Description
Factory-direct pricing with no middlemen — every S235JR S355 ERW welded square steel tube ships straight from our Jinan mill with full mill test certificates and CE documentation for EU customs clearance.
Technical Specifications
| Parameter | Value |
|---|---|
| Designation | S235JR / A36 / S355 / SS400 ERW Welded Square Steel Pipe |
| Product Type | Welded Square Steel Tube (ERW) |
| Steel Grade | S235JR, A36, S355, SS400, Q235B |
| Standard | ASTM A500, EN 10219, EN 10210, JIS G3466, GB/T 6728 |
| Section Shape | Square |
| Technique | ERW (Electric Resistance Welded) |
| Surface Treatment | Cold Rolled / Galvanized (optional) |
| Tolerance | ±1% |
| Length | Customized |
| Processing Service | Welding, Punching, Cutting, Bending, Decoiling |
| Invoicing | By Theoretical Weight |
| Oiled or Non-oiled | Non-oiled |
| Origin | Shandong, China |
Application Suitability
| Industry | Typical Applications |
|---|---|
| Building Construction | Structural frames, trusses, columns, greenhouse supports |
| Infrastructure | Bridge auxiliary structures, stage trusses, highway barriers |
| Machinery Manufacturing | Machine tool frames, conveyor supports, automation equipment |
| Vehicle Manufacturing | Trailer chassis, RV frames, commercial vehicle subframes |
| Home Decor & Furniture | Stair handrails, security windows, furniture frames |
Where Dimensional Tolerance Decides Structural Fit on an ERW Welded Square Steel Tube Order
±1% tolerance keeps bolt-hole alignment tight and eliminates on-site reaming.
When square tubes arrive with corner radii exceeding spec or wall thickness drifting beyond tolerance, fabricators face cascading costs — misaligned joints, rejected weld inspections, and delayed handovers. Buyers sourcing S235JR S355 ERW welded square steel tube for structural frames often discover that inconsistent corner geometry forces rework on curtain wall connections or machinery base plates. Material certificates showing grade equivalence gaps between EN 10219 and ASTM A500 compound the problem at customs. [NEED_CITE: EN 10219 cold-formed welded structural hollow sections dimensional tolerances]
How ERW Welded Square Steel Tube Matches Structural Frame Requirements
S235JR and S355 grades deliver the yield strength range that structural engineers specify for building frames and machinery bases without overpaying for higher-alloy alternatives. The ERW welding process produces a consistent longitudinal seam that handles compressive loads in column applications while maintaining square geometry for bolted end-plate connections. Our ±1% tolerance ensures that when a facade contractor receives S235JR S355 ERW welded square steel tube for curtain wall framing, the tubes stack true without shimming. Custom lengths cut to drawing dimensions reduce on-site welding and scrap rates.
Engineering Compliance and Grade Selection for Load-Bearing Applications
Structural frames designed under EN 1993 or AISC 360 require material certificates confirming chemical composition and mechanical properties per the specified standard. S235JR suits general construction where moderate yield strength suffices, while S355 serves heavier load paths in bridges and industrial structures. [NEED_CITE: steel grade equivalence between EN 10219 and ASTM A500 standards] CE certification under EN 10219/EN 10210 is mandatory for EU market entry — missing this documentation triggers customs holds. Galvanized surface treatment extends service life in corrosive environments without field painting, while cold-rolled finish provides clean aesthetics for exposed architectural applications.
Understanding ERW Welding and Multi-Grade Coverage in Square Tubes
ERW (Electric Resistance Welded) square tubes form from cold-rolled coil through continuous roll-forming followed by high-frequency resistance welding along the longitudinal seam. This process delivers tight dimensional control and smooth surface finish compared to SSAW alternatives, making it ideal for architectural and precision machinery applications. The S-series grades (S235JR, S355) follow EN specifications with guaranteed impact toughness at sub-zero temperatures, while ASTM A36 and JIS SS400 serve North American and Asian projects respectively. Q235B offers cost-effective domestic-grade performance for non-regulated markets. Each grade maintains distinct chemical composition limits that affect weldability and forming characteristics — specifying the correct standard prevents material substitution disputes during inspection. [NEED_CITE: ERW versus seamless versus SSAW welding process comparison for structural tubes]
Hidden Costs When Grade Documentation or Corner Quality Falls Short
Purchasing square tubes without verified mill test certificates risks material rejection at project inspection — a single failed tensile test can halt an entire batch acceptance. Corner quality matters beyond aesthetics: rounded corners from poor roll-forming create gaps in welded connections that compromise load transfer and trigger welder requalification. [NEED_CITE: structural hollow section corner radius requirements for welded connections] Non-oiled surfaces without proper storage develop rust staining that requires abrasive blasting before painting, adding surface preparation costs. Missing CE marks on S355 tubes destined for EU construction sites result in customs detention and demurrage charges that exceed the original material savings from unverified suppliers.
Why Project Buyers Source S235JR S355 ERW Welded Square Steel Tube From Us
Our Jinan facility operates three dedicated ERW tube mills producing square sections across 2,800+ specifications with wall thickness reaching 40mm — covering both stock sizes for urgent orders and custom non-standard dimensions for specialized machinery frames. Every batch undergoes dimensional, chemical, and mechanical testing in our in-house laboratory before release, with mill test certificates documenting actual heat-by-heat results rather than generic specifications. We hold CE certification under EN 10219/EN 10210, ISO 9001:2015 registration, and Singapore FPC approval — documentation packages that clear EU, Middle East, and Southeast Asian customs without delay. Custom processing services including cutting, punching, and bending reduce your fabrication shop workload and shipping volume. Professional container loading with steel-frame bracing prevents the corner damage and surface scratches that plagued my early shipping days in Foshan.
Documentation & Compliance
- Mill test certificate documenting S235JR or S355 chemical composition and mechanical properties per EN 10219, including yield strength, tensile strength, and elongation values from each production heat
- CE certificate confirming compliance with EN 10219 for cold-formed welded structural hollow sections and EN 10210 for hot-finished profiles, required for EU construction product regulation
- ISO 9001:2015 quality management system certificate covering the complete production process from coil receiving through final inspection and packaging
- SGS or BV third-party inspection report verifying dimensional accuracy, surface quality, and marking compliance before container sealing
- Material traceability documentation linking each tube bundle to its heat number, coil certificate, and production date for project quality audits
- Complete customs documentation package including commercial invoice, packing list, bill of lading, and certificate of origin formatted for destination country requirements
Packaging, Loading & Delivery
- ERW welded square tubes bundled with high-tensile steel strips at regular intervals, with edge protectors preventing corner damage during handling and ocean transit
- Galvanized square tubes packed with waterproof interleave separators to preserve zinc coating integrity and prevent white rust formation during humid shipping conditions
- Custom-length tubes cut to project drawings and nested by size for efficient container loading, maximizing payload per 20ft or 40ft container while maintaining weight distribution
- Heat number and steel grade stenciled on each tube end with weather-resistant marking paint, enabling site identification without certificate cross-referencing
- Professional container loading using steel-frame cradles and anti-rubbing protection to prevent surface scratches and corner dents — lessons learned from watching poorly secured tubes arrive bent at destination ports
- FOB, CIF, and DDP shipping terms available with complete export documentation and real-time tracking until project site delivery
Getting Your S235JR S355 ERW Welded Square Steel Tube Quote Started
Send your specification sheet with section dimensions, wall thickness, steel grade, surface treatment preference, total tonnage, and destination port — we respond within 12 hours with unit pricing, production lead time, and shipping terms. Request mill test certificate samples and CE documentation for your project consultant review before committing. Confirm custom cutting lengths or processing requirements so we can optimize container loading and reduce your fabrication costs.
Frequently Asked Questions
Q: Can you provide S355 square tubes with CE certification for EU construction projects?
A: Yes, all our S355 ERW welded square steel tubes carry CE certification under EN 10219 and EN 10210 standards. We provide complete documentation packages including CE declarations of performance, mill test certificates, and third-party inspection reports that satisfy EU construction product regulation requirements for customs clearance and project acceptance.
Q: What is the tolerance on corner radius for your ERW welded square tubes?
A: Our ERW welded square steel tubes maintain ±1% dimensional tolerance across all specifications, with corner radii controlled to meet EN 10219 requirements for structural hollow sections. This precision ensures proper fit-up for welded connections and bolted end-plate joints without requiring on-site reaming or shimming.
Q: Do you offer custom cutting and processing services for square tubes?
A: Yes, we provide cutting to exact project lengths, punching for bolt holes or service penetrations, bending for curved structural members, and welding for assembled components. These processing services reduce your fabrication shop workload and optimize container loading by nesting cut pieces efficiently.
Q: How do you ensure material traceability for each shipment?
A: Every tube bundle carries heat number marking stenciled on the ends, linking back to the original coil certificate and production test records. Mill test certificates document chemical composition and mechanical properties for each heat number, providing full traceability from raw material through final inspection for project quality audits.
Q: What surface treatment options are available for corrosion protection?
A: We offer cold-rolled finish for clean aesthetics in interior architectural applications, hot-dip galvanized coating for exterior exposure and corrosive environments, and optional oiling for temporary rust prevention during storage and transit. Galvanized tubes receive special packaging with waterproof separators to preserve coating integrity during ocean shipping.
Get Your S235JR S355 ERW Welded Square Steel Tube Quote With Mill Test Certificates
Submit your specifications including dimensions, steel grade, quantity, and destination port to receive pricing and documentation samples within 12 hours.
Shandong Xin Jiyuan Special Steel Tube Co., Ltd
Website: www.sdxjypipe.com
Mobile/WhatsApp/WeChat: +86 188 5315 7756
Email: admin@sdxjypipe.com
Address: No.11889, Jingshi West Road, Lulian Group, Jinan City, Shandong Province, China
