Description
Factory-Direct Welded SHS Supply — S235JR, A36, S355, SS400, and Q235B square steel tubes produced on three dedicated ERW lines with wall thickness up to 40mm, shipped under CE EN 10219 and ISO 9001 certification to 50+ countries.
Technical Specifications
| Parameter | Value |
|---|---|
| Designation | S235JR / A36 / S355 / SS400 Square Steel Tube |
| Product Type | Welded Square Steel Tube |
| Steel Grade | S235JR, A36, S355, SS400, Q235B |
| Standard | ASTM A500, EN 10219, EN 10210, JIS G3466, GB/T 6728 |
| Section Shape | Square |
| Size Range | Customized side length |
| Wall Thickness | Customized, up to 40mm |
| Length | Customized |
| Technique | ERW (Electric Resistance Welded) |
| Surface Treatment | Cold Rolled / Galvanized (optional) |
| Tolerance | ±1% |
| Processing Service | Welding, Punching, Cutting, Bending, Decoiling |
| Invoicing | By Theoretical Weight |
| MOQ | Negotiable per specification |
| Origin | Shandong, China |
Application Suitability
| Industry | Typical Applications |
|---|---|
| EPC Contractors | Steel structure frames for factories, stadiums, and commercial centers |
| Machinery Manufacturers | Machine tool frames, conveyor supports, automation equipment bases |
| Construction Companies | Bridge auxiliary structures, greenhouse frames, high-rise building columns |
| Infrastructure Development | Trailer chassis, RV frames, industrial platform supports |
What Negative Tolerance Gambling Costs on a Structural Frame Order
When wall thickness slips below the acceptable floor, theoretical invoicing diverges from actual load-bearing capacity — and the entire shipment risks rejection at destination port.
I came up from the rolling floor before moving into export, so tolerance deviation is something I watch obsessively. Early in my career, a batch of square tubes shipped to a Middle East project came in nearly two tons under theoretical weight because negative tolerance had been pushed to the extreme. The client’s third-party inspector rejected the entire container, and the cargo sat at port for weeks accumulating demurrage. That kind of mismatch between invoiced weight and real structural performance doesn’t just cost money — it erodes trust with the end user’s engineering team. [NEED_CITE: EN 10219 dimensional tolerance requirements for cold-formed hollow sections]
How Multi-Grade Welded SHS Matches Structural and Machinery Applications
S235JR serves general construction where moderate yield strength suffices, while S355JR steps up for heavier load paths in industrial frames and bridge components. A36 and SS400 cover North American and Japanese specification systems respectively, letting procurement teams source a single supplier across multi-standard projects. The ERW welding process produces a consistent weld seam suitable for bending and punching operations — critical when these tubes arrive on-site pre-cut and pre-drilled for conveyor structures or machinery bases. A S355JR square steel tube manufacturer with in-house processing eliminates the coordination gap between raw material supply and fabrication readiness.
Engineering Compliance and Certification Pathways Across Markets
Structural steelwork in the European Union requires CE marking under EN 10219 for cold-formed welded hollow sections, and customs authorities increasingly demand the Declaration of Performance alongside mill documentation. [NEED_CITE: CE marking requirements for structural steel under EN 10219] For North American projects, ASTM A500 Grade B or C governs the same product category, while JIS G3466 applies to Japanese-specification infrastructure. Surface treatment selection — cold rolled for indoor machinery frames, hot-dip galvanized for outdoor greenhouse structures or bridge components — directly affects corrosion resistance and service life. Custom length cutting reduces on-site welding and secondary processing, which matters when labor costs dominate project budgets in developed markets.
Steel Grade Equivalence and ERW Process Fundamentals
S235JR, A36, SS400, and Q235B occupy roughly equivalent positions in the EN, ASTM, JIS, and GB grading systems respectively — all are mild structural steels with similar carbon content and weldability, though exact chemical composition limits differ by standard. S355JR delivers higher yield strength for applications requiring greater load capacity without increasing section size. The ERW process forms the tube from coiled steel strip through continuous rolling and high-frequency electric resistance welding, producing a clean internal weld bead suitable for most structural applications. Wall thickness tolerance of ±1% ensures dimensional consistency across long production runs, which matters when hundreds of identical frames must bolt together on an assembly line. Sharp-corner geometry — available through proprietary forming technology — improves joint fit-up for welded connections and creates cleaner visual lines for architectural applications like stair handrails and furniture frames.
Hidden Costs of Unverified Steel Procurement
Purchasing welded square tubes without independent mill test verification invites three failure modes: chemical composition outside the specified grade range compromises weld integrity, dimensional deviation beyond tolerance triggers engineering rejection, and missing CE or ASTM documentation blocks customs clearance entirely. [NEED_CITE: consequences of non-compliant steel in structural applications] A shipment held at port for documentation disputes accrues storage fees, delays project timelines, and forces emergency sourcing at premium prices. The cost of proper certification and third-party inspection is marginal compared to the expense of rejected cargo or structural rework.
Why Procurement Teams Consolidate Welded SHS Orders Here
Three dedicated ERW production lines cover over 2,800 specifications in square and rectangular hollow sections, with wall thickness reaching 40mm — eliminating the need to split orders across multiple suppliers for different size ranges. An in-house physical and chemical laboratory tests every heat before release, generating mill test certificates that document actual composition and mechanical results rather than nominal values. Forty-one patents include proprietary sharp-corner rectangular tube technology that fills specification gaps competitors cannot address. CE certification under EN 10210 and EN 10219, Lloyd’s Register verification, Singapore FPC, and ISO 9001:2015 cover the documentation requirements for EU, Commonwealth, and global projects. Professional loading plans optimize container utilization for mixed-size shipments, and door-to-door logistics coordination handles FOB, CIF, and DDP terms across 50+ destination countries.
Documentation & Compliance
- Mill test certificate documenting S235JR, S355JR, or A36 chemical composition and mechanical properties per EN 10219 or ASTM A500 for each heat number
- CE certificate covering EN 10219 cold-formed welded hollow sections for EU market customs clearance and project compliance
- ISO 9001:2015 quality management system certificate demonstrating controlled production and inspection processes
- SGS or BV third-party inspection report available for independent verification of dimensions, surface quality, and mechanical properties
- Material traceability documentation linking each bundle to heat number, production date, and test results
- Customs documentation package including packing list, bill of lading, and certificate of origin formatted for destination port requirements
Packaging, Loading & Delivery
- Welded square tubes bundled with steel strips and edge protectors to prevent surface damage to cold rolled or galvanized finish during ocean transit
- Galvanized square steel tubes separated by rubber spacers within bundles to preserve zinc coating integrity at contact points
- Custom-length tubes cut to project specifications and marked with heat number, steel grade, and size for on-site identification
- Mixed-size container loading plans optimized for 20ft and 40ft equipment, maximizing weight utilization for heavy-wall S355JR sections
- Bundle markings display steel grade (S235JR / A36 / S355 / SS400), size dimensions, wall thickness, and heat number for traceability
- FOB, CIF, and DDP shipping terms available with professional port coordination and real-time shipment tracking
How to Initiate a Welded SHS Procurement Inquiry
Submit your specification requirements — including steel grade, side length, wall thickness, total quantity, and destination port — to receive a detailed quotation with unit pricing, production lead time, and applicable certification documentation. For non-standard sizes or custom processing including cutting, bending, or punching, provide drawings or dimensional schedules for engineering review. Confirm whether third-party inspection or specific certification documents are required for your project compliance before contract execution.
Frequently Asked Questions
Q: What is the difference between S235JR, A36, SS400, and Q235B for square steel tube applications?
A: These grades represent equivalent mild structural steel categories across different standard systems — S235JR follows EN standards, A36 follows ASTM, SS400 follows JIS, and Q235B follows Chinese GB standards. All offer similar weldability and formability for general structural applications, though exact chemical composition limits and testing requirements vary by standard. Your project specification or engineering consultant determines which standard applies.
Q: Can you produce non-standard sizes outside typical catalog dimensions?
A: Yes, custom side lengths and wall thicknesses are available beyond standard catalog sizes, with wall thickness reaching up to 40mm. Non-standard specifications may have different minimum order quantities and production lead times compared to standard sizes. Submit your dimensional requirements for engineering feasibility review and quotation.
Q: What surface treatment options are available for welded square steel tubes?
A: Cold rolled finish provides a clean surface suitable for indoor applications and further painting or powder coating. Hot-dip galvanizing offers corrosion protection for outdoor structures, greenhouse frames, and infrastructure applications exposed to weather. Surface treatment selection depends on your service environment and project specifications.
Q: What certification documents are provided for EU market projects?
A: CE marking under EN 10219 for cold-formed welded hollow sections, accompanied by Declaration of Performance and mill test certificates documenting actual chemical composition and mechanical properties. Lloyd’s Register certification and Singapore FPC are also available for projects requiring additional third-party verification.
Q: How do you handle mixed-size container loading for project shipments?
A: Professional loading plans optimize container utilization for mixed-size shipments, balancing weight distribution for heavy-wall sections and volumetric efficiency for lighter gauges. Loading diagrams are provided before shipment for client approval, and real-time tracking is available throughout transit.
Start Your S235JR A36 S355 SS400 Square Steel Tube Inquiry
Submit your specifications — steel grade, dimensions, wall thickness, quantity, and destination — to receive a detailed quotation with mill test certificate documentation and production timeline.
Company: Shandong Xin Jiyuan Special Steel Tube Co., Ltd
Website: www.sdxjysteel.com
Tel: +86 531 8573 6315
Mobile/WhatsApp/WeChat: +86 188 5315 7756
Email: admin@sdxjysteel.com
Address: No.11889, Jingshi West Road, Lulian Group, Jinan City, Shandong Province, China
