Description
Factory Direct Supply — vertically integrated mill and fabrication under one quality system
Technical Specifications
| Parameter | Value |
|---|---|
| Designation | Pre-Galvanized Square Rectangular Welded Steel Tube |
| Product Type | Square and Rectangular Steel Tube (SHS / RHS) |
| Steel Grade | Q235, Q235B, S275, S275JR, A53, ST37, SGCC, CGCC, DX51D |
| Standard | GB |
| Section Shape | Square / Rectangle |
| Wall Thickness | 1.2 – 20 mm |
| Length | 1 – 12 m (or as customer request) |
| Technique | Hot Rolled Based / Welded |
| Surface Treatment | Pre-Galvanized (Zinc Coating Z121 – Z180) |
| Spangle Type | Zero Spangle |
| Hardness | Full Hard |
| Skin Pass | Yes |
| Surface Condition | Non-oiled |
| Tolerance | ±1% |
| Processing Service | Welding, Punching, Cutting, Bending, Decoiling |
| Application | Steel structures, construction frames, fencing, container frames, scaffolding, making pipes, cutting sheets, making small tools, making corrugated sheets |
| MOQ | 5 Tons |
| Origin | China |
Application Suitability
| Industry | Typical Applications |
|---|---|
| Construction & Infrastructure | Structural frames, columns, beams for commercial buildings and industrial facilities |
| Fencing & Container Manufacturing | Pre-galvanized tubes ready for fabrication without additional surface treatment |
| EPC & General Contractor Projects | Complete quality documentation package for international compliance |
| Warehousing & Logistics | Storage rack systems, mezzanine platforms, loading bay frameworks |
| Agricultural & Industrial Sheds | Roof trusses, wall purlins, portal frame structures |
What Zinc Coating Class Z121–Z180 Means for Your Project Timeline
Pre-galvanized square rectangular steel tube with zero spangle finish delivers uniform corrosion protection that eliminates on-site painting delays.
When overseas buyers source galvanized SHS/RHS from fragmented suppliers, zinc coating thickness often varies between batches — some tubes arrive with adequate protection while others show premature white rust formation within weeks of installation. The root cause lies in inconsistent galvanizing line control: bath temperature fluctuations, uneven withdrawal speeds, and inadequate passivation treatment. For EPC firms managing tight construction schedules, receiving tubes that fail coating thickness inspection at site means either costly re-galvanizing or full replacement — neither option fits a compressed project timeline. A Pre-Galvanized Square Rectangular Steel Tube Supplier operating an integrated mill-to-fabrication model controls every galvanizing parameter in-house, ensuring Z121–Z180 coating consistency across the entire order. [NEED_CITE: hot-dip galvanizing coating thickness standards for structural steel]
How Pre-Galvanized SHS/RHS Matches Structural Frame Requirements
Pre-galvanized square rectangular steel tube in grades Q235B, S275JR, and A53 provides structural engineers with immediate corrosion resistance upon delivery — no secondary surface treatment required before erection. The zero spangle finish offers uniform appearance for exposed architectural applications where visual consistency matters. Wall thickness range from 1.2 mm to 20 mm covers both light-gauge purlin systems and heavy-load column sections. Skin-passed surface ensures flatness critical for precise connection plate welding. Our vertically integrated facility produces these tubes from raw steel through galvanizing, maintaining material traceability from heat number to finished bundle — a documentation chain that satisfies EN 1090 and AISC compliance requirements for international projects.
Engineering Compliance and Certification Pathways
Structural steel fabrication for EU markets requires CE marking per EN 10219 for cold-formed welded hollow sections, while North American projects typically specify ASTM A500 or A53 compliance. Pre-galvanized square rectangular steel tube in S275JR grade meets the yield strength threshold for most portal frame and bracing applications under Eurocode 3, while Q235B serves equivalent functions in GB-standard projects. The ±1% dimensional tolerance ensures connection details fabricated to shop drawings maintain fit-up accuracy — critical when bolted connections require precise hole alignment. Third-party inspection by SGS or BV before shipment provides independent verification of coating thickness and dimensional accuracy, reducing customs clearance friction at destination ports. [NEED_CITE: EN 10219 cold-formed structural hollow section certification requirements]
Understanding Steel Grade Selection and Galvanizing Process
The steel grade designation directly determines load-bearing capacity: Q235B offers minimum 235 MPa yield strength suitable for secondary structures and bracing, while S275JR provides 275 MPa yield for primary frame members carrying higher loads. ASTM A53 covers both structural and mechanical applications with chemical composition requirements aligned to international practice. Pre-galvanizing involves passing formed and welded tubes through a molten zinc bath at controlled temperature, creating metallurgical bonding between zinc and steel substrate. The Z121–Z180 coating class indicates zinc mass per square meter — Z121 provides basic protection for indoor or sheltered applications, while Z180 offers extended service life in moderate outdoor environments. Zero spangle finish results from specialized bath chemistry and cooling control, producing smooth uniform surface ideal for painting over if color matching becomes necessary later. Wall thickness tolerance of ±1% means actual weight stays predictable for structural calculations — negative tolerance beyond specification creates hidden cost through reduced load capacity that only becomes apparent during engineering review.
Hidden Costs of Specifying Wrong Coating Class or Tolerance
Ordering Pre-Galvanized Square Rectangular Steel Tube with insufficient zinc coating for the service environment leads to accelerated corrosion at weld zones and cut edges — areas where protection is thinnest. When coating fails inspection at destination, the buyer faces three costly options: reject the entire shipment and delay the project, arrange local re-galvanizing at premium rates, or accept reduced design life with liability exposure. Similarly, wall thickness below specified tolerance creates structural safety concerns that engineers cannot sign off on, triggering replacement orders that compress already tight construction schedules. Material certification gaps — missing heat numbers or incomplete mill test certificates — cause customs holds in markets requiring EN 10204 3.1 or 3.2 documentation, turning straightforward deliveries into weeks-long clearance delays. [NEED_CITE: material certification requirements for structural steel imports]
Why Integrated Mill and Fabrication Changes Your Procurement Risk
Our facility combines steel production with tube fabrication under single ownership, eliminating the material sourcing gaps that plague buyers working with trading companies or disconnected workshops. When you order Pre-Galvanized Square Rectangular Steel Tube from us, the same quality system controls raw material chemistry, welding parameters, galvanizing bath composition, and final dimensional inspection — one point of accountability from billet to bundled shipment. Our 2,800+ specification range means standard sizes ship from stock while custom lengths and non-standard dimensions receive dedicated production scheduling. Every bundle carries heat number traceability linking back to original mill test certificates, satisfying auditor requirements for projects in EU, Middle East, and Southeast Asian markets. Professional loading teams understand oversized cargo requirements for 12-meter tubes, optimizing container utilization while protecting galvanized surfaces from transit damage. Complete export documentation packages — including packing lists, bills of lading, certificates of origin, and third-party inspection reports — clear customs smoothly at destination ports.
Documentation & Compliance
- Mill test certificate documenting Q235B and S275JR chemical composition and mechanical properties per GB standards with heat number traceability
- CE certificate confirming EN 10219 compliance for cold-formed welded structural hollow sections exported to European markets
- ISO 9001 quality management system certificate covering integrated steel production and tube fabrication processes
- SGS or BV third-party inspection report verifying zinc coating thickness Z121–Z180 and dimensional tolerance ±1% before shipment
- Material traceability documentation linking each bundle to specific heat numbers and production batch records
- Complete customs clearance package including packing list, bill of lading, and certificate of origin for destination port requirements
Packaging, Loading & Delivery
- Pre-galvanized square rectangular steel tube bundled with steel strips and edge protectors to preserve zero spangle zinc coating during ocean transit
- Surface protection maintained through non-oiled condition with careful handling procedures preventing zinc layer scratches at contact points
- Container loading optimized for 1–12 m lengths with wooden cradles preventing tube-to-tube abrasion during 20ft and 40ft container shipments
- Custom cut-to-length service available for 12 m standard tubes, reducing on-site waste and cutting labor costs at project locations
- Heat number and steel grade markings stenciled on each bundle end for site identification and inspection traceability
- FOB, CIF, and DDP shipping terms available with professional export documentation supporting customs clearance at destination ports
Starting Your Pre-Galvanized Tube Procurement Process
Submit your project drawings, required steel grades, coating class specifications, and destination port to receive detailed quotation including material costs, fabrication charges, and shipping logistics. Our engineering team reviews shop drawings within 24 hours, confirming dimensional feasibility and suggesting material optimizations that reduce total project cost. Third-party inspection coordination and complete documentation packages are confirmed before production begins, ensuring smooth customs clearance and site acceptance.
Frequently Asked Questions
Q: What is the difference between Z121 and Z180 zinc coating classes?
A: Z121 indicates 121 grams of zinc per square meter of tube surface, suitable for indoor applications or sheltered outdoor use. Z180 provides 180 grams per square meter, offering extended corrosion protection for exposed outdoor structures in moderate environments. The choice depends on your project’s service environment and required design life.
Q: Can you provide mill test certificates for international projects?
A: Yes, every shipment includes mill test certificates documenting chemical composition and mechanical properties for the specific heat numbers in your order. We also coordinate third-party inspection by SGS, BV, or Intertek before shipment if your project requires independent verification.
Q: What steel grades are available for structural applications?
A: We supply Q235B for general structural use, S275JR for higher load-bearing requirements meeting European standards, and A53 for projects following ASTM specifications. SGCC and DX51D grades serve lighter gauge applications like fencing and container frames.
Q: Can you cut tubes to custom lengths?
A: Yes, we offer cut-to-length service for tubes in the 1–12 m range. Custom lengths reduce on-site cutting waste and labor costs. Please specify your required lengths when requesting quotation, and our team will confirm feasibility and pricing.
Q: What is the minimum order quantity?
A: Our minimum order quantity is 5 tons for standard specifications. Custom dimensions or non-standard steel grades may have different MOQ requirements depending on production scheduling.
Request Your Pre-Galvanized Steel Tube Quotation
Send your project specifications, steel grade requirements, and destination port to receive detailed pricing with complete mill test certificates and third-party inspection options.
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
Address: No.11889, Jingshi West Road, Lulian Group, Jinan City, Shandong Province, China
