Description
Factory-Direct Galvanized SHS/RHS — Q195 to Q345 grades produced on our own ERW lines with in-house galvanizing, eliminating trader markups and specification mismatches.
Technical Specifications
| Parameter | Value |
|---|---|
| Designation | Q195 Q235 Pre Galvanized Square and Rectangular Steel Tube |
| Product Type | Galvanized Square and Rectangular Steel Tube (SHS/RHS) |
| Steel Grade | Q195, Q215, Q235, Q345 |
| Standard | BS, EN, GB, AISI, ASTM, DIN, JIS |
| Section Shape | Square, Rectangular, Round |
| Size Range | Customizable outer diameter / side length |
| Wall Thickness | 0.6–28 mm |
| Length | 1–12 m or customized |
| Technique | ERW (Electric Resistance Welded) |
| Surface Treatment | Pre Galvanized, Hot Dip Galvanized, PVC Coated, Black and Color Painting |
| Tolerance | ±1% |
| Ends | Plain (default) |
| Processing Service | Welding, Punching, Cutting, Bending, Decoiling |
| Application | Fluid Pipe, Gas Pipe, Oil Pipe, Structure Pipe, Steel Structures, Construction Frames, Machinery, Scaffolding |
| MOQ | 10 Ton |
| Origin | Shandong, China |
Application Suitability
| Industry | Typical Applications |
|---|---|
| EPC Contractors & Construction | Building frames, high-rise structural columns, bridge support members, scaffolding systems |
| Machinery Manufacturers | Conveyor frames, automation equipment bases, precision structural components |
| Infrastructure & Industrial | Fluid transport lines, gas distribution piping, oil field support structures |
Where Galvanizing Thickness Decides Port Acceptance
A 40 μm zinc layer passing factory inspection but failing SGS复检 at destination port turns a profitable shipment into a demurrage bill.
I have watched entire containers of galvanized square tubes sit at Jebel Ali because the coating measured below contract spec. Pre-galvanized and hot-dip galvanized processes produce fundamentally different zinc thicknesses, and without in-house coating measurement before loading, buyers inherit the risk. When your Q235 galvanized square steel tube supplier ships without a coating thickness report attached to the mill test certificate, customs inspectors at the destination port have every reason to hold the cargo for third-party re-inspection. [NEED_CITE: EN 10219 cold-formed hollow section requirements]
Matching Wall Thickness to Structural Load Paths
A Q235 galvanized square steel tube selected for a conveyor frame carries different demands than the same grade used in scaffolding. The 0.6–28 mm wall thickness range covers light-gauge framing all the way to heavy structural columns, but the ±1% tolerance means a 10 mm wall tube can legally arrive at 9.9 mm. For load-bearing frames designed to EN 1993, that difference must be accounted for in the original engineering calculation. Our ERW welding process produces a consistent seam that meets EN 10219 dimensional tolerances, and the 2,800+ specification catalog means non-standard sizes do not require minimum-order compromises that delay project timelines.
Structural Compliance and Certification Alignment
European EPC contractors specifying cold-formed hollow sections need documentation that traces back to EN 10219-1 and EN 10219-2 for tolerances and sectional properties. [NEED_CITE: EN 10219 dimensional tolerance requirements for structural hollow sections] Our CE certification under EN 10210/EN 10219 covers the full Q195–Q345 grade range, and each heat number links to chemical composition and mechanical test data from our physical laboratory. For North American projects, the same production lines deliver tubes conforming to ASTM A500, with mill test certificates formatted to satisfy both AISC referencing requirements and customs documentation. [NEED_CITE: steel grade equivalence between Q series and ASTM standards]
Understanding Q-Grade Steels and ERW Welding
The Q-series designation (Q195, Q215, Q235, Q345) follows the Chinese GB standard system where the number indicates minimum yield strength in MPa. Q235 remains the workhorse grade for general structural frames because it balances formability with adequate strength, while Q345 serves higher-load applications without requiring thicker walls. ERW welding uses high-frequency current to fuse the tube seam, producing a weld zone with mechanical properties comparable to the base metal when properly controlled. Pre-galvanized coating applies zinc before forming, giving uniform coverage but thinner layers; hot-dip galvanizing coats the finished tube, producing thicker zinc at the cost of slightly rounded corners. For outdoor scaffolding and marine-adjacent structures, hot-dip galvanizing delivers superior corrosion resistance; for indoor machinery frames, pre-galvanized finish provides adequate protection at lower cost.
The Hidden Cost of Unverified Coating Thickness
Ordering Q235 galvanized square steel tube based on price alone ignores the failure modes that emerge after delivery. Zinc coating below contract specification triggers rejection at project inspection, forcing either re-galvanizing at local cost or complete material replacement. Missing or incomplete mill test certificates delay customs clearance in the EU, where CE marking under EN 10219 is mandatory for structural hollow sections. [NEED_CITE: CE marking requirements for structural steel products in EU construction] Negative tolerance stacking across multiple batches can reduce actual structural capacity below design assumptions, creating liability exposure that no price discount justifies.
Procurement Confidence Built on Verifiable Controls
Every Q195 Q235 Pre Galvanized Square and Rectangular Steel Tube we produce passes through our in-house physical and chemical laboratory before leaving the mill. We hold 41 invention patents including proprietary sharp-corner rectangular tube technology that eliminates the gap problems standard rolls leave at corners. Our three dedicated production lines cover 2,800+ specifications, so non-standard dimensions do not require sourcing from multiple suppliers. Factory-direct pricing means no trader margins inflate your unit cost, and our export team has shipped galvanized tubes to 50+ countries with complete documentation packages that clear customs on first submission. Professional loading plans optimize container space for your specific length and section combination, reducing freight cost per ton.
Documentation & Compliance
- Mill test certificate documenting Q195/Q235/Q345 chemical composition and mechanical properties per heat number
- CE certificate confirming compliance with EN 10210/EN 10219 for structural hollow section applications in EU markets
- ISO 9001:2015 quality management system certificate covering the full production and testing process
- SGS or BV third-party inspection report available for coating thickness, dimensional verification, and material traceability
- Material traceability report linking each bundle to heat number, production date, and test results
- Complete customs documentation package including packing list, bill of lading, and certificate of origin
Packaging, Loading & Delivery
- Q195–Q345 galvanized tubes bundled with steel strips and edge protectors to preserve zinc coating during ocean transit
- Pre-galvanized and hot-dip galvanized surfaces separated during loading to prevent zinc scratching and coating damage
- Container loading plans optimized for 1–12 m lengths to maximize payload per 20ft or 40ft container
- Custom cutting to project-specified lengths available before shipment, reducing on-site waste and handling
- Heat number and steel grade stenciled on each bundle for site identification and traceability verification
- FOB, CIF, and DDP shipping terms available with door-to-door logistics coordination to 50+ countries
Submit Specifications for Project Pricing
Send your required section dimensions, wall thickness, steel grade, quantity, and destination port to receive a detailed quotation including unit price, production lead time, and applicable certification documentation. Our engineering team reviews non-standard size requests within one working day and provides mill test certificate samples for quality confirmation before contract signing.
Request Your Quotation with Mill Test Certificate
Submit your specifications via email at admin@sdxjysteel.com or contact us by phone at +86 531 8573 6315, WhatsApp/WeChat at +86 188 5315 7756.
Frequently Asked Questions
Q: What is the difference between pre-galvanized and hot-dip galvanized Q235 square tubes?
A: Pre-galvanized tubes receive zinc coating before the forming process, resulting in a thinner but more uniform zinc layer suitable for indoor and moderate-corrosion environments. Hot-dip galvanized tubes are coated after forming, producing a thicker zinc layer that provides superior corrosion resistance for outdoor, marine, or high-humidity applications. Both processes are available for Q195–Q345 grades in our production lines.
Q: Can you provide third-party inspection for coating thickness and material certification?
A: Yes. SGS and BV third-party inspections are available upon request to verify zinc coating thickness, dimensional tolerances, and chemical composition. Each shipment includes mill test certificates documenting heat number, chemical analysis, and mechanical test results from our in-house laboratory.
Q: What is the minimum order quantity for custom non-standard sizes?
A: Our standard MOQ is 10 tons. For custom non-standard dimensions outside our 2,800+ specification catalog, we evaluate production feasibility based on section size, wall thickness, and total quantity. Contact our engineering team with your specific requirements for a tailored assessment.
Q: Do your galvanized square tubes comply with EN 10219 for European structural applications?
A: Yes. Our galvanized square and rectangular tubes are CE certified under EN 10210/EN 10219, meeting the dimensional tolerances, mechanical properties, and documentation requirements for structural hollow sections in EU construction projects. Mill test certificates and CE declaration of performance are provided with each shipment.
Q: How do you ensure zinc coating thickness meets contract specifications?
A: Every production batch undergoes coating thickness measurement in our in-house laboratory before shipment. Results are documented in the mill test certificate and available for third-party verification by SGS or BV. We recommend specifying required zinc coating thickness (e.g., 60 μm, 80 μm) in your inquiry to ensure alignment with project requirements.
Get Project Pricing with Full Certification Package
Send your specifications to admin@sdxjysteel.com or call +86 531 8573 6315 to receive a detailed quotation including mill test certificates, coating thickness reports, and CE documentation for your Q195 Q235 Pre Galvanized Square and Rectangular Steel Tube requirements.
