Description
Factory-Direct SHS Production — Welded square hollow sections rolled, welded, and inspected under one roof at our own steel mill in Jinan, eliminating third-party sourcing gaps for S235 and S355 grades.
Technical Specifications
| Parameter | Value |
|---|---|
| Designation | S235/S355 Welded Square Steel Tube |
| Product Type | Welded Square Steel Tube / Square Hollow Section (SHS) |
| Steel Grade | Gr.B, S235, S275, S355, STK400, Q235B, Q345B |
| Standard | ASTM A500, ASTM A53, GB/T 3091 |
| Section Shape | Square |
| Size Range | 19mm×19mm – 800mm×800mm |
| Wall Thickness | 1 – 30 mm |
| Length | 5.8m / 6m / 11.8m / 12m / Random Length |
| Technique | ERW (Welded) / Seamless |
| Surface Treatment | Black Painting / Galvanized / Varnish / Bare |
| Tolerance | ±1% |
| Ends | Plain |
| Application | Construction structures / Building frames / Curtain walls / Support tubes / Machinery / Steel structures |
| MOQ | 5 Tons |
| Origin | Shandong, China |
Application Suitability
| Industry | Typical Applications |
|---|---|
| EPC Contractors | Steel structure frames for industrial buildings, warehouses, and logistics centers |
| General Contractors | Construction support tubes, curtain wall mullions, and column systems |
| Infrastructure Projects | Bridge support structures, sound barrier frames, and foundation piles |
| Machinery Manufacturers | Equipment bases, conveyor support frames, and crane boom sections |
What Wall-Thickness Tolerance Costs on a Structural Frame Order
A S355 square steel tube supplier who cannot guarantee ±1% tolerance will cost you rework, rejected inspections, and delayed handover.
When overseas buyers source welded SHS from fragmented suppliers, the wall thickness often drifts beyond acceptable limits — especially on heavier sections above 10mm. Third-party inspectors flag dimensional deviations, components fail to fit connection plates, and entire batches get held at port. On a recent Middle East warehouse project, a 250×250×12mm SHS order arrived with actual wall thickness at 10.8mm — well below the specified 12mm with standard negative tolerance allowed. The contractor faced a choice: accept structurally compromised members or wait six weeks for replacement. [NEED_CITE: EN 10219 dimensional tolerance requirements for cold-formed hollow sections]
Matching S355 SHS to Structural Load Requirements
S355 square steel tube in sizes from 100×100mm to 400×400mm with wall thickness 6–20mm serves as primary load-bearing members in portal frame structures. The higher yield strength of S355 over S235 allows thinner walls for equivalent load capacity — reducing self-weight and foundation costs. For EPC contractors building warehouses across Southeast Asia and Africa, sourcing S355 square steel tube with full EN 10219 compliance means faster customs clearance and fewer questions from local building inspectors. Our vertically integrated production from billet to finished SHS ensures every heat number traces back to our own mill test records.
Engineering Compliance for International Projects
Structural hollow sections destined for EU markets must carry CE marking per EN 10210 (hot-finished) or EN 10219 (cold-formed welded) — without this, customs holds the shipment regardless of physical quality. North American projects specify ASTM A500 Gr.B or Gr.C, requiring different chemical composition limits than European S-series grades. [NEED_CITE: steel grade equivalence between EN 10219 and ASTM A500 standards] Our engineering team reviews shop drawings before production, flagging potential conflicts between specified grades and available mill stock. For projects requiring third-party verification, we coordinate SGS or BV inspection at our facility before container loading — dimensional checks, coating thickness measurement, and weld seam ultrasonic testing all documented in the final dossier.
Understanding ERW Welding and Grade Selection
The ERW (Electric Resistance Welding) process joins formed steel strip edges under high-frequency current, creating a weld seam that matches base metal strength when proper WPS procedures are followed. Unlike seamless tube manufacturing, ERW production allows tighter dimensional control on large square sections — the 800×800mm SHS we produce maintains ±1% tolerance across all four sides. Steel grade selection directly impacts structural performance: S235 serves light-duty applications like curtain wall supports, while S355 handles primary columns and truss chords in industrial buildings. Q345B, the Chinese equivalent to S355JR, offers identical mechanical properties at competitive pricing for projects without strict origin requirements. Surface treatment choice depends on installation environment — hot-dip galvanized SHS resists corrosion in coastal or chemical plant settings, while black painted tubes suit interior applications where fire-rated intumescent coating will be applied on-site.
Hidden Costs of Unverified Material Certification
Purchasing S355 square steel tube without EN 10204 3.1 or 3.2 mill test certificates creates downstream liability — if structural failure occurs, the contractor bears responsibility for unverified material. Negative tolerance abuse (actual wall thickness below minimum allowed) reduces load capacity while invoicing by theoretical weight means paying for steel that does not exist. [NEED_CITE: EN 10204 inspection document types for steel products] Customs authorities in the EU and Middle East increasingly demand CE certificates and material traceability documentation — shipments without proper paperwork face rejection or costly re-export.
Why Project Teams Source SHS From Our Mill
Our Jinan facility operates three production lines covering 2,800+ specifications of welded square and rectangular hollow sections — from 19×19mm small sections to 800×800mm heavy structural members. Every S355 square steel tube we ship carries mill test certificates documenting chemical composition and mechanical properties per the specified standard. For projects requiring EN 10219 compliance, we hold CE certification and can provide third-party inspection reports from SGS, BV, or Intertek before loading. Our engineering team provides shop drawing review and material optimization — on a recent African mining project, we reduced steel tonnage by suggesting 300×300×10mm SHS instead of specified 350×350×12mm, maintaining load capacity while cutting weight and cost. Professional container loading plans maximize payload for 40ft OT and FR containers, with oversized sections secured using welded lashing points and edge protectors to prevent coating damage during ocean transit.
Documentation & Compliance
- Mill test certificate documenting S355JR chemical composition and yield strength per EN 10219, including heat number traceability from billet to finished tube
- CE certificate confirming EN 10219 compliance for cold-formed welded hollow sections destined for European Union markets
- ISO 9001 quality management system certificate covering the full production process from raw material inspection to final dimensional verification
- SGS or BV third-party inspection report verifying wall thickness tolerance, weld seam quality, and coating thickness before container loading
- Material traceability documentation linking each bundle to specific heat numbers, production dates, and test results
- Complete customs documentation package including packing list, bill of lading, certificate of origin, and commercial invoice formatted for destination country requirements
Packaging, Loading & Delivery
- S355 SHS bundled with high-tensile steel strips at minimum four points per bundle, with end caps protecting plain ends from impact damage during handling
- Galvanized square tubes packed with edge protectors and separated by rubber spacers to preserve zinc coating integrity during ocean transit
- Container loading plans optimized for 6m and 12m lengths in 40ft standard containers, with oversized sections above 400×400mm loaded in 40ft OT or FR with welded securing points
- Custom cutting to exact project lengths available — 5.8m, 6m, 11.8m, or 12m — reducing on-site waste and welding requirements
- Each bundle marked with heat number, steel grade (S355/S235), size specification, and production date for site identification and traceability
- FOB Jinan/Qingdao port for standard orders, with CIF and DDP options available for project sites requiring door-to-door delivery coordination
Starting Your SHS Procurement Process
Submit your project specifications — including steel grade (S235/S355), section sizes, wall thickness, total tonnage, and destination port — to receive a detailed quotation with production timeline and mill test certificate samples. Our engineering team reviews drawings within 24 hours, identifying potential material optimization opportunities and confirming compliance with your project’s required standards. For non-standard sizes or custom lengths outside our standard range, we provide feasibility assessment and lead time confirmation before contract signing.
Request Your S355 Square Steel Tube Quotation
Share your project drawings and specifications to receive pricing, mill test certificate samples, and production schedule within 24 hours.
Shandong Xin Jiyuan Special Steel Tube Co., Ltd
Website: www.xjystructure.com
Tel: +86 531 8573 6315
Mobile/WhatsApp/WeChat: +86 188 5315 7756
Email: admin@xjystructure.com
Address: No.11889, Jingshi West Road, Lulian Group, Jinan City, Shandong Province, China
Frequently Asked Questions
Q: How do S355JR, ASTM A500 Gr.B, and Q345B compare in mechanical properties?
A: S355JR (EN 10219) and Q345B (GB/T 1591) share similar yield strength around 355 MPa, making them interchangeable for most structural applications. ASTM A500 Gr.B specifies minimum yield strength of 290 MPa for round tubes and 42 ksi (290 MPa) for square tubes — lower than S355 but widely accepted in North American projects. Our mill produces all three grades with full certification, and we provide grade equivalence documentation for projects requiring material substitution approval.
Q: Can you provide EN 10204 3.2 certificates and third-party mill test reports?
A: Yes. We issue EN 10204 3.1 mill test certificates with every shipment, documenting chemical composition and mechanical properties per the specified standard. For projects requiring 3.2 certificates with independent inspector witness, we coordinate third-party inspection from SGS, BV, or Intertek at our facility. The inspector witnesses sampling, testing, and reviews documentation before signing the certificate.
Q: What is the minimum order quantity for non-standard sizes like 250×250×12mm?
A: Our standard MOQ is 5 tons per size. For non-standard dimensions outside our regular stock range, MOQ depends on whether the size falls within our mill’s roll tooling capability. Sections between 19×19mm and 800×800mm with wall thickness 1–30mm are generally producible. We confirm feasibility and exact MOQ after reviewing your specific size requirements.
Q: When should I choose galvanized versus black painted surface treatment for structural tubes?
A: Hot-dip galvanized SHS suits outdoor, coastal, or high-humidity environments where corrosion resistance is critical — the zinc coating provides 50+ years of protection in moderate atmospheres. Black painted tubes work for interior applications or projects where fire-rated intumescent coating will be applied on-site. Bare or varnished tubes serve temporary structures or situations where the contractor handles surface treatment based on final installation conditions.
Q: How do you handle oversized SHS packaging and container loading for 40ft OT/FR?
A: Sections up to 400×400mm load efficiently in standard 40ft containers using optimized nesting plans. Larger sections like 500×500mm and above require 40ft Open Top or Flat Rack containers. We prepare detailed loading plans showing bundle positioning, lashing points, and weight distribution before shipping. Welded steel lashing eyes secure bundles against movement during ocean transit, and edge protectors prevent coating damage from steel straps.
