Description
Factory-Direct ERW Hollow Sections — Q195–Q345 / S235–S355 grades produced on 3 in-house lines with original mill test certificates for every batch.
Technical Specifications
| Parameter | Value |
|---|---|
| Designation | Q195-Q345 Black ERW Square & Rectangular Hollow Section |
| Product Type | Square and Rectangular Steel Tube (Hollow Section) |
| Steel Grade | Q195, Q215, Q235, Q345, 10#, 20#, Gr.A, Gr.B, Gr.C, S235, S275, S355, A36, SS400 |
| Standard | ASTM A500, EN 10219, EN 10210, JIS G3466, GB/T 6728 |
| Section Shape | Square / Rectangular |
| Size Range | Square: 16×16mm – 400×400mm; Rectangular: 20×40mm – 300×500mm |
| Wall Thickness | 0.8 – 20mm |
| Length | 3 – 12m (or per client requirement) |
| Technique | ERW (High-Frequency Welded) |
| Surface Treatment | Black Iron / Oiled / Painted (Black Varnish Lacquer) / Hot Dipped Galvanized (220–260g/m²) / Pre-Galvanized (30–150g/m²) / Bare |
| Tolerance | ±1% |
| Ends | Plain End / Bevel End / Groove End / Flange Joint / Threaded with Coupling & Plastic Cap |
| Application | Construction & building materials / Steel structures / Scaffolding / Fence posts / Fire protection systems / Greenhouse frames / Low-pressure fluid transport / Irrigation / Handrails |
| MOQ | 25 Tons |
| Origin | Shandong, China |
Application Suitability
| Industry | Typical Applications |
|---|---|
| Construction & EPC | Building frames, column-beam assemblies, mezzanine structures, commercial facility skeletons |
| Infrastructure | Scaffolding systems, fence posts, highway guardrail supports, utility pole bases |
| Agriculture | Greenhouse frames, irrigation pipe networks, equipment support structures |
| Municipal Engineering | Fire protection system piping, low-pressure water and gas conveyance, handrail systems |
| Industrial Fabrication | Machinery frames, conveyor structures, equipment bases, workshop partitions |
What Wall-Thickness Tolerance Costs on a Structural Frame Order
A ±1% tolerance on ERW hollow sections is the line between passing structural inspection and rebuilding an entire floor.
I once watched a Middle East project reject an entire container of rectangular tubes because the wall thickness measured 2.6mm instead of the specified 3.0mm — the supplier had pushed negative tolerance to the edge, and the beam load capacity fell below design requirements. The buyer paid for return freight, replacement production, and a three-week schedule delay. On a Black ERW Square and Rectangular Hollow Section Steel Tube Supplier order, every batch leaves our mill with original test certificates showing actual measured thickness, and SGS or BV third-party inspection is available before the container is sealed [NEED_CITE: EN 10219 cold-formed hollow section dimensional tolerance requirements]. When specifiers call for EN 10219 or ASTM A500, the tolerance band is not a suggestion — it determines whether the steel carries the load the engineer calculated.
Matching Hollow Section Profiles to Structural and Architectural Demands
Square and rectangular hollow sections serve two distinct engineering functions: closed-section torsional resistance for load-bearing frames, and flat-surface geometry for clean architectural connections. Our Black ERW Square and Rectangular Hollow Section Steel Tube Supplier range covers 16×16mm to 400×400mm square and 20×40mm to 300×500mm rectangular profiles, with wall thickness from 0.8mm for light greenhouse framing up to 20mm for heavy industrial columns. The high-frequency ERW welding process produces a continuous longitudinal seam that maintains uniform strength across the cross-section, while the flat outer faces allow direct bolted or welded connections without gusset plates — a detail that cuts fabrication time on steel structure projects.
Engineering Compliance Across EN, ASTM, and GB Standards
Structural hollow sections specified under EN 10219 must satisfy cold-formed welding requirements, dimensional tolerances, and material traceability rules that differ from ASTM A500 or GB/T 6728. For European market projects, CE certification per EN 10210 and EN 10219 is mandatory for customs clearance, and the mill test certificate must reference the heat number and chemical composition traceable to the original slab [NEED_CITE: steel grade equivalence between EN 10219 S355 and ASTM A500 Gr.C]. Our production covers Q195–Q345 (GB), S235–S355 (EN), Gr.A–Gr.C (ASTM), and SS400 (JIS) within a single order, so EPC contractors sourcing for multi-country projects receive consistent documentation across all destination markets. Custom cut-to-length from 3m to 12m and end preparations including bevel, groove, and flange joint options reduce on-site secondary processing.
How Steel Grade Selection Affects Load Capacity and Weldability
The Q-series (Q195, Q235, Q345) follows the Chinese GB system where the number indicates minimum yield strength in MPa; Q345 delivers higher load capacity than Q235 but requires preheat consideration for thick-wall welding. The S-series (S235, S275, S355) under EN 10219 uses a similar naming logic, with S355 offering the highest yield tier for heavy structural frames. ASTM A500 Gr.A, Gr.B, and Gr.C serve the North American market with different chemical composition limits and elongation requirements. Our Black ERW Square and Rectangular Hollow Section Steel Tube Supplier inventory spans all three systems, and the in-house metallurgical lab verifies each heat against the relevant standard before release. Surface treatment selection — black iron for indoor structural use, pre-galvanized for moderate corrosion environments, hot-dipped galvanized for outdoor or coastal exposure — is matched to the project’s service conditions during the quotation stage.
The Hidden Cost of Unverified Hollow Sections on Project Sites
Ordering structural hollow sections without original mill test certificates or third-party inspection creates a chain of risks: customs authorities in the EU and Middle East routinely detain shipments lacking CE documentation or traceable heat numbers; engineers cannot sign off on load calculations without verified material properties; and negative tolerance abuse — where actual wall thickness falls below the specified minimum — compromises structural integrity without visible warning [NEED_CITE: consequences of non-compliant steel hollow sections in structural engineering]. A Black ERW Square and Rectangular Hollow Section Steel Tube Supplier that provides full chemical composition reports, mechanical test results, and dimensional inspection records for every batch eliminates these risks before the container leaves the port.
Why Project Buyers Source ERW Hollow Sections Through Xin Jiyuan
Founded in 2013, Shandong Xin Jiyuan Special Steel Tube Co., Ltd operates 3 simultaneous ERW production lines with monthly capacity exceeding 20,000 tons, covering over 2,800 specifications in square, rectangular, and round profiles. Every order ships with original mill test certificates traceable to heat number, and our in-house laboratory conducts three-stage inspection covering chemical composition, mechanical properties, and dimensional accuracy. CE certification per EN 10210 and EN 10219, ISO 9001:2015 quality management, and FPC certification ensure compliance for European and international markets. We offer factory-direct pricing with volume discounts for long-term partners, flexible MOQ from trial orders to full-container bulk, and professional export handling including container loading optimization and complete customs documentation. SGS and BV third-party inspection is arranged on request before shipment.
Documentation & Compliance
- Mill test certificate documenting Q195–Q345 / S235–S355 chemical composition and mechanical properties per EN 10219 or ASTM A500, traceable to heat number
- CE certificate per EN 10210 and EN 10219 for European market customs clearance and structural compliance
- ISO 9001:2015 quality management system certificate covering production and inspection processes
- SGS or BV third-party inspection report available on request, covering dimensional tolerance, surface quality, and weld integrity
- Material traceability documentation linking each bundle to original slab heat number and production batch
- Complete customs document package including packing list, bill of lading, and certificate of origin
Packaging, Loading & Delivery
- ERW square and rectangular tubes packed in hexagonal seaworthy bundles secured with steel strips for OD under 273mm, or loose piece-by-piece for larger sections, with edge protectors preserving surface treatment during transit
- Black iron and oiled finishes protected by waterproof wrapping; hot-dipped galvanized and pre-galvanized tubes bundled with separators to prevent zinc coating damage
- Container loading optimized for mixed-size orders, nesting smaller sections inside larger profiles to maximize payload per 20ft or 40ft container
- Cut-to-length service available from 3m to 12m per client requirement, with end preparations (plain, bevel, groove, threaded) completed before packing
- Heat number and steel grade stenciled on each bundle for on-site traceability and inspection verification
- FOB, CIF, and DDP shipping terms with professional export team handling customs clearance and real-time shipment tracking
Start Your ERW Hollow Section Procurement
Submit your specification sheet including section dimensions, wall thickness, steel grade, quantity, and destination port to receive a competitive bulk quotation with volume discount pricing, production lead time, and mill test certificate sample. Our team responds within 12 hours with technical confirmation and shipping options.
Request Quotation and Mill Test Certificate
Send your Black ERW Square and Rectangular Hollow Section requirements via email or WhatsApp for factory-direct pricing and full documentation package.
Contact: Shandong Xin Jiyuan Special Steel Tube Co., Ltd
Email: admin@sdxinjiyuan.com
WhatsApp: +86 188 5315 7756
Website: www.sdxinjiyuan.com
Frequently Asked Questions
Q: Are EN 10219 S355J2H and ASTM A500 Gr.C interchangeable for the same structural application?
A: Both grades deliver similar minimum yield strength levels, but chemical composition limits, elongation requirements, and impact testing conditions differ between EN and ASTM standards. Our mill produces both grades within the same order, and we provide cross-reference documentation showing the specific chemical and mechanical properties for each standard to support engineer approval.
Q: What documents are included with each shipment of ERW hollow sections?
A: Every batch ships with original mill test certificates showing chemical composition, mechanical properties, and dimensional inspection results traceable to heat number. CE certificate per EN 10210/EN 10219, ISO 9001 certificate, packing list, bill of lading, and certificate of origin are included. SGS or BV third-party inspection reports are arranged on request before shipment.
Q: Can you produce non-standard dimensions outside the 16×16mm to 400×400mm range?
A: Custom sizes beyond standard catalog dimensions are available with typical production lead times for non-standard orders. We operate 3 ERW production lines with flexible tooling, and MOQ for custom profiles starts at 25 tons. Send your drawing or specification for technical confirmation and pricing.
Q: When should I specify hot-dipped galvanized versus pre-galvanized surface treatment?
A: Hot-dipped galvanized coating at 220–260g/m² provides long-term corrosion protection for outdoor, coastal, or high-humidity environments. Pre-galvanized coating at 30–150g/m² suits indoor or moderate conditions where cost optimization is prioritized. Black iron or oiled finishes are specified for indoor structural applications or when the project includes on-site painting.
Q: How do you optimize container loading for mixed-size hollow section orders?
A: Our export team prepares detailed loading plans that nest smaller square and rectangular tubes inside larger sections, maximizing payload per container. This approach reduces shipping cost per ton and supports split shipments for projects requiring multiple size profiles in a single order.
