Description
Factory-direct pricing with in-house lab verification — Every batch of Q235 Q345 hot dip galvanized ERW square steel tube ships with original mill test certificates and third-party inspection reports from our own physical and chemical laboratory, eliminating middlemen markups and quality guesswork.
Technical Specifications
| Parameter | Value |
|---|---|
| Designation | Q235 / Q195 / Q345 / A36 Hot Dip Galvanized ERW Square Steel Tube |
| Product Type | Welded Square and Rectangular Steel Tube |
| Steel Grade | Q235, Q195, Q345, ASTM A36 |
| Standard | ASTM |
| Section Shape | Square / Rectangular / Round |
| Size Range | 10×10mm – 600×600mm |
| Wall Thickness | 0.5mm – 12.0mm |
| Length | 1m – 12m or customized |
| Technique | ERW (Electric Resistance Welded) |
| Surface Treatment | Hot Dip Galvanized / Black / PVC Coated / Color Painting |
| Tolerance | ±1% |
| Coating | Z10 – Z29 |
| Hardness | Full Hard |
| Spangle Type | Regular Spangle |
| Ends | Plain |
| Application | Steel structures / Construction frames / Fences / Furniture frames / Machinery / Scaffolding / Container manufacturing / Corrugated sheet production / Engineering supports / Handrails / Exterior decoration |
| MOQ | 1 Ton |
| Origin | Shandong, China |
Application Suitability
| Industry | Typical Applications |
|---|---|
| Construction & Infrastructure | Building frames, scaffolding systems, handrails, structural supports for high-rise and bridge projects |
| Industrial & Machinery | Container manufacturing, machinery frames, engineering supports, conveyor structures |
| Architectural & Decorative | Fences, furniture frames, exterior decoration panels, curtain wall supports |
Where Coating Thickness Decides Project Acceptance
Inconsistent zinc coating is the number one reason galvanized tubes fail third-party inspection at destination ports.
I have seen entire containers of galvanized square tubes held up at Riyadh customs because the coating measured 45 microns instead of the contracted 70. The buyer paid for re-galvanizing locally — a cost that wiped out the original price advantage. With our Q235 Q345 hot dip galvanized ERW square steel tube, every heat number is tested in our in-house laboratory before loading. The coating weight (Z10–Z29) is documented on the mill test certificate, and SGS or BV can verify it independently before the container is sealed. [NEED_CITE: hot dip galvanized coating thickness standards for structural steel]
Matching Structural Load Requirements to Wall Thickness
For scaffolding and structural frames, the 0.5mm–12.0mm wall thickness range of Q235 Q345 hot dip galvanized ERW square steel tube covers everything from light-duty handrail posts to heavy-load container corner castings. The ±1% dimensional tolerance ensures that connection plates and gussets fit without on-site reaming. Our 2,800+ specification inventory means you can source 10×10mm small sections and 600×600mm large sections from a single production batch, maintaining consistent steel grade and coating quality across your entire bill of materials.
Compliance with International Structural Codes
Projects in the EU require CE certification under EN 10210/EN 10219, while North American buyers typically specify ASTM A500 or A36 equivalence. Our Q235 Q345 hot dip galvanized ERW square steel tube meets both frameworks, with mill test certificates showing chemical composition and mechanical properties mapped to the relevant standard. Singapore FPC certification opens Southeast Asian government projects. [NEED_CITE: EN 10219 cold-formed hollow section requirements]
Understanding Steel Grade Selection for Galvanized Tubes
Q195 offers the lowest carbon content, making it ideal for cold bending and furniture frames where formability matters more than load-bearing capacity. Q235 is the workhorse grade for general construction — balanced strength and weldability at competitive pricing. Q345 (equivalent to S355JR in EN standards) delivers higher yield strength for structural frames carrying heavier loads, reducing section size and weight. ASTM A36 serves North American projects requiring direct standard compliance. The ERW welding process produces a clean, straight seam that accepts hot dip galvanizing uniformly, with the zinc coating bonding metallurgically to the steel surface for long-term corrosion protection.
The Hidden Cost of Unverified Coating and Grade
Purchasing galvanized tubes without mill test certificates or third-party inspection creates three failure points: coating thickness below specification leads to premature rust and rejection at handover; steel grade substitution (Q195 shipped as Q235) causes structural deflection under design loads; and missing CE or ISO documentation triggers customs delays that idle cranes and crews at the project site. [NEED_CITE: steel grade equivalence between GB Q series and EN S series]
Why Global Buyers Source From Xin Jiyuan
We operate three dedicated production lines with in-house physical and chemical laboratories — every Q235 Q345 hot dip galvanized ERW square steel tube is tested for coating adhesion, thickness, and chemical composition before shipment. Our 41 invention patents include proprietary sharp-corner rectangular tube technology that eliminates the radius at corners, improving connection fit-up for structural frames. With 2,800+ specifications in stock and custom non-standard sizes available, you consolidate procurement across square, rectangular, and round sections from a single factory. CE (EN 10210/10219), ISO 9001:2015, Singapore FPC, and SGS/BV verification ensure your documentation clears customs in the EU, North America, and Southeast Asia. Professional loading plans optimize container weight for 1m–12m lengths, and door-to-door logistics cover 50+ countries.
Documentation & Compliance
- Mill test certificate documenting Q235/Q345 chemical composition, yield strength, and hot dip galvanized coating weight (Z10–Z29) per heat number
- CE certificate under EN 10210/EN 10219 for European structural projects requiring factory production control
- ISO 9001:2015 quality management certificate covering ERW welding, hot dip galvanizing, and final inspection processes
- SGS or BV third-party inspection report verifying coating thickness, dimensional tolerance (±1%), and surface quality before container sealing
- Material traceability by heat number linking each bundle to its original steel coil test report
- Customs documents including packing list, bill of lading, and certificate of origin formatted for destination port requirements
Packaging, Loading & Delivery
- Hot dip galvanized Q235 Q345 square steel tubes bundled with steel strips and edge protectors to prevent zinc coating damage during ocean transit
- Surface protection maintained through proper stacking separation and moisture barriers for Z10–Z29 coated sections
- Container loading optimized for 1m–12m lengths with weight distribution plans maximizing 20ft and 40ft payload capacity
- Custom cutting to project-specific lengths available, reducing on-site waste and handling for scaffolding and frame assembly
- Heat number and steel grade (Q235/Q345/A36) marked on each bundle for site identification and inspection traceability
- FOB, CIF, and DDP shipping options with real-time tracking to ports across the EU, North America, Middle East, and Southeast Asia
Getting Your Quote and Mill Test Certificate
Submit your specifications — section size, wall thickness, steel grade, coating requirement (Z10–Z29), quantity, and destination port — and receive a detailed quotation within 12 hours including unit price, delivery timeline, payment terms, and applicable certification documents. Request original mill test certificates and arrange SGS or BV third-party inspection before shipment to verify coating thickness and dimensional compliance.
Frequently Asked Questions
Q: What is the difference between hot dip galvanized and pre-galvanized steel tubes, and which coating thickness suits my project environment?
A: Hot dip galvanized coating (Z10–Z29) provides thicker zinc coverage with metallurgical bonding to the steel substrate, offering superior corrosion resistance for outdoor and industrial environments. Pre-galvanized tubes have thinner electroplated coatings suitable for indoor or dry conditions. For coastal, high-humidity, or chemical exposure applications, hot dip galvanized Q235 Q345 ERW square steel tubes with Z20 or higher coating weight are recommended.
Q: Can you provide mill test certificates and arrange third-party inspection before shipment?
A: Yes. Every batch of Q235 Q345 hot dip galvanized ERW square steel tube ships with original mill test certificates documenting chemical composition, mechanical properties, and coating weight. SGS or BV third-party inspection can be arranged to verify coating thickness, dimensional tolerance, and surface quality before container sealing.
Q: What are the available steel grade equivalents between GB (Q235/Q345), ASTM (A36), and EN standards?
A: Q235 corresponds approximately to S235JR (EN 10025) and ASTM A36 in yield strength range. Q345 aligns with S355JR (EN 10025) and ASTM A572 Grade 50. Mill test certificates can include cross-reference tables showing chemical composition and mechanical properties mapped to multiple international standards for customs and engineering approval.
Q: Do you accept custom non-standard sizes beyond the 10×10–600×600mm range, and what is the MOQ?
A: Yes. Beyond the standard 10×10mm to 600×600mm range with 0.5mm–12.0mm wall thickness, we produce custom non-standard sizes and special profiles through our dedicated production lines. The MOQ is 1 Ton, with typical production lead times for custom specifications confirmed at quotation stage.
Q: How do you ensure coating uniformity and adhesion for hot dip galvanized tubes?
A: Our in-house physical and chemical laboratory tests coating adhesion through bend tests and measures thickness at multiple points per bundle using magnetic gauges. The hot dip galvanizing process ensures metallurgical bonding between zinc and steel substrate. Coating weight (Z10–Z29) is documented on mill test certificates, and third-party inspection (SGS/BV) can verify compliance before shipment.
[Request Your Quotation and Mill Test Certificate Today]
Send your specifications — section size, wall thickness, steel grade, coating requirement, quantity, and destination port — to receive a detailed quotation within 12 hours, including original mill test certificates and applicable CE/ISO/SGS documentation.
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
