Description
Full-Range Galvanized SHS/RHS Direct Mill Supply — We stock and produce galvanized square and rectangular hollow sections from 20×20 mm up to 500×500 mm with wall thicknesses from 1.2 mm to 20 mm, shipped with original mill test certificates and CE compliance documentation.
Technical Specifications
| Parameter | Value |
|---|---|
| Designation | Q235B Galvanized Square Steel Tube |
| Product Type | Galvanized Square / Rectangular Steel Tube (Hollow Section) |
| Steel Grade | Q195, Q235B, Q345B, S235JR, A53, St37, St52 |
| Standard | ASTM A53, JIS G3466, GB/T 6728, BS, DIN |
| Section Shape | Square and Rectangular |
| Size Range | Square: 20×20 mm – 500×500 mm; Rectangular: 20×40 mm – 300×500 mm |
| Wall Thickness | 1.2 mm – 20 mm |
| Length | 2.0 m – 12 m (standard 6 m / 6.4 m / 12 m) |
| Technique | Cold bending + high-frequency welding (ERW); hot-dip galvanized after forming |
| Surface Treatment | Galvanized (zinc coating 60 g/m² – 600 g/m²; Z30, Z40, Z80, Z275) |
| Tolerance | ±1% |
| Ends | Plain ends |
| Processing Service | Welding, punching, cutting, bending |
| Application | Construction structural frames, solar mounting structures, fence posts, greenhouse frames |
| MOQ | Negotiable per specification |
| Origin | Shandong, China |
Application Suitability
| Industry | Typical Applications |
|---|---|
| Construction & Building | Structural steel frames for warehouses, commercial buildings, and high-rise secondary structures |
| Solar & Renewable Energy | Ground-mounted and rooftop solar panel mounting structures requiring corrosion resistance |
| Agriculture | Greenhouse skeleton frames and livestock fencing posts |
| Infrastructure | Highway guardrail posts, bridge handrail supports, and perimeter fencing systems |
| Machinery & Scaffolding | Scaffolding uprights, conveyor support frames, and equipment base structures |
What Hidden Negative Tolerance Costs on a Galvanized Hollow Section Order
A 0.3 mm wall-thickness shortfall on a galvanized square tube can void an entire structural inspection and trigger a full-container return.
Project buyers ordering Q235B galvanized square steel tube often discover the damage only when fabrication begins — welds fail to penetrate through the zinc layer evenly, cut surfaces reveal uneven wall distribution, and the dimensional report on arrival does not match the purchase order. The root cause is almost always unverified negative tolerance from suppliers who quote by theoretical weight but ship by actual weight. On a 500×500 mm SHS with 12 mm wall, even a small deviation compounds across hundreds of meters of structural framing. Without original mill test certificates tied to heat numbers, there is no way to trace which batch failed or demand replacement from the rolling mill [NEED_CITE: EN 10219 cold-formed hollow section tolerance requirements].
How Galvanized Square and Rectangular Sections Match Structural Framing Demands
Galvanized square and rectangular hollow sections serve as the backbone of solar mounting arrays and building frames where both load-bearing capacity and atmospheric corrosion resistance are non-negotiable. The zinc coating — ranging from Z30 for indoor sheltered use to Z275 for outdoor exposed environments — provides a sacrificial barrier that eliminates the need for post-fabrication painting on most structural applications. Our Q235B galvanized square steel tube is cold-formed through high-frequency ERW welding and then hot-dip galvanized, ensuring the zinc layer covers both external surfaces and the internal weld zone, which is where untreated ERW tubes typically begin to corrode first.
Engineering Compliance and Certification Requirements for Galvanized Hollow Sections
Structural hollow sections used in load-bearing frames must comply with dimensional and mechanical delivery conditions defined by recognized standards. For European market projects, EN 10219 governs cold-formed welded structural hollow sections and mandates verifiable chemical composition, mechanical properties, and tolerance class documentation [NEED_CITE: EN 10219 cold-formed hollow section requirements]. In North America, ASTM A53 covers the equivalent structural tube category. The Q235B grade supplied here corresponds broadly to S235JR under EN standards and A53 Grade A under ASTM, but cross-standard equivalence requires explicit mill certification rather than assumption. CE marking and ISO 9001:2015 quality management certification ensure that each production batch undergoes documented inspection before release. Third-party inspection through SGS or BV is available for projects requiring independent dimensional and coating weight verification.
Steel Grade Selection and Galvanizing Process Explained
The Q-series grades (Q195, Q235B, Q345B) follow the Chinese GB system where the number indicates minimum yield strength in MPa. Q235B remains the most specified grade for general structural framing due to its balance of formability, weldability, and cost. For projects requiring European or American standard compliance, S235JR and A53 are supplied with cross-referenced mill test certificates. The galvanizing process matters as much as the steel grade: hot-dip galvanizing after forming (post-galvanizing) deposits a metallurgically bonded zinc-iron alloy layer that is significantly more durable than pre-galvanized (electro-galvanized) coil, which is why structural hollow sections for outdoor use almost always specify hot-dip treatment. Wall thickness tolerance of ±1% ensures that theoretical weight calculations match actual delivered weight, preventing the cost overruns that come from under-spec material being rejected at site inspection.
The Real Cost of Procuring Without Verified Mill Documentation
Ordering galvanized hollow sections based on price alone, without requiring original mill test certificates and dimensional inspection reports, exposes the project to three compounding risks. First, material that fails to meet the specified steel grade will not pass structural engineering sign-off, forcing costly replacement after delivery. Second, zinc coating weight below the specified Z-class means premature corrosion in outdoor environments, leading to maintenance claims years after project handover. Third, customs authorities in markets requiring CE documentation or EN 10219 compliance will hold shipments without proper certification, generating demurrage charges and schedule delays [NEED_CITE: steel grade equivalence between EN and ASTM standards]. Every Q235B galvanized square steel tube we ship carries a heat-number-linked mill test certificate documenting chemical composition and mechanical properties.
Procurement Confidence Backed by Production and Inspection Capability
XJY Plate operates as the dedicated steel plate and coil division of Shandong Xin Jiyuan Special Steel Tube Co., Ltd, giving us direct access to mill rolling schedules and finished stock across the full galvanized hollow section range. Every tube is inspected in our in-house理化 testing laboratory before release — wall thickness is verified by ultrasonic measurement at multiple points, zinc coating weight is confirmed by weighing method, and dimensional reports are generated per shipment. We hold ISO 9001:2015 and CE certification, and third-party inspection through SGS or BV can be arranged for projects requiring independent verification. Our logistics team specializes in heavy cargo loading — flatbed trucks for domestic delivery, open-top containers for oversized sections, and break-bulk shipping for project volumes — ensuring that long-length galvanized tubes arrive without coating damage or bending deformation. Custom cutting, punching, and bending to fabrication drawings eliminates secondary processing at the job site.
Documentation & Compliance
- Mill test certificate documenting Q235B/Q345B/S235JR chemical composition and mechanical properties per GB/T 6728 or EN 10219, linked to heat number for full traceability
- CE certificate confirming compliance with EN 10219 cold-formed welded structural hollow section requirements for European market projects
- ISO 9001:2015 quality management system certificate covering production, inspection, and delivery processes
- SGS or BV third-party inspection report available for independent verification of zinc coating weight, wall thickness, and dimensional accuracy
- Complete customs documentation including packing list, bill of lading, and certificate of origin for import clearance in destination country
Packaging, Loading & Delivery
- Galvanized Q235B square and rectangular tubes bundled with steel strips and edge protectors to prevent zinc coating abrasion during handling and ocean transit
- Hot-dip galvanized surface protected by waterproof wrapping on outer layer for container shipment, preventing white rust formation during humid sea freight
- Open-top container or flatbed loading optimized for 6 m and 12 m standard lengths, with weight distribution calculated to avoid container overweight penalties on heavy-wall sections (10 mm – 20 mm)
- Custom cut-to-length service available for 2.0 m – 12 m requirements, with cut ends deburred and re-galvanized touch-up applied to exposed steel surfaces
- Heat number and steel grade stenciled on each bundle for on-site identification and traceability verification
- FOB, CIF, and DDP shipping terms available with professional heavy cargo logistics coordination from Shandong port to destination site
Request a Quotation with Mill Test Documentation
Submit your specification sheet — including steel grade (Q235B, Q345B, S235JR, or A53), section dimensions, wall thickness, length, zinc coating class, and destination port — and receive a detailed quotation with material cost, processing fees, and shipping terms within 12 hours. We provide original mill test certificates before shipment for your quality verification, and third-party inspection can be confirmed at the time of order. For custom cutting, punching, or bending to fabrication drawings, share your processing requirements and we will include these in the quotation.
Frequently Asked Questions
Q: What is the difference between hot-dip galvanized and pre-galvanized square steel tube?
A: Hot-dip galvanizing is performed after the tube is fully formed, immersing the complete section in molten zinc to create a metallurgically bonded coating that covers external surfaces, internal cavity, and the weld zone. Pre-galvanized (electro-galvanized) tube is made from already-coated steel coil, meaning the weld zone and internal surfaces have minimal or no zinc protection. For structural applications exposed to moisture or outdoor environments, hot-dip galvanized is the standard specification.
Q: How do I verify that the wall thickness meets my order specification?
A: Every shipment of Q235B galvanized square steel tube is accompanied by a dimensional inspection report measuring wall thickness at multiple points using ultrasonic equipment. Original mill test certificates are provided with heat number traceability. Third-party inspection through SGS or BV can be arranged for independent verification before shipment.
Q: Can I order small quantities or custom cut-to-size lengths?
A: Yes. We supply galvanized hollow sections in custom lengths from 2.0 m to 12 m and offer cutting, punching, and bending services to fabrication drawings. Minimum order quantities are flexible and confirmed per specification during quotation.
Q: Which steel grade should I specify for structural use — Q235B, S235JR, or A53?
A: Q235B (Chinese GB standard), S235JR (European EN standard), and A53 Grade A (American ASTM standard) are broadly equivalent in minimum yield strength for general structural framing. The correct grade to specify depends on the project’s governing standard and the engineer’s specification. We supply cross-standard mill test certificates confirming equivalence.
Q: What zinc coating weight should I choose for outdoor applications?
A: For outdoor structural applications such as solar mounting frames, fence posts, and building frames, Z275 (275 g/m²) is the typical specification, providing long-term corrosion resistance in most atmospheric conditions. For sheltered or indoor applications, Z80 or Z120 may be sufficient. We supply zinc coating weights from Z30 to Z275 per your project requirements.
Get Your Galvanized Hollow Section Quotation with Full Mill Documentation
Send your specification — steel grade, dimensions, wall thickness, quantity, and destination — to receive a detailed quotation and original mill test certificate preview within 12 hours.
Contact: Shandong Xin Jiyuan Special Steel Tube Co., Ltd
Website: www.xjyplate.com
Tel: +86 531 8573 6315
Mobile/WhatsApp/WeChat: +86 188 5315 7756
Email: admin@xjyplate.com
