Description
Factory-Direct Q235 Rectangular Steel Tube Pricing — Every Q235 galvanized rectangular steel tube ships from our own ERW mill, eliminating trading markups while maintaining full mill test traceability.
Technical Specifications
| Parameter | Value |
|---|---|
| Designation | Q235 Rectangular Steel Tube |
| Product Type | Welded Rectangular Steel Tube / RHS Hollow Section |
| Steel Grade | Q235, Gr.B, S235, S275, S355, STK400 |
| Standard | ASTM A500, ASTM A53, GB/T 3091 |
| Section Shape | Rectangular |
| Size Range | 15mm×20mm – 700mm×800mm |
| Wall Thickness | 1 – 30 mm |
| Length | 5.8m / 6m / 11.8m / 12m / Random Length |
| Technique | ERW / Welded |
| Surface Treatment | Black Painting / Galvanized / Varnish / Bare |
| Tolerance | ±1% |
| Ends | Plain |
| Application | Steel structures / Construction frames / Curtain wall / Building structures / Machinery / Scaffolding |
| MOQ | 5 Tons |
| Origin | Shandong, China |
Application Suitability
| Industry | Typical Applications |
|---|---|
| EPC Contractors | Steel structure frames for industrial warehouses and commercial buildings |
| Construction Companies | Curtain wall support systems and high-rise building column structures |
| Machinery Manufacturers | Equipment base frames and conveyor support structures |
| Infrastructure Developers | Scaffolding systems and temporary structural supports |
What Missing Mill Test Certificates Cost on a Galvanized RHS Order
A rejected container at destination port costs more than the steel itself.
I learned this the hard way early in my career — a batch of HDG rectangular tubes arrived at a Dubai high-rise site with zinc coating barely half the specified thickness. The third-party inspector flagged it immediately, the entire lot was rejected, and someone had to fly out to sort it personally. When sourcing a Q235 galvanized rectangular steel tube supplier, fragmented procurement from multiple vendors means inconsistent documentation, unclear heat number traceability, and certification gaps that trigger customs delays or outright rejection at the port. [NEED_CITE: EN 10219 cold-formed hollow section documentation requirements]
How Q235 RHS Performs in Structural Frame Applications
Q235 rectangular steel tubes in the 15×20mm to 700×800mm range cover everything from light-duty curtain wall purlins to heavy-load building columns. The ERW welded process produces a consistent seam that meets ASTM A500 and GB/T 3091 requirements, while the ±1% dimensional tolerance ensures predictable load-bearing behavior in frame connections. For galvanized applications, the hot-dip coating provides corrosion resistance suitable for both indoor structural frames and exposed scaffolding systems, making this Q235 galvanized rectangular steel tube supplier choice practical across multiple project phases.
Structural Compliance and Surface Protection Requirements
Load-bearing rectangular hollow sections must conform to recognized engineering standards — ASTM A500 governs North American structural applications, while EN 10219 applies to European cold-formed hollow sections. [NEED_CITE: steel grade equivalence between Q235, S235, and ASTM A500 Gr.B] Galvanized surface treatment adds corrosion protection critical for outdoor construction frames, curtain wall systems exposed to weather, and scaffolding that cycles between sites. The available length options — 5.8m, 6m, 11.8m, and 12m — align with standard container dimensions and reduce on-site cutting waste. For projects requiring third-party verification, SGS or BV inspection can be arranged before shipment to confirm dimensional accuracy and coating thickness.
Understanding Q235 Steel Grade and ERW Welding Process
Q235 is a Chinese standard carbon structural steel with yield strength positioning it between S235 (European EN standard) and ASTM A500 Gr.B (American standard). [NEED_CITE: steel grade equivalence between EN and ASTM standards] The equivalent grades S235, S275, and S355 are available from the same production lines, allowing engineers to specify higher strength grades for increased load requirements without changing supplier. The ERW (Electric Resistance Welding) process forms rectangular tubes by rolling steel strip into shape and welding the seam under pressure — this method suits the 1–30mm wall thickness range efficiently, offering cost advantages over seamless alternatives for structural applications where internal pressure is not a factor. Surface treatment selection depends on the environment: hot-dip galvanizing provides long-term corrosion protection for outdoor structures, black painting suits indoor applications, and bare finish works for projects that will receive additional coating on-site.
The Hidden Costs of Incorrect Steel Grade Selection
Specifying the wrong steel grade or accepting tubes without proper certification creates risks that surface only during installation or inspection. Material that fails to meet the declared standard can cause structural connections to underperform, trigger engineering re-assessments, or fail third-party audits entirely. Missing CE certification blocks EU customs clearance; absent mill test certificates prevent material traceability verification. [NEED_CITE: consequences of non-compliant steel in structural applications] Negative tolerance abuse — where actual wall thickness falls below the declared minimum — reduces load capacity while maintaining theoretical weight calculations, creating a gap between documented and actual structural performance that only emerges under load testing.
Why Source Q235 RHS from Xin Jiyuan
Our factory operates three dedicated ERW production lines with in-house physical and chemical laboratories, meaning every Q235 galvanized rectangular steel tube undergoes real-time quality monitoring from incoming raw material to final inspection. We hold 41 invention patents including proprietary sharp-corner rectangular tube technology, and our product range covers 2,800+ specifications — so non-standard sizes that other suppliers cannot fulfill become routine orders here. All products carry CE EN 10210/10219 certification for EU market compliance, ISO 9001:2015 quality management registration, and we arrange SGS or BV third-party inspection for clients who require independent verification. Professional loading plans optimize container utilization for the 15×20mm to 700×800mm size range, and we handle FOB, CIF, and DDP logistics to 50+ countries with complete documentation packages.
Documentation & Compliance
- Mill test certificate documenting Q235 chemical composition and mechanical properties per GB/T 3091, with heat number traceability for every batch
- CE certificate confirming compliance with EN 10210/EN 10219 for hot-finished and cold-formed structural hollow sections
- ISO 9001:2015 quality management system certificate covering the full production process from raw material inspection to final packaging
- SGS or BV third-party inspection report available upon request, verifying dimensional tolerance, surface coating thickness, and weld quality
- Material traceability documentation linking each bundle to its production heat number and test results
- Complete customs documents including packing list, bill of lading, and certificate of origin for destination port clearance
Packaging, Loading & Delivery
- Q235 rectangular tubes bundled with steel strips and edge protectors to prevent coating damage during transit, with bundle weight optimized for the 15×20mm to 700×800mm size range
- Galvanized surfaces receive additional protective wrapping to preserve zinc coating integrity during ocean freight and handling
- Container loading plans maximize utilization for 5.8m and 6m lengths in 20ft containers, while 11.8m and 12m lengths ship in 40ft open-top or flat-rack configurations
- Plain ends capped or wrapped to prevent moisture ingress and edge damage during storage and transport
- Each bundle marked with heat number, steel grade Q235, dimensional specifications, and production date for on-site identification
- FOB, CIF, and DDP shipping terms available with real-time tracking and door-to-door logistics coordination to 50+ countries
Start Your Q235 RHS Procurement
Submit your specifications — including dimensions, wall thickness, steel grade, surface treatment, quantity, and destination port — and receive a detailed quotation within 12 hours. We provide original mill test certificates, arrange third-party inspection if required, and confirm container loading plans before production begins. For non-standard sizes outside the 15×20mm to 700×800mm range, our engineering team reviews custom requirements and provides feasibility confirmation with lead time estimates.
Frequently Asked Questions
Q: What is the steel grade equivalence between Q235, S235, and ASTM A500 Gr.B?
A: Q235, S235, and ASTM A500 Gr.B are considered equivalent grades for structural rectangular hollow sections, with similar chemical composition and mechanical property ranges. We can produce to any of these standards from the same production lines — specify your required standard in the inquiry and we will provide the corresponding mill test certificate.
Q: Can you provide third-party inspection for galvanized rectangular tubes?
A: Yes, we arrange SGS or BV third-party inspection before shipment. The inspection covers dimensional verification, surface coating thickness measurement, visual weld quality assessment, and review of mill test certificates. Inspection reports are issued directly to the client.
Q: What is the minimum order quantity for custom non-standard sizes?
A: Standard sizes from 15×20mm to 700×800mm with 1–30mm wall thickness have a 5-ton MOQ. For non-standard dimensions outside this range, MOQ depends on the specific size and production setup — submit your requirements and we will confirm feasibility and minimum quantity.
Q: How do you ensure galvanized coating quality?
A: Every galvanized batch undergoes in-house coating thickness testing before loading. We use magnetic coating thickness gauges to verify compliance with the specified coating class. Third-party inspection by SGS or BV can additionally verify coating quality if required by the client.
Q: What documentation do you provide for EU customs clearance?
A: We provide CE certificate conforming to EN 10210/EN 10219, mill test certificates with chemical and mechanical test results, packing list, bill of lading, and certificate of origin. This documentation package satisfies EU customs requirements for structural steel imports.
Request Q235 Galvanized Rectangular Steel Tube Quotation
Send your specifications — size range, wall thickness, steel grade, surface treatment, quantity, and destination — to receive pricing and mill test certificate samples within 12 hours.
Shandong Xin Jiyuan Special Steel Tube Co., Ltd
Website: www.sdxjysteel.com
Mobile/WhatsApp/WeChat: +86 188 5315 7756
Email: admin@sdxjysteel.com
