Description
ERW square steel tube supplier — Factory-direct S235JR and S355JR welded square tubes with ±1% tolerance, backed by CE EN10219 and ISO 9001 certifications for structural projects across 50+ countries.
Technical Specifications
| Parameter | Value |
|---|---|
| Designation | S235JR/S355JR ERW Square Steel Tube |
| Product Type | Welded Square Steel Tube (ERW) |
| Steel Grade | S235JR, S355JR, A36, SS400, Q235B |
| Standard | ASTM A500, EN10219, EN10210, JIS G3466, GB/T 6728 |
| Section Shape | Square |
| Size Range | 80×40 mm and custom sizes available |
| Wall Thickness | 2 mm and customized per requirement |
| Length | Customized |
| Technique | ERW (Electric Resistance Welded) |
| Surface Treatment | Cold Rolled / Galvanized (optional) |
| Tolerance | ±1% |
| Invoicing | By Theoretical Weight |
| Application | Steel structures, construction frames, machinery manufacturing, scaffolding, furniture, infrastructure construction |
| Origin | Shandong, China |
Application Suitability
| Industry | Typical Applications |
|---|---|
| Construction & Steel Structures | Building frames, column supports, truss systems for commercial and industrial projects |
| Machinery Manufacturing | Equipment base frames, conveyor support structures, automation rigging |
| Infrastructure & Facades | Bridge auxiliary structures, curtain wall sub-frames, architectural steel framing |
| Scaffolding & Temporary Works | Scaffold uprights, ledger braces, shoring tower components |
What Dimensional Tolerance Costs on a Structural Frame Order
Inconsistent wall thickness and corner geometry create cascading rework at the fabrication stage.
When ERW square steel tube arrives at a steel fabricator’s yard with wall thickness drifting beyond acceptable limits, the entire cutting and welding sequence is compromised. Fit-up gaps widen, weld consumable usage spikes, and structural engineers question whether the as-built frame matches the design calculations. [NEED_CITE: EN 10219 cold-formed welded structural hollow sections dimensional tolerance requirements] For projects specifying S355JR under EN10219, even minor deviations in side length or out-of-squareness force fabricators to reject batches — or worse, accept material that understates the load-bearing capacity assumed in structural models.
How ERW Square Tubes Match Structural Frame Requirements
ERW square steel tube in S235JR and S355JR grades provides the dimensional consistency that structural fabricators depend on for moment-resisting frames and braced systems. The electric resistance welding process produces a uniform weld seam along the full length, and the ±1% tolerance ensures that bolt-hole patterns and connection plates align without field modification. For curtain wall sub-frames and facade龙骨 applications, the square profile delivers clean bearing surfaces against gusset plates and bracket connections — a critical detail when architectural tolerances are tight.
Engineering Compliance and Certification Requirements
Structural hollow sections used in load-bearing frames must comply with recognized engineering standards. EN10219 covers cold-formed welded structural hollow sections of non-alloy and fine grain steels, while EN10210 addresses hot-finished profiles — both require documented chemical composition and mechanical properties verified through mill test certificates. [NEED_CITE: CE marking requirements for structural steel products under EN 10219 in EU markets] For projects in North America, ASTM A500 Grade B or C equivalents apply, and the grade equivalence between EN S355JR and ASTM A500 Gr.C must be clearly stated on documentation to avoid customs delays. Surface treatment selection — whether cold rolled black finish, hot-dip galvanized, or painted — depends on the corrosion environment and the project’s design working life.
Steel Grade Selection and ERW Process Fundamentals
The S-series structural steels (S235JR, S355JR) follow the European EN standard system, where the number indicates minimum yield strength in MPa — S355JR delivers higher load capacity than S235JR for the same cross-section, allowing designers to reduce member sizes in heavily loaded frames. The A36 and SS400 grades serve similar roles in ASTM and JIS systems respectively, while Q235B is the Chinese GB standard equivalent. ERW welding uses high-frequency electric current to fuse the strip edges under pressure, producing a weld seam that is typically narrower and more consistent than submerged arc welding — making it suitable for square and rectangular hollow sections where internal corner radii must remain uniform. Cold rolled surface finish provides a clean appearance for exposed architectural applications, while galvanized coating extends service life in corrosive environments without additional maintenance.
Hidden Costs of Procuring Non-Conforming Hollow Sections
Ordering ERW square steel tube without verified mill test certificates or third-party inspection creates exposure across the entire project chain. Material that fails to meet the specified grade — for instance, S235JR steel with carbon content exceeding the EN10219 limit — cannot be legally used in CE-marked structures within the EU, triggering full container rejection at port. [NEED_CITE: consequences of non-compliant structural steel in EU construction projects] Negative tolerance abuse — where actual wall thickness falls systematically below the ordered specification — reduces the section’s moment capacity and may not be detected until on-site ultrasonic testing, by which point fabrication is already underway and schedule delays are unavoidable.
Why Project Teams Source from SD XJY Pipe
Every shipment of ERW square steel tube leaves our facility with a mill test certificate documenting chemical composition and mechanical properties, verified by our in-house physical and chemical laboratory. We hold CE certification under EN10219 and EN10210, ISO 9001:2015 registration, and Singapore FPC approval — enabling customs clearance across EU, Middle Eastern, and Southeast Asian markets without documentation disputes. Our production lines cover over 2,800 specifications with wall thickness up to 40mm, meaning non-standard sizes and custom lengths are manufactured to order rather than sourced from traders with uncertain material traceability. Third-party inspection through SGS, BV, or Lloyd’s is arranged on request, and our export loading team uses purpose-built cradles and edge protectors to prevent bending and surface damage during ocean transit.
Documentation & Compliance
- Mill test certificate (EN 10204 3.1) documenting S235JR/S355JR chemical composition, yield strength, and tensile properties per EN10219
- CE certificate covering EN10210 and EN10219 structural hollow sections for EU market compliance
- ISO 9001:2015 quality management system certificate covering production and inspection processes
- SGS or BV third-party inspection report verifying dimensional accuracy, surface quality, and weld seam integrity
- Material traceability by heat number linking each bundle to its original steel coil and production batch
- Full customs documentation including packing list, bill of lading, and certificate of origin
Packaging, Loading & Delivery
- ERW square steel tubes bundled with galvanized steel strips at intervals suited to the section size and length, preventing shift during handling
- Cold rolled surface tubes coated with anti-rust oil and wrapped in waterproof paper to preserve finish during ocean transit
- Galvanized tubes loaded with edge protectors and separated by timber dunnage to prevent zinc coating abrasion
- Custom-length tubes cut to order and bundled by size for direct delivery to fabrication yards, reducing on-site waste
- Each bundle marked with heat number, steel grade, section dimensions, and purchase order reference for site identification
- Shipping terms available as FOB, CIF, or DDP with professional container loading optimized for the specific section geometry
Getting Your ERW Square Steel Tube Quote
Submit your required section dimensions, steel grade, surface treatment preference, quantity, and destination port — we respond within 12 hours with a detailed quotation including unit price, lead time, and shipping terms. For non-standard sizes or custom lengths outside our standard range, we provide manufacturing drawings and tolerance confirmations before production begins. Mill test certificates and third-party inspection arrangements are confirmed at contract stage, and professional loading plans are shared before container sealing.
Frequently Asked Questions
Q: What is the grade equivalence between S355JR and ASTM A500?
A: S355JR per EN10219 is broadly comparable to ASTM A500 Grade C in terms of minimum yield strength, though the chemical composition requirements and testing frequencies differ between the two standards. We provide cross-reference documentation with each shipment to support customs clearance and engineering approval.
Q: Can you produce non-standard square tube sizes outside your listed range?
A: Yes. Our production lines cover over 2,800 specifications, and we manufacture custom non-standard sizes to order. Minimum order quantities apply for non-standard sections, and we provide dimensional drawings for confirmation before production.
Q: What surface treatment options are available for ERW square tubes?
A: We supply ERW square steel tube in cold rolled (black) finish, hot-dip galvanized coating, or oiled surface for temporary corrosion protection. The choice depends on the project’s corrosion environment and design working life.
Q: Do your products carry CE marking for EU construction projects?
A: Yes. Our structural hollow sections are CE certified under EN10210 and EN10219, with full factory production control documentation. Mill test certificates conform to EN 10204 3.1 requirements.
Q: How do you prevent damage during container loading and ocean transit?
A: We use purpose-built steel cradles, timber dunnage, and edge protectors sized to the specific tube geometry. Bundles are secured with steel strapping, and galvanized tubes receive additional separation to prevent coating abrasion. Loading plans are shared with the client before container sealing.
Request Your ERW Square Steel Tube Quotation
Send your section dimensions, steel grade, quantity, and destination port to receive a detailed quotation with mill test certificate confirmation and lead time.
Contact: +86 188 5315 7756 (WhatsApp/WeChat) | Email: admin@sdxjypipe.com
