Description
Factory-direct ERW welded square and rectangular steel tubes — Q235, SS400, and ASTM A500 grades held in ready stock across 20×20 mm to 200×200 mm sections with wall thickness up to 30 mm, shipped with original mill test certificates from Jinan production lines.
Technical Specifications
| Parameter | Value |
|---|---|
| Designation | Q235 / SS400 ERW Square and Rectangular Steel Tube |
| Product Type | ERW Welded Square and Rectangular Steel Tube |
| Steel Grade | Q195, Q215, Q235, Q345, S235, SS400, ASTM A500 |
| Standard | ASTM, API, JIS, ISO 9001, CE |
| Section Shape | Square / Rectangular / Round |
| Size Range | 20×20 mm – 200×200 mm |
| Wall Thickness | 1.5 – 30 mm |
| Length | 1 – 12 m (6 m / 6.4 m / 12 m standard, custom available) |
| Technique | ERW (Electric Resistance Welded) |
| Surface Treatment | Hot Rolled / Galvanized Coated / Slightly Oiled |
| Tolerance | ±5% |
| Ends | Plain |
| Application | Structure Pipe, Fluid Pipe, Boiler Pipe, Gas Pipe, Oil Pipe, Construction, Bridge, Car Manufacturing, Electrical Installation, Mining |
| MOQ | 25 Tons (one 20ft container) |
| Origin | Shandong, China |
Application Suitability
| Industry | Typical Applications |
|---|---|
| Construction & Infrastructure | Structural frames for warehouses and factories, scaffolding systems, building column supports, bridge guardrail posts |
| Industrial & Energy | Fluid and gas transport pipelines, boiler tube assemblies, mining equipment support frames, oil rig platform structures |
| Manufacturing & Fabrication | Machinery base frames, car manufacturing chassis components, electrical installation conduit frameworks, conveyor support structures |
What Wall-Thickness Tolerance Costs on a Structural Frame Order
A ±5% tolerance window on a 30 mm wall tube means 1.5 mm of deviation — enough to shift load distribution across a welded joint.
I have seen containers held at port for weeks because ultrasonic thickness readings fell outside the acceptable band on heavy-wall sections. When an ERW carbon steel square rectangular tube supplier ships material at the lower edge of tolerance without declaring it, the receiving engineer recalculates load capacity and the entire batch gets rejected on site. The real cost is not the replacement steel — it is the crane idle time, the re-welding of already-positioned sections, and the customs paperwork that expires while you wait for a new shipment. Quality uncertainty on wall thickness is one of the most frequent reasons bulk steel procurement projects face delay [NEED_CITE: ERW hollow section dimensional tolerance standards for structural applications].
How Section Geometry Matches Structural Load Paths
Square and rectangular ERW sections from 20×20 mm up to 200×200 mm give engineers a predictable moment of inertia in both axes, which matters when a column must resist lateral wind load as well as vertical gravity. The flat faces of a rectangular tube sit flush against gusset plates and base brackets without the grinding that round pipe demands. For an ERW carbon steel square rectangular tube supplier covering wall thickness from 1.5 mm light-gauge framing to 30 mm heavy structural, the same production line can feed a scaffolding contractor in Dubai and a mining equipment fabricator in Chile from one stock holding.
Engineering Compliance Across Destination Markets
Structural hollow sections destined for European projects must conform to EN 10219 for cold-formed welded structural tubing, while North American specifiers reference ASTM A500 Grade B or C. An ERW carbon steel square rectangular tube supplier shipping Q235 to Southeast Asia and ASTM A500 to the Americas needs separate mill test certificates referencing each standard’s chemical and mechanical requirements. Surface treatment choice — hot rolled for indoor structural use, galvanized coated for outdoor or corrosive environments, slightly oiled for temporary protection during transit — must align with the end-use environment before the material leaves the mill [NEED_CITE: EN 10219 cold-formed structural hollow section requirements].
Steel Grade Selection and ERW Process Fundamentals
Q235 remains the workhorse grade across Chinese domestic construction and exports to markets that accept GB-standard equivalence, offering adequate formability and weldability for general structural frames. SS400, the Japanese JIS equivalent, appears frequently in orders from Southeast Asian infrastructure projects where JIS G3466 is the referenced standard. ASTM A500 Grade B and Grade C serve North American specifiers who require documented yield and tensile values in imperial units. The ERW process itself — passing a continuous strip through forming rolls and fusing the seam with high-frequency electric resistance — produces a weld zone that is typically the strongest part of the cross-section, though the heat-affected zone requires controlled cooling to maintain toughness. Wall thickness from 1.5 mm to 30 mm covers everything from thin-wall electrical conduit frames to heavy-wall pressure-containing applications, and the ±5% tolerance applies across the full range.
The Hidden Cost of Unverified Mill Certificates
Ordering an ERW carbon steel square rectangular tube supplier without confirmed original mill test certificates means the material arriving on site carries no traceable heat number. When a customs inspector in the EU requests CE documentation under EN 10210 and the importer cannot produce it, the container sits at the port accruing demurrage. When a third-party inspector from SGS or BV finds that the chemical composition on a delivered Q345 section does not match the paperwork, the entire lot fails acceptance testing regardless of whether the steel would actually perform. Engineering codes from AISC to Eurocode 3 require documented material traceability — not a supplier’s word, but a certificate tied to the heat [NEED_CITE: steel grade equivalence between EN and ASTM standards for structural hollow sections].
Why Project Buyers Return for Repeat Orders
Every batch of ERW carbon steel square rectangular tube produced on our Jinan lines passes through a three-stage in-house inspection covering dimensional accuracy, weld seam integrity, and surface condition before release. Original mill test certificates accompany each shipment, with heat number traceability from slab to finished tube. Our facility holds CE certification under EN 10210 and EN 10219 alongside ISO 9001:2015, and we arrange SGS or BV third-party inspection on request — a step that has cleared customs hold-ups for clients across 50+ countries. With 2,800+ specifications in ready stock and three production lines running simultaneously at 20,000+ tons monthly capacity, standard sizes ship within days while custom dimensions and non-standard lengths follow typical production lead times. We handle the full export documentation package and optimize container loading for mixed-size orders, so a single 20ft container can carry square, rectangular, and round sections consolidated for one project site.
Documentation & Compliance
- Mill test certificate documenting Q235 and SS400 chemical composition and mechanical properties per ASTM / API / JIS standards, with heat number traceability
- CE certificate covering EN 10210 hot-finished and EN 10219 cold-formed structural hollow sections for European market compliance
- ISO 9001:2015 quality management certificate covering ERW welding, forming, and finishing processes
- SGS or BV third-party inspection report available on request for independent verification of dimensions, surface quality, and material properties
- Material traceability by heat number from steel slab through ERW forming to finished tube, recorded in batch test archives
- Full customs documentation package including packing list, bill of lading, and certificate of origin for destination-country clearance
Packaging, Loading & Delivery
- ERW welded square and rectangular tubes bundled with steel strips and edge protectors, sized to match the 1–12 m length range for stable ocean transit
- Galvanized coated tubes wrapped with anti-scratch separators to preserve the zinc layer during handling and container loading
- Container loading optimized for mixed-size orders — 20×20 mm small sections nested inside 200×200 mm larger tubes to maximize 20ft container payload
- Custom cut-to-length service available for 6 m, 6.4 m, and 12 m standard lengths, with plain ends prepared for on-site welding
- Heat number and steel grade stenciled on each bundle for site identification and inspection traceability
- FOB, CIF, and DDP shipping terms available from Jinan production facility to major ports worldwide
Requesting a Bulk Quote with Mill Documentation
Submit your required section dimensions, wall thickness, steel grade, total tonnage, and destination port — we respond within 12 hours with pricing, available stock status, and typical production lead times for any non-standard items. If your project requires CE documentation for EU import or ASTM A500 certificates for North American compliance, confirm this at inquiry stage so the correct mill test certificates are prepared alongside your order.
Start Your ERW Steel Tube Inquiry
Send your specification list and destination details to receive a bulk quotation with original mill test certificate confirmation and container loading plan.
Contact: Shandong Xin Jiyuan Special Steel Tube Co., Ltd
Mobile / WhatsApp / WeChat: +86 188 5315 7756
Email: admin@sdxinjiyuan.com
Website: www.sdxinjiyuan.com
