Description
Factory-Direct Galvanized SHS/RHS — integrated steel mill output with ASTM-compliant coating and dimensional control
Technical Specifications
| Parameter | Value |
|---|---|
| Designation | Q235B/Q345B Galvanized Square and Rectangular Steel Tube |
| Product Type | Galvanized Square / Rectangular Steel Tube (SHS / RHS) |
| Steel Grade | Q195, Q235, Q235B, Q345, Q345B, SS400, SS330-SS540 |
| Standard | ASTM |
| Section Shape | Square / Rectangular / Round |
| Size Range | Wall Thickness 0.5–200 mm |
| Length | 6 m / 6.4 m / 12 m (customizable) |
| Technique | Hot Rolled / Cold Rolled; Galvanized (Hot-dip / Electro-galvanized) |
| Surface Treatment | Galvanized (Zinc Coated) |
| Tolerance | ±1% |
| Ends | As per customer requirement |
| Application | Construction structures / Bridges / Railways / Ships / Vehicles / Machinery manufacturing / Petrochemical industry / Marine development / Fluid transport / Offshore oil fields |
| MOQ | 5 Tons |
| Origin | Shandong, China |
Application Suitability
| Industry | Typical Applications |
|---|---|
| Construction & Infrastructure | Structural frames, scaffolding, support columns, warehouse purlins, and mezzanine beams |
| Petrochemical & Marine | Low-pressure fluid piping, offshore platform bracing, and pipe rack supports |
| Machinery & Transportation | Vehicle chassis frames, railway carriage components, conveyor structures, and crane booms |
| Industrial Facilities | Factory roof trusses, equipment support platforms, and silo frameworks |
Where Zinc Coating Thickness Decides Site Acceptance
A galvanized square hollow section that fails third-party coating inspection on arrival costs more than re-galvanizing — it costs the project schedule.
Procurement teams sourcing galvanized SHS/RHS from overseas fabricators frequently encounter zinc coating thickness below contract specification upon third-party inspection at the destination port. [NEED_CITE: EN 10219 cold-formed hollow section surface treatment requirements] When coating falls short, the entire batch must be stripped and re-galvanized locally — or rejected outright — adding weeks of delay and unplanned freight. The root cause is rarely the galvanizing process itself; it is the absence of in-line coating measurement and traceable mill documentation before the container is sealed. A galvanized square and rectangular steel tube supplier that controls both the base steel production and the galvanizing line under one quality system eliminates the gap where coating data gets lost between material mill and coating subcontractor.
How Galvanized SHS/RHS Matches Structural Frame Requirements
Galvanized square and rectangular steel tube in Q235B and Q345B grades provides the corrosion resistance needed for exposed structural frames, warehouse purlins, and scaffolding systems without requiring field painting. The hot-dip galvanizing process produces a metallurgically bonded zinc-iron alloy layer that withstands handling, welding at connection points, and decades of atmospheric exposure in tropical and coastal environments. Our in-house bending, cutting, and welding services allow the galvanized square and rectangular steel tube to be fabricated to project-specific shop drawings before shipment — reducing on-site secondary processing and preserving coating integrity at cut edges through touch-up procedures compliant with ASTM standards.
Engineering Compliance and Certification Pathways
Structural hollow sections used in load-bearing frames must conform to recognized dimensional and mechanical standards. For European projects, EN 10219 governs cold-formed welded structural hollow sections, requiring CE marking and factory production control certification. [NEED_CITE: CE marking requirements for structural steel hollow sections under CPR regulation] For North American and international tenders referencing ASTM, the galvanized square and rectangular steel tube must carry mill test certificates showing chemical composition and mechanical properties traceable to heat numbers. Our Q345B and Q235B grades are produced under ISO 9001 quality management, with full documentation packages — including WPS, PQR, dimensional inspection reports, and coating thickness records — prepared for each shipment to support customs clearance and engineering approval at destination.
Steel Grade Selection and Galvanizing Process Fundamentals
The Q-series grades (Q195, Q235B, Q345B) follow the Chinese GB/T standard system where the “Q” prefix denotes yield strength in MPa — Q235B provides approximately 235 MPa minimum yield, suitable for general structural frames and scaffolding, while Q345B offers higher strength for heavier load-bearing applications such as crane booms and bridge components. SS400 and SS330-SS540 represent the Japanese JIS equivalent range, commonly specified in Southeast Asian and Middle Eastern projects. [NEED_CITE: steel grade equivalence between Chinese GB, Japanese JIS, and European EN standards] The choice between hot-dip and electro-galvanized surface treatment depends on service environment: hot-dip galvanizing produces thicker coatings (typically 60–100 μm) for long-term outdoor and marine exposure, while electro-galvanizing yields thinner, more uniform coatings for indoor or decorative applications. Wall thickness tolerance of ±1% ensures dimensional consistency across fabrication operations — critical when multiple tubes must align at welded or bolted connections.
The Hidden Cost of Unverified Coating and Negative Tolerance
Ordering galvanized SHS/RHS without requiring pre-shipment coating thickness verification and independent mill test certificates exposes the project to rejection at destination inspection. Coating below specification triggers re-galvanizing costs that frequently exceed the original galvanizing premium. Similarly, excessive negative tolerance on wall thickness reduces actual load-bearing capacity below engineering calculations — a discrepancy that only surfaces during structural testing or, worse, under service load. [NEED_CITE: structural hollow section tolerance requirements under EN 10219-2] The cost of replacing rejected material, combined with project delay penalties, typically dwarfs the price difference between verified and unverified supply sources.
Why Procurement Teams Source from XJY Structure
Our vertically integrated operation combines an in-house steel mill producing 2,800+ specifications of raw material with a dedicated structural steel fabrication workshop — meaning the base steel for every galvanized square and rectangular steel tube is produced, tested, and documented under a single quality system. We maintain certified welding procedures (AWS/EN) and qualified welders on staff, with complete quality documentation packages prepared for each order including material traceability by heat number. Third-party inspection by SGS, BV, or TÜV is available before shipment to provide independent verification of coating thickness, dimensional accuracy, and mechanical properties. Our engineering team reviews shop drawings, optimizes material utilization, and sequences fabrication to match project delivery schedules — eliminating the coordination gaps that occur when material supply and fabrication are sourced separately.
Documentation & Compliance
- Mill test certificate documenting Q235B/Q345B chemical composition and mechanical properties per ASTM, traceable to heat number
- CE certificate confirming compliance with EN 10219 for cold-formed welded structural hollow sections
- ISO 9001 quality management system certificate covering the full production and fabrication process
- SGS or BV third-party inspection report verifying zinc coating thickness and dimensional tolerance before shipment
- Material traceability report linking each galvanized square and rectangular steel tube to its production heat and galvanizing batch
- Complete customs documentation package including packing list, bill of lading, and certificate of origin
Packaging, Loading & Delivery
- Galvanized Q235B/Q345B SHS/RHS bundled with steel strips and edge protectors to preserve zinc coating integrity during ocean transit
- Surface protection maintained through separation layers between tubes, preventing zinc scratching and white rust formation in humid conditions
- Container loading optimized for 6 m / 6.4 m / 12 m lengths with professional lashing plans for oversized structural components
- Custom cutting to project-specified lengths available before shipment, reducing on-site waste and secondary processing
- Heat number and steel grade clearly marked on each tube for site identification and traceability verification
- FOB, CIF, and DDP shipping terms available with door-to-door logistics coordination for project sites
Starting Your Procurement Process
Submit your project drawings (PDF/DWG), steel grade requirements, surface treatment specification, and destination port to receive a detailed quotation including material, fabrication, coating, packing, and shipping costs — along with the mill test certificate format and third-party inspection arrangement for your review.
Request Quotation with Full Documentation Package
Share your specifications and required standards to receive pricing, production schedule, and compliance documentation within 24 hours.
Contact: Shandong Xin Jiyuan Special Steel Tube Co., Ltd
Website: www.xjystructure.com
Tel: +86 531 8573 6315
Mobile/WhatsApp/WeChat: +86 188 5315 7756
Email: admin@xjystructure.com
Frequently Asked Questions
Q: What is the difference between hot-dip and electro-galvanized coating for SHS/RHS?
A: Hot-dip galvanizing produces a thicker zinc coating (typically 60–100 μm) with a metallurgically bonded zinc-iron alloy layer, providing superior corrosion resistance for outdoor and marine environments. Electro-galvanizing yields a thinner, more uniform coating suitable for indoor applications or where precise dimensional control is critical. The choice depends on your project’s service environment and coating thickness requirements specified in the contract.
Q: Can you provide steel grade equivalence between Q235B, S235JR, and ASTM A500 Grade B?
A: Yes. Q235B (Chinese GB standard) is broadly equivalent to S235JR (European EN standard) and ASTM A500 Grade B (US standard) in terms of yield strength range and application suitability. Our engineering team provides detailed chemical composition and mechanical property comparison tables to support your material specification and customs documentation requirements.
Q: What is the MOQ for custom-sized galvanized square and rectangular steel tubes?
A: The standard MOQ is 5 tons. For custom sizes outside our regular stock range, the MOQ may vary depending on the specific dimensions and production requirements. We maintain 2,800+ specifications in stock for immediate dispatch, and custom fabrication including bending, cutting, and welding is available for project-specific requirements.
Q: Do you provide third-party inspection before shipment?
A: Yes. We arrange third-party inspection by SGS, BV, or TÜV upon request. The inspection covers zinc coating thickness measurement, dimensional accuracy verification, visual surface quality, and review of mill test certificates. The inspection report is provided before container loading to confirm compliance with your contract specifications.
Q: How is theoretical weight versus actual weight calculated for invoicing?
A: Invoicing can be based on theoretical weight calculated from nominal dimensions and standard density, or on actual weight measured at our facility before shipment — depending on your preference and contract terms. We clarify the invoicing method in the quotation to avoid discrepancies. Negative tolerance on wall thickness is controlled within ±1% per our standard specification.
