Description
Factory-direct Galvanized Square Steel Tube — Q235B and Q345B grades produced on 3 dedicated lines covering 21.3 mm to 660 mm side lengths with hot-dipped or pre-galvanized coating applied in-house.
Technical Specifications
| Parameter | Value |
|---|---|
| Designation | Q235B / Q345B Galvanized Square Steel Tube |
| Product Type | Galvanized Square Steel Tube |
| Steel Grade | Q235B, Q345B, SS400 |
| Standard | ASTM A53, ASTM A500, ASTM A36, BS1387, EN10255, ISO65, ANSI C80, DIN2440, JIS G3444, GB/T3091, GB/T13793 |
| Section Shape | Square |
| Size Range | 21.3 mm – 660 mm (1/2″ – 26″) |
| Length | 5.8 m / 6 m / 11 m or customized |
| Technique | Cold Rolled / Hot Rolled |
| Surface Treatment | Galvanized Coating (Hot Dipped / Pre-Galvanized) |
| Pipe Ends | Plain ends, Beveled ends, Threaded ends, Grooved ends |
| Tolerance | ±1% |
| Application | Construction building materials, fluid/gas/oil transportation, hydraulic systems, precision machinery parts, power & boiler structures, petrochemical industry, scaffolding, steel structures |
| MOQ | 1 Ton |
| Origin | Shandong, China |
Application Suitability
| Industry | Typical Applications |
|---|---|
| Construction & Building | Structural framing, curtain wall supports, scaffolding uprights, roof truss members |
| Industrial Machinery | Hydraulic cylinder housings, conveyor frame sections, equipment base structures |
| Infrastructure & EPC | Bridge handrails, solar panel mounting frames, utility pole bases |
| Petrochemical & Power | Low-pressure fluid conveyance lines, boiler support columns, pipe rack structures |
Where Galvanized Coating Thickness Decides Site Acceptance
Hot-dipped coating survives handling; pre-galvanized coating saves budget on indoor runs.
Procurement teams often receive galvanized square steel tube shipments where the zinc layer peels during cutting or bending on site. The root cause is usually a mismatch between the coating process specified and the actual fabrication method planned. Pre-galvanized tubes carry a thinner zinc layer applied before forming — adequate for indoor structural framing but vulnerable to abrasion during field welding. Hot-dipped tubes receive full immersion coating after forming, providing thicker zinc coverage at weld seams and cut edges. When a project demands outdoor exposure or coastal installation, specifying the wrong coating type leads to premature rust streaks and costly repaint cycles [NEED_CITE: hot-dip vs pre-galvanized coating thickness comparison for structural steel].
Matching Coating Process to Corrosion Exposure
Every Galvanized Square Steel Tube order requires aligning the galvanizing method with the installation environment. Hot-dipped galvanizing deposits 45–85 microns of zinc on all surfaces including interior corners, making it the default choice for outdoor scaffolding, solar mounting structures, and coastal infrastructure. Pre-galvanized tubes, formed from already-coated strip, offer uniform appearance and tighter dimensional tolerance — preferred for indoor machinery frames and architectural curtain wall supports where aesthetics matter more than corrosion resistance. End finishing options (plain, beveled, threaded, grooved) further determine how the tube connects on site, affecting whether field welding or mechanical joining is used.
Structural Compliance and Certification Requirements
Galvanized square steel tube used in load-bearing frames must satisfy dimensional tolerance and material traceability requirements set by project engineers. For EU-regulated construction, CE marking under EN 10219 confirms the tube meets cold-formed hollow section standards for structural use. North American projects typically reference ASTM A500 Grade B or C, requiring mill test certificates that document chemical composition and mechanical properties per heat number. Dimensional tolerance of ±1% ensures that batch-after-batch consistency supports automated cutting and welding on fabrication shop floors. Third-party inspection by SGS or BV before shipment provides independent verification of coating thickness, dimensional accuracy, and surface quality [NEED_CITE: EN 10219 cold-formed structural hollow section dimensional tolerance requirements].
Steel Grade Selection and Galvanizing Compatibility
Q235B and Q345B represent the two most widely specified Chinese structural grades for galvanized square steel tube. Q235B offers adequate strength for general construction framing, scaffolding, and non-critical structural members where formability and weldability take priority. Q345B delivers higher yield strength for load-bearing columns, crane runway beams, and heavy machinery bases where section weight reduction matters. Both grades galvanize well due to their silicon content falling within the Sandelin range, preventing excessive zinc-iron alloy formation that causes brittle coating. SS400, the Japanese equivalent, appears in projects sourced for Southeast Asian infrastructure where JIS standards govern procurement. Cross-referencing Q235B to ASTM A36 or S235JR, and Q345B to ASTM A572 Gr.50 or S355JR, ensures material substitution approval without re-engineering [NEED_CITE: steel grade equivalence mapping between GB, ASTM, and EN standards].
Hidden Costs of Incorrect Galvanizing Specification
Ordering pre-galvanized tube for an outdoor coastal project seems like a cost saving until salt spray accelerates coating breakdown at cut edges. The repair cycle — sandblasting, re-galvanizing or repainting on site — typically costs multiples of the original price difference between coating types. Similarly, accepting tubes with negative tolerance beyond specification reduces section modulus and compromises structural calculations approved by the project engineer. Missing or incomplete mill test certificates trigger customs holds in regulated markets, delaying project timelines and generating demurrage charges. Certification gaps — such as CE marking referencing the wrong EN standard — can result in entire shipments being rejected at the port of entry [NEED_CITE: consequences of missing CE documentation for structural steel imports into EU].
Why Buyers Specify Our Galvanized Square Steel Tube
Our factory operates three dedicated production lines producing over 2,800 specifications of square and rectangular tube, including galvanized variants in Q235B and Q345B. Every coil undergoes chemical and mechanical testing in our in-house laboratory before galvanizing, with results documented on EN 10204 3.1 mill test certificates traceable by heat number. We hold CE certification under EN 10210 and EN 10219, ISO 9001:2015 registration, and Singapore FPC approval — covering the certification requirements for EU, Middle East, and Southeast Asian construction projects. Custom non-standard sizes, cut-to-length services, and end finishing (threaded, grooved, beveled) are available with low minimum order quantities starting at 1 Ton. Our professional container loading team uses timber spacers and edge protectors specifically designed for galvanized surfaces, preventing zinc coating damage during ocean transit — a lesson learned from years of handling thin-wall galvanized tube shipments to overseas job sites.
Documentation & Compliance
- Mill test certificate documenting Q235B or Q345B chemical composition and mechanical properties per GB/T3091, traceable by heat number
- CE certificate under EN 10219 confirming compliance for structural hollow sections intended for EU construction markets
- ISO 9001:2015 quality management system certificate covering galvanizing process control and dimensional inspection
- SGS or BV third-party inspection report verifying zinc coating thickness, surface quality, and dimensional tolerance before shipment
- Material traceability sheet linking each bundle to its production heat number and galvanizing batch record
- Full customs documentation including packing list, bill of lading, and certificate of origin formatted for destination port requirements
Packaging, Loading & Delivery
- Galvanized square steel tube bundled with steel strips and separated by timber spacers to prevent zinc coating abrasion during transit
- Edge protectors applied to all bundle corners, preserving the galvanized layer at vulnerable corner positions throughout ocean freight
- Container loading optimized by side length: 21.3–114 mm tubes loaded nested to maximize 20ft container payload; 114–660 mm tubes loaded single-layer with dunnage to prevent rolling
- Cut-to-length service available for 5.8 m, 6 m, or 11 m standard lengths, with custom lengths produced to reduce on-site welding for construction projects
- Heat number and steel grade stenciled on each tube end for site identification and mill test certificate cross-referencing
- FOB, CIF, and DDP shipping terms available with professional container loading plans provided before dispatch
Requesting a Quotation with Full Technical Documentation
Submit your required side length, wall thickness, steel grade (Q235B or Q345B), coating type (hot-dipped or pre-galvanized), and destination port to receive a detailed quotation including unit price, production lead time, and shipping terms. We provide mill test certificates, CE documentation, and third-party inspection reports as standard with every Galvanized Square Steel Tube order. Custom sizes and end finishing options are confirmed within 12 hours of inquiry.
Frequently Asked Questions
Q: What is the difference between hot-dipped and pre-galvanized square steel tube?
A: Hot-dipped galvanizing coats the finished tube after forming, providing thicker zinc coverage (45–85 microns) ideal for outdoor and corrosive environments. Pre-galvanized tube is formed from already-coated steel strip, offering a smoother surface finish and tighter tolerances suited for indoor structural and architectural applications.
Q: Can Q235B and Q345B be substituted for ASTM or EN grades?
A: Q235B corresponds to ASTM A36 and EN S235JR in general structural applications. Q345B maps to ASTM A572 Grade 50 and EN S355JR for higher-strength requirements. Mill test certificates confirm chemical composition and mechanical properties for engineer approval.
Q: What is the minimum order quantity for galvanized square steel tube?
A: The minimum order quantity is 1 Ton. Custom non-standard sizes and cut-to-length services are available for smaller project requirements.
Q: What certifications are provided for EU market imports?
A: We supply CE certification under EN 10219 for structural hollow sections, ISO 9001:2015 quality certificates, EN 10204 3.1 mill test certificates, and SGS/BV third-party inspection reports as required for EU customs clearance.
Q: How are galvanized tubes protected during container loading?
A: Galvanized square steel tube is bundled with timber spacers between layers and edge protectors at corners to prevent zinc coating damage. A detailed container loading plan is provided before shipment to confirm weight distribution and surface protection measures.
Get Your Galvanized Square Steel Tube Quotation Today
Send your specifications — side length, wall thickness, steel grade, coating type, and quantity — to receive pricing, mill test certificates, and delivery terms within 12 hours.
Tel: +86 531 8573 6315
Mobile/WhatsApp/WeChat: +86 188 5315 7756
Email: admin@sdxjypipe.com
