Description
Full-Range Galvanized SHS Direct from Mill — Q235B galvanized square steel tube supplier covering 20×20 to 500×500 mm with zinc coatings from Z30 to Z275, shipped with mill test certificates and CE documentation.
Technical Specifications
| Parameter | Value |
|---|---|
| Designation | Q235B Galvanized Square Steel Tube |
| Product Type | Galvanized Square Steel Tube / Square Hollow Section (SHS) |
| Steel Grade | Q195, Q235, Q235B, Q345, S235JR, A53, St37, St52 |
| Standard | ASTM A53, JIS G3466, GB, BS, DIN, EN 10219 |
| Section Shape | Square and Rectangular |
| Size Range (Square) | 20×20 mm – 500×500 mm |
| Size Range (Rectangular) | 20×40 mm – 300×500 mm |
| Wall Thickness | 1.2 mm – 20 mm |
| Length | 2.0 m – 12 m |
| Technique | Cold bending + high-frequency welding / Hot-dip galvanizing |
| 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 |
| Invoicing | By Actual Weight |
| Origin | Shandong, China |
Application Suitability
| Industry | Typical Applications |
|---|---|
| Construction & Building | Structural steel frames for residential and commercial buildings, column supports, roof trusses |
| Solar & Renewable Energy | Solar panel mounting structures, ground-screw foundations, inverter support frames |
| Agriculture & Greenhouse | Greenhouse skeleton framing, irrigation pipe supports, livestock shelter structures |
| Infrastructure & Fencing | Highway guardrail posts, perimeter fencing systems, utility pole bases |
| Machinery & Equipment | Conveyor frame structures, equipment guarding frames, platform handrails |
What Missing Zinc Coating Data Costs You on a Galvanized Tube Order
Inconsistent zinc thickness is the single most common reason galvanized hollow sections fail site inspection in coastal and industrial zones.
Buyers ordering Q235B galvanized square steel tube from multiple suppliers often discover that zinc coating varies wildly between batches — Z80 on one lot, Z275 on another — even though the purchase order specified the same grade. Without in-house coating weight verification, the tubes may look acceptable on arrival but begin white-rust corrosion within months in humid or saline environments. Worse, some suppliers ship pre-galvanized tubes labeled as hot-dip, and the difference only surfaces when weld seams start rusting before the flat surfaces do [NEED_CITE: hot-dip vs pre-galvanized coating thickness comparison for structural hollow sections].
How Wall Thickness and Zinc Class Match Real Project Environments
Selecting the right Q235B galvanized square steel tube goes beyond outer dimensions — it requires matching wall thickness to structural load and zinc class to the service environment. For indoor structural frames in dry conditions, Z80 pre-galvanized coating provides adequate protection at lower cost. However, outdoor applications such as solar mounting structures or coastal fencing demand hot-dip galvanizing with Z275 or higher to resist continuous moisture and salt spray exposure. Wall thickness from 1.2 mm suits light-duty framing, while 10–20 mm sections carry primary structural loads in building frames and bridge supports. Our in-house lab tests both dimensional tolerance (±1%) and zinc coating weight before dispatch, ensuring each batch matches the specified class.
Structural Compliance and Certification Requirements Across Markets
Engineering projects in the EU require galvanized hollow sections to conform to EN 10219 for cold-formed welded structural hollow sections, with CE marking under the Construction Products Regulation. North American specifiers typically reference ASTM A53 or ASTM A500, while Middle East and Southeast Asian tenders often accept GB or JIS G3466 equivalents [NEED_CITE: EN 10219 cold-formed hollow section dimensional tolerance requirements]. The steel grade equivalence between Q235B, S235JR, and A53 must be documented on the mill test certificate — a mismatch here has caused entire shipments to be held at EU ports. Our facility holds Lloyd’s CE certification for EN 10219 and EN 10210, Singapore FPC, and ISO 9001:2015, and we provide third-party SGS or BV inspection on request to satisfy any project compliance matrix.
Understanding Q235B, S235JR, and A53 in Galvanized Square Tubes
The steel grades listed for Q235B galvanized square steel tube span three major standard systems. Q195 and Q235B belong to the Chinese GB system, where the “Q” prefix denotes yield strength class — Q235B indicates a minimum yield point suitable for general structural welding and forming. S235JR is the European EN equivalent, with “JR” specifying room-temperature impact energy at 27 J, making it appropriate for non-cold-climate structural use. ASTM A53 Grade B serves the same role in North American specifications. The key difference lies in chemical composition limits and testing protocols rather than raw strength. Cold-forming these grades into square hollow sections through high-frequency welding produces consistent corner geometry, and subsequent hot-dip galvanizing bonds the zinc layer to the steel surface for long-term corrosion protection. Choosing the correct grade ensures weldability, formability, and compliance with the project’s governing code without over-specifying material cost.
The Hidden Price of Wrong-Grade Galvanized Tubes on Site
Ordering Q235B galvanized square steel tube that arrives with sub-standard zinc coating or incorrect steel grade creates costs far beyond the material price difference. A tube stamped S235JR but actually producing Q195 chemistry will show lower yield strength on independent testing — the structural engineer must either reject the shipment or redesign the connection details, both of which delay the project timeline. Coating weight below the specified Z class leads to premature corrosion at weld zones and cut edges, triggering maintenance calls under warranty. Certification gaps — missing CE marks or EN 10219 references on test certificates — result in customs holds at EU destination ports, with demurrage charges accumulating daily [NEED_CITE: steel grade equivalence between EN and ASTM standards for structural hollow sections]. These are not theoretical risks; they are recurring issues we have helped buyers resolve after other suppliers failed to deliver compliant material.
Why Project Buyers Source Q235B Galvanized Square Steel Tube from Xin Jiyuan
As the original inventor of sharp-corner rectangular tubes in China with 41 patents, we operate three dedicated production lines covering over 2,800 specifications — including the full 20×20 to 500×500 mm galvanized SHS range at wall thicknesses up to 20 mm. Our in-house physical and chemical laboratory tests every heat for dimensional accuracy, mechanical properties, and zinc coating weight before release. We hold full international certifications: ISO 9001:2015, Lloyd’s CE (EN 10219/10210), Singapore FPC, and SGS/BV verification. Custom non-standard sizes, cutting, punching, and bending services are available with low MOQ, and our export team handles professional container loading with anti-damage measures — a critical detail for preserving galvanized surface quality during ocean freight. We currently export to 50+ countries, serving construction firms, solar EPC contractors, and steel distributors who need consistent quality and complete documentation.
Documentation & Compliance
- Mill test certificate documenting Q235B chemical composition, yield strength, and zinc coating weight per heat number
- CE certificate covering EN 10219 cold-formed welded structural hollow sections for EU market import
- ISO 9001:2015 quality management system certificate valid for all production lines
- SGS or BV third-party inspection report available upon request for project-specific compliance
- Material traceability linked to heat number stamped on each tube for site verification
- Full customs documentation including packing list, bill of lading, and certificate of origin
Packaging, Loading & Delivery
- Q235B galvanized square tubes bundled with steel strips and edge protectors to prevent zinc coating scratches during handling and transit
- Seaworthy packaging with waterproof wrapping for hot-dip galvanized surfaces to block moisture condensation inside containers
- Container loading optimized for 6 m and 12 m lengths with nested smaller sections (20×20 to 100×100 mm) to maximize payload per 20ft or 40ft GP
- Cut-to-length service available for 2.0 m to 12 m requirements, with plain ends deburred and marked with heat number and steel grade
- Shipping terms FOB, CIF, or DDP to major ports across EU, North America, Middle East, and Southeast Asia with full export tracking
Getting Your Galvanized SHS Quote Started
Send your specification sheet including outer dimensions, wall thickness, steel grade (Q235B / S235JR / A53), zinc coating class, total quantity, and destination port. We respond within 12 hours with unit pricing, production lead time, and available mill test certificate samples. For non-standard sizes or custom processing such as punching and bending, share your drawing and we confirm feasibility and tooling requirements before contract.
Frequently Asked Questions
Q: What is the difference between Z80, Z275, and hot-dip galvanizing for outdoor structural use?
A: Z80 and Z275 refer to zinc coating weight in grams per square meter, typically applied through pre-galvanizing (continuous galvanizing of the steel strip before tube forming). Hot-dip galvanizing immerses the finished tube in molten zinc, producing a thicker, metallurgically bonded coating — generally 600 g/m² class — that provides superior corrosion resistance for outdoor, coastal, or industrial environments. For solar structures and fencing exposed to weather, hot-dip is the recommended choice.
Q: How do Q235B, S235JR, and A53 compare across GB, EN, and ASTM standards?
A: These three grades occupy equivalent positions in their respective standard systems for general structural carbon steel. Q235B (GB) and S235JR (EN) share similar yield strength levels and chemical composition ranges, while ASTM A53 Grade B serves the same function in North American specifications. The differences lie in testing methods, impact energy requirements, and documentation format. We provide cross-reference documentation on the mill test certificate to satisfy any governing code.
Q: Can you produce non-standard square tube dimensions, and what is the minimum order quantity?
A: Yes. Beyond our standard 20×20 to 500×500 mm range, we produce custom non-standard sizes across our 2,800+ specification catalog. MOQ for custom sizes depends on the specific dimension and steel grade — contact us with your drawing for a confirmed MOQ and lead time. Standard sizes in Q235B often ship from stock.
Q: Do your galvanized tubes carry CE marking under EN 10219 for European market import?
A: Yes. Our facility holds Lloyd’s CE certification for EN 10219 (cold-formed welded structural hollow sections) and EN 10210. Every shipment to EU destinations includes the CE declaration of performance, factory production control documentation, and mill test certificates referencing the correct EN standard designation.
Q: How are galvanized tubes packed to prevent surface damage during ocean freight?
A: Galvanized tubes are bundled with steel strips and separated by rubber or nylon edge protectors to prevent metal-to-metal contact. Waterproof wrapping seals the bundle against condensation inside the container. Our loading team uses professional lashing and blocking to prevent shifting, which is the primary cause of zinc coating scratches and tube bending during transit.
Get Your Q235B Galvanized Square Steel Tube Quote with Mill Test Certificate
Submit your dimensions, steel grade, zinc coating requirement, and destination port — we will return a detailed quotation with available certifications and typical production lead times within 12 hours.
Contact: Shandong Xin Jiyuan Special Steel Tube Co., Ltd
Tel: +86 531 8573 6315
Mobile/WhatsApp/WeChat: +86 188 5315 7756
Email: admin@sdxjypipe.com
Website: www.sdxjypipe.com
