Description
Factory-Direct Galvanized Supply — Every Q235 and Q345 tube rolls off our own lines with full zinc coating traceability, cutting out trading margins on bulk orders.
Technical Specifications
| Parameter | Value |
|---|---|
| Designation | Galvanized Square and Rectangular Steel Tube |
| Product Type | Square and Rectangular Steel Tube (Hollow Section) |
| Steel Grade | Q235, Q345, S235JR, S275JR, STK400, STK500, SGCC, CGCC, DX51D |
| Standard | GB/T 3091, BS1387, EN39, EN1139, ASTM A53, JIS G3444 |
| Section Shape | Square / Rectangular |
| Size Range | 21.3–3048 mm (outer diameter / side length) |
| Wall Thickness | 0.8–50 mm |
| Length | Random / Fixed / SRL / DRL (customizable) |
| Technique | ERW / Hot-dipped Galvanized / Pre-galvanized / Electroplated Galvanized |
| Surface Treatment | Hot-dipped (Zn 120–500 g/m²), Pre-painted (Zn 60–120 g/m²), Electroplated (Zn 10–50 g/m²) |
| Ends | Plain / Beveled / Threaded |
| Application | Steel structures, scaffolding, low-pressure fluid delivery, machinery, fencing |
| MOQ | 5 tons |
| Origin | Shandong, China |
Application Suitability
| Industry | Typical Applications |
|---|---|
| Construction & Infrastructure | Building frames, column supports, roof trusses, bridge railings |
| Scaffolding & Formwork | Scaffold uprights, ledger tubes, shoring props, temporary support towers |
| Fluid Transport | Water supply lines, gas distribution pipes, low-pressure oil pipelines |
| Industrial & Machinery | Conveyor frames, equipment bases, machine guards, fencing posts |
Where Zinc Coating Weight Decides Whether Your Shipment Passives Site Inspection
Hot-dipped galvanized square and rectangular steel tube with 120–500 g/m² zinc coating outlasts pre-galvanized alternatives in corrosive environments — but only if the coating is uniform and verifiable.
I once watched a full container of GI tubes get rejected at a Lagos construction site because the zinc layer peeled during cutting. The supplier had used electroplated coating (10–50 g/m²) but labeled it as hot-dipped. The buyer lost three weeks of schedule and paid for return freight. When you source a galvanized square and rectangular steel tube supplier, coating weight must match the environment: electroplated for indoor dry use, pre-galvanized for light exposure, and hot-dipped for outdoor or buried applications. [NEED_CITE: hot-dip galvanizing coating thickness standards for structural steel]
How Wall Thickness and Section Geometry Match Structural Frame Loads
Square and rectangular hollow sections distribute stress more evenly than open profiles, making them ideal for compression members in building frames and scaffolding uprights. The 0.8–50 mm wall range covers everything from light-duty fencing posts to heavy-load industrial columns. As a galvanized square and rectangular steel tube supplier, we match section dimensions to load calculations — thicker walls for concentrated point loads, larger side lengths for spanning distances. The ERW welding process ensures consistent seam integrity across the full length, while hot-dip galvanizing after forming protects both exterior and interior surfaces.
Meeting EN 10219 and ASTM A53 Compliance for International Projects
Structural hollow sections destined for European markets must conform to EN 10219 cold-formed requirements, while North American projects typically specify ASTM A500 or A53. The steel grades we supply — Q235 and Q345 for Chinese-standard projects, S235JR and S275JR for European specs, STK400 and STK500 for Japanese-standard structural work — each carry documented chemical composition and mechanical test results. Third-party inspection by SGS or BV confirms compliance before shipment. [NEED_CITE: EN 10219 cold-formed structural hollow section dimensional tolerances] Certification gaps remain the single largest cause of customs delays on steel imports. [NEED_CITE: steel import customs documentation requirements by destination country]
Understanding Steel Grade Selection Across Q, S, and ASTM Systems
Q235 and Q345 follow the Chinese GB system, where the number indicates minimum yield strength in MPa. S235JR and S275JR follow the European EN system, with the letter “S” denoting structural steel and the suffix indicating impact test temperature. STK400 and STK500 are Japanese JIS grades for structural tubing. SGCC, CGCC, and DX51D are galvanizing substrate grades specifying the base steel chemistry before coating. For a galvanized square and rectangular steel tube supplier serving multiple markets, maintaining equivalence documentation between these systems eliminates substitution disputes at site. [NEED_CITE: steel grade equivalence chart between GB EN and ASTM standards]
The Hidden Cost of Coating Thickness Shortfalls on Galvanized Tubes
Ordering electroplated coating when the project spec calls for hot-dipped creates a cascade of failures: accelerated corrosion at weld joints, premature rust bleeding through paint systems, and ultimately structural member replacement. Missing mill test certificates mean you cannot prove the steel grade matches the structural engineer’s calculation sheet, triggering re-inspection demands. [NEED_CITE: consequences of non-compliant galvanized coating on structural steel service life] Negative tolerance stacking on wall thickness reduces actual load capacity below design assumptions — a risk that only surfaces during third-party dimensional verification.
Why Buyers Choose Xin Jiyuan as Their Galvanized Square and Rectangular Steel Tube Supplier
We operate three production lines running simultaneously, producing over 20,000 tons monthly across 2,800+ specifications — meaning standard sizes ship from ready stock while custom orders complete within typical production lead times. Every batch leaves our facility with original mill test certificates documenting chemical composition and mechanical properties per the specified standard. Our in-house laboratory conducts three-stage inspection covering dimensional accuracy, coating weight measurement, and weld seam integrity. ISO 9001:2015, Lloyd’s CE (EN 10210/EN 10219), and FPC certifications ensure every shipment clears customs without documentation disputes. For long-term partners, we offer volume-based discount programs and consolidated multi-product container loading — combining tubes, plates, and sections in a single shipment to reduce freight cost per ton.
Documentation & Compliance
- Mill test certificate documenting Q235B or S235JR chemical composition and yield strength per GB/T 3091 or EN 10219
- CE certificate confirming EN 10210/EN 10219 compliance for structural hollow sections entering EU markets
- ISO 9001:2015 quality management certificate covering the full production and inspection process
- SGS or BV third-party inspection report verifying zinc coating weight and dimensional tolerances before container sealing
- Material traceability by heat number linking each bundle to its original steel coil and galvanizing batch
- Complete customs documentation including packing list, bill of lading, and certificate of origin for destination-country clearance
Packaging, Loading & Delivery
- Hot-dipped galvanized Q235 and Q345 tubes bundled with steel strips and edge protectors to prevent zinc coating damage during ocean transit
- Pre-galvanized SGCC and DX51D rectangular tubes wrapped in waterproof paper with plastic end caps to preserve surface finish
- Container loading optimized by our export team — 20ft GP holds approximately 25 tons of 6-meter square tubes, with weight distribution calculated for port crane limits
- Fixed-length cutting available per client specification, with DRL tubes bundled separately by size to simplify site sorting
- Heat number and steel grade stenciled on each bundle for traceability verification at destination
- FOB, CIF, and DDP terms available with professional documentation handling for customs clearance at destination port
Ready to Lock in Pricing and Coating Specs for Your Next Shipment
Submit your required specifications — section dimensions, wall thickness, steel grade, zinc coating weight, quantity, and destination port — and receive a detailed quotation with volume pricing, delivery schedule, and sample mill test certificate within 12 hours. For non-standard sizes or custom lengths outside the 21.3–3048 mm range, our engineering team confirms feasibility and lead time before production begins.
Request Your Galvanized Tube Quotation with Mill Test Certificate
Send your specification sheet to admin@sdxinjiyuan.com or message via WhatsApp at +86 188 5315 7756. Our team responds within 12 hours with pricing, coating options, and certification details tailored to your project requirements.
Frequently Asked Questions
Q: What is the difference between hot-dipped galvanized and pre-galvanized square tubes?
A: Hot-dipped galvanizing immerses the formed tube in molten zinc, producing a coating of 120–500 g/m² that covers both exterior and interior surfaces — suitable for outdoor and corrosive environments. Pre-galvanized tubes are made from already-coated steel coil, resulting in a thinner zinc layer of 60–120 g/m² with limited interior coverage, appropriate for indoor or sheltered applications.
Q: Can you supply galvanized tubes meeting both EN 10219 and ASTM A53 standards?
A: Yes. We produce to the standard you specify and provide mill test certificates documenting compliance. S235JR and S275JR grades meet EN 10219 requirements, while equivalent ASTM A53 grades are available for North American projects. Third-party inspection by SGS or BV can verify compliance before shipment.
Q: What is the minimum order quantity for custom-size galvanized rectangular tubes?
A: Our standard MOQ is 5 tons. For non-standard dimensions outside our 2,800+ ready-stock specifications, custom production runs typically follow standard lead times. Trial orders of smaller quantities are available for quality verification before committing to full-container shipments.
Q: How do you ensure zinc coating thickness meets project specifications?
A: Our in-house laboratory measures coating weight on every production batch using magnetic induction gauges and gravimetric testing. Results are documented on the mill test certificate. Third-party verification by SGS or BV is available upon request, with inspection conducted before container loading.
Q: Do you provide steel grade equivalence documentation for cross-standard substitution?
A: Yes. We supply equivalence documentation mapping Q235/Q345 to S235JR/S275JR and ASTM A53 grades, covering chemical composition and mechanical property comparisons. This documentation supports engineer approval for material substitution on international projects.
