7,000 t · 30.6 m spans
Industrial park frame with 30.6 m single spans.
Z275 galvanized purlinsHDG grating and stairsSame model, same shipment
Secondary Structural Steel: C/Z Purlins, Industrial Stairs & Platforms
C/Z purlins and girts, industrial and spiral stairs, equipment platforms, grating walkways and embedded parts. Detailed in the same Tekla model as the primary frame and shipped in the same containers.
C100–C300C purlin range
Z120–Z300Z purlin range
M20–M64Anchor bolts
1 packagePrimary + secondary
01Engineering definition
The small items that stop a site when they are missing
Secondary steel is a small share of the tonnage and a large share of the piece count. A warehouse that needs 600 t of frame may need 4,000 purlins, cleats, sag rods and bolts. If they come from a different supplier, on a different ship, the frame stands without a roof.
We detail secondary members in the same Tekla model as the primary steel, so every hole lines up and every piece carries an erection mark. Purlins, stairs, platforms and embeds are packed with the frame, and anchor bolts ship first so the foundations are ready.
- Purlins, girts, bracing, sag rods and cleats
- Stairs, platforms, ladders and guardrails
- Anchor bolts, templates and embed plates
Purlin roll-forming line
02Section types
Four secondary steel packages
Select a package to see what is included.
Cold-formed roof and wall secondary members
C and Z sections are roll-formed from pre-galvanized coil, punched and cut to length in one pass from the NC list. Z purlins are lapped over the rafters for continuity; C sections suit simple spans, girts and door framing. Bracing, sag rods and cleats are supplied with them.
- C100–C300 and Z120–Z300, 1.5–3.0 mm
- Z275 pre-galvanized or hot-dip galvanized
- Holes punched to the cladding layout
Stairs delivered as complete flights
Stringers in channel or plate, treads in grating or checker plate, and guardrails are welded or bolted into flights in the shop. We make straight, dog-leg and spiral stairs for plants, warehouses, equipment floors and public buildings, with landings and fixings to the frame.
- Width 800–1,500 mm, pitch 30–45°
- Guardrail height 1,100 mm typical
- Spiral stairs rolled and trial-fitted
Equipment, maintenance and access platforms
Platforms combine H or channel framing, grating or checker plate, handrails and kick plates. They are sized for equipment loads, maintenance access or mezzanine storage, and bolt to the primary frame with pre-drilled cleats.
- Live load 3–10 kPa typical
- Grating 30 × 100 mm pitch, HDG
- Ladders with cages and gates
The interface between steel and concrete
Anchor bolts, base plate templates, embed plates for beams, façade and equipment, and cast-in channels are shipped ahead of the steel so the foundations are ready when columns arrive.
- Anchor bolts M20–M64 with nuts and washers
- Setting templates to hold bolt groups
- Shipped first, before the main frame
03Dimensional & processing limits
Secondary steel ranges
Typical ranges. Sections outside these ranges are fabricated from plate or rolled sections.
| Item | Range | Note |
|---|---|---|
| C purlin | C100–C300, t = 1.5–3.0 mm | Q235 / Q355, Z275 coating |
| Z purlin | Z120–Z300, t = 1.5–3.0 mm | Lapped for continuity |
| Purlin length | ≤ 11.8 m for 40HQ | Longer by break-bulk |
| Stair width | 800–1,500 mm | Pitch 30–45° |
| Stair treads | Grating or checker plate | Anti-slip nosing |
| Platform live load | 3–10 kPa typical | Per project design |
| Grating | 30 × 100 mm pitch, 25–50 mm bar | Hot-dip galvanized |
| Guardrail | 1,100 mm high, toe plate 100 mm | To local code where specified |
| Anchor bolts | M20–M64 | Grade 4.6 to 8.8, HDG option |
Ranges are typical. Final sizes follow the project drawings and local code.
Plant limits that apply
| Item | Capability |
|---|---|
| Max. piece length | ≤ 24 m in the shop; ≤ 11.8 m for 40HQ containers; full length by break-bulk |
| Drilling | 3D CNC drilling Φ12–60 mm |
| Surface treatment | Shot blasting Sa2.5; epoxy zinc-rich + MIO + polyurethane; HDG (bath ≤ 12 m); intumescent fire coating |
| Lead time | 25–40 days (standard members) / 40–60 days (complex members) after shop drawing approval |
Typical values. Final limits are confirmed per project in our quotation.
Full plant limits for every member family are in the capability table.
04Materials & welding
Coil, plate and corrosion protection
Purlins and girts are roll-formed from Q235 or Q355 pre-galvanized coil with Z275 zinc coating (275 g/m²). Stairs, platforms and embeds use Q235B or Q355B plate and sections, and are either hot-dip galvanized after fabrication or blasted and painted to the same system as the primary steel.
Welding is GMAW (CO₂) to qualified procedures. Anchor bolts are threaded, fitted with nuts and washers and protected for transport. All secondary items are tagged with the same piece marks as the Tekla model.
| Item | Material | Protection |
|---|---|---|
| Purlins and girts | Q235 / Q355 coil | Z275 pre-galvanized |
| Stairs and platforms | Q235B / Q355B | HDG or paint system |
| Grating | Q235B | HDG |
| Embeds and anchors | Q235B / Q355B, 4.6–8.8 bolts | HDG threads or bare for casting |
Plate bending for stair stringers and platforms
05Quality control
Checks on secondary items
Inspection records are issued with the shipping documents.
Profile and hole checks
Purlin section, length and hole pattern checked on the first piece and by sample.
Coating thickness
Zinc and paint DFT measured and recorded per batch.
Stair trial fit
Flights, landings and rails fitted in the shop before galvanizing.
One coded package
Secondary items packed and labelled to the same erection model as the frame.
Related services
Tekla model, connection design, shop drawings, NC files and a weight-accurate BOM.
Z275 pre-galvanized coil, hot-dip galvanizing after fabrication and paint systems.
100% UT on CJP welds, dimensional reports, MTC 3.1, packing and port logistics.
06Applications
Where this member family is used
Building systems where this member family does most of the work.
07Reference project
Xiangxue Health Industrial Park
The Xiangxue Health Industrial Park used about 7,000 t of steel with 30.6 m single spans. On industrial parks of this size we detail purlins, bracing, stairs and platforms with the primary frame and deliver them in erection sequence, so roof and wall cladding follow the frame without waiting for parts.
Secondary packages can be added to any order from 50 t. Our guide on 40HQ container loading shows how purlins nest inside frame shipments.
Related members
08FAQ
Secondary steel questions
Send your drawings and our engineers reply within 24 hours.
Can I order purlins only?
Purlins are usually supplied with a building frame. Stand-alone purlin orders are accepted when they reach the 50 t minimum.
C or Z purlins: which should I use?
Z purlins lap over rafters for continuous spans and are more efficient on multi-bay roofs. C purlins suit single spans, girts, door and window framing.
Are purlins galvanized?
Yes, as standard they are roll-formed from Z275 pre-galvanized coil. Hot-dip galvanizing after fabrication is available for aggressive environments.
Do you make spiral staircases?
Yes. Spiral stringers are rolled, treads and rails welded, and the flight is trial-fitted before coating.
When do anchor bolts ship?
First, ahead of the main frame, with setting templates and a layout drawing so foundations can be cast before the steel arrives.
Send your drawings. Get a 24-hour BOM and FOB price.
DWG, IFC, Tekla or PDF. Engineering review by our Tekla team, from 50 t or 2,000 m².