Description
Factory-direct pricing with full mill traceability — Every Q235 Q345 galvanized square and rectangular steel tube leaves our ERW lines with zinc coating verified by in-house film thickness testing, shipped with heat-numbered MTC to your port.
Technical Specifications
| Parameter | Value |
|---|---|
| Designation | Q235 Q345 Galvanized Square and Rectangular Steel Tube |
| Product Type | Galvanized SHS / RHS |
| Steel Grade | Q195, Q235, Q345, 10#, 20#, 45#, 16Mn, A53 (Grade A/B), St37, St42, St35.4, St52.4, SS400 |
| Standard | GB, BS EN, AISI, ASTM, DIN, JIS |
| Section Shape | Square / Rectangular |
| Size Range (Side Length) | 10 mm – 1000 mm |
| Wall Thickness | 0.6 – 28 mm |
| Length | 1 – 12 m |
| Technique | ERW (Hot Rolled / Cold Rolled) |
| Surface Treatment | Galvanized (Zinc Coating 30 – 275 g/m²); also Bared, Oiled, Color Paint, 3PE |
| Ends | Plain / Beveled / Threaded with couplings or sockets |
| Tolerance | ±1% |
| Application | Steel structures, construction frames, machinery, scaffolding, furniture, bridges, ships, boilers, automotive, general engineering |
| MOQ | 1 Ton |
| Origin | Shandong, China |
Application Suitability
| Industry | Typical Applications |
|---|---|
| EPC Contractors & Construction | Building frames, scaffolding systems, high-rise structural columns, bridge support members |
| Machinery Manufacturers | Equipment frames, conveyor support structures, precision structural profiles |
| Infrastructure & Industrial | Fencing systems, greenhouse frames, non-pressure fluid conveyance, industrial platforms |
Where Zinc Coating Consistency Decides Site Acceptance
Inconsistent galvanizing thickness is the single most common reason galvanized tubes get rejected at project inspection.
I once watched an entire container of 6-meter galvanized square tubes get turned away at a Suzhou infrastructure site because the zinc layer measured 45 microns against a 65-micron contract requirement. The rework cycle — shipping back, re-galvanizing, re-shipping — cost the buyer over three weeks of delay. For buyers sourcing a Q235 Q345 galvanized square and rectangular steel tube, zinc coating variance between 30 g/m² and 275 g/m² must be verified per batch, not assumed from the order sheet. Missing or incomplete mill test certificates compound the problem, triggering customs holds and project compliance failures across EU, Southeast Asia, and Middle East destinations [NEED_CITE: hot-dip galvanized coating thickness standards for structural steel].
Matching Structural Profiles to Engineering Load and Environment
Galvanized SHS and RHS in Q235 and Q345 grades serve load-bearing frames where corrosion resistance and structural rigidity must coexist. The 10–1000 mm side length range with wall thickness up to 28 mm covers everything from light-duty furniture frames to heavy industrial support columns. For coastal or chemical-exposure environments, specifying 275 g/m² zinc coating rather than 30 g/m² extends service life significantly without changing the structural design. Our ERW production lines produce both hot-rolled and cold-rolled variants, allowing engineers to select based on surface finish requirements and dimensional precision needs for their Q235 Q345 galvanized square and rectangular steel tube installations.
Engineering Compliance and Certification Requirements
Structural hollow sections used in load-bearing applications must conform to recognized engineering standards. For EU projects, EN 10219 (cold-formed welded structural hollow sections) and EN 10210 (hot-finished welded structural hollow sections) define the certification baseline — without CE marking under these standards, customs clearance fails regardless of material quality [NEED_CITE: EN 10219 cold-formed hollow section requirements]. North American projects typically require ASTM A500 or A53 compliance, while Southeast Asian markets may demand additional local certifications such as SNI or SONCAP. Our Q235 Q345 galvanized square and rectangular steel tubes carry CE certification under EN 10210/EN 10219, ISO 9001:2015 quality management, and Singapore FPC approval, with third-party verification available through SGS, BV, or Lloyd’s Register before shipment.
Steel Grade Selection and ERW Process Fundamentals
Q235 and Q345 represent the two most widely specified carbon structural grades in Chinese standard systems, with Q345 offering higher yield strength for demanding load applications. The equivalence mapping between Q-series (GB), S-series (EN), and ASTM grades requires careful cross-reference — Q235 broadly corresponds to S235JR and ASTM A36, while Q345 aligns with S355JR and ASTM A572 Grade 50 [NEED_CITE: steel grade equivalence between EN and ASTM standards]. ERW (Electric Resistance Welding) production creates a longitudinal weld seam suitable for structural applications up to moderate pressure ratings, with hot-rolled feedstock providing better formability and cold-rolled offering tighter dimensional tolerance. The galvanized zinc coating applied post-welding (30–275 g/m²) protects both base metal and weld zone from atmospheric corrosion, with coating weight selected based on expected exposure conditions.
Hidden Costs of Procurement Shortcuts
Choosing the lowest quoted price on a Q235 Q345 galvanized square and rectangular steel tube often masks material substitution — suppliers may ship Q195 or lower-grade material while invoicing Q345, creating structural safety risks that only surface during load testing or years later through premature corrosion failure. Missing heat-number traceability on mill test certificates prevents verification of actual chemical composition and mechanical properties, while negative tolerance abuse — shipping walls thinner than the specified 0.6–28 mm range under the guise of “acceptable variance” — reduces load capacity without reducing the buyer’s cost per ton. Certification gaps compound these issues: a shipment arriving without proper CE documentation faces customs detention, demurrage charges, and project delays that dwarf any initial price savings [NEED_CITE: consequences of non-compliant structural steel in construction projects].
Procurement Confidence Through Verified Capability
Our three dedicated ERW production lines manufacture Q235 Q345 galvanized square and rectangular steel tubes across 2,800+ specifications with wall thickness up to 28 mm, eliminating the fragmented sourcing that forces buyers to coordinate pipes, plates, and fabrication from separate suppliers. Every batch undergoes incoming, in-process, and final inspection in our in-house physical and chemical laboratory, with full mill test certificates issued per heat number for complete traceability. Our proprietary sharp-corner rectangular tube technology — backed by 41 patents — fills specification gaps that standard catalogs cannot cover, while custom non-standard sizes remain available with low minimum order quantities. Factory-direct pricing removes intermediary markups, and professional loading optimization ensures efficient container utilization for shipments to 50+ countries across EU, North America, India, Southeast Asia, and the Middle East.
Documentation & Compliance
- Mill Test Certificate (EN 10204 3.1) documenting Q235 and Q345 chemical composition, yield strength, and tensile properties per heat number
- CE Certificate under EN 10210 (hot-finished) and EN 10219 (cold-formed) for EU customs clearance and structural compliance
- ISO 9001:2015 Quality Management System certification covering full production and inspection processes
- Third-Party Inspection Reports from SGS, BV, or Lloyd’s Register available upon request before shipment
- Material Traceability Documentation linking each Q235 Q345 galvanized square and rectangular steel tube to specific heat numbers and production batches
- Customs Clearance Package including packing list, bill of lading, and certificate of origin formatted for destination country requirements
Packaging, Loading & Delivery
- Galvanized Q235 Q345 square and rectangular tubes bundled with steel strips and edge protectors to preserve zinc coating integrity during ocean transit
- Surface protection maintained through plastic end caps and anti-rust treatment for 30–275 g/m² zinc-coated finishes
- Container loading optimized for 1–12 m lengths with professional stowage plans maximizing 20ft and 40ft utilization
- Custom cutting to project-specific lengths available within the 1–12 m range to reduce on-site waste
- Heat number and steel grade marking applied to each bundle for site identification and traceability verification
- FOB, CIF, and DDP shipping terms with door-to-door logistics coordination to 50+ countries
Start Your Procurement With Verified Specifications
Submit your Q235 Q345 galvanized square and rectangular steel tube requirements — including side length, wall thickness, zinc coating weight, steel grade, and destination port — to receive detailed pricing, production lead time, and mill test certificate samples within 12 hours. Our engineering team will confirm certification requirements for your destination market and provide custom solutions for non-standard dimensions or sharp-corner specifications.
Request Factory-Direct Pricing and Mill Test Certificates
Send your specifications via email to admin@sdxjysteel.com or contact us at +86 188 5315 7756 (WhatsApp/WeChat available) for immediate quotation and technical documentation.
Frequently Asked Questions
Q: How do Q235 and Q345 grades map to European EN and American ASTM standards?
A: Q235 broadly corresponds to S235JR (EN 10025) and ASTM A36, while Q345 aligns with S355JR and ASTM A572 Grade 50. We provide full cross-reference documentation and mill test certificates confirming chemical composition and mechanical properties meet your specified standard.
Q: Can you provide third-party inspection and what certifications accompany shipment?
A: Yes, SGS, BV, and Lloyd’s Register inspections are available before shipment. Every Q235 Q345 galvanized square and rectangular steel tube ships with EN 10204 3.1 mill test certificates, CE certification under EN 10210/EN 10219 for EU destinations, and complete customs documentation.
Q: What is the minimum order quantity for custom dimensions and sharp-corner rectangular tubes?
A: Standard specifications carry 1 Ton MOQ. Custom non-standard sizes and our proprietary sharp-corner rectangular tubes also maintain low MOQ requirements — contact us with your drawings for specific pricing and lead time.
Q: When should I specify 275 g/m² zinc coating versus 30 g/m²?
A: 275 g/m² suits outdoor, coastal, or industrial-corrosive environments requiring extended corrosion protection. 30 g/m² serves indoor or temporary exposure applications. We produce the full 30–275 g/m² range and can advise based on your project environment.
Q: What documentation do you provide for customs clearance in EU, Southeast Asia, and Middle East markets?
A: We supply CE certificates (EN 10210/EN 10219) for EU, Singapore FPC for Southeast Asia, and can coordinate destination-specific certifications including SNI, SONCAP, and SABS. Complete customs packages include packing list, bill of lading, and certificate of origin.
Secure Your Q235 Q345 Galvanized Square and Rectangular Steel Tube Supply
Email admin@sdxjysteel.com with your specifications, quantities, and destination to receive factory-direct pricing and mill test certificate samples within 12 hours.
