Description
Factory-Direct ERW Square Tubes — Produced on 3 dedicated lines covering 2,800+ specifications with wall thickness up to 40 mm, shipped with full mill test certificates and professional container loading.
Technical Specifications
| Parameter | Value |
|---|---|
| Designation | Q195/Q235/Q345/S355JR Welded Square Steel Tube |
| Product Type | Welded Square Steel Tube (ERW) |
| Steel Grade | Q195, Q235, Q345, S235JR, S275JR, S355JR |
| Standard | ASTM |
| Section Shape | Square |
| Wall Thickness | 0.9 mm |
| Length | 6 m / 6.4 m / 12 m |
| Technique | ERW (Electric Resistance Welded) |
| Surface Treatment | Hot Rolled |
| Tolerance | ±1% |
| Ends | Plain |
| Oiled or Non-oiled | Non-oiled |
| Processing Service | Welding, Punching, Cutting, Bending, Decoiling |
| Application | Fluid Pipe, Boiler Pipe, Drill Pipe, Hydraulic Pipe, Gas Pipe, Oil Pipe, Chemical Fertilizer Pipe, Structure Pipe |
| MOQ | 1 Ton |
| Origin | Shandong, China |
Application Suitability
| Industry | Typical Applications |
|---|---|
| Construction & Infrastructure | Building frames, scaffolding systems, bridge support structures |
| Industrial Machinery | Equipment bases, conveyor frames, hydraulic cylinder housings |
| Oil & Gas | Gas transmission lines, chemical fertilizer distribution pipes, drilling support pipes |
| Energy & Power | Boiler tubes, fluid conveyance systems, hydraulic pipelines |
What Wall-Thickness Tolerance Costs on a Carbon Steel Welded Square Steel Tube Order
A ±1% tolerance on 0.9 mm wall thickness means every meter either meets structural design loads or triggers rejection at site inspection.
Procurement teams ordering Carbon Steel Welded Square Steel Tube often discover mid-project that wall thickness deviates beyond acceptable limits. When theoretical weight calculations diverge from actual measured weight, the entire batch faces SGS re-inspection, customs delays, or outright rejection. Missing mill test certificates compound the problem — without verified chemical composition and mechanical properties, engineers cannot confirm grade compliance, forcing costly reordering from alternative suppliers while project timelines slip.
Matching ERW Welded Square Tubes to Structural and Fluid Applications
The 0.9 mm wall thickness and ±1% tolerance make these ERW welded square tubes suitable for light-to-medium structural frames and fluid conveyance systems where precision dimensions matter more than extreme pressure ratings. Hot rolled surface treatment provides adequate corrosion resistance for indoor structural applications, while plain ends allow on-site welding and punching without additional preparation. The multi-grade availability from Q195 through S355JR enables single-source procurement for mixed-specification projects, reducing logistics complexity and certification management overhead.
Engineering Compliance and Grade Selection for ASTM Standard Tubes
ASTM standard compliance ensures these welded square tubes meet North American procurement specifications for structural and fluid applications. The Q-series grades (Q195, Q235, Q345) correspond to Chinese GB standards, while S-series grades (S235JR, S275JR, S355JR) align with European EN specifications — understanding this equivalence prevents ordering errors when projects span multiple regulatory frameworks [NEED_CITE: steel grade equivalence between EN and ASTM standards]. For EU-bound shipments, CE certification under EN 10219 cold-formed hollow sections becomes mandatory for customs clearance, while ASTM A500 Grade B/C/D applies to North American structural applications. The 6 m, 6.4 m, and 12 m length options accommodate standard container configurations and on-site cutting requirements, minimizing secondary fabrication costs at destination.
Understanding ERW Process and Hot Rolled Surface Treatment
Electric Resistance Welding creates longitudinal seams through high-frequency current without filler material, producing consistent weld quality suitable for structural and low-to-medium pressure fluid applications. The hot rolled surface treatment removes mill scale and provides a clean finish ready for painting, galvanizing, or direct installation in non-corrosive environments. Wall thickness at 0.9 mm represents the thin-wall category, where dimensional tolerance becomes critical — even minor deviations significantly affect weight calculations and structural load capacity. Processing services including cutting, punching, bending, and welding allow fabrication-ready delivery, reducing labor costs and quality control variables at construction sites.
Hidden Costs of Incorrect Grade Selection and Missing Documentation
Ordering Q235 when project specifications require S355JR creates structural safety risks that only surface during load testing or inspection — by then, replacement costs include not just material but demolition, reinstallation, and project delay penalties. Missing CE marks on EU-bound shipments trigger customs holds averaging weeks, while incomplete mill test certificates force third-party testing at buyer’s expense. Negative tolerance exceeding contractual limits means theoretical weight pricing becomes actual weight overcharge, with disputes consuming procurement resources long after delivery.
Why Source Carbon Steel Welded Square Steel Tube from SD XJY Pipe
Our in-house physical and chemical laboratory tests every batch for dimensional accuracy, mechanical properties, and chemical composition before shipment, providing full mill test certificates with heat number traceability. The 3 dedicated production lines cover 2,800+ specifications including non-standard sizes and custom lengths, eliminating the need to split orders across multiple suppliers. Full international certifications — ISO 9001:2015, Lloyd’s CE (EN 10210/10219), Singapore FPC, and SGS/BV verification — ensure customs clearance across 50+ destination countries. Professional container loading with anti-damage measures prevents bending and surface scratches during ocean transit, while our patented sharp-corner rectangular tube technology (41 invention patents) serves architectural applications requiring true right-angle aesthetics.
Documentation & Compliance
- Mill test certificate documenting Q195/Q235/Q345/S355JR chemical composition and mechanical properties per ASTM standard
- CE certificate under EN 10219 for cold-formed structural hollow sections, required for EU customs clearance
- ISO 9001:2015 quality management system certificate covering production and inspection processes
- SGS or BV third-party inspection report available upon request for independent verification
- Material traceability by heat number linking each tube to production batch and test results
- Complete customs documentation including packing list, bill of lading, and certificate of origin
Packaging, Loading & Delivery
- ERW welded square tubes bundled with steel strips and edge protectors to maintain 0.9 mm wall thickness integrity during handling
- Hot rolled surface treatment requires no additional coating protection, but bundles are wrapped to prevent moisture contact during ocean transit
- 6 m, 6.4 m, and 12 m lengths optimized for 20ft and 40ft container configurations, maximizing payload while preventing overhang damage
- Custom cutting services available to deliver fabrication-ready lengths, reducing on-site waste and labor costs
- Heat number and steel grade marked on each tube for site identification and quality traceability
- FOB, CIF, and DDP shipping terms available with professional loading plans preventing tube deformation
Getting Your Carbon Steel Welded Square Steel Tube Quote
Submit your specifications including steel grade (Q195 through S355JR), dimensions, wall thickness, quantity, and destination port to receive detailed pricing with mill test certificates and certification documents within 12 hours. For non-standard sizes or custom lengths beyond the 6 m / 6.4 m / 12 m range, our engineering team provides fabrication drawings and production timelines. Confirm CE/ASTM certification requirements and third-party inspection needs before contract signing to ensure smooth customs clearance at destination.
Frequently Asked Questions
Q: How do Q235/Q345 grades compare to S235JR/S355JR and ASTM equivalents?
A: Q235 corresponds roughly to S235JR in yield strength, while Q345 aligns with S355JR. ASTM A500 Grade B provides similar mechanical properties to Q235, while Grade C matches Q345/S355JR performance. Always confirm grade equivalence with project engineers before substitution, as chemical composition requirements may differ between standards.
Q: What is the MOQ for custom non-standard sizes?
A: Standard sizes ship from stock with 1 Ton MOQ. Custom non-standard sizes and special lengths require minimum production runs — contact us with your specifications for exact MOQ and production timelines based on current mill scheduling.
Q: Can you provide third-party inspection before shipment?
A: Yes, SGS and BV third-party inspections are available upon request. Our in-house laboratory performs dimensional, mechanical, and chemical testing first, then third-party inspectors verify results independently. Inspection costs and scheduling depend on order volume and destination requirements.
Q: How are these tubes packed to prevent damage during ocean freight?
A: ERW welded square tubes are bundled with steel strips, separated by edge protectors, and loaded with anti-damage measures including wooden cradles for heavy wall sections. Professional loading plans maximize container space while preventing bending, surface scratches, and weld seam damage during transit.
Get Your Carbon Steel Welded Square Steel Tube Quote with Mill Test Certificates
Send your specifications — steel grade, dimensions, wall thickness, quantity, and destination — to receive pricing, mill test certificates, and certification documents within 12 hours.
Company: Shandong Xin Jiyuan Special Steel Tube Co., Ltd
Website: www.sdxjypipe.com
Tel: +86 531 8573 6315
Mobile/WhatsApp/WeChat: +86 188 5315 7756
Email: admin@sdxjypipe.com
