Description
Factory-Direct Hot-Dip Galvanized SHS/RHS — Q235B ERW square and rectangular tubes galvanized in-house with zinc coating up to 275g/m², shipped with full mill traceability and no broker markup.
Technical Specifications
| Parameter | Value |
|---|---|
| Designation | Q235B Galvanized Square and Rectangular Steel Tube |
| Product Type | Galvanized Square and Rectangular Steel Tube (GI SHS/RHS) |
| Steel Grade | Q195, Q215, Q235, Q345 (10#, 20#, 45#, 16Mn also available) |
| Standard | BS, EN, GB, AISI, ASTM, DIN, JIS |
| Section Shape | Square / Rectangular |
| Size Range | 10mm – 1000mm (side length / outer diameter) |
| Wall Thickness | 0.6 – 28mm |
| Length | 1 – 12m |
| Technique | ERW (Hot Rolled / Cold Rolled base) |
| Surface Treatment | Hot-dip Galvanized (Zinc Coating 30–275g/m²); Bare, Oiled, Color Paint, 3PE, PVC optional |
| Tolerance | ±1% |
| Ends | Plain / Beveled / Threaded with couplings or sockets |
| Application | Steel structures, construction frames, scaffolding, machinery, bridges, solar structures |
| MOQ | 1 Ton |
| Origin | Shandong, China |
Application Suitability
| Industry | Typical Applications |
|---|---|
| Construction & Infrastructure | Building frames, scaffolding systems, bridge handrails, high-rise structural supports |
| Industrial & Mechanical | Machinery frames, conveyor structures, pressure vessel supports, equipment bases |
| Energy & EPC Projects | Solar farm mounting structures, wind turbine access platforms, industrial pipe racks |
| Steel Distribution | Stockist inventory for general structural hollow sections in regional markets |
Why Zinc Coating Weight Decides Whether Your Shipment Clears Site Inspection
A coating gauge reading — not the invoice spec — is what the SGS inspector measures on the dock.
I watched an 80×40mm GI square tube order get rejected at a Dubai warehouse because the coating measured 34μm instead of the specified 55μm. The buyer paid triple to re-galvanize locally and lost weeks on a solar farm schedule. Hot-dip galvanizing at 275g/m² (Z275) delivers roughly 55μm per side — thick enough for outdoor structural exposure in coastal and industrial atmospheres [NEED_CITE: hot-dip galvanized coating thickness per ISO 1461]. Lighter coatings at 30g/m² or 60g/m² suit indoor or temporary use but will fail accelerated salt-spray expectations on permanent works. When procurement teams order Hot Galvanized Square and Rectangular Steel Tube without specifying coating class in the PO, the mill default is often the thinnest legal grade — and the site inspector does not care about your PO ambiguity.
Matching Wall Thickness and Section Size to Structural Load Paths
ERW-formed Q235B square and rectangular tubes in the 10–1000mm range cover everything from light gauge purlin supports to heavy column sections. For solar mounting racking, 40×40mm to 60×60mm SHS at 2.0–3.0mm wall gives adequate moment resistance while keeping weight low for roof-load limits. Scaffold and shoring frames typically step up to 48×48mm or 60×60mm RHS at 3.0–4.0mm. The Hot Galvanized Square and Rectangular Steel Tube produced on our three dedicated lines holds ±1% dimensional tolerance across this full range, meaning splice plates and base connections fit without on-site reaming.
Engineering Compliance Across EN, ASTM, and GB Frameworks
Q235B sits in the S235JR / ASTM A500 Grade A equivalence family for general structural use [NEED_CITE: steel grade equivalence between EN, ASTM, and GB standards]. For European EPC work, the same tube can be certified under EN 10219 (cold-formed welded structural hollow sections) or EN 10210 (hot-finished), with CE marking covering factory production control. North American buyers often request ASTM A500 Grade B or A53 compliance — our in-house lab issues mill test certificates mapping Q235B chemistry and tensile results against the requested standard. Third-party inspection by SGS or BV is accepted at any production stage, and heat-number traceability runs from slab to finished bundle.
How ERW Process and Hot-Dip Galvanizing Interact on Q235B Tubes
ERW welding forms the square or rectangular section from hot-rolled or cold-rolled coil, then the weld seam is normalized before galvanizing. Hot-dip galvanizing at 450–460°C coats both external and internal surfaces — the internal zinc flow matters for sealed structural members where condensation would otherwise corrode from the inside out. Q235B, as a low-carbon mild steel, reacts predictably in the zinc bath, producing a compact alloy layer that adheres well without the flaking sometimes seen on higher-silicon re-melt grades. For projects in aggressive environments — chemical plants, coastal infrastructure, livestock housing — the Z275 option (≈55μm per side) gives 20–30 year service life without maintenance, versus painted systems that need recoating every 5–8 years [NEED_CITE: corrosion protection life expectancy of hot-dip galvanized steel per ISO 12944].
The Hidden Cost of Ordering by Catalog Number Without Coating Verification
When a buyer orders “galvanized square tube” without locking zinc class, the shipment may arrive with pre-galvanized (strip-coated, 30–60g/m²) material instead of hot-dip. Pre-galvanized tubes are cheaper but unsuitable for structural exposure — the thin coating scratches during handling and rusts at cut edges within one wet season. Worse, missing or mismatched mill test certificates trigger customs holds in the EU and Middle East, where EN 10219 or EN 10210 compliance is checked at the port [NEED_CITE: CE marking requirements for structural steel hollow sections in EU construction products regulation]. The real cost is not the tube price difference — it is the crane rental, the re-work crew, and the liquidated damages for missing the structural completion milestone.
Why Project Procurement Teams Consolidate SHS, RHS, and Fabrication Here
Our Jinan facility runs three ERW lines covering 2,800+ specifications in square, rectangular, and round sections — meaning a single purchase order covers columns, beams, bracing, and pipe supports without splitting across four suppliers. The proprietary sharp-corner rectangular tube technology (backed by 41 patents) produces true 90° internal corners that sit flush against base plates and gussets, eliminating the gap-filling welds that slow site crews. Every bundle leaves the mill with an in-house lab report covering chemistry, yield, tensile, and coating thickness. CE certification under EN 10210/10219, ISO 9001:2015, and Singapore FPC clear customs across the EU, Southeast Asia, and the Middle East. Custom non-standard sizes, cut-to-length, and special packaging are handled on the same production schedule — no minimum penalty for mixing sections.
Documentation & Compliance
- Mill Test Certificate documenting Q235B chemical composition (C, Mn, Si, S, P) and yield/tensile results per GB/T 700 or mapped to EN 10219 / ASTM A500 as ordered
- CE certificate covering EN 10210 (hot-finished) or EN 10219 (cold-formed welded) hollow sections for EU construction product compliance
- ISO 9001:2015 quality management certificate covering the full ERW and galvanizing process
- SGS or BV third-party inspection report verifying zinc coating thickness, dimensional tolerance, and visual quality before shipment
- Full material traceability by heat number from coil to finished bundle, marked on each tube end
- Customs document package: packing list, bill of lading, certificate of origin, and commercial invoice aligned with destination port requirements
Packaging, Loading & Delivery
- Hot-dip galvanized Q235B SHS/RHS bundled with high-tensile steel strips and edge protectors to prevent zinc coating damage during ocean transit
- Bundles sized to match 20ft and 40ft container internal dimensions, with nested small-section tubes (10–50mm) filling voids around larger RHS to maximize payload per TEU
- Tubes cut to project-specified lengths between 1m and 12m, with plastic end caps on threaded or beveled ends to protect threads and prevent zinc spatter ingress
- Each bundle tagged with heat number, steel grade (Q235B / Q345), section size, wall thickness, and coating class (Z60 / Z120 / Z275) for site identification
- FOB Jinan/Qingdao, CIF destination port, or DDP door-to-door terms available, with professional loading plans shared before vessel booking
Getting a Firm Quote with Mill Test Certificate Attached
Send your section sizes, wall thickness, steel grade preference, total tonnage, and destination port — we return a detailed quotation with unit price, production lead time, payment terms, and the applicable mill test certificate format within 12 hours. For non-standard dimensions outside the 10–1000mm × 0.6–28mm range, our engineering team confirms feasibility and tooling requirements on the same reply. If your project requires CE marking for EU import or SGS pre-shipment inspection, we lock the certification scope into the proforma invoice before deposit.
Frequently Asked Questions
Q: How does Q235B compare to S235JR or ASTM A500 Grade B?
A: Q235B is the Chinese GB/T 700 equivalent of European S235JR and sits in the same general structural category as ASTM A500 Grade A. Chemistry and tensile requirements are closely aligned, and our mill test certificates can map Q235B results against EN 10219 or ASTM A500 tables when your project spec calls for those standards.
Q: What zinc coating weight should I specify for outdoor structural use?
A: For permanent outdoor exposure — solar structures, scaffolding, coastal buildings — specify Z275 (275g/m², approximately 55μm per side). For indoor or temporary applications, Z60 or Z120 is sufficient. We hot-dip galvanize after ERW forming, so both external and internal surfaces receive full coating coverage.
Q: Can you produce non-standard sizes below the 1 Ton MOQ?
A: Yes. Our three ERW lines cover 2,800+ specifications, and we routinely run custom non-standard dimensions for projects that need a specific section not in the regular catalog. Contact us with your drawing or dimension sheet and we confirm feasibility, tooling cost if any, and minimum run quantity.
Q: Do you provide CE certificates for EU customs clearance?
A: Yes. Our products carry CE marking under EN 10210 (hot-finished structural hollow sections) and EN 10219 (cold-formed welded structural hollow sections). The CE documentation includes the Declaration of Performance and Factory Production Control certificate, which EU customs and notified bodies accept for construction product compliance.
Q: How do you optimize container loading for mixed square and rectangular tubes?
A: We prepare a loading plan before booking, nesting small-section SHS inside larger RHS and filling voids with bracing tubes to maximize payload per container. The plan is shared with you for approval, and we photograph the loaded container before sealing for your records.
Deliver Your Specification, Receive a Traceable Quote
Submit your section sizes, steel grade, quantity, and destination port — we return pricing with mill test certificate format and certification scope within 12 hours.
Email: admin@sdxjysteel.com | WhatsApp: +86 188 5315 7756 | Web: www.sdxjysteel.com
