Description
Factory-Direct Supply, No Middlemen — Every Q235 welded square steel tube rolls out of our own Jinan production lines, cutting out trading markups so your project budget stays on track.
Technical Specifications
| Parameter | Value |
|---|---|
| Designation | Q235 Welded Square Steel Tube |
| Product Type | Welded Square and Rectangular Steel Tube |
| Steel Grade | Q195, Q235, Q345 |
| Standard | ASTM, JIS, DIN |
| Section Shape | Square / Rectangular |
| Size Range | 100×100 mm – 500×500 mm |
| Wall Thickness | 0.5 – 30 mm |
| Length | 6 – 12 m |
| Technique | Hot Rolled / Cold Rolled (Welded) |
| Surface Treatment | Hot Rolled (Black / Oiled / Non-oiled) |
| Tolerance | ±1% |
| Ends | Plain |
| Application | Steel structures / Construction frames / Bridges / Building material / Machinery / Roofing structures |
| MOQ | 5 Tons |
| Origin | Shandong, China |
Application Suitability
| Industry | Typical Applications |
|---|---|
| Construction & EPC | Building frames, column supports, roof trusses for commercial and industrial facilities |
| Steel Structure Fabrication | Primary and secondary structural members for warehouses, workshops, and multi-story buildings |
| Infrastructure & Bridges | Bridge railings, pedestrian walkway supports, sound barrier frames |
| Machinery & Equipment | Equipment bases, conveyor frame structures, crane boom sections |
| Roofing & Facade Systems | Purlin supports, curtain wall sub-frames, architectural facade grids |
What Dimensional Tolerance Actually Means When Your Frame Won’t Square Up
A ±1% tolerance on a 500×500 Q235 welded square steel tube keeps bolt holes aligned and weld joints tight across an entire structural bay.
Buyers who source Q235 welded square steel tube from multiple suppliers often discover that tubes from different mills don’t stack or mate properly on site. One batch measures 498mm, the next 503mm — and suddenly your fabricator is grinding, re-drilling, or scrapping cut pieces. On a 200-ton structural frame order, that tolerance drift compounds into days of rework and thousands in labor cost. [NEED_CITE: EN 10219 dimensional tolerance requirements for cold-formed structural hollow sections]
How Q235 Welded Square Steel Tube Fits Structural Frame Engineering
When engineers specify Q235 welded square steel tube for building frames and machinery bases, they’re balancing yield strength against fabrication cost. The Q235 grade delivers sufficient load-bearing capacity for most non-heavy-industrial structures while remaining easy to weld, drill, and bolt on site. Our 100×100 to 500×500 mm range with wall thickness up to 30 mm covers everything from light purlin supports to heavy column sections. The ±1% tolerance means your fabricator receives consistent geometry — no surprise fit-up gaps when 12-meter lengths meet at moment connections.
Meeting Engineering Codes and Customs Requirements
Structural frames for export projects must satisfy both design codes and import regulations. Q235 welded square steel tube produced under ASTM, JIS, or DIN standards provides the documentation trail that customs agents and third-party inspectors require. For EU-bound shipments, our CE certification under EN 10219 and EN 10210 ensures the tubes clear Rotterdam or Hamburg without delay. [NEED_CITE: CE marking requirements for structural steel hollow sections under EN 10210] The 6–12 m length range aligns with standard container dimensions, reducing on-site splicing and preserving structural continuity.
Understanding Q235 Grade and Welded Tube Manufacturing
Q235 sits in the mild carbon steel range, offering good ductility and weldability without the hardness that complicates field connections. Compared to Q345, Q235 requires less preheat for thick-section welding and accepts standard E6013 or E7018 electrodes without special procedures. The welded manufacturing process — whether hot-rolled or cold-formed — creates a longitudinal seam that, when properly controlled, delivers consistent mechanical properties around the entire perimeter. Surface treatment options (black, oiled, or non-oiled) let you choose between immediate rust protection during transit or a clean surface ready for galvanizing or painting at destination.
The Hidden Cost of Unverified Wall Thickness
Ordering Q235 welded square steel tube based on price alone often means accepting negative tolerance beyond standard limits. A 10mm wall specified at 9.2mm actual reduces load capacity and fails third-party inspection — triggering container rejection, air-freight replacement, or costly on-site reinforcement. [NEED_CITE: ASTM A500 wall thickness tolerance requirements for structural tubing] Certification gaps compound the problem: missing mill test certificates or incorrect EN standard references block EU customs clearance, stranding your cargo in port while demurrage charges accumulate.
Why Projects Specify Our Q235 Welded Square Steel Tube
We manufacture Q235 welded square steel tube in our own Jinan facility with 3 dedicated production lines covering 2,800+ specifications — no trading company markup between mill and job site. Every heat runs through our in-house physical and chemical laboratory before shipping, generating mill test certificates that document actual chemistry and mechanical results. Our 41 invention patents include China’s original sharp-corner rectangular tube technology, filling gaps where standard rounded-corner tubes fail architectural facade requirements. Full international certifications (ISO 9001:2015, Lloyd’s CE EN 10219/10210, Singapore FPC, SGS/BV verification) support exports to 50+ countries. Custom non-standard sizes and cut-to-length service keep your MOQ at 5 tons while matching exact project requirements.
Documentation & Compliance
- Mill test certificate documenting Q235 chemical composition (C, Mn, Si, P, S) and yield strength per ASTM / JIS / DIN standards
- CE certificate under EN 10219 and EN 10210 for EU market access and customs clearance
- ISO 9001:2015 quality management certificate covering welded tube production processes
- SGS or BV third-party inspection report verifying dimensional accuracy and surface condition before loading
- Material traceability by heat number linking each Q235 welded square steel tube to its production batch and test results
- Complete customs documentation including packing list, bill of lading, and certificate of origin
Packaging, Loading & Delivery
- Q235 welded square steel tube bundled with steel strips and edge protectors to prevent surface damage during ocean transit
- Oiled surface treatment applied to black finish tubes for corrosion protection during long-distance shipping
- Container loading optimized for 6m and 12m lengths to maximize payload and minimize freight cost per ton
- Cut-to-length service available for 100×100 to 500×500 mm sections, reducing on-site waste and handling
- Heat number and steel grade marked on each tube for site identification and inspection traceability
- FOB, CIF, and DDP shipping terms with professional container loading to prevent bending and deformation
Ready to Lock in Pricing and Mill Test Certificates
Submit your Q235 welded square steel tube requirements — section size, wall thickness, length, quantity, and destination port — and receive a detailed quotation with mill test certificate samples within 12 hours. We’ll confirm third-party inspection availability, CE certification status, and container loading plans before you sign the proforma invoice.
Frequently Asked Questions
Q: Can you provide Q235 welded square steel tube with CE certification for EU projects?
A: Yes, our welded square and rectangular tubes carry full CE certification under EN 10219 and EN 10210, issued by Lloyd’s Register. Every shipment to EU ports includes the Declaration of Performance and factory production control documentation required for customs clearance.
Q: What is the minimum order quantity for custom non-standard sizes?
A: Our MOQ is 5 tons for standard specifications. For custom non-standard sizes outside the 100×100 to 500×500 mm range, we can accommodate project-specific requirements through our 2,800+ specification coverage — contact us with your drawing or dimension sheet for feasibility confirmation.
Q: How do you ensure wall thickness meets ASTM A500 tolerance requirements?
A: Every production batch undergoes dimensional inspection in our in-house laboratory using calibrated ultrasonic thickness gauges. We provide mill test certificates documenting actual measurements, and third-party inspection by SGS or BV is available upon request before container loading.
Q: Can you supply Q235 welded square steel tube with galvanized surface treatment?
A: Yes, we offer hot-dip galvanizing service for welded square and rectangular tubes. Galvanized coating provides long-term corrosion protection for outdoor structural applications. Lead time for galvanized orders is typically longer than black finish — confirm current production schedule when placing your inquiry.
Q: Do you provide professional container loading to prevent tube damage during shipping?
A: Yes, our loading team uses specialized techniques for welded square steel tube including wooden cradles, steel strip bundling, and edge protectors. We photograph each loaded container before sealing and provide loading plans showing weight distribution to prevent shifting during ocean transit.
Request Your Q235 Welded Square Steel Tube Quotation Today
Send your specifications — section size, wall thickness, length, quantity, and destination — to receive pricing and mill test certificate samples within 12 hours.
Contact:
Mobile/WhatsApp/WeChat: +86 188 5315 7756
Email: admin@sdxjypipe.com
Website: www.sdxjypipe.com
