Description
Factory Direct Galvanized Tubes — Vertically integrated steel mill and fabrication workshop controlling every step from raw material to finished Q235 Q345 Galvanized Square Rectangular Steel Tube 20-500mm Factory Direct shipment.
Technical Specifications
| Parameter | Value |
|---|---|
| Designation | Q235 Q345 Galvanized Square and Rectangular Steel Tube |
| Product Type | Square / Rectangular Steel Tube (Welded, Galvanized) |
| Steel Grade | Q195, Q215, Q235A, Q235B, Q235C, Q235D, Q255A, Q255B, Q275, Q345B, Q345C, Q345D, Q345E, S235JR, S275JR, S355JR, S420NL, S460NL, SS400, A36, Grade 50 |
| Standard | AISI, ASTM, DIN, JIS, GB, EN |
| Section Shape | Square / Rectangular |
| Size Range | 20mm–500mm side length |
| Wall Thickness | 0.3mm–100mm |
| Length | 5.8m–12m |
| Technique | ERW (Electric Resistance Welded) / Hot Rolled / Cold Rolled |
| Surface Treatment | Hot Dip Galvanized (Zinc Coating 30g–275g), PVC Coated, Black, Color Painting, Oiled, Anti-rust Oil |
| Tolerance | ±1% |
| Ends | Plain / with or without end caps |
| Application | Steel structures, Construction frames, Machinery frames, Scaffolding, Furniture, Industrial platforms, Warehouse and logistics center structures |
| Origin | Shandong, China |
Application Suitability
| Industry | Typical Applications |
|---|---|
| Commercial & Industrial Construction | Steel frame structures, columns, beams, and platforms for warehouses, factories, and logistics centers |
| Infrastructure & EPC Projects | Support structures for renewable energy installations, bridges, and Belt & Road construction programs |
| Machinery & Equipment | Structural tubing for industrial machinery frames, scaffolding systems, and material handling equipment |
What Wall-Thickness Tolerance Costs on a Structural Frame Order
A Galvanized Square and Rectangular Steel Tube Q235 Q345 Supplier with ±1% tolerance control prevents rejection at site inspection.
Overseas buyers outsourcing steel tube procurement to China face quality uncertainty when wall thickness falls below specified tolerance. A shipment of Q345 galvanized square tubes once arrived at a Middle East port where the site supervisor measured wall thickness with a caliper and rejected the entire container — the negative tolerance exceeded acceptable limits by a marginal amount. The cargo sat at the port for months, incurring demurrage charges and project delays. Material traceability gaps compound this risk: when fabricators source steel from third-party mills without integrated quality control, certification chains break down, and buyers cannot verify whether the delivered tubes match the mill test certificates. [NEED_CITE: EN 10219 cold-formed hollow section tolerance requirements]
How Galvanized Square and Rectangular Tubes Match Structural Frame Requirements
A Galvanized Square and Rectangular Steel Tube Q235 Q345 Supplier delivering 20mm–500mm side lengths with 0.3mm–100mm wall thickness serves both light-gauge scaffolding and heavy-load industrial platforms. The hot dip galvanized surface treatment with 30g–275g zinc coating provides corrosion resistance for outdoor construction environments, while ERW welded seams with certified welding procedures ensure structural integrity under load. Our vertically integrated facility controls material from raw steel production through galvanizing, eliminating the traceability gaps that plague fragmented supply chains.
Engineering Compliance and Certification for Global Projects
Structural steel tubes for European markets require CE marking per EN 10210 or EN 10219, with complete documentation including Mill Test Certificates showing chemical composition and mechanical properties traceable to heat numbers. [NEED_CITE: CE marking requirements for structural hollow sections under EN 10210] North American projects specify ASTM A500 or A36 grades, while Southeast Asian and African infrastructure programs often accept GB standards with third-party inspection from SGS or BV. The ±1% tolerance on wall thickness and side length ensures dimensional accuracy for prefabricated construction and BIM-coordinated shop drawings. Custom non-standard sizes outside the 20mm–500mm range require minimum order quantity confirmation, and定尺长度 within the 5.8m–12m range reduces on-site cutting waste.
Steel Grade Selection and ERW Welding Process
The Q235 and Q345 series represent Chinese standard grades where Q345 offers higher yield strength than Q235, making it suitable for heavy-load structural applications. International equivalents include S235JR and S355JR per EN standards, A36 and Grade 50 per ASTM, and SS400 per JIS — a Galvanized Square and Rectangular Steel Tube Q235 Q345 Supplier must provide grade equivalence documentation for customs clearance and engineering approval. ERW (Electric Resistance Welded) technique produces longitudinal seams with certified welding procedures (WPS/PQR) and qualified welders, ensuring seam integrity for structural applications without the cost premium of seamless tubes. Hot dip galvanizing with 30g–275g zinc coating provides sacrificial corrosion protection, while PVC coating suits highly corrosive industrial environments. Wall thickness tolerance of ±1% prevents the negative tolerance issues that cause site rejections — a critical factor when theoretical weight calculations depend on precise dimensions. [NEED_CITE: steel grade equivalence between GB Q series and EN S series]
Hidden Costs of Incorrect Steel Grade and Certification
Ordering Q235 tubes when the engineering specification requires Q345 results in structural under-capacity that fails load testing, requiring complete replacement and project delays. Missing CE certification for European projects triggers customs holds and demurrage charges, while absent Mill Test Certificates prevent material traceability verification during quality audits. Negative tolerance exceeding ±1% on galvanized square tubes causes caliper measurement failures at site inspection, leading to container rejection and months of port storage. A Galvanized Square and Rectangular Steel Tube Q235 Q345 Supplier with integrated quality control and complete documentation eliminates these hidden costs through one quality system and one point of accountability. [NEED_CITE: consequences of material certification gaps in structural steel procurement]
Why Source from an Integrated Mill and Fabrication Facility
Our vertically integrated operation combines raw steel production with fabrication workshop capabilities, controlling material from molten steel through finished galvanized tubes. This integration ensures material traceability from heat number to finished product, with complete quality documentation including WPS, PQR, dimensional inspection reports, and coating thickness reports. The facility maintains 2,800+ specifications in inventory, enabling one-stop procurement for projects requiring multiple sizes and grades. Certified welding procedures and qualified welders per AWS and EN standards guarantee seam integrity, while third-party inspection from SGS, BV, or TÜV verifies dimensional accuracy and coating quality before shipment. Professional packing and oversized cargo loading expertise prevents zinc coating damage during ocean transit, and complete export documentation supports customs clearance in destination countries.
Documentation & Compliance
- Mill Test Certificate documenting Q235B and Q345B chemical composition and mechanical properties per GB standards, with heat number traceability
- CE certificate per EN 10210 and EN 10219 for structural hollow sections, enabling European market access and customs clearance
- ISO 9001 quality management system certificate covering the integrated production and fabrication process
- SGS or BV third-party inspection report verifying wall thickness tolerance, zinc coating thickness, and dimensional accuracy
- Material traceability documentation linking each tube to specific heat numbers and production batches
- Complete customs documents including packing list, bill of lading, and certificate of origin for destination country clearance
Packaging, Loading & Delivery
- Galvanized Q235 Q345 square and rectangular tubes bundled with steel strips and edge protectors to preserve the zinc coating during ocean transit
- Hot dip galvanized surface treatment with 30g–275g zinc coating protected by waterproof wrapping for containers shipped to humid coastal destinations
- 5.8m–12m length tubes optimized for 20ft and 40ft container loading, with professional lashing plans preventing movement during transit
- Custom cutting to project-specific lengths within the 5.8m–12m range reduces on-site waste and labor costs
- Heat number and steel grade markings clearly identified on each tube bundle for site inspection and material traceability
- FOB, CIF, and DDP shipping terms available, with door-to-door logistics coordination for EPC projects
How to Request a Quotation for Your Project
Submit your project drawings (PDF/DWG), specifying steel grade (Q235B, Q345B, or international equivalents), side length, wall thickness, length, surface treatment requirement, and destination port. We respond within 24 hours with a detailed quotation including material, fabrication, coating, packing, and shipping costs, along with shop drawing timeline and production schedule. For custom non-standard sizes or certification requirements, specify the applicable standards (EN 10219, ASTM A500, JIS G3466) and third-party inspection preferences.
Get Your Galvanized Steel Tube Quotation with Mill Test Certificates
Share your project specifications and required standards to receive a detailed quotation with complete quality documentation within 24 hours.
Company: 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
Frequently Asked Questions
Q: How do Q235 and Q345 grades compare to S235JR and S355JR per EN standards?
A: Q235 and Q345 are Chinese standard grades under GB specifications, with Q345 offering higher yield strength than Q235. The international equivalents are S235JR and S355JR per EN 10219, A36 and Grade 50 per ASTM A500, and SS400 per JIS G3466. We provide grade equivalence documentation and Mill Test Certificates showing chemical composition and mechanical properties for customs clearance and engineering approval.
Q: Can you provide Mill Test Certificates and arrange third-party inspection before shipment?
A: Yes, we provide Mill Test Certificates per EN 10204 3.1/3.2 standards, documenting chemical composition and mechanical properties traceable to heat numbers. Third-party inspection from SGS, BV, or TÜV is available for dimensional accuracy, zinc coating thickness, and welding quality verification before shipment.
Q: What is the minimum order quantity for custom sizes outside the standard 20mm–500mm range?
A: Standard sizes from 20mm–500mm side length with 0.3mm–100mm wall thickness are available from inventory. For custom non-standard sizes, minimum order quantity depends on the specific dimensions and production requirements. Submit your specifications for a detailed quotation including production timeline.
Q: When should I choose hot dip galvanized versus PVC coated or black finish?
A: Hot dip galvanized with 30g–275g zinc coating provides sacrificial corrosion protection for outdoor construction and infrastructure projects. PVC coating suits highly corrosive industrial environments such as chemical plants or coastal installations. Black or oiled finish is appropriate for indoor applications or projects where additional surface treatment will be applied on-site.
Q: Do your products carry CE marking for European customs clearance?
A: Yes, our structural hollow sections carry CE marking per EN 10210 and EN 10219 standards, with complete documentation including Mill Test Certificates, welding procedure qualifications, and dimensional inspection reports. This enables European market access and customs clearance without delays.
