Description
Factory-direct JIS square tubes — Own steel mill with 2,800+ raw material specs ensures Q235/Q345 square steel tubes meet JIS tolerance without third-party sourcing gaps.
Technical Specifications
| Parameter | Value |
|---|---|
| Designation | Q235/Q345 Square Steel Tube (JIS Standard) |
| Product Type | Square Steel Tube |
| Steel Grade | Q195, Q215, Q235, Q345, S235JR, S275JR, S355JR |
| Standard | JIS |
| Section Shape | Square |
| Outer Diameter or Side Length | Customizable |
| Wall Thickness | Customizable |
| Length | 1–12 m (6 m / 6.4 m / 12 m available) |
| Technique | Cold Rolled / Hot Rolled |
| Surface Treatment | Black Painted / Non-oiled |
| Tolerance | ±1% |
| Ends | Plain |
| Processing Service | Welding, Punching, Cutting, Bending, Decoiling |
| Application | Construction, Mechanical engineering, Steel structure engineering, Shipbuilding, Solar power brackets, Power engineering, Power plant, Agricultural and chemical machinery, Glass curtain wall, Car chassis, Airports |
| MOQ | 10 Tons |
| Origin | Shandong, China |
Application Suitability
| Industry | Typical Applications |
|---|---|
| Steel Structure Engineering | Building frames, columns, beams, platform supports for commercial and industrial construction |
| Infrastructure Projects | Solar power brackets, airport terminal structures, power plant support systems |
| Mechanical Engineering | Equipment frames, chassis, structural supports for agricultural and chemical machinery |
| Shipbuilding | Deck structures, hatch frames, internal partition supports |
| Architectural Facades | Glass curtain wall mullions, decorative structural elements |
What Wall-Thickness Tolerance Costs on a Structural Frame Order
±1% tolerance from a vertically integrated mill eliminates the weight-discrepancy disputes that plague third-party sourced JIS standard square steel tube shipments.
When fabricators source square tubes from market stock rather than their own rolling lines, wall thickness often sits at the extreme negative edge of tolerance. On a recent Riyadh project, a third-party supplier delivered Q235 square tubes where theoretical weight and actual weight differed by nearly one ton per shipment. The ultrasonic thickness gauge told the story: every single piece was at the absolute limit of negative tolerance. That batch came from market allocation, not a dedicated production line, and dimensional control was impossible to guarantee.
For structural frames carrying load calculations based on nominal dimensions, this discrepancy triggers re-inspection costs, customs documentation challenges, and in worst cases, structural re-engineering delays. [NEED_CITE: JIS G3466 dimensional tolerance requirements for structural hollow sections]
How JIS Square Tubes Match Structural Frame Engineering Requirements
JIS standard square steel tubes in Q235 and Q345 grades serve as primary load-bearing members in steel frame construction, where predictable dimensional accuracy directly affects connection design and weld fit-up. The ±1% tolerance specification ensures that when engineers calculate moment capacity based on section properties, the actual delivered material performs within design assumptions. For solar bracket structures and airport terminal frames, where hundreds of identical connections must align, consistent side length and wall thickness prevent cumulative fit-up errors that compound across bays. Our own rolling lines produce these JIS standard square steel tube dimensions with mill test documentation that traces each heat number from raw slab to finished section.
Engineering Compliance and Surface Treatment Selection for JIS Square Tubes
Structural applications under JIS standards require material certification that confirms both chemical composition and mechanical properties meet grade specifications. Q235 serves general construction where moderate strength suffices, while Q345 provides higher yield strength for heavier load paths in industrial buildings and power plant structures. Surface treatment selection depends on exposure conditions: black painted finish suits interior applications or projects receiving field coating, while non-oiled material works for immediate welding without surface preparation delays. For projects requiring CE marking or third-party inspection, complete documentation packages including WPS, PQR, and dimensional inspection reports accompany each shipment. [NEED_CITE: steel grade equivalence between JIS, EN, and ASTM standards]
Steel Grade Selection and Cold Rolled vs Hot Rolled Process Differences
The Q-series grades (Q195, Q215, Q235, Q345) follow Chinese naming convention where the number indicates minimum yield strength in MPa, making Q345 suitable for primary structural members while Q195 serves non-structural applications. S235JR, S275JR, and S355JR represent European equivalents with JR indicating room-temperature impact toughness, allowing direct specification matching for international projects. Cold rolled square tubes offer tighter dimensional tolerance and smoother surface finish compared to hot rolled sections, making them preferable for architectural applications where appearance matters or where precise fit-up reduces welding preparation time. Hot rolled tubes typically serve structural applications where ultimate surface quality is secondary to section properties and cost efficiency. Wall thickness tolerance becomes critical when designers specify connections assuming nominal dimensions; tubes produced at extreme negative tolerance reduce effective section modulus and may require connection redesign.
The Hidden Cost of Sourcing JIS Square Tubes from Market Stock
Material traceability gaps and tolerance non-compliance create costs that far exceed initial price savings from third-party sourcing.
When square tubes come from market allocation rather than dedicated mill production, the certification chain breaks. Heat numbers on mill test certificates may not match actual material, creating compliance failures during project inspection or customs clearance. Negative tolerance stacking across multiple shipments means theoretical weight calculations diverge from actual delivered tonnage, triggering payment disputes and schedule delays. Engineering firms specifying JIS standard square steel tube for structural frames expect documentation proving material meets standard requirements; market-sourced tubes often lack complete test certificates or show inconsistent chemistry across heats. [NEED_CITE: material traceability requirements in structural steel procurement]
Why Source JIS Square Tubes from a Vertically Integrated Manufacturer
Our facility operates three production lines with direct control over raw material procurement, rolling parameters, and final inspection. This vertical integration means every JIS standard square steel tube leaving our warehouse carries documentation traceable to specific heat numbers, with chemical composition and mechanical properties verified in our own laboratory. We maintain over 2,800 raw material specifications in inventory, eliminating the need to source from external suppliers when projects require non-standard dimensions or specific grade combinations. Certified welding procedures (AWS and EN standards) and qualified welders support custom fabrication services including CNC cutting, drilling, bending, and shot blasting. Complete quality documentation packages accompany each shipment: WPS, PQR, weld maps, dimensional inspection reports, and coating reports ensure compliance with international project requirements. Third-party inspection through SGS or BV remains available upon request for projects requiring independent verification. Professional loading and lashing procedures handle oversized components and complete export documentation supports customs clearance in destination countries.
Documentation & Compliance
- Mill test certificate documenting Q235/Q345 chemical composition and mechanical properties per JIS standard, traceable to specific heat numbers from our own rolling mill
- CE certificate confirming compliance with EN 10210/EN 10219 for projects requiring European market access alongside JIS specification
- ISO 9001 quality management certificate covering the complete production process from raw material inspection through final dimensional verification
- SGS or BV third-party inspection report available upon request for projects requiring independent verification of dimensions, surface quality, and material properties
- Material traceability documentation linking each JIS standard square steel tube bundle to specific heat numbers, rolling records, and test certificates
- Complete customs documentation package including packing list, bill of lading, and certificate of origin formatted for destination country requirements
Packaging, Loading & Delivery
- Q235/Q345 square steel tubes bundled with high-tensile steel strips at regular intervals, with edge protectors preventing surface damage to black painted finish during ocean transit
- Non-oiled JIS standard square steel tube surfaces receive temporary corrosion protection suitable for typical shipping durations, with options for enhanced protection based on destination climate
- Custom length options from 1–12 meters allow container loading optimization, with 6-meter and 12-meter lengths maximizing 20-foot and 40-foot container utilization for structural applications
- Cut-to-length services available for projects requiring specific dimensions, reducing on-site waste and handling costs for solar bracket and mechanical engineering applications
- Each bundle marked with heat number, steel grade (Q235/Q345), dimensions, and production date for site identification and quality verification
- FOB, CIF, and DDP shipping terms available with professional lashing procedures for oversized structural components and complete export documentation supporting customs clearance
How to Request Quotation for JIS Standard Square Steel Tubes
Submit your project specifications including required steel grade (Q195/Q235/Q345 or S-series equivalents), dimensions, wall thickness, length, quantity, and destination port to receive detailed pricing with mill test certificate documentation. For non-standard dimensions or custom fabrication requirements including cutting, welding, or bending services, provide engineering drawings for technical review and fabrication sequencing. We confirm certification requirements, third-party inspection availability, and production lead times within 24 hours of inquiry receipt.
Get Your JIS Square Steel Tube Quote with Full Mill Test Documentation
Share your project specifications, steel grade requirements, and destination details to receive pricing with complete quality documentation.
Company: Shandong Xin Jiyuan Special Steel Tube Co., Ltd
Website: www.xjystructure.com
Tel: +86 531 8573 6315
Mobile/WhatsApp/WeChat: +86 188 5315 7756
Email: admin@xjystructure.com
Address: No.11889, Jingshi West Road, Lulian Group, Jinan City, Shandong Province, China
Frequently Asked Questions
Q: What is the difference between Q235 and Q345 steel grades for JIS standard square steel tubes?
A: Q235 provides moderate yield strength suitable for general construction and non-critical structural applications, while Q345 offers higher yield strength for primary load-bearing members in industrial buildings and heavy structures. Both grades meet JIS standard requirements with complete mill test documentation available.
Q: Can you provide third-party inspection for JIS standard square steel tube shipments?
A: Yes, SGS and BV third-party inspection services are available upon request. Inspection covers dimensional verification, surface quality assessment, material property testing, and documentation review to confirm compliance with JIS standards and project specifications.
Q: What surface treatment options are available for JIS square steel tubes?
A: We offer black painted finish for interior applications or projects receiving field coating, and non-oiled surface condition for immediate welding without surface preparation. Both options suit structural applications with standard shipping protection.
Q: What is the minimum order quantity for custom dimension JIS standard square steel tubes?
A: The minimum order quantity is 10 tons. Custom dimensions including non-standard side lengths and wall thickness are available from our own rolling lines with complete material traceability and mill test certification.
Q: How do you ensure material traceability for JIS standard square steel tubes?
A: Each production batch carries unique heat numbers traceable from raw material procurement through rolling, inspection, and final shipment. Mill test certificates document chemical composition and mechanical properties for each heat number, ensuring complete certification chain integrity.
