Description
Factory-Direct Galvanized Tubes — every batch tested in-house before shipping, no middlemen markup.
Technical Specifications
| Parameter | Value |
|---|---|
| Designation | Q195 Q235 Q345 Hot Dipped Galvanized Square and Rectangular Steel Tube |
| Product Type | Square and Rectangular Steel Tube (Galvanized) |
| Steel Grade | Q195, Q235, Q345, 10#, 20#, 45#, 16Mn, ASTM A53 (Grade A/B), St37, St42, St35.4, St52.4, Grade B, Grade C, Grade D, Grade 50 |
| Standard | BS EN, GB, AISI, ASTM, DIN, JIS |
| Section Shape | Square / Rectangular |
| Size Range | 10 mm – 1000 mm (side length or outer diameter) |
| Wall Thickness | 0.6 mm – 28 mm |
| Length | 1 m – 12 m |
| Technique | Hot Rolled / Cold Rolled / ERW |
| Surface Treatment | Hot Dipped Galvanized (Zinc Coating 30–275 g/m²); also Bare, Oiled, Color Paint, 3PE |
| Ends | Plain / Beveled / Threaded with couplings or sockets |
| Application | Structural frames, construction, machinery, trailers, sign posts, agricultural equipment, shipbuilding |
| MOQ | 1 Ton |
| Origin | Shandong, China |
Application Suitability
| Industry | Typical Applications |
|---|---|
| EPC Contractors & Construction | Building frames, bridge components, architectural columns, scaffolding structures |
| Machinery Manufacturers | Equipment frames, conveyor system supports, industrial machine housings |
| Infrastructure & Agriculture | Highway sign posts, greenhouse frames, trailer beds, irrigation structures |
| Industrial Fabrication | Boiler supports, pressure vessel frames, shipbuilding structural members |
Inconsistent Zinc Coating Is the Silent Budget Killer on Galvanized Tube Orders
A 45μm coating where 70μm was specified means one rejected container and an air-freight bill you never planned for.
Global procurement teams ordering Hot Dipped Galvanized Square and Rectangular Steel Tube from fragmented supplier networks routinely face three compounding failures: coating thickness that drifts below spec on random bundles, mill test certificates that arrive incomplete or missing heat numbers, and customs holds triggered by absent CE documentation for EU-bound cargo [NEED_CITE: EN 10219 cold-formed hollow section compliance requirements]. When a Dubai contractor’s third-party inspector flagged an entire shipment for sub-spec zinc, the replacement air-freight cost exceeded the original ocean freight by a factor that erased the project margin. That scar now drives our in-house lab protocol — every galvanized batch gets coating-thickness verification before it leaves Jinan.
How Wall Thickness Range Meets Structural Load Demands Across Project Types
From 0.6 mm thin-wall sections for signage frames to 28 mm heavy-wall profiles for bridge load-bearing members, Hot Dipped Galvanized Square and Rectangular Steel Tube in this range covers the full spectrum of structural and light-fabrication needs. The 10 mm to 1000 mm side-length span means a single procurement call can consolidate greenhouse purlins, conveyor uprights, and main structural columns — eliminating the coordination overhead of sourcing thin-wall and heavy-wall from separate mills. Our three dedicated production lines hold 2,800+ specification combinations in stock, and the proprietary sharp-corner rectangular tube patent fills a gap that standard round-corner profiles cannot address when flush-fit connections matter.
Engineering Compliance Paths for Galvanized Hollow Sections in Regulated Markets
Structural engineers specifying EN 10219 cold-formed welded hollow sections require documented conformity that travels with the cargo through customs and site inspection [NEED_CITE: steel grade equivalence between EN and ASTM standards]. Q235 maps to S235JR under EN standards and roughly to ASTM A36, while Q345 aligns with S355JR — but the equivalence is not automatic on paper, and missing cross-reference documentation triggers hold-ups at EU and North American ports. Hot dip galvanizing at 275 g/m² delivers corrosion protection rated for decades in coastal and industrial atmospheres, while 30 g/m² coatings serve indoor or temporary-exposure applications at lower cost. CE certification under EN 10210 and EN 10219 is mandatory for structural hollow sections entering the EU market, and SGS or BV third-party inspection reports provide the independent verification that project owners and main contractors demand before releasing payment milestones.
Steel Grade Selection and Manufacturing Process Fundamentals
The Q-series grades (Q195, Q235, Q345) follow the Chinese GB system where the number indicates minimum yield strength in MPa — Q235 delivers adequate formability for general frames, while Q345 steps up to higher load-bearing applications without moving to alloy steel pricing. ASTM A53 Grade A/B covers standard pipe applications in North American spec books, and the St-series (St37, St52.4) maps to DIN-based European machinery specifications. ERW welding produces the longitudinal seam on most square and rectangular profiles, offering cost efficiency at moderate wall thicknesses; hot rolling handles the heavier 20–28 mm walls where seamless-like integrity matters. Hot dip galvanizing immerses the formed tube in molten zinc, creating a metallurgical bond that outperforms electro-galvanized or painted alternatives in outdoor and corrosive environments — the 30–275 g/m² range lets buyers match coating mass to actual exposure severity rather than over-specifying across the board.
The Hidden Cost of Unverified Material Claims on Structural Projects
Accepting a supplier’s verbal grade confirmation without mill test certificate traceability exposes the project to three failure modes: structural members that fail load testing because actual yield strength falls below the specified Q345 minimum, customs authorities holding the container because CE documentation is absent or forged, and on-site welders discovering that the chemistry of unverified material produces cracking under standard welding procedures [NEED_CITE: EN 10210 structural hollow section tolerance requirements]. Each failure mode carries a cost multiplier — re-welding delays the critical path, customs demurrage compounds daily, and structural rejection after erection requires crane-time demolition that no material-cost saving can offset. Engineering specifications reference EN 10219 tolerance tables and ASTM A500 grade requirements precisely because these standards define the boundary between acceptable variation and structural non-compliance [NEED_CITE: hot dip galvanized coating thickness inspection standards].
Why Procurement Teams Consolidate Galvanized Tube Orders Here
Factory-direct pricing flows from owning three production lines rather than brokering through trading desks — the margin that middlemen layer onto each ton stays in your project budget. Every heat number gets tested in our physical and chemical laboratory before shipment, producing mill test certificates that document actual chemistry and mechanical results rather than catalog promises. The 2,800+ specification range means thin-wall signage tubes, mid-range structural sections, and heavy-wall bridge members ship from one source in one consolidated container, cutting freight cost and eliminating multi-supplier coordination risk. Our proprietary sharp-corner rectangular tube technology — backed by 41 invention patents — delivers flush-fit connections that standard rounded-corner profiles cannot achieve, closing a gap that has forced engineers to accept compromises on global projects. CE certification under EN 10210/EN 10219, ISO 9001:2015 registration, and SGS/BV third-party inspection acceptance clear the documentation path for EU, North American, and Middle Eastern customs. Custom non-standard sizes and定尺 lengths down to 1-ton MOQ serve projects that fall outside catalog dimensions without forcing full-mill minimum orders. Professional loading plans optimize container weight distribution for 12 m bundles, and FOB/CIF/DDP delivery options cover the full logistics chain to 50+ destination countries.
Documentation & Compliance
- Mill test certificate documenting Q195/Q235/Q345 chemical composition and mechanical properties per GB standard, with heat-number traceability
- CE certificate confirming EN 10210/EN 10219 conformity for structural hollow sections entering EU member-state markets
- ISO 9001:2015 quality management system certificate covering production, testing, and dispatch processes
- SGS or BV third-party inspection report verifying zinc coating thickness, dimensional tolerances, and surface quality
- Material traceability sheet linking each bundle to heat number, production date, and test results
- Customs documentation package including packing list, bill of lading, and certificate of origin for destination-country clearance
Packaging, Loading & Delivery
- Hot dipped galvanized tubes bundled with steel strips and edge protectors to preserve the zinc coating from abrasion during ocean transit
- 12 m standard length bundles loaded with interlayer separators to prevent contact damage to the galvanized surface
- Container loading plans optimized for 10–1000 mm section sizes, balancing weight distribution across 20ft and 40ft equipment
- Custom cut-to-length service available for 1–12 m requirements, with plain, beveled, or threaded ends per project specification
- Bundle identification tags showing steel grade (Q235/Q345), heat number, size, and length for on-site inventory control
- FOB Jinan/Qingdao, CIF destination port, or DDP door-to-door delivery options with real-time shipment tracking
Start Your Procurement With Verified Specifications
Submit your size range, wall thickness, steel grade, zinc coating requirement, and destination port — our team responds within 12 hours with pricing, mill test certificate samples, and confirmed production lead times. Non-standard dimensions and sharp-corner rectangular tube requirements receive custom feasibility review against our 2,800+ specification catalog.
Request Your Quote and Mill Test Certificate
Email your specifications to admin@sdxjysteel.com or message via WhatsApp at +86 188 5315 7756 for pricing, certification documents, and container loading plans.
Frequently Asked Questions
Q: How do Q235 and Q345 steel grades compare to European and American equivalents?
A: Q235 corresponds to S235JR under EN standards and is roughly equivalent to ASTM A36 in the American system. Q345 aligns with S355JR for yield strength classification. We provide cross-reference documentation with every shipment to support customs clearance and engineering approval in EU and North American markets.
Q: What zinc coating thickness should I specify for different environments?
A: The 30 g/m² coating serves indoor or sheltered applications where corrosion exposure is minimal. For outdoor structural work, coastal installations, or industrial atmospheres, 275 g/m² provides long-term protection rated for decades of service. Our in-house lab tests every batch to confirm coating mass meets your specification before shipment.
Q: Can you produce non-standard sizes or sharp-corner rectangular tubes with low MOQ?
A: Yes. Our proprietary sharp-corner rectangular tube technology — covered by 41 invention patents — fills a gap in the global market for flush-fit structural connections. Custom non-standard dimensions are available across our 2,800+ specification range, and the MOQ starts at 1 ton to accommodate project-specific requirements without forcing full-mill order quantities.
Q: What certification documents do you provide for EU customs clearance?
A: Every shipment includes CE certification under EN 10210 and EN 10219 for structural hollow sections, mill test certificates with heat-number traceability, and a complete customs documentation package (packing list, bill of lading, certificate of origin). SGS or BV third-party inspection reports are available upon request for projects requiring independent verification.
Q: How do you optimize container loading for mixed-size galvanized tube orders?
A: Our logistics team prepares container loading plans that balance weight distribution and maximize space utilization for 10–1000 mm section sizes across 20ft and 40ft containers. Bundles are separated to protect the galvanized coating, and edge protectors prevent zinc abrasion during transit. FOB, CIF, and DDP delivery options cover the full supply chain to 50+ countries.
