Description
Factory-direct galvanized square and rectangular steel tubes — every Q235B and Q345 batch leaves our warehouse with verified coating thickness and original mill test certificates, cutting out middlemen for volume buyers.
Technical Specifications
| Parameter | Value |
|---|---|
| Designation | Q235B/Q345 Galvanized Square / Rectangular Steel Tube |
| Product Type | Galvanized Square / Rectangular Steel Tube |
| Steel Grade | Q195, Q215, Q235, Q345, GR.A, GR.B, S235, S355 |
| Standard | ASTM A213, DIN EN 10217-1 |
| Section Shape | Square / Rectangular |
| Size Range | Wall thickness 0.8–30 mm |
| Length | 500 mm / 1,000 mm / 4,000 mm / 5,800 mm / 11,800 mm (customizable) |
| Technique | Welded (ERW) / Seamless |
| Surface Treatment | Pre-galvanized / Hot-dipped galvanized / Bare / Oiled / Black original steel |
| Tolerance | ±1% |
| Processing Service | Welding, Punching, Cutting, Bending, Decoiling |
| Invoicing | By theoretical weight |
| Packing | Standard seaworthy packing |
| Application | Steel structures, Steel fences, Steel posts, Warehouse construction, Building construction |
| MOQ | 10 Tons |
| Origin | Shandong, China |
Application Suitability
| Industry | Typical Applications |
|---|---|
| Construction & Infrastructure | Structural frames for warehouses, building columns, roof trusses, mezzanine supports |
| Fencing & Outdoor Structures | Perimeter fencing posts, highway guardrail supports, agricultural gate frames |
| Machinery & Equipment | Conveyor system frames, equipment support structures, machine bases |
| Steel Fabrication | Welded assemblies, bracket systems, load-bearing frameworks |
Where Galvanized Coating Thickness Decides Site Acceptance
A 25μm difference between spec and actual coating can reject half a container at the project gate.
I handled procurement for a Dubai high-rise where Q235B galvanized square tubes arrived with mill certs showing compliance, but third-party on-site testing revealed zinc coating at just 35μm against the 60μm requirement. Half the batch failed inspection, re-shipping wasn’t viable, and the project faced weeks of delay sourcing replacement material. That failure pattern repeats across global construction sites where buyers trust paper certificates without verifying actual coating thickness before loading [NEED_CITE: galvanized coating thickness verification methods for structural steel]. When sourcing a Galvanized Square Rectangular Steel Tube Supplier, the question isn’t whether certificates exist — it’s whether coating thickness gets physically measured and documented before the container leaves the factory floor.
Matching Structural Load Requirements to Steel Grade Selection
For warehouse frames and building construction, Q235B provides adequate yield strength for non-primary structural members, while Q345 delivers higher load-bearing capacity for main columns and beam systems. Our Galvanized Square Rectangular Steel Tube supply covers both grades across the full 0.8–30 mm wall thickness range, allowing engineers to specify material properties that match actual structural calculations rather than defaulting to oversized sections “just to be safe.” The hot-dipped galvanizing process ensures zinc coating penetrates corners and edges — critical for welded connections where corrosion typically initiates first.
Engineering Compliance and Certification Requirements
Structural projects in the EU require EN 10219 compliance for cold-formed welded hollow sections, while North American projects reference ASTM A500 for structural tubing [NEED_CITE: EN 10219 cold-formed hollow section requirements]. Our Q235B and Q345 galvanized tubes carry CE certification under EN 10210/EN 10219, ensuring customs clearance and project compliance across European markets. For projects requiring third-party verification, SGS or BV inspection reports document chemical composition and mechanical properties per heat number, providing traceability from raw material to finished tube.
Understanding Steel Grade Equivalence and Manufacturing Process
The Q-series (Q195–Q345) follows Chinese GB standards, while S-series (S235–S355) aligns with European EN standards — both systems specify minimum yield strength in MPa, making Q345 roughly equivalent to S355 in structural applications [NEED_CITE: steel grade equivalence between EN and ASTM standards]. Our ERW welded process produces square and rectangular tubes with consistent weld seam quality, while seamless options serve applications requiring higher pressure integrity. Pre-galvanized tubes offer cost efficiency for indoor or mild environments, while hot-dipped galvanizing provides superior corrosion resistance for outdoor exposure, coastal installations, or aggressive industrial atmospheres.
Hidden Costs of Incorrect Material Specification
Ordering Q235B when structural calculations require Q345 means oversized sections, higher transport costs, and potential re-engineering delays. Conversely, specifying Q345 for non-critical applications wastes budget on unnecessary strength. More critically, galvanized tubes with insufficient coating thickness or incomplete mill certificates face customs holds, project rejection, and costly replacement cycles. The ±1% tolerance standard means theoretical weight invoicing can diverge from actual weight — understanding this calculation method prevents budget overruns on large-volume orders [NEED_CITE: theoretical weight calculation for steel tubes].
Procurement Confidence Through Verified Supply Chain
As a Galvanized Square Rectangular Steel Tube Supplier operating since 2013, we maintain 2,800+ specifications in ready stock across Q195–Q345 grades, enabling immediate dispatch for standard sizes while custom orders complete within typical production lead times. Our in-house metallurgical lab conducts three-stage inspection — raw material verification, in-process weld quality, and final coating thickness measurement — before any batch receives mill test certification. Every container benefits from professional loading optimization: 11,800 mm tubes maximize 40ft container capacity, while mixed-size loading consolidates multi-specification orders into single shipments serving 50+ countries.
Documentation & Compliance
- Mill test certificate documenting Q235B/Q345 chemical composition and yield strength per ASTM A213 and DIN EN 10217-1
- CE certificate confirming compliance with EN 10210/EN 10219 for European structural applications
- ISO 9001:2015 quality management certification covering production and inspection processes
- SGS or BV third-party inspection report available for independent coating thickness and mechanical property verification
- Material traceability by heat number linking each tube to original steel coil certification
- Complete customs documentation including packing list, bill of lading, and certificate of origin
Packaging, Loading & Delivery
- Hot-dipped galvanized tubes bundled with edge protectors and waterproof wrapping to preserve zinc coating integrity during ocean transit
- 11,800 mm standard length optimized for 40ft container loading, maximizing volume while preventing transit damage
- Pre-galvanized and bare tubes packed in steel strip bundles with anti-rust oil coating for surface protection
- Custom cutting to 500 mm–5,800 mm lengths available, with each bundle labeled by heat number, steel grade, and dimensions
- FOB, CIF, and DDP shipping terms with professional export documentation handling for smooth customs clearance
Securing Your Galvanized Tube Supply with Verified Specifications
Submit your project requirements — steel grade, dimensions, wall thickness, surface treatment, and destination port — to receive competitive bulk pricing with volume discounts, delivery timelines, and mill test certificate samples. Our engineering team reviews specifications for grade equivalence and coating suitability, ensuring your Galvanized Square Rectangular Steel Tube order matches both structural requirements and environmental conditions.
Request Your Galvanized Square Rectangular Steel Tube Quote
Send specifications via email or WhatsApp to receive factory-direct pricing, coating thickness verification reports, and CE certification documentation within 12 hours.
Contact: admin@sdxinjiyuan.com | WhatsApp: +86 188 5315 7756
Frequently Asked Questions
Q: What is the difference between pre-galvanized and hot-dipped galvanized finish for square tubes?
A: Pre-galvanized tubes receive zinc coating before forming, resulting in thinner coating (typically 20–40μm) suitable for indoor or sheltered applications. Hot-dipped galvanizing immerses finished tubes in molten zinc, producing thicker coating (60μm and above) with superior corrosion resistance for outdoor, coastal, or industrial environments.
Q: Can you produce non-standard dimensions outside your listed size range?
A: Yes. While our ready stock covers standard specifications, our three production lines handle custom orders for non-standard wall thickness, special lengths, and unique cross-section dimensions. Minimum order quantity for custom production is 10 tons, with typical lead times for non-standard specifications.
Q: How do Q235B and Q345 steel grades compare to European S235 and S355 standards?
A: Q235B and S235 both specify minimum 235 MPa yield strength, making them structurally equivalent for most applications. Q345 and S355 both require minimum 345 MPa yield strength. Our Galvanized Square Rectangular Steel Tube supply covers both systems, with mill test certificates documenting actual test results per the specified standard.
Q: Do your CE certificates ensure smooth customs clearance in European markets?
A: Yes. Our CE certification under EN 10210/EN 10219 confirms compliance with European structural steel requirements. Each shipment includes complete documentation — CE certificate, mill test certificates, packing list, and certificate of origin — preventing customs delays and project compliance issues.
Q: How is invoicing calculated — by theoretical weight or actual weight?
A: We invoice by theoretical weight based on standard density calculations for the specified dimensions and steel grade. The ±1% tolerance means actual weight may vary slightly from theoretical calculation. We provide detailed weight calculation sheets with each quotation for transparent budgeting.
Get Factory-Direct Galvanized Steel Tubes with Verified Coating
Submit your project specifications to receive competitive pricing, mill test certificates, and CE documentation — delivered directly from our production facility to your project site.
Contact: admin@sdxinjiyuan.com | WhatsApp: +86 188 5315 7756
