Description
Factory-Direct Galvanized Tubes — Hot rolled and cold rolled ERW base material processed in-house with zinc coating up to 275 g/m², shipped without trading markup.
Technical Specifications
| Parameter | Value |
|---|---|
| Designation | Q195 Q235 Q345 Hot Dipped Galvanized Square / Rectangular Steel Tube |
| Product Type | Galvanized Square / Rectangular Steel Tube |
| Steel Grade | Q195, Q235, Q345 |
| Standard | BS, EN, GB, AISI, ASTM, DIN, JIS |
| Section Shape | Square / Rectangular |
| Size Range (Side Length) | 10 mm – 1000 mm |
| 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); optional Bared, Oiled, Color Paint, 3PE |
| Ends | Plain, Beveled, Threaded with Couplings or Sockets; plastic caps and steel rings available |
| Application | General fabrication, structural frames, trailers, construction, bridge and highway, automobile chassis, industrial equipment, sign posts, agricultural equipment |
| MOQ | 1 Ton |
| Origin | Shandong, China |
Application Suitability
| Industry | Typical Applications |
|---|---|
| EPC Contractors | Structural frames for industrial plants, bridge and highway guardrail posts, load-bearing columns |
| Construction Companies | Building architecture, scaffolding systems, sign posts, curtain wall supports |
| Machinery Manufacturers | Equipment frames, trailer beds, conveyor structures, agricultural machinery chassis |
| Infrastructure Developers | Highway sound barriers, lighting pole foundations, solar panel mounting structures |
Why Zinc Coating Weight Decides Whether Your Galvanized Tubes Pass Site Inspection
A 30 g/m² coating and a 275 g/m² coating look identical to the naked eye — but their service life in corrosive environments differs by a factor of ten.
Procurement teams often specify “hot dipped galvanized” without locking down the zinc coating weight, leaving room for suppliers to deliver the minimum threshold. In coastal or industrial atmospheres, a thin zinc layer corrodes through within months, exposing the Q235 base metal to rapid oxidation. We have seen entire container loads rejected at Middle Eastern project sites because a coating thickness gauge reading fell below 40 μm — the result of uncontrolled bath temperature and dipping time at the galvanizing plant. Every batch of Hot Dipped Galvanized Square Rectangular Steel Tube we ship carries a zinc coating verified against the 30–275 g/m² range you specify, documented in the mill test certificate. [NEED_CITE: hot dip galvanizing coating thickness requirements per ASTM A123]
Matching Galvanized Square and Rectangular Tubes to Structural and Fabrication Loads
The Q195, Q235, and Q345 steel grades cover a yield strength progression that maps directly to load-bearing requirements in structural frames, trailer beds, and industrial equipment. Q195 serves light-duty fabrication where formability matters more than strength; Q235 handles general construction framing and sign post foundations; Q345 steps into bridge components and heavy machinery chassis where higher yield strength reduces section weight while maintaining rigidity. The 0.6–28 mm wall thickness range and 10–1000 mm side length coverage mean a single Hot Dipped Galvanized Square Rectangular Steel Tube order can supply everything from purlin supports to primary columns without splitting the purchase across multiple vendors.
Engineering Compliance and Certification Pathways for Galvanized Hollow Sections
Structural engineers designing to EN 1993 require hollow sections that conform to dimensional and tolerance standards — for European projects, this means EN 10219 cold-formed welded structural hollow sections. [NEED_CITE: EN 10219 cold-formed hollow section requirements] The Q195/Q235/Q345 grades map to S235/S275/S355 equivalents under EN 10219, and our CE certification under EN 10210/EN 10219 ensures the Hot Dipped Galvanized Square Rectangular Steel Tube clears EU customs without compliance disputes. For North American projects, ASTM A500 Grade B/C equivalents are available from the same production lines. Third-party inspection by SGS or BV can be arranged before shipment to verify coating weight, dimensional tolerance, and weld integrity — a step that prevents costly re-inspection at the destination port.
Understanding Q-Grade Steel and ERW Welding for Galvanized Tubes
The Chinese Q-grade system (Q195, Q235, Q345) designates yield strength in MPa — Q235 yields at a minimum of 235 MPa, Q345 at 345 MPa — making grade selection a direct lever for structural optimization. These grades correspond broadly to S235/S275/S355 in the EN system and ASTM A500 Grades B/C in the American system, though exact chemical composition and impact testing requirements differ. [NEED_CITE: steel grade equivalence between Chinese GB and international EN/ASTM standards] Our Hot Dipped Galvanized Square Rectangular Steel Tube is produced via ERW (Electric Resistance Welding) from either hot rolled or cold rolled coil, giving you the choice between cost-effective hot rolled base material for general structural use and cold rolled stock where tighter dimensional tolerance and smoother surface finish are needed before galvanizing. The hot dip galvanizing process immerses the formed and welded tube in a molten zinc bath, creating a metallurgical bond that covers all external and internal surfaces — far more durable than electroplated or pre-galvanized alternatives for outdoor and corrosive environments.
The Hidden Cost of Unverified Galvanizing and Missing Mill Certificates
Ordering Hot Dipped Galvanized Square Rectangular Steel Tube without specifying zinc coating weight in the purchase contract invites suppliers to deliver the thinnest acceptable layer — saving them zinc cost while shifting corrosion risk to your project. When a structural inspector on-site pulls out a coating thickness gauge and reads below the project specification, the entire batch faces rejection, re-galvanizing, or scrap. Worse, if the mill test certificate is missing or forged, customs authorities in the EU or Middle East can hold the container for weeks, demurrage accumulating daily. [NEED_CITE: consequences of missing mill test certificates in steel import customs clearance] The real cost is never the per-ton price difference — it is the delayed project handover, the re-welding of corroded connections, and the structural safety liability that follows.
Procurement Confidence from a Jinan-Based Galvanized Tube Manufacturer
We operate three dedicated production lines in Jinan, Shandong, covering square and rectangular tubes from 10 mm to 1000 mm side length and up to 28 mm wall thickness — all processed in-house from raw coil to finished Hot Dipped Galvanized Square Rectangular Steel Tube. Our in-house physical and chemical laboratory tests every heat for composition and mechanical properties before galvanizing, and the galvanizing bath temperature and immersion time are logged per batch — a discipline born from an early export lesson where a Middle Eastern client’s coating gauge caught a sub-standard dip. We hold CE certification under EN 10210/EN 10219, ISO 9001:2015, Singapore FPC, and SGS/BV verification. With over 2,800 specifications in our rolling schedule and 41 patented technologies — including sharp-corner rectangular tube production — your non-standard dimensions can be accommodated without the typical high-MOQ barriers. We export to 50+ countries and handle professional container loading plans that maximize weight utilization for heavy galvanized sections.
Documentation & Compliance
- Mill test certificate documenting Q195/Q235/Q345 chemical composition, yield strength, and zinc coating weight per heat number
- CE certificate under EN 10210/EN 10219 for European market compliance and customs clearance
- ISO 9001:2015 quality management system certificate covering the full production and galvanizing process
- SGS or BV third-party inspection report verifying dimensional tolerance, coating thickness, and weld quality before shipment
- Material traceability report linking each bundle to its heat number, coil origin, and galvanizing batch log
- Full customs document package: packing list, bill of lading, certificate of origin, and commercial invoice
Packaging, Loading & Delivery
- Hot Dipped Galvanized Square Rectangular Steel Tube bundled with high-tensile steel strips and edge protectors to prevent zinc coating abrasion during transit
- Plastic end caps fitted on all tube ends to block moisture ingress and protect threaded or beveled finishes
- Container loading plan optimized for 1–12 m lengths, maximizing payload within 20GP and 40GP weight limits for heavy-wall galvanized sections
- Heat number and steel grade stenciled on each bundle tag for on-site traceability and inspection matching
- FOB Jinan/Qingdao, CIF, or DDP delivery options with real-time shipment tracking to 50+ countries
- Custom cutting to project-specific lengths available before galvanizing to reduce on-site waste
Getting Your Galvanized Tube Quote and Mill Test Certificate
Submit your specification sheet — side length, wall thickness, length, steel grade, zinc coating requirement, and destination port — and we respond within 12 hours with a detailed quotation, production lead time, and sample mill test certificate from a comparable recent batch. For non-standard dimensions outside the 10–1000 mm range or wall thickness beyond 28 mm, our engineering team reviews feasibility and tooling requirements within the same response cycle.
Request Your Hot Dipped Galvanized Square Rectangular Steel Tube Quotation
Send your specifications and quantity to receive pricing, coating options, and mill test documentation.
Company: Shandong Xin Jiyuan Special Steel Tube Co., Ltd
Website: www.sdxjysteel.com
Tel: +86 531 8573 6315
Mobile/WhatsApp/WeChat: +86 188 5315 7756
Email: admin@sdxjysteel.com
Address: No.11889, Jingshi West Road, Lulian Group, Jinan City, Shandong Province, China
Frequently Asked Questions
Q: How do Q195, Q235, and Q345 steel grades compare to EN and ASTM equivalents?
A: Q195, Q235, and Q345 are Chinese GB standard grades where the number indicates minimum yield strength in MPa. Q235 broadly corresponds to S235 in EN 10219 and ASTM A500 Grade B; Q345 maps to S355 in EN and ASTM A500 Grade C. Exact equivalence depends on chemical composition and impact testing requirements, which we detail in the mill test certificate for each heat.
Q: What is the difference between hot dipped galvanized and pre-galvanized square tubes?
A: Hot dipped galvanizing immerses the finished tube in a molten zinc bath, creating a metallurgical bond with coating weights from 30 to 275 g/m² that covers all surfaces including the weld seam and interior. Pre-galvanized tubes are made from already-coated coil, leaving the weld zone and cut ends with reduced zinc protection. For outdoor, coastal, or industrial corrosive environments, hot dipped galvanizing delivers significantly longer service life.
Q: Can you produce non-standard sizes outside the 10–1000 mm range?
A: Yes. Our production lines cover over 2,800 specifications, and we manufacture custom non-standard square and rectangular sizes beyond the standard catalog range. Lead times for custom tooling are confirmed after reviewing your drawing, and the MOQ depends on the specific profile and quantity.
Q: How do you verify zinc coating weight before shipment?
A: Our in-house laboratory conducts coating weight tests per batch using the weigh-gauge-weigh method, and results are recorded in the mill test certificate. Third-party inspection by SGS or BV can be arranged to independently verify coating thickness and adhesion before the container is sealed.
Q: What documents do you provide for EU customs clearance?
A: We supply the CE certificate under EN 10210/EN 10219, mill test certificate with chemical and mechanical test results, packing list, bill of lading, and certificate of origin. The CE mark and FPC documentation ensure the Hot Dipped Galvanized Square Rectangular Steel Tube meets EU construction product regulation requirements for structural applications.
