Description
Factory-direct ERW square tubes — dedicated production lines covering 19×19mm to 800×800mm with wall thickness up to 30mm, shipped with mill test certificates to 50+ countries.
Technical Specifications
| Parameter | Value |
|---|---|
| Designation | Carbon Steel Square Steel Tube |
| Product Type | Welded Square Steel Tube |
| Steel Grade | Gr.B, S235, S275, S355, STK400 |
| Standard | ASTM A500, ASTM A53, GB/T 3091 |
| Section Shape | Square |
| Size Range | 19mm × 19mm – 800mm × 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 walls / Support structures / Building frames |
| MOQ | 1 Ton |
| Origin | Shandong, China |
Application Suitability
| Industry | Typical Applications |
|---|---|
| EPC Contractors | Industrial plant structural frames, pipe rack supports, equipment bases |
| Construction Companies | High-rise building frames, curtain wall mullions, column sections |
| Machinery Manufacturers | Conveyor system frames, automation equipment bases, machine guards |
| Infrastructure Developers | Bridge support structures, transit station frameworks, utility pole bases |
What Wall-Thickness Tolerance Costs on a Structural Frame Order
A ±1% tolerance verified by in-house lab testing separates compliant frames from costly field rework.
When an ASTM A500 square steel tube arrives at a job site with wall thickness outside the declared tolerance, the structural engineer must either reject the batch or recalculate load capacity — neither option is cheap. We have seen projects where negative tolerance exceeded acceptable limits, causing weld cracks at corner joints during bending operations. The ASTM A500 square steel tube supplier who cannot guarantee real-time thickness control passes that risk directly to the buyer. [NEED_CITE: EN 10219 cold-formed hollow section dimensional tolerance requirements]
Matching Square Tube Sections to Structural Load Paths
The 19×19mm to 800×800mm size range of this ASTM A500 square steel tube covers everything from light-duty curtain wall mullions to heavy-load column sections in industrial plants. The square cross-section provides equal moment of inertia on both axes, simplifying connection design for moment frames and braced systems. For EPC contractors procuring structural frames across multiple load zones, sourcing a single ASTM A500 square steel tube supplier who can deliver both small and large sections under one contract eliminates coordination gaps between spec calls.
Structural Code Compliance and Surface Protection Selection
Load-bearing square tubes must conform to the dimensional and mechanical requirements of EN 1993-1-1 or AISC 360 depending on the project jurisdiction. [NEED_CITE: structural steel hollow section design codes EN 1993-1-1 and AISC 360] Surface treatment selection — black painted for indoor use, hot-dip galvanized for outdoor or corrosive environments, bare for field-applied coatings — must align with both the service environment and the project specification. CE certification under EN 10210/EN 10219 is mandatory for EU-bound shipments, while ASTM A500 compliance governs North American structural projects. Custom cut-to-length service at 5.8m, 6m, 11.8m, or 12m reduces on-site welding and secondary cutting waste.
Understanding ERW Welded Process and Steel Grade Selection
The ERW (Electric Resistance Welded) process forms the square profile from coiled steel strip, welding the longitudinal seam under pressure without filler metal. This method delivers consistent wall thickness and tight dimensional tolerance across the full 1–30mm range. Steel grade selection follows the project’s structural demand: Gr.B and S235 serve light structural and non-load applications, while S275 and S355 provide higher yield strength for primary load-bearing members. STK400 meets JIS G3466 requirements for general structural use in Japanese-spec projects. [NEED_CITE: steel grade equivalence between ASTM A500 and EN 10219 standards] The ±1% tolerance on wall thickness ensures that theoretical weight calculations match actual delivered weight, preventing budget overruns on tonnage-based contracts.
Hidden Costs of Unverified Material and Missing Certificates
Purchasing an ASTM A500 square steel tube without a valid mill test certificate creates exposure at every project stage: customs may hold the shipment without proper documentation, the structural engineer cannot sign off on material compliance, and the client’s QA team will flag missing heat number traceability. [NEED_CITE: mill test certificate requirements for structural steel hollow sections] Material that fails to meet the declared steel grade — whether through substitution or uncontrolled chemistry — can lead to weld failures, load test rejection, or in worst cases, structural safety incidents that trigger full batch replacement and project delays.
Procurement Confidence Through Verified Factory Capability
Every ASTM A500 square steel tube we ship comes with a mill test certificate generated by our in-house physical and chemical laboratory, documenting chemical composition and mechanical properties per heat number. Our dedicated ERW production lines cover 2,800+ specifications across square, rectangular, and round profiles, meaning your project’s full spec list — from 19×19mm mullions to 800×800mm columns — ships from a single source. We hold CE certification under EN 10210/EN 10219 for EU compliance, ISO 9001:2015 for quality management, and accept SGS or BV third-party inspection before loading. Custom non-standard sizes and cut-to-length service eliminate the need for secondary processing at your yard. Professional container loading plans optimize weight distribution for heavy-wall sections, and door-to-door logistics coordination covers FOB, CIF, and DDP terms to 50+ countries.
Documentation & Compliance
- Mill test certificate documenting Gr.B, S235, S275, S355, or STK400 chemical composition and mechanical properties per ASTM A500 or GB/T 3091, traceable by heat number
- CE certificate under EN 10210 / EN 10219 for EU market compliance on welded hollow structural sections
- ISO 9001:2015 quality management system certificate covering the full ERW welded square tube production process
- SGS or BV third-party inspection report available upon request, covering dimensional checks, surface quality, and witness testing
- Material traceability sheet linking each bundle to its heat number, steel grade, and production date
- Full customs document package including packing list, bill of lading, and certificate of origin for destination clearance
Packaging, Loading & Delivery
- ERW welded square tubes bundled with steel strips and edge protectors, sized to match the 19×19mm–800×800mm profile range to prevent transit damage
- Black painted or varnished surfaces wrapped with waterproof paper; galvanized tubes separated by rubber spacers to preserve the zinc coating during ocean transit
- Container loading plans optimized for 5.8m, 6m, 11.8m, and 12m lengths, maximizing payload for heavy-wall 30mm sections within 20GP and 40HC units
- Cut-to-length service available at 5.8m / 6m / 11.8m / 12m or random length per order, reducing on-site cutting waste for construction frame applications
- Each bundle tagged with heat number, steel grade (Gr.B / S235 / S275 / S355 / STK400), size, and length for yard identification
- FOB, CIF, and DDP shipping terms with door-to-door logistics coordination to EU, North America, Middle East, Southeast Asia, and 50+ countries
Submit Specifications for Quotation and Mill Test Review
Send your size list, steel grade requirement, quantity, and destination port to receive a detailed quotation with production lead time and applicable certification package. Our team will confirm dimensional feasibility against the 19×19mm–800×800mm × 1–30mm range and advise on standard versus custom non-standard options. Third-party inspection via SGS or BV can be arranged before loading for projects requiring independent verification.
Frequently Asked Questions
Q: Can you supply ASTM A500 square tubes in both small and large sizes from one order?
A: Yes. Our ERW welded production lines cover 19×19mm to 800×800mm with wall thickness from 1mm to 30mm, so a single order can include light curtain wall sections and heavy structural columns under one contract.
Q: What documentation do you provide for customs clearance and structural approval?
A: Every shipment includes a mill test certificate per heat number, packing list, bill of lading, and certificate of origin. CE certification under EN 10210/EN 10219 is available for EU projects, and SGS or BV third-party inspection can be arranged before loading.
Q: Do you offer custom non-standard sizes outside the listed range?
A: Yes. Beyond the standard 19×19mm to 800×800mm catalog, we produce custom non-standard square sections per your drawing, with MOQ flexibility for trial orders.
Q: How do you ensure wall thickness matches the declared tolerance?
A: Our in-house physical and chemical laboratory conducts real-time thickness measurement during production. Every batch is verified against the ±1% tolerance before release, with results documented on the mill test certificate.
Q: Which surface treatment is best for outdoor structural applications?
A: Hot-dip galvanized provides the longest corrosion protection for outdoor exposure. Black painted or varnished finishes suit indoor or sheltered environments. Bare tubes can be field-coated per project specification.
Request Your ASTM A500 Square Steel Tube Quotation
Submit your specifications — size, wall thickness, steel grade, quantity, and destination — to receive a factory-direct quotation with mill test certificate and certification package. Contact us via email at admin@sdxjysteel.com or WhatsApp at +86 188 5315 7756.
