Description
Factory-Direct Pricing, No Middlemen — Every Q235 S235 SS400 ERW Welded Square Rectangular Steel Tube 1.5-30mm Wall Factory Direct rolls off our own production lines in Jinan, shipped with full mill documentation straight to your project site.
Technical Specifications
| Parameter | Value |
|---|---|
| Designation | ASTM Q235/S235/SS400 ERW Welded Square & Rectangular Steel Tube |
| Product Type | Welded Square and Rectangular Steel Tube (ERW) |
| Steel Grade | Q195, Q215, Q235, Q345, S235, SS400, ASTM |
| Standard | ASTM, API, CE, JIS, ISO 9001, SGS |
| Section Shape | Square / Rectangular / Round |
| Size Range | 20×20 mm – 200×200 mm |
| Wall Thickness | 1.5 – 30 mm |
| Length | 1 – 12 m (6 m / 6.4 m / 12 m standard; customizable) |
| Technique | ERW (Electric Resistance Welded) |
| Surface Treatment | Hot Rolled / Galvanized Coated / Slightly Oiled |
| Tolerance | ±5% |
| Ends | Plain / Beveled (per order) |
| Application | Structure, Fluid, Boiler, Gas, Oil, Chemical Fertilizer, Construction, Bridge, Machinery, Mining |
| MOQ | 25 Tons (1×20ft container) |
| Origin | Shandong, China |
Application Suitability
| Industry | Typical Applications |
|---|---|
| EPC Contractors & Construction | Building frames, scaffolding systems, bridge support columns, high-rise structural cores |
| Machinery Manufacturers | Hydraulic cylinder housings, conveyor framework, equipment base plates, crane boom sections |
| Oil, Gas & Industrial | Fluid transport lines, gas distribution piping, chemical fertilizer plant structural supports |
| Infrastructure & Mining | Tunnel reinforcement frames, mining conveyor structures, electrical installation poles |
What Negative Wall Tolerance Really Costs on a Structural Frame Order
A minus-8% wall deviation on a 200×100×6mm ERW rectangular tube turns a certified ASTM A500 Grade B section into a liability that fails third-party inspection on site.
I watched a full container of ERW welded square rectangular steel tube ASTM API certified supplier material get half-rejected at a Riyadh project because the wall thickness drifted well beyond acceptable limits. The mill certificate looked clean on paper, but the SGS re-inspection caught what the factory lab should have flagged before loading. The contractor lost two weeks waiting for replacement sections, and we lost the next two tenders from that client. When you source from fragmented suppliers without in-house physical and chemical laboratories, you are gambling that someone along the chain actually verified the dimensions against the steel grade claimed on the certificate. [NEED_CITE: EN 10219 cold-formed structural hollow section tolerance requirements]
Matching Section Geometry to Structural Load Paths
ERW welded square rectangular steel tube ASTM API certified supplier sections in the 20×20 to 200×200 mm range cover everything from light gauge scaffolding uprights to heavy-duty conveyor support frames. The square profile distributes compressive loads evenly across four flat bearing surfaces, making it ideal for bolted and welded connections in building frames and machinery bases. Rectangular sections offer higher moment of inertia along the strong axis, which is why EPC contractors specify them for bridge components and long-span structural members where bending resistance matters more than uniform compression. Wall thickness from 1.5 mm to 30 mm lets you match the section to the actual load calculation rather than over-specifying and paying for steel you do not need.
Engineering Compliance and Certification Requirements
Structural applications in the European market require CE certification under EN 10210 for hot-formed or EN 10219 for cold-formed hollow sections — without this documentation, customs will hold your shipment regardless of the physical quality. [NEED_CITE: CE marking requirements for structural steel hollow sections under EN 10210 and EN 10219] North American projects typically call for ASTM A500 Grade B or C, and the mill test certificate must show chemical composition and mechanical properties traceable to the heat number. For oil and gas applications, API certification adds another layer of traceability and testing frequency. Our in-house laboratory runs incoming raw material checks, in-process weld inspections, and final dimensional verification on every Q235 S235 SS400 ERW Welded Square Rectangular Steel Tube 1.5-30mm Wall Factory Direct order before any certificate is signed. Custom cut-to-length service eliminates on-site welding and reduces field labor costs, while beveled ends are available for projects requiring full-penetration butt welds. [NEED_CITE: ASTM A500 structural tubing specification requirements]
Understanding Steel Grade Selection and ERW Welding Process
The Q-series (Q195, Q215, Q235, Q345) follows the Chinese GB standard where the number indicates minimum yield strength in MPa — Q235 is the workhorse grade for general structural applications across Asia and the Middle East. The S-series (S235) is the European EN equivalent, and SS400 is the Japanese JIS designation; all three occupy roughly the same yield strength range and are interchangeable for non-critical structural framing when proper documentation accompanies the shipment. ERW welding forms the tube by rolling steel strip into a circular or box shape and passing high-frequency current through the open edges to create a forge weld — this process produces a consistent weld seam with mechanical properties that match the parent material when properly controlled. The alternative, seamless tube, eliminates the weld seam entirely but costs more and is typically reserved for high-pressure fluid applications rather than structural framing. Surface treatment choice depends on the installation environment: hot rolled finish is economical for indoor or painted structures, galvanized coating provides corrosion resistance for outdoor exposure without ongoing maintenance, and slight oiling protects the bare steel during ocean transit and short-term storage.
Hidden Costs of Sourcing Without Verified Certification
Buying ERW welded square rectangular steel tube ASTM API certified supplier material from a trading company that cannot produce EN 10204 3.1 or 3.2 mill test certificates means you are accepting material with no verified chemical composition and no confirmed mechanical properties. When that tube arrives at a European port without CE marking under EN 10219, customs holds the container and your project timeline collapses. [NEED_CITE: steel grade equivalence tables between EN 10025, ASTM A500, and JIS G3466 standards] Negative wall tolerance beyond the specified ±5% reduces the actual load-bearing capacity below the structural engineer’s calculation, creating a safety liability that no amount of paperwork can fix after installation. Replacing rejected sections mid-project costs far more than the original material — you pay for the replacement steel, the return freight or disposal, the delay penalties, and the reputational damage with your client.
Why Procurement Teams Source ERW Tubes Directly from Our Jinan Facility
We operate three dedicated ERW production lines covering 2,800+ specifications in square, rectangular, and round profiles with wall thickness up to 30 mm — when you need a non-standard size outside the typical catalog range, we can produce it without the minimum order inflation that trading companies add. Our in-house physical and chemical laboratory tests every heat for chemical composition and mechanical properties before we issue the mill test certificate, so you receive documentation backed by actual test data rather than a template filled in after the fact. We hold 41 invention patents including proprietary sharp-corner rectangular tube technology that produces tighter corner radii than standard ERW processes — this matters for architectural applications where appearance and connection fit-up are critical. Every Q235 S235 SS400 ERW Welded Square Rectangular Steel Tube 1.5-30mm Wall Factory Direct order ships with CE certification under EN 10210/10219 for European projects, ISO 9001:2015 quality management documentation, and third-party inspection reports from SGS or BV available upon request. Our professional loading team optimizes container stowage based on your specific length and dimension mix, reducing freight cost per ton and preventing transit damage. We export to 50+ countries with door-to-door logistics capability under FOB, CIF, or DDP terms, and our international business team handles the technical documentation that keeps your customs clearance moving.
Documentation & Compliance
- Mill Test Certificate documenting Q235, S235, or SS400 chemical composition and mechanical properties per heat number, formatted to EN 10204 3.1 standard
- CE certificate confirming compliance with EN 10210 (hot-formed) or EN 10219 (cold-formed) for European market structural applications
- ISO 9001:2015 quality management system certificate covering the full production process from raw material incoming inspection to final dimensional verification
- SGS or BV third-party inspection report available for projects requiring independent verification of wall thickness, dimensions, and surface quality
- Material traceability sheet linking each bundle to the original heat number, steel grade, and production date for full supply chain transparency
- Complete customs documentation package including packing list, bill of lading, and certificate of origin formatted for your destination country requirements
Packaging, Loading & Delivery
- Q235 and S235 ERW welded tubes bundled with high-tensile steel strips at regular intervals, with edge protectors on galvanized surfaces to prevent zinc coating damage during handling and ocean transit
- Hot rolled finish tubes receive anti-rust oil coating on inner and outer surfaces before bundling, providing protection during typical 30-45 day sea freight periods
- Container loading plans optimized for 6m, 6.4m, and 12m standard lengths in 20ft and 40ft containers, maximizing weight utilization while maintaining safe weight distribution
- Custom cut-to-length service available for 1m to 12m requirements, with cut ends deburred and prepared for welding or mechanical connection
- Each bundle marked with heat number, steel grade (Q235/S235/SS400), dimensions, and length for immediate identification at the project site
- FOB, CIF, and DDP shipping terms available with professional port coordination at Qingdao and other major Chinese ports, plus door-to-door delivery to 50+ countries
Getting Your Quotation and Technical Confirmation
Submit your specification sheet with section dimensions, wall thickness, steel grade, total quantity, and destination port — we respond within 12 hours with unit pricing, production lead time, and the applicable certification package. If your project requires non-standard dimensions outside our 2,800+ specification catalog, we will confirm feasibility and tooling requirements before you commit. Request the mill test certificate format and third-party inspection scope during the inquiry stage so there are no documentation surprises when your shipment arrives.
Start Your ERW Tube Procurement with Verified Documentation
Send your specification requirements to admin@sdxjysteel.com or contact us via WhatsApp at +86 188 5315 7756 to receive your quotation and sample mill test certificate within 12 hours.
Shandong Xin Jiyuan Special Steel Tube Co., Ltd
No.11889, Jingshi West Road, Lulian Group, Jinan City, Shandong Province, China
www.sdxjysteel.com
