Description
Factory-Direct ERW Square Tubes — In-house production lines deliver ASTM A500 Gr.B and EN S355 welded square hollow sections without trading margins, backed by original mill test certificates for every heat number.
Technical Specifications
| Parameter | Value |
|---|---|
| Designation | ASTM A500 Welded Square Steel Tube |
| Product Type | Welded Square Steel Tube (SHS) |
| 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 / SRL / DRL / Random Length |
| Technique | ERW (Welded) |
| Surface Treatment | Black Painting / Galvanized / Varnish / Bare |
| Tolerance | ±1% |
| Ends | Plain (default) |
| Application | Construction structures / Building frames / Curtain wall systems / Support tubes / Structural pipe / Fertilizer tubes |
| MOQ | 5 Tons |
| Origin | Shandong, China |
Application Suitability
| Industry | Typical Applications |
|---|---|
| Construction & Infrastructure | Building frames, column supports, roof truss systems, portal frame structures |
| Commercial Architecture | Curtain wall mullions, facade support tubes, canopy frameworks |
| Industrial & Machinery | Equipment bases, conveyor support structures, platform framing, machine guards |
| Agricultural & Utility | Fertilizer tubes, irrigation support frames, storage rack uprights |
What Wall-Thickness Tolerance Costs on a Structural Frame Order
A ±1% tolerance on a 100×100×4mm ASTM A500 welded square steel tube means the difference between passing structural inspection and facing a full-batch rejection at destination port.
When buyers specify 4.0mm wall thickness and receive 3.5mm actual — a negative tolerance deviation common in unverified supply chains — the load-bearing capacity drops below design calculations. Third-party inspectors at destination ports measure with ultrasonic gauges; a single container failing tolerance checks triggers full rejection, demurrage charges, and project delays measured in weeks, not days. [NEED_CITE: EN 10219 cold-formed hollow section dimensional tolerance requirements]
Matching Structural Load Requirements Across Size Ranges
The 19×19mm to 800×800mm range of our ASTM A500 welded square steel tube production covers everything from light-gauge curtain wall mullions to heavy-load column sections. For EPC contractors sourcing mixed-size orders for portal frame buildings, consolidating 100×100mm columns, 150×150mm rafters, and 50×50mm purlin tubes from a single ERW line ensures consistent weld quality and matching mill certificates across the entire bill of materials — eliminating the traceability gaps that plague fragmented procurement.
Engineering Compliance and Certification Alignment
Structural hollow sections for European projects must conform to EN 10219 (cold-formed welded) or EN 10210 (hot-formed welded), with CE marking mandatory for load-bearing applications. Our ASTM A500 welded square steel tube in S355 grade carries CE certification under EN 10210/10219, ensuring customs clearance across EU member states without documentation disputes. For North American projects, ASTM A500 Gr.B and Gr.C grades meet AISC specification requirements for structural tubing. [NEED_CITE: steel grade equivalence mapping between ASTM A500 and EN 10219 standards]
Steel Grade Selection and ERW Welding Process
The grade range — Gr.B, S235, S275, S355, STK400 — spans three international standards systems, allowing project-spec compliance without cross-ordering from multiple mills. S355 delivers higher yield strength than S235 for load-critical columns, while Gr.B remains the workhorse for general structural framing in ASTM-specified projects. The ERW welding process forms the tube from coiled strip through continuous forming and high-frequency electric resistance welding, producing a longitudinal weld seam that undergoes full-length ultrasonic inspection. For wall thicknesses up to 30mm and sizes reaching 800×800mm, ERW offers cost efficiency over seamless alternatives while maintaining structural integrity for non-pressure applications. Surface treatment selection — hot-dip galvanized for outdoor corrosion exposure, black painted for interior use, or bare for further coating by the fabricator — is matched to the installation environment during order confirmation.
The Hidden Cost of Unverified Negative Tolerance
Sourcing ASTM A500 welded square steel tube without independent tolerance verification exposes buyers to cumulative margin erosion: theoretical weight invoicing assumes nominal dimensions, but actual weight delivered at excessive negative tolerance means paying for steel that does not arrive. Beyond weight discrepancies, undersized walls compromise structural performance — a 100×100×4mm tube at 3.5mm actual carries approximately 12% less load than calculated, triggering engineer rejection during site inspection. [NEED_CITE: structural hollow section tolerance impact on load-bearing capacity calculations] Missing or incomplete mill test certificates compound the problem: without heat-number traceability and verified chemical composition, customs authorities in strict-import markets hold shipments for re-inspection, generating port storage fees that exceed the original material cost savings.
Why Procurement Teams Source Welded Square Tubes Here
Every ASTM A500 welded square steel tube order ships with original mill test certificates documenting chemical composition and mechanical properties per heat number — not photocopies, not templates, but lab-generated reports from our in-house testing facility. Three production lines running simultaneously deliver monthly capacity exceeding 20,000 tons, supporting both urgent single-container orders and phased delivery for multi-month infrastructure projects. Our quality management system holds ISO 9001:2015 certification, and every batch undergoes three-stage in-house inspection before release. For buyers requiring independent verification, SGS or BV third-party inspection is arranged on request, with reports provided before container sealing. The full size range from 19×19mm to 800×800mm across 2,800+ stocked specifications means consolidated loading — mixing structural columns, purlins, and bracing tubes in a single container reduces freight cost per ton versus sourcing each size from separate suppliers.
Documentation & Compliance
- Mill Test Certificate documenting ASTM A500 Gr.B chemical composition and mechanical properties per heat number
- CE Certificate confirming EN 10210/EN 10219 compliance for S355 structural hollow sections exported to European markets
- ISO 9001:2015 Quality Management System certificate covering ERW welding and dimensional inspection processes
- SGS or BV Third-Party Inspection Report available for pre-shipment verification of wall thickness, surface coating, and dimensional accuracy
- Full Material Traceability linking each bundle to heat number, production date, and test certificate
- Export Documentation including packing list, bill of lading, and certificate of origin for customs clearance at destination port
Packaging, Loading & Delivery
- Black painted and bare ASTM A500 welded square steel tubes bundled with steel strips and edge protectors, sized for 6m and 12m lengths to maximize 20ft and 40ft container utilization
- Hot-dip galvanized square tubes packed with non-metallic separators to preserve zinc coating integrity during ocean transit and prevent white rust formation
- Mixed-size container loading plans optimized for 100×100mm to 400×400mm structural sections, with nested smaller tubes filling void spaces to reduce per-ton freight cost
- Heat number stenciled on each tube end with steel grade marking (Gr.B / S355) for site identification and traceability verification during installation
- FOB Jinan/Qingdao port or CIF destination port arrangements with professional export documentation handling for customs clearance
Ready to Specify Your Square Tube Order
Submit your ASTM A500 welded square steel tube requirements — including size, wall thickness, steel grade, quantity, and destination port — to receive factory-direct pricing with volume discount tiers and confirmed delivery schedules. Our technical team reviews specifications within 12 hours and provides mill test certificate samples for quality verification before contract commitment.
Request Factory-Direct Pricing and Mill Test Certificates
Send your ASTM A500 welded square steel tube specifications via email or WhatsApp to receive bulk pricing, CE/ISO documentation confirmation, and container loading optimization within 12 hours.
Email: admin@sdxinjiyuan.com
WhatsApp: +86 188 5315 7756
Frequently Asked Questions
Q: How does ASTM A500 Gr.B compare to EN S355 for structural applications?
A: ASTM A500 Gr.B specifies minimum yield strength of 290 MPa for square tubes, while EN S355 requires 355 MPa minimum yield. Both grades are suitable for structural framing, but S355 offers higher load capacity for the same section size. We stock both grades and provide cross-reference documentation for projects requiring grade substitution approval from structural engineers.
Q: Can I verify wall thickness tolerance before shipment?
A: Yes. Every ASTM A500 welded square steel tube order includes original mill test certificates with dimensional inspection results. Additionally, SGS or BV third-party inspection can be arranged for pre-shipment verification, with ultrasonic thickness measurement reports provided before container loading.
Q: What is the minimum order quantity for custom sizes outside standard stock?
A: Standard sizes from 19×19mm to 800×800mm are available from stock with 5-ton MOQ. Custom non-standard sizes or specific length requirements follow typical production lead times with flexible MOQ starting from 1-ton trial orders for qualification testing.
Q: How do you handle mixed-size container loading for project procurement?
A: Our export team develops container loading plans that consolidate multiple sizes — such as 100×100mm columns, 150×150mm rafters, and 50×50mm bracing tubes — into single shipments. This reduces freight cost per ton and simplifies customs clearance versus sourcing each size from separate suppliers.
Q: Are galvanized and black painted tubes available from the same production line?
A: Yes. ERW welded square tubes are produced in bare condition, then surface-treated per order specification. Hot-dip galvanizing, black painting, or varnish coating is applied after welding and inspection, with coating thickness verified before bundling and shipment.
Secure Your ASTM A500 Welded Square Steel Tube Supply
Submit your project specifications — size, grade, quantity, destination — to receive factory-direct pricing and mill test certificate samples within 12 hours.
Email: admin@sdxinjiyuan.com
WhatsApp: +86 188 5315 7756
