Carbon Steel Z Bar — Cold-Formed Z-Section Purlin | Factory Direct | Huaxia-Steel
Carbon steel Z bar is a cold-formed section shaped like the letter Z. It is most often used as a purlin or girt in pre-engineered metal buildings (PEMB), supporting roof and wall cladding. The Z-shape lets you overlap consecutive sections at supports, creating a continuous beam across multiple spans without welding each piece – which reduces labor and material cost.
Huaxia-Steel supplies carbon steel Z bar in ASTM A653 / A1008 hot-dip galvanized coil-formed, with cut-to-length, punched, and dimpled options. We ship directly from the mill to your job site or warehouse.
Product Overview
Z purlins are produced by roll-forming galvanized or cold-rolled steel coil into a Z cross-section. The standard depth ranges from 100 mm to 300 mm with thickness 1.5 mm to 3.0 mm. Holes and slots for bolting and overlapping are punched in-line as part of the roll-forming process, allowing fast on-site assembly.
- Standard: ASTM A653 (galvanized), ASTM A1008 (cold-rolled), EN 10346 (galvanized, European), GB/T 2518 (galvanized, China).
- Steel grade: ASTM A653 SS Grade 33 / 40 / 50 Class 1; equivalent to S250GD, S350GD.
- Coating: Z120 to Z275 (galvanized coating mass in g/m², total both sides).
- Length: Standard 6 m; cut-to-length up to 12 m; hole-punched and dimpled.
Common Sizes and Section Properties
| Section Depth (mm) | Flange Width (mm) | Lip (mm) | Thickness (mm) | Weight (kg/m) | Ix (cm4) |
|---|---|---|---|---|---|
| 100 | 50 | 15 | 1.5 | 2.10 | 28.1 |
| 100 | 50 | 15 | 2.0 | 2.80 | 37.4 |
| 150 | 55 | 18 | 2.0 | 3.65 | 110 |
| 150 | 60 | 20 | 2.5 | 4.65 | 142 |
| 200 | 65 | 20 | 2.0 | 4.65 | 247 |
| 200 | 70 | 22 | 2.5 | 5.85 | 315 |
| 250 | 75 | 22 | 2.5 | 7.00 | 580 |
| 250 | 80 | 25 | 3.0 | 8.45 | 695 |
| 300 | 85 | 25 | 2.5 | 8.10 | 970 |
| 300 | 90 | 28 | 3.0 | 9.75 | 1,170 |
Custom depths, flange widths, and thicknesses are routinely produced; specify your project requirements and we can propose section properties.
Specifications and Tolerances
| Parameter | Tolerance |
|---|---|
| Depth (A) | +/- 1.0 mm or 0.5% of A |
| Flange width (B) | +/- 2.0 mm |
| Lip length (C) | +/- 2.0 mm |
| Thickness | +/- 0.05 mm for <=2 mm; +/- 0.07 mm for >2 mm |
| Length | +10 / -5 mm or per project spec |
| Camber / sweep | 1 mm / m, max 10 mm |
| Twist | 1 degree per meter, max 5 degrees total |
| Hole spacing | +/- 1.0 mm typical |
| Hole diameter | +0.5 / -0.0 mm |
Material Standards
| Standard | Grade | Yield ReH min (MPa) | Tensile Rm (MPa) | Notes |
|---|---|---|---|---|
| ASTM A653 / A653M | SS Grade 33 Class 1 | 230 | 360 min | Light-duty purlin |
| ASTM A653 / A653M | SS Grade 40 Class 1 | 275 | 390 min | Standard commercial |
| ASTM A653 / A653M | SS Grade 50 Class 1 | 340 | 450 min | Heavy-duty purlin |
| ASTM A1008 / A1008M | SS Grade 40 | 275 | 365-450 | Uncoated (black / oiled) |
| EN 10346 | S250GD | 250 | 330 | European galvanized |
| EN 10346 | S350GD | 350 | 420 | High strength |
| GB/T 2518 | DX51D+Z | 240-280 | 360-510 | Chinese galvanized |
| GB/T 2518 | S350GD+Z | 350 | 420-510 | High strength |
Coating Weight and Corrosion Resistance
Z bar is typically hot-dip galvanized for corrosion resistance. Common zinc coating weights:
| Coating Designation | Total coating weight (g/m², both sides) | Typical environment |
|---|---|---|
| Z120 | 120 | Indoor / dry climate |
| Z180 | 180 | Temperate outdoor |
| Z275 | 275 | Industrial / coastal |
| Z350 / Z450 | 350-450 | Highly corrosive / coastal |
| ZM30 / ZM60 | Zinc-Magnesium equivalent | High humidity, livestock buildings |
For more demanding environments (industrial chemical exposure, marine splash zones), use ZM coating (zinc-magnesium) or specify post-galvanizing plus paint system.
Typical Hole Patterns (Optional)
Z purlin hole punching is normally done in-line during roll-forming:
- Two rows of bolt holes at 6.5 mm, 8.5 mm, 10.5 mm, 12.5 mm, 14.5 mm, or 16.5 mm diameter.
- Hole spacing: typically 60 mm across the section, 50 mm between consecutive pairs.
- Slots for overlapping: 12 x 18 mm to 18 x 30 mm.
- End dimples for nesting and self-alignment during erection.
- Hole positioning tolerance +/- 1.0 mm.
Send us your erection drawing and we can program the hole pattern per your layout.
Applications
- Roof purlins in pre-engineered metal buildings (PEMB).
- Wall girts for cladding support.
- Eave strut and gable wall framing.
- Solar mounting structures (compatibility with Z-bracket clamps).
- Industrial sheds and warehouses.
- Cold storage building framing.
- Agricultural buildings, poultry sheds.
- Carports and canopies.
Design Codes Referenced
- ANSI / AISC 360 – Specification for Structural Steel Buildings (cold-formed section supplements).
- AISI S100 – North American Specification for the Design of Cold-Formed Steel Structural Members.
- EN 1993-1-3 – Eurocode 3: Design of Steel Structures – Cold-formed thin gauge members.
- GB 50018 – Technical Code for Cold-Formed Thin-Walled Steel Structures.
- AS / NZS 4600 – Cold-formed steel structures (Australia / New Zealand).
Quality Assurance
- Coil incoming inspection: yield, tensile, elongation, coating weight.
- In-process inspection: depth, flange width, lip length per setup sheet.
- Final inspection: hole pattern, length tolerance, camber, twist.
- End-of-line visual: no dents, scratches, or coating damage.
- Sampling: ASTM A653 requires specific tests per heat; we random test 1 of 50 pieces per shift.
- MTC to EN 10204 3.1 issued per shipment.
- Third-party inspection by SGS, BV, Intertek, or TUV on request.
Packaging and Shipping
- Bundled with steel strapping; 10-15 pieces per bundle depending on size.
- Wooden pallet or crate for export; fumigated if required.
- Plastic wrap around bundles for moisture protection during ocean transit.
- Each bundle tagged with: section size, length, gauge, coating weight, heat number, quantity.
- Standard 20′ container can hold 18-25 tons depending on section size.
- 40′ container can hold 25-30 tons depending on section size.
Comparison: Z Bar vs C Purlin
| Aspect | Z Bar | C Purlin |
|---|---|---|
| Section shape | Z (symmetric around the rotated axis) | C (asymmetric) |
| Best for | Continuous span, lap joint at supports | Single span; lighter loads |
| Connection | Lap joint with bolts – high efficiency | Single piece span to column |
| Structural efficiency | Higher per kg | Lower |
| Typical use | Roof purlin in PEMB with multi-span | Wall girts, light roofing |
| Cost | 5-10% higher than C purlin | Cheaper for short spans |
Frequently Asked Questions
Q1: What is the standard Z purlin depth?
Common depths are 100, 150, 200, 250, and 300 mm. Z purlin depth is chosen based on span, load, and spacing. 200-250 mm is typical for spans of 6-9 m.
Q2: Can I get pre-punched Z purlin?
Yes. Holes, slots, and dimples are punched in-line during roll forming. Provide your erection drawing and bolt layout; we will program the line accordingly.
Q3: Is Z bar the same as Z section?
Yes. “Z bar,” “Z purlin,” “Z section,” “Zed,” “Zed-bar,” and “Z-profile” all refer to the same cold-formed steel member.
Q4: How long does delivery take?
Stock sizes are dispatched within 7-15 days. Custom sizes with special hole patterns take 20-35 days from order confirmation.
Q3: Is third-party inspection available?
Yes. SGS, BV, Intertek, TUV, or other agencies can witness testing and sign release notes at our mills.
Q4: Can Z bar be welded?
Light welding (e.g., attaching brackets) is acceptable, but full structural welding is not common because the section is thin and the galvanizing would be damaged. Bolted connections are preferred.
Q5: What is the minimum quantity per order?
For stock sizes, 5-10 tons is standard. For custom hole punching, the minimum is typically one container (around 25 tons).
Conclusion
Carbon steel Z bar is the workhorse purlin of pre-engineered buildings. Choosing the right depth, gauge, coating, and grade ensures your structure stays within deflection and stress limits and that corrosion is controlled. Z is preferred over C in continuous lap-joint construction where spans exceed 6 m.
Huaxia-Steel supplies Z purlin in standard and custom sizes with Z120-Z275 coating, optional pre-punched holes, and EN 10204 3.1 documentation. Send your project specifications for a quote.
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