Description
Factory-direct thick wall galvanized rectangular steel tube — vertically integrated from raw steel production to finished RHS with zero spangle coating, eliminating material traceability gaps between supplier and fabricator.
Technical Specifications
| Parameter | Value |
|---|---|
| Designation | Q195/Q235/Q345 Galvanized Rectangular Steel Tube |
| Product Type | Galvanized Rectangular Steel Tube (RHS) |
| Steel Grade | Q195, Q235, Q345, 10#, 20#, 45#, A106, A53, A36 |
| Standard | ASTM, CE, RoHS, BIS, SASO, SABS, JIS, ISO9001, API |
| Section Shape | Rectangular |
| Wall Thickness | 1.2–15.7 mm |
| Length | 6m / 6.4m / 12m |
| Technique | Cold Rolled Based |
| Surface Treatment | Galvanized (Z81–Z120), Zero Spangle, Non-oiled |
| Tolerance | ±1% |
| Application | Greenhouse structures, Steel structures, Construction frames, Fencing, Making Pipes, Making Corrugated Sheets, Making Container |
| Origin | Shandong, China |
Application Suitability
| Industry | Typical Applications |
|---|---|
| Agriculture & Horticulture | Greenhouse frame structures, shade house supports, irrigation framework |
| Industrial Construction | Factory building frames, mezzanine platforms, equipment support structures |
| Logistics & Warehousing | Warehouse racking systems, container chassis frames, loading dock structures |
| Infrastructure | Fencing systems, highway guardrail posts, sound barrier supports |
What Zero Spangle Galvanizing Means for Greenhouse Corrosion Resistance
Smooth zinc coating without visible crystallization patterns delivers uniform corrosion protection across welded joints and cut edges.
When sourcing galvanized rectangular tubes for greenhouse projects in humid coastal regions, the spangle pattern isn’t just cosmetic — large spangles create micro-galvanic cells between crystal boundaries that accelerate localized corrosion. Zero spangle coating (Z81–Z120) provides a metallurgically uniform zinc layer that maintains consistent protection even after field cutting and welding. We’ve seen third-party inspectors reject entire container loads at destination ports because the zinc coating thickness varied by 3 microns between batches, triggering re-inspection costs that exceeded the material savings from switching suppliers. For structural greenhouse frames exposed to fertilizer mist and condensation, this coating consistency directly determines service life before maintenance repainting becomes necessary. [NEED_CITE: galvanized coating thickness standards for agricultural structures]
Precision Wall Thickness for Structural Load Calculations
The ±1% tolerance on wall thickness from 1.2mm to 15.7mm means engineers can rely on published section modulus values without applying excessive safety factors for dimensional uncertainty. Cold rolled based production maintains tighter dimensional control than hot formed alternatives, which matters when thick wall Q345 RHS serves as primary load-bearing columns in industrial frames. Our vertically integrated mill produces the substrate steel and applies the galvanizing in one continuous process, so the coating adhesion and thickness remain consistent across the full 1.2–15.7mm range — no third-party coating subcontractor introducing variability between material batches.
Meeting EN 10219 and ASTM A500 for International Projects
Structural hollow sections for European markets must comply with EN 10219 cold-formed welded hollow section requirements covering dimensional tolerances, material traceability, and weld integrity. [NEED_CITE: EN 10219 cold-formed hollow section requirements] North American projects typically specify ASTM A500 Grade B or C with corresponding chemical composition limits. Our Q235 and Q345 grades meet the mechanical property ranges for these international standards, and we provide full documentation packages including mill test certificates with heat number traceability, dimensional inspection reports, and coating thickness measurements. The CE marking and ISO 9001 certification support customs clearance across EU member states and Belt & Road markets.
Understanding Q-Series Steel Grades for Structural Applications
The Q195, Q235, and Q345 designations follow the Chinese GB/T 700 standard system where the number indicates minimum yield strength in MPa. Q195 serves light-duty applications like greenhouse purlins and fencing posts where formability matters more than load capacity. Q235 is the workhorse grade for general construction frames, offering balanced strength and weldability. Q345 (equivalent to S355 in EN standards) provides higher yield strength for heavy-duty industrial structures, crane runway beams, and multi-story building frames. The cold rolled based production technique combined with mid-hard hardness delivers the dimensional accuracy needed for precision-cut greenhouse components while maintaining sufficient ductility for field bending and connection drilling.
The Hidden Cost of Coating Thickness Variability
Ordering galvanized RHS from trading companies who subcontract coating to third-party galvanizers creates a documentation gap — you receive material certificates showing substrate chemistry but no verifiable coating weight data. When project specifications require Z120 minimum coating and the delivered product averages Z85 with spot readings below Z60, the entire shipment fails third-party inspection at destination. Re-galvanizing on-site is impossible for assembled structures, and air freight replacement costs destroy project margins. Our integrated production from raw steel to finished galvanized tube means one mill test certificate covers both substrate and coating, with full traceability from iron ore to final bundle. [NEED_CITE: material traceability requirements for structural steel certification]
Why Source Thick Wall Galvanized Rectangular Steel Tube from XJY Structure
Our own steel mill with three production lines produces the substrate steel, applies the galvanizing, and fabricates the finished rectangular tubes — eliminating the quality disconnect between material supplier and coating subcontractor. The 2,800+ specification range covers your full project bill of materials from 1.2mm light gauge to 15.7mm heavy wall in one purchase order. Certified welding procedures (WPS/PQR) and qualified welders per AWS and EN standards mean the tubes arrive ready for your fabrication team without additional procedure qualification. Every shipment includes complete quality documentation: mill test certificates with heat numbers, dimensional inspection reports, coating thickness measurements, and weld maps for fabricated assemblies. Professional loading plans for oversized cargo and complete export documentation handle the logistics complexity of international project delivery.
Documentation & Compliance
- Mill test certificate documenting Q195/Q235/Q345 chemical composition and mechanical properties per GB/T 700 with heat number traceability
- CE certificate confirming compliance with EN 10219 cold-formed welded structural hollow sections for EU market access
- ISO 9001 quality management system certificate covering integrated steel production and galvanizing processes
- SGS or BV third-party inspection reports verifying dimensional tolerances and galvanized coating thickness (Z81–Z120)
- Material traceability documentation linking each bundle to specific heat numbers and production dates
- Complete customs documents including packing list, bill of lading, and certificate of origin for destination clearance
Packaging, Loading & Delivery
- Thick wall galvanized rectangular tubes bundled with steel strips and edge protectors to preserve zero spangle zinc coating during ocean transit
- Non-oiled surface treatment requires moisture barrier wrapping for container shipping to prevent white rust formation
- 6m and 12m standard lengths optimized for 20ft and 40ft container loading with professional lashing plans for heavy wall sections
- Custom cut-to-length service available for greenhouse projects requiring precise component lengths to reduce on-site waste
- Heat number and steel grade stenciled on each tube end for site identification and inspection traceability
- FOB, CIF, and DDP shipping terms with door-to-door logistics coordination for project sites in Middle East, Southeast Asia, and Africa
Request Quotation with Full Technical Documentation
Submit your project drawings, steel grade requirements, coating specifications, and destination port to receive detailed pricing with mill test certificate samples and production lead time confirmation. Our engineering team reviews shop drawings for material optimization and fabrication sequencing before contract signing, ensuring the thick wall galvanized rectangular steel tube specifications match your structural calculations and international standard compliance requirements.
Get Factory-Direct Pricing with Complete Quality Documentation
Share your project specifications and quantity requirements to receive quotation with mill test certificate samples and delivery schedule.
Shandong Xin Jiyuan Special Steel Tube Co., Ltd
Website: www.xjystructure.com
Mobile/WhatsApp/WeChat: +86 188 5315 7756
Email: admin@xjystructure.com
Frequently Asked Questions
Q: What galvanized coating weights are available and how do I choose for greenhouse versus industrial applications?
A: We provide Z81 to Z120 coating weights with zero spangle finish. For greenhouse structures in humid coastal environments, Z100–Z120 provides extended corrosion resistance against fertilizer mist and condensation. Industrial indoor applications with controlled environments can specify Z81 to reduce cost while maintaining adequate protection.
Q: Can you provide custom cut-to-length and pre-punched rectangular tubes for greenhouse assembly?
A: Yes, our fabrication division offers CNC cutting, punching, and bending services to deliver ready-to-assemble greenhouse components. This reduces on-site labor costs and material waste compared to field cutting full-length tubes.
Q: How does your vertically integrated mill ensure material traceability and certification compliance?
A: Our own steel mill produces the substrate steel, applies galvanizing, and fabricates finished tubes in one continuous process. Each bundle carries heat number traceability from raw material to finished product, documented in mill test certificates covering both substrate chemistry and coating thickness.
Q: What standards do your galvanized RHS comply with for international projects?
A: Our products meet ASTM, CE, JIS, ISO9001, and other international standards. The Q235 and Q345 grades correspond to S235 and S355 in EN standards, supporting EU market access with EN 10219 compliance documentation.
Q: What is the production lead time and how do you handle oversized cargo shipping?
A: Typical production lead times apply after drawing approval and deposit receipt. We provide professional loading plans for heavy wall sections and oversized cargo, with complete export documentation and tracking until site delivery.
