip galvanized | A123 / A153 (ASTM) | EN ISO 1461 | JIS H8641 | DIN 50976 | Hot-dip galvanized structural steel (GB/T 13912) |
| Q235B | A36 / A283 Gr.C | S235JR (EN 10025-2) | SS400 (JIS G3101) | St37-2 | Carbon structural steel (GB/T 700) |
Grade Notes
- Q235B + hot-dip galvanized — Zinc coating of 30–700 g/m² gives 5–30+ years of atmospheric corrosion protection depending on thickness and environment.
- Q235B — The workhorse structural grade in China. Fully weldable, excellent cost-performance, the closest Chinese equivalent to ASTM A36 / EN S235JR.
Chemical Composition (%, ladle analysis)
Typical specification limits. Actual heat values are reported on the mill test certificate supplied with every shipment.
| Grade | C | Si | Mn | P max | S max | Other elements |
|---|---|---|---|---|---|---|
| Q235B | ≤0.20 | ≤0.35 | ≤1.40 | ≤0.045 | ≤0.045 | — |
Mechanical Properties
Minimum values at room temperature unless stated. ReL = yield strength; Rp0.2 = 0.2% proof stress; Rm = tensile strength; A = elongation after fracture.
| Grade | Yield (ReL) | Proof (Rp0.2) | Tensile (Rm) | Elongation A | Impact / others | |
|---|---|---|---|---|---|---|
| Q235B + hot-dip galvanized | — | — | — | — | — | Coating 30–700 g/m² (both sides), made to order Adhesion per GB/T 13912 bend test |
| Q235B | ≥235 MPa | — | 370–500 MPa | ≥26% | +20 °C, ≥27 J | — |
Standards & Documents
- GB/T 13912 — hot-dip galvanized coatings on fabricated iron and steel articles
- ISO 1461 / EN ISO 1461 — hot-dip galvanized coatings, international equivalent
- ASTM A123 — zinc (hot-dip galvanized) coatings on iron and steel products
- JIS H8641 — hot-dip zinc coatings, Japanese equivalent
- GB/T 702 — hot-rolled steel bars, dimensions, shape and tolerance of the base bar
- Zinc bath to EN 1179 with Zn not less than 99.995 percent; coating mass test report with each lot
Typical Applications
| Industry / Application | Typical use |
|---|---|
| Earthing grids & lightning protection | Substation earthing conductors, transmission line earth electrodes, switch-room earth busbars and buried ring conductors, where conductivity matters as much as corrosion resistance. |
| Cable trays & support systems | Tray edges, hangers, brackets, clamps and stanchions in outdoor cable routes, including marine and petrochemical installations. |
| Fencing & security barriers | Post frames, horizontal rails, gate reinforcement and mesh tensioning strips for perimeter fencing that has to last without repainting. |
| Outdoor frames & handrails | Stair and platform handrail frames, roof-edge and canopy frames, ladders and walkway supports. |
| Road & municipal furniture | Guard-rail members, sign frames, bench frames, litter-bin frames and drainage grating edges. |
| Agricultural & greenhouse structures | Greenhouse frame reinforcement, livestock penning, irrigation support brackets and barn fittings. |
| General fabrication | Any flat, punched or bolted member that will stand outdoors or in a wet or humid environment and is expected to remain maintenance-free. |
Common Problems Buyers Face — and How We Prevent Them
These are the issues that most often cause claims on steel imports. Each one is controlled in our process before shipment.
White rust on the surface on arrival
Why it happens: Zinc reacts with moisture when air cannot circulate inside a tightly bundled stack, producing wet-storage stain. It is a surface product, not a loss of protective coating, but it reads as a defect at goods-in.
Our control: Bundles are packed with spacers so air can pass, shipped dry, and given VCI paper on long or humid routes. If the appearance of the finished work matters, ask for a passivation treatment, which suppresses wet-storage stain during transit.
Coating thickness failing a spot reading at receiving inspection
Why it happens: Uneven immersion time or a low bath temperature leaves thin or bare patches, and a single magnetic gauge reading can then fail an acceptance rule that is really about average mass per square metre.
Our control: Coating mass is measured on a sample basis per lot to GB/T 13912 and the report accompanies the shipment, so acceptance can be argued against the standard rather than one spot reading. Where the project specifies a heavier coating, we quote and dip to that figure.
Bare steel showing after site cutting, drilling or welding
Why it happens: Fabrication after galvanizing removes the zinc locally and leaves the steel exposed at the cut or at the weld.
Our control: We punch, drill and cut to length before dipping so the finished part arrives fully coated. Where site welding is unavoidable, the weld zone should be repaired with zinc-rich paint, and we can supply the correct touch-up material with the order.
Long thin strips arriving bowed or twisted
Why it happens: Narrow, thin sections of flat bar heat and cool unevenly during dipping, and their low stiffness means handling can set a permanent bend.
Our control: For long thin members we jig the material during dipping, check straightness after galvanizing, and pack with edge protection and spacers. If a member is distortion-sensitive, tell us at the enquiry and we will propose a heavier section or an alternative treatment for that item.
Coating weight delivered heavier or lighter than the specification
Why it happens: Coating mass is often quoted casually as thick or standard, and the difference between 60 g/m² and 500 g/m² changes both cost and service life without changing the appearance.
Our control: The coating mass is written into the order acknowledgement in g/m², tested against that figure and reported. Tell us where the material will be installed and we will nominate a coating weight, so the specification is decided by the service environment instead of by habit.
Our Supply & Manufacturing Advantages
- Coating made to your figure — 30 to 700 g/m² quoted on the enquiry and verified by test, with the coating matched to the atmosphere the work will actually stand in.
- Processing before dipping — Cutting to length, punching and drilling are done before galvanizing, so the finished part is fully coated and needs no site touching up.
- Earthing-grade consistency — Stable section dimensions and clean, flat faces for clamped and bolted earthing joints, with a coating that does not interfere with conductivity at the connection.
- Coating documentation — Coating mass test report for each lot plus an EN 10204 3.1 mill test certificate for the base bar.
- Mixed specification in one container — Different widths, thicknesses and coating weights can be consolidated in one shipment, which matters when one project needs both a light indicator strip and a heavy buried conductor.
- Export packing built for coatings — Spacers, edge protection and dry packing as standard so the coating survives container handling and a long sea voyage.
Packaging, Delivery & Payment
- Packing: loose in bulk vessel, or bundled and containerised to your requirement. Galvanized and coated products get VCI paper, waterproof wrapping and edge protection. See our export packaging methods.
- Availability: both stock and custom production. Tell us the specification and we will confirm the route.
- MOQ: no strict minimum — one ton can ship.
- Lead time: stock dispatched to port within 3 days; orders needing export packaging about 1 week; custom production quoted per product.
- Payment: stock — 10% deposit, balance before shipment; custom production — 50% deposit, balance before shipment.
- Documents: EN 10204 3.1 mill test certificate with every shipment; third-party inspection (SGS / BV) on request.
Frequently Asked Questions
What coating weight should I specify for earthing strip?
For above-ground indoor earthing, 60 to 100 g/m² is normally sufficient. For outdoor substation grids and exposed conductors, 275 g/m² is the common export specification, and for buried or coastal work we recommend 500 g/m² or more, up to 700 g/m². Tell us whether the conductor is buried, the soil or chloride conditions, and the design life, and we will nominate the coating weight.
Does the zinc coating reduce the conductivity of an earthing strip?
No. Zinc is itself an electrical conductor, and a bolted or clamped earthing joint made through galvanized flat bar performs in the same way as one made through black bar. Where a connection is buried, the coating is a benefit because it keeps the joint free of corrosion product that would otherwise raise resistance over time.
Is galvanized flat bar the same as hot-dip galvanized round bar for earthing?
Both are used, and the choice is really about surface area and jointing. Flat bar provides a larger contact face for bolted and clamped connections and is easier to lay flat in a trench, while round bar is often used for driven electrodes. Flat bar is the usual choice for the grid conductor and round bar for the electrode.
Can you supply galvanized flat bar compliant with ASTM A123?
Yes. The coating is produced and tested to meet ASTM A123 as well as GB/T 13912 and ISO 1461. If your project references ASTM A123 explicitly, state it on the enquiry and the coating inspection will be carried out and reported against that standard.
What is the equivalent of EN S235JR galvanized flat bar?
Q235B to GB/T 700 is the closest Chinese equivalent to S235JR and is the base grade we galvanize for the European market. We can also supply the strip over S235JR-certified or Q355B base material where the base grade itself is specified. The base grade and the coating specification both appear on the documents.
Who supplies hot-dip galvanized flat bar from China?
We do. Dayang supplies galvanized flat bar to electrical contractors, earthing specialists, fencing manufacturers and steel stockists worldwide, cut and drilled to drawing where required, with the coating weight stated in grams per square metre and tested before shipment. Send the drawing and the coating specification for a quotation.
Do you have a minimum order quantity?
No strict minimum, and one ton can ship for a trial or a small maintenance requirement. Because coating is normally done in batches, very small quantities of an unusual coating weight may be grouped with other work, which we will tell you at quotation stage.
What documents accompany a galvanized flat bar shipment?
An EN 10204 3.1 mill test certificate for the base bar and a coating mass test report, plus the commercial invoice, packing list and certificate of origin. Pre-shipment inspection by SGS or BV can be arranged on request.
How is galvanized flat bar packed so the coating is not damaged?
Bundles are strapped with steel band, separated with spacers so air can circulate, and fitted with edge protection at the sling points. Cut-to-length and drilled orders are packed to the sequence of your cutting list where the order allows, so the site check and the installation sequence are straightforward.
Request a Quotation Export Packaging
Live Stock & Indicative Price
The table below lists live stock at the time of publication, with indicative EXW China reference prices in USD per tonne (converted at 6.70 CNY/USD). Steel prices move with the mill market every week — send us your size, quantity and destination and we will confirm availability and issue a firm FOB or CIF quotation.
| Product | Size / Model | Grade | Price (USD/t, EXW) | Stock (t) |
|---|---|---|---|---|
| Galvanized Flat Bar (strip) | 20 × 2 mm | Q235B | $534 | 7 |
| Galvanized Flat Bar (strip) | 25 × 3.5 mm | Q235B | $528 | 7 |
| Galvanized Flat Bar (strip) | 25 × 3.75 mm | Q235B | $528 | 7 |
| Galvanized Flat Bar (classic) | 25 × 4 mm | Q235B | $631 | 9 |
| Galvanized Flat Bar (classic) | 25 × 4.75 mm | Q235B | $624 | 4 |
| Galvanized Flat Bar (classic) | 25 × 5.75 mm | Q235B | $624 | 5 |
| Galvanized Flat Bar (strip) | 25 × 2 mm | Q235B | $534 | 9 |
| Galvanized Flat Bar (strip) | 25 × 2.2 mm | Q235B | $528 | — |
| Galvanized Flat Bar (strip) | 25 × 2.5 mm | Q235B | $528 | 7 |
| Galvanized Flat Bar (strip) | 25 × 2.75 mm | Q235B | $528 | 1 |
| Galvanized Flat Bar (strip) | 25 × 3 mm | Q235B | $528 | 2 |
| Galvanized Flat Bar (classic) | 30 × 3.5 mm | Q235B | $624 | 5 |
| Galvanized Flat Bar (classic) | 30 × 3.75 mm | Q235B | $624 | 1 |
| Galvanized Flat Bar (classic) | 30 × 4.75 mm | Q235B | $624 | 4 |
| Galvanized Flat Bar (classic) | 30 × 5.75 mm | Q235B | $624 | 5 |
| Galvanized Flat Bar (strip) | 30 × 3 mm | Q235B | $528 | 5 |
| Galvanized Flat Bar (strip) | 30 × 2.5 mm | Q235B | $506 | 1 |
| Galvanized Flat Bar (strip) | 30 × 2.75 mm | Q235B | $528 | 6 |
| Galvanized Flat Bar (strip) | 30 × 2 mm | Q235B | $524 | 1 |
| Galvanized Flat Bar (strip) | 30 × 2.2 mm | Q235B | $528 | 1 |
| Galvanized Flat Bar (in-line) | 40 × 3.5 mm | Q235B | $515 | 4 |
| Galvanized Flat Bar (in-line) | 40 × 3.75 mm | Q235B | $515 | 3 |
| Galvanized Flat Bar (in-line) | 40 × 4 mm | Q235B | $537 | 4 |
| Galvanized Flat Bar (strip) | 40 × 3 mm | Q235B | $528 | 5 |
| Galvanized Flat Bar (in-line) | 40 × 4.5 mm | Q235B | $539 | 1 |
| Galvanized Flat Bar (in-line) | 40 × 4.75 mm | Q235B | $539 | — |
| Galvanized Flat Bar (classic) | 40 × 5.5 mm | Q235B | $576 | 8 |
| Galvanized Flat Bar (in-line) | 40 × 5.75 mm | Q235B | $539 | — |
| Galvanized Flat Bar (strip) | 40 × 2.5 mm | Q235B | $506 | 4 |
| Galvanized Flat Bar (strip) | 40 × 2.75 mm | Q235B | $506 | 1 |
| Galvanized Flat Bar (in-line) | 40 × 3.25 mm | Q235B | $543 | 1 |
| Galvanized Flat Bar (strip) | 40 × 2 mm | Q235B | $534 | 8 |
| Galvanized Flat Bar (strip) | 40 × 2.2 mm | Q235B | $528 | 1 |
| Galvanized Flat Bar (in-line) | 50 × 4.5 mm | Q235B | $537 | 7 |
| Galvanized Flat Bar (in-line) | 50 × 4.75 mm | Q235B | $537 | 3 |
| Galvanized Flat Bar (in-line) | 50 × 5 mm | Q235B | $537 | 4 |
| Galvanized Flat Bar (in-line) | 50 × 3.5 mm | Q235B | $537 | 6 |
| Galvanized Flat Bar (in-line) | 50 × 3.75 mm | Q235B | $537 | 5 |
| Galvanized Flat Bar (in-line) | 50 × 5.5 mm | Q235B | $539 | 1 |
| Galvanized Flat Bar (in-line) | 50 × 5.75 mm | Q235B | $539 | 2 |
| Galvanized Flat Bar (classic) | 50 × 7.5 mm | Q235B | $564 | 5 |
| Galvanized Flat Bar (classic) | 50 × 7.75 mm | Q235B | $564 | 6 |
| Galvanized Flat Bar (classic) | 50 × 9.75 mm | Q235B | $567 | — |
| Galvanized Flat Bar (strip) | 50 × 2.5 mm | Q235B | $531 | 4 |
| Galvanized Flat Bar (strip) | 50 × 2.75 mm | Q235B | $531 | 5 |
| Galvanized Flat Bar (strip) | 50 × 3 mm | Q235B | $531 | 3 |
| Galvanized Flat Bar (strip) | 58 × 2.75 mm | Q235B | $528 | 1 |
| Galvanized Flat Bar (in-line) | 60 × 5.5 mm | Q235B | $537 | 4 |
| Galvanized Flat Bar (in-line) | 60 × 5.75 mm | Q235B | $537 | 7 |
| Galvanized Flat Bar (classic) | 60 × 6 mm | Q235B | $566 | — |
| Galvanized Flat Bar (in-line) | 60 × 4.5 mm | Q235B | $539 | 1 |
| Galvanized Flat Bar (in-line) | 60 × 4.75 mm | Q235B | $539 | 3 |
| Galvanized Flat Bar (classic) | 60 × 7.5 mm | Q235B | $561 | 6 |
| Galvanized Flat Bar (classic) | 60 × 7.75 mm | Q235B | $561 | 1 |
| Galvanized Flat Bar (classic) | 60 × 9.5 mm | Q235B | $561 | 5 |
| Galvanized Flat Bar (classic) | 60 × 9.75 mm | Q235B | $561 | 6 |
| Galvanized Flat Bar (classic) | 70 × 5.75 mm | Q235B | $575 | 5 |
| Galvanized Flat Bar (classic) | 70 × 7.75 mm | Q235B | $569 | 7 |
| Galvanized Flat Bar (classic) | 70 × 9.75 mm | Q235B | $569 | 2 |
| Galvanized Flat Bar (classic) | 75 × 11.75 mm | Q235B | $569 | 2 |
| Galvanized Flat Bar (classic) | 80 × 4.5 mm | Q235B | $566 | 4 |
| Galvanized Flat Bar (classic) | 80 × 4.75 mm | Q235B | $566 | 8 |
| Galvanized Flat Bar (classic) | 80 × 5.5 mm | Q235B | $561 | 8 |
| Galvanized Flat Bar (classic) | 80 × 5.75 mm | Q235B | $561 | 7 |
| Galvanized Flat Bar (classic) | 80 × 7.5 mm | Q235B | $561 | 7 |
| Galvanized Flat Bar (classic) | 80 × 7.75 mm | Q235B | $561 | 10 |
| Galvanized Flat Bar (classic) | 80 × 9.5 mm | Q235B | $561 | 3 |
| Galvanized Flat Bar (classic) | 80 × 9.75 mm | Q235B | $561 | 5 |
| Galvanized Flat Bar (classic) | 100 × 3.5 mm | Q235B | $591 | 7 |
| Galvanized Flat Bar (in-line) | 100 × 3.75 mm | Q235B | $542 | 3 |
| Galvanized Flat Bar (classic) | 100 × 4.5 mm | Q235B | $570 | 5 |
| Galvanized Flat Bar (classic) | 100 × 4.75 mm | Q235B | $570 | 7 |
| Galvanized Flat Bar (classic) | 100 × 5.5 mm | Q235B | $561 | 5 |
| Galvanized Flat Bar (classic) | 100 × 5.75 mm | Q235B | $561 | 7 |
| Galvanized Flat Bar (classic) | 100 × 7.5 mm | Q235B | $561 | 8 |
| Galvanized Flat Bar (classic) | 100 × 7.75 mm | Q235B | $561 | 7 |
| Galvanized Flat Bar (classic) | 100 × 9.5 mm | Q235B | $561 | 3 |
| Galvanized Flat Bar (classic) | 100 × 9.75 mm | Q235B | $561 | 8 |
| Galvanized Flat Bar (classic) | 100 × 11.75 mm | Q235B | $561 | 1 |
| Galvanized Flat Bar (strip) | 100 × 2.5 mm | Q235B | $534 | 3 |
| Galvanized Flat Bar (strip) | 100 × 2.75 mm | Q235B | $534 | 4 |
| Galvanized Flat Bar (strip) | 100 × 3 mm | Q235B | $534 | 3 |
Showing 82 of 82 listed sizes. Price range USD 506–631 per tonne (EXW China). MOQ from 1 tonne; stock dispatched to port within 3 days. Mill test certificate (EN 10204 3.1) and third-party inspection available on request.