Description
Factory-Direct S355JR Square Rectangular Steel Tube — Every batch rolls off our own lines with in-house lab verification before it leaves Jinan.
Technical Specifications
| Parameter | Value |
|---|---|
| Designation | Q235B / S355JR Square and Rectangular Carbon Steel Tube |
| Product Type | Square / Rectangular Steel Tube (Hollow Section) |
| Steel Grade | Q195, Q235, Q355, S235JR, S355JR, A53 Grade A, A53 Grade B, A500 Grade A, A500 Grade B, A500 Grade C, STK400, SS400, ST42.2 |
| Standard | EN10219, EN10210, GB/T 6728, JIS G3466, ASTM A500, ASTM A36 |
| Section Shape | Square / Rectangular |
| Size Range | Square: 20×20mm – 500×500mm; Rectangular: 20×40mm – 300×500mm |
| Wall Thickness | 1.2mm – 20mm |
| Length | 3m – 12m (random / cut-to-length) |
| Technique | Hot Rolled / Welded |
| Surface Treatment | Black (Oiled / Non-oiled) / Pre-galvanized (40–80g/m²) / Hot-dip Galvanized (200–600g/m²) |
| Tolerance | ±1% |
| Ends | Plain |
| Processing Service | Bending, Welding, Decoiling, Punching, Cutting |
| Application | Construction / Steel structures / Solar structure components / Fence posts / Greenhouse frames / Machinery manufacturing / Shipbuilding |
| MOQ | 1 Ton |
| Origin | Shandong, China |
Application Suitability
| Industry | Typical Applications |
|---|---|
| EPC Contractors & Construction | Steel structure frames, building columns, solar panel support structures, scaffolding uprights |
| Machinery Manufacturing | Equipment base frames, conveyor system uprights, industrial platform structures |
| Infrastructure & Agriculture | Highway fence posts, greenhouse skeleton frames, boundary enclosures |
| Shipbuilding & Power Engineering | Deck structures, cable tray supports, equipment housings |
Where Wall-Thickness Tolerance Decides Structural Acceptance on Site
A ±1% tolerance on a 20mm wall S355JR square tube means the difference between passing inspector sign-off and scrapping an entire container.
I have watched project engineers reject full shipments because the wall thickness drifted beyond the allowable negative tolerance — even when the mill cert looked clean on paper. When you order S355JR square and rectangular steel tube for load-bearing frames, every millimeter of wall matters. Inconsistent thickness across a batch means some pieces carry less than the design load, and the structural engineer cannot approve what cannot be verified. Add missing or mismatched EN 10219 certification, and customs holds the cargo at the port while your erection schedule falls apart. [NEED_CITE: EN 10219 cold-formed structural hollow sections dimensional tolerances]
Matching S355JR Hollow Sections to Structural Frame and Solar Mounting Demands
The S355JR square and rectangular steel tube in wall thicknesses from 1.2mm to 20mm covers everything from light greenhouse purlins to heavy industrial column sections. For solar mounting structures, the pre-galvanized finish at 40–80g/m² provides sufficient corrosion resistance for inland installations, while coastal projects specify hot-dip galvanized at 200–600g/m² to withstand salt spray exposure over the design life. Our proprietary sharp-corner rectangular tube technology ensures tight corner radii that sit flush against gusset plates and connection brackets — eliminating gaps that would otherwise require shimming or rework during assembly.
Engineering Compliance and Certification Pathways Across Markets
Structural hollow sections intended for European projects must conform to EN 10219 (cold-formed welded) or EN 10210 (hot-finished welded), and the CE mark under these standards is non-negotiable for customs clearance in EU member states. [NEED_CITE: CE marking requirements for structural steel under EN 10210 and EN 10219] North American buyers typically specify ASTM A500 Grade B or C, while Japanese infrastructure projects call for STK400 per JIS G3466. The steel grade cross-reference between Q355, S355JR, and ASTM A500 Grade C is well established, but the mill test certificate must explicitly state the standard to which the material was tested and certified. Cut-to-length service at 3m–12m reduces on-site welding and secondary cutting, which matters when your erection crew is working to a fixed crane schedule. [NEED_CITE: steel grade equivalence mapping between GB, EN, and ASTM standards]
Steel Grade Selection and Surface Treatment Logic for Carbon Hollow Sections
S235JR serves general fabrication where yield demands are moderate, while S355JR delivers higher yield strength for structural frames carrying heavier design loads — the grade jump directly reduces section size and weight for the same load capacity. The Q-series (Q195–Q355) follows the Chinese GB system, S-series follows European EN, and ASTM A500 covers the North American market; all three systems are producible on the same lines with proper chemistry control. Black oiled finish suits indoor or short-term outdoor use where painting or further coating will follow; pre-galvanized offers a balance of cost and corrosion protection for moderate environments; hot-dip galvanized is specified when the tube will face persistent moisture or chemical exposure without maintenance access. Wall thickness tolerance of ±1% ensures that the theoretical weight calculation matches the actual delivered weight — critical when procurement is priced by ton and structural calculations depend on exact section properties.
The Hidden Cost of Accepting Off-Spec Wall Thickness and Missing Mill Certs
When a supplier ships S355JR tube with wall thickness below the specified tolerance, the structural engineer cannot approve the as-built condition — the entire batch may need replacement or reinforcement, multiplying material cost and delaying the project by weeks. Missing or incorrect mill test certificates trigger customs holds at the destination port, generating demurrage charges that often exceed the original freight cost. [NEED_CITE: consequences of non-compliant structural steel in international construction projects] Material traceability failures mean you cannot prove which heat number corresponds to which installed member, complicating warranty and liability documentation long after project completion.
Why Global Buyers Source S355JR Square Rectangular Steel Tube From Our Jinan Facility
Every order ships with a mill test certificate generated by our own physical and chemical laboratory — not a document pulled from a different batch or a trading company’s template. We hold 41 patented technologies, including sharp-corner rectangular tube manufacturing that fills a gap in the global market for tight-radius structural connections. Our three dedicated production lines cover over 2,800 specifications in square, rectangular, and round sections, meaning your EPC project can source tubes, beams, and plates from a single factory-direct source without coordinating multiple vendors. Lloyd’s Register EU CE certification under EN 10210 and EN 10219, ISO 9001:2015 quality management, and third-party SGS/BV inspection availability ensure that your documentation package clears customs and satisfies project auditors in over 50 export markets. Custom non-standard sizes and cut-to-length service eliminate on-site waste, while professional container loading plans maximize payload per shipment and reduce per-ton freight cost.
Documentation & Compliance
- Mill test certificate documenting S355JR chemical composition and mechanical properties per EN 10219, traceable to heat number
- CE certificate covering EN 10210 and EN 10219 structural hollow sections for EU market customs clearance
- ISO 9001:2015 quality management system certificate covering the full production and inspection process
- SGS or BV third-party inspection report available upon request before shipment departure
- Material traceability sheet linking each bundle to its heat number, chemical analysis, and dimensional inspection record
- Full customs document package including packing list, bill of lading, and certificate of origin
Packaging, Loading & Delivery
- Hot-dip galvanized S355JR tubes bundled with steel strips and edge protectors to preserve the zinc coating during ocean transit
- Black oiled square tubes packed in seaworthy bundles with waterproof wrapping, sized to match 20ft and 40ft container internal dimensions
- Cut-to-length rectangular tubes at 3m–12m loaded with optimized stowage plans to maximize container payload and minimize void space
- Each bundle tagged with heat number, steel grade (S355JR / Q355 / A500), section dimensions, and wall thickness for on-site identification
- FOB, CIF, and DDP shipping terms available with real-time tracking from Jinan inland depot to destination port or project site
Submit Your S355JR Square and Rectangular Steel Tube Inquiry
Send your section dimensions, wall thickness, steel grade, surface treatment preference, and destination port — we return a detailed quotation including unit price, production lead time, applicable certifications, and loading plan within 12 hours.
Request a Factory-Direct Quote with Mill Test Certificate
Email: admin@sdxjysteel.com | WhatsApp: +86 188 5315 7756 | Tel: +86 531 8573 6315
Frequently Asked Questions
Q: How do Q235/Q355 steel grades map to S235JR/S355JR and ASTM A500?
A: Q235 and S235JR share similar yield strength levels and are often interchangeable in general fabrication; Q355 and S355JR offer higher yield strength for structural applications and correspond roughly to ASTM A500 Grade C. We supply cross-standard equivalence documentation upon request so your engineer can verify material suitability.
Q: Can you provide EN 10204 3.1 Mill Test Certificates and arrange third-party inspection?
A: Yes. Every shipment includes an EN 10204 3.1 mill test certificate generated by our in-house laboratory, covering chemical composition and mechanical properties traceable to the heat number. SGS or BV third-party inspection can be arranged before shipment at the buyer’s request.
Q: What is the minimum order quantity for custom non-standard dimensions?
A: The standard MOQ is 1 Ton. For custom non-standard section sizes or special wall thicknesses outside our regular catalog, we evaluate each inquiry based on production feasibility and provide a tailored quotation.
Q: When should I specify pre-galvanized versus hot-dip galvanized surface treatment?
A: Pre-galvanized coating at 40–80g/m² suits indoor applications or moderate outdoor environments where cost efficiency is a priority. Hot-dip galvanized coating at 200–600g/m² is recommended for coastal, high-humidity, or chemically exposed environments where long-term corrosion resistance without maintenance is required.
Q: Do your CE certificates cover EN 10210 and EN 10219 for EU project compliance?
A: Yes. Our Lloyd’s Register EU CE certification covers both EN 10210 (hot-finished structural hollow sections) and EN 10219 (cold-formed welded structural hollow sections), ensuring full compliance for European construction and infrastructure projects.
Get Your S355JR Square Rectangular Steel Tube Quote Today
Share your specifications, quantity, and destination — we respond within 12 hours with pricing, certification details, and a loading plan.
Email: admin@sdxjysteel.com | WhatsApp: +86 188 5315 7756
