Description
Factory-Direct ERW Square Tubes — Every ASTM A500 welded square steel tube ships with original mill test certificates and in-house lab verification, eliminating middleman markups on bulk structural orders.
Technical Specifications
| Parameter | Value |
|---|---|
| Designation | ASTM A500 Welded Square Steel Tube |
| Product Type | Welded Square Steel Tube / SHS (Square Hollow Section) |
| Steel Grade | Gr.B, S235, S275, S355, STK400, Q235B, Q345B |
| Standard | ASTM A500, ASTM A53, GB/T 3091, EN 10219 |
| 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 (Electric Resistance Welded) |
| Surface Treatment | Black Painting / Galvanized / Varnish / Bare |
| Tolerance | ±1% |
| Ends | Plain |
| Application | Construction structures, Building frames, Curtain wall supports, Machinery frames, Scaffolding, Structural fabrication |
| MOQ | 5 Tons |
| Origin | Shandong, China |
Application Suitability
| Industry | Typical Applications |
|---|---|
| EPC / Construction | Steel structure frames for industrial warehouses, portal frame bracing, scaffolding uprights |
| Commercial Building | Curtain wall mullion supports, facade cladding sub-frames, roof truss members |
| OEM / Manufacturing | Machinery bases, conveyor support frames, equipment skid structures |
| Infrastructure | Sound barrier posts, highway sign gantries, utility pole bases |
What Missing Mill Certificates Cost at Port Customs
A shipment without traceable heat-number documentation can be held at destination port for weeks.
Global buyers repeatedly face customs holds because the mill test certificate format does not match EN 10204 3.1 requirements, or the steel grade listed on the packing list contradicts the certificate. For an ASTM A500 welded square steel tube order entering the EU, customs agents cross-check the CE mark against EN 10219 factory production control records — a gap here means the entire container sits in bonded storage. [NEED_CITE: EN 10219 cold-formed welded hollow section certification requirements]
How Wall-Thickness Tolerance Matches Structural Load Paths
An ASTM A500 welded square steel tube with ±1% wall-thickness tolerance ensures that calculated section modulus values hold across the full 19×19mm to 800×800mm range. For portal frame bracing in industrial warehouses, the 1–30mm thickness span covers both light purlin supports and heavy crane-runway columns without switching suppliers. Our three-stage in-house inspection catches tolerance drift before the material reaches the loading bay, so site welders do not encounter unexpected thin-wall sections mid-fabrication.
Structural Code Compliance and Surface Protection Choices
Engineering specifications for steel structures typically reference EN 1993 or AISC 360, both of which require documented material traceability for load-bearing hollow sections. [NEED_CITE: EN 1993 structural steel hollow section design requirements] For outdoor curtain wall supports in coastal cities, hot-dip galvanized finish resists salt-spray corrosion without field coating; for indoor machinery frames, black painted or bare finish allows the OEM to apply their own powder-coat system. CE certification to EN 10210 / EN 10219 is mandatory for European project compliance, while ASTM A500 Gr.B satisfies North American structural codes. Custom cut-to-length at 5.8m or 6m reduces on-site welding and secondary cutting waste.
Steel Grade Selection and ERW Weld Integrity
The Gr.B / S235 / S275 / S355 / STK400 / Q235B / Q345B range spans three international designation systems — ASTM, EN, JIS, and GB — allowing a single purchase order to serve multi-region projects without grade substitution confusion. S-series grades follow a minimum yield strength progression where each step up increases load capacity for the same cross-section. ERW welding produces a longitudinal seam that, when properly heat-treated and inspected, delivers weld-zone mechanical properties matching the parent metal — critical for square tubes used in moment-resisting frames. [NEED_CITE: steel grade equivalence mapping between ASTM A500 and EN 10219] Surface treatment choice directly affects service life: galvanized coating adds decades of corrosion protection in humid environments, while bare tubes suit controlled indoor conditions or projects where the buyer applies custom finishes.
The Hidden Price of Wrong-Grade Substitution
Specifying S355 but receiving Q235B material looks identical on the outside, yet the yield strength gap means the structural member may fail under design load without visible warning. Engineering inspectors flagging a mismatch during final acceptance force full member replacement — cutting, re-welding, re-painting — while the project schedule absorbs delay penalties. [NEED_CITE: structural steel grade substitution risks in load-bearing applications] Missing or forged mill test certificates compound the problem: the shipment cannot be legally installed, and reverse logistics for heavy steel cargo cost multiples of the original freight.
Why Bulk Buyers Source ASTM A500 Welded Square Steel Tube Here
Our factory runs three ERW lines producing 20,000+ tons monthly, so volume buyers receive direct mill pricing without trader margins layered on. Every heat is tested in our own理化 lab — spectrometer for chemical composition, tensile machine for yield and elongation — before the mill test certificate is issued. We hold 2,800+ specifications in ready stock, meaning a 150-ton order of mixed 100×100mm to 300×300mm S355 tubes can ship within days rather than weeks. CE (EN 10210/10219) and ISO 9001:2015 certifications are current, and SGS/BV third-party inspection is arranged on request at no coordination burden to the buyer. Our export team optimizes container loading for heavy square tubes, maximizing payload per 40ft HC and reducing per-ton freight cost.
Documentation & Compliance
- Mill test certificate documenting Gr.B / S355 / Q345B chemical composition and mechanical properties per ASTM A500 or EN 10219, with heat-number traceability
- CE certificate covering EN 10210 hot-finished and EN 10219 cold-formed welded hollow sections for European market entry
- ISO 9001:2015 quality management system certificate covering the full ERW square tube production process
- SGS or BV third-party inspection report verifying dimensional tolerance, surface finish, and weld-seam quality before shipment
- Material traceability sheet linking each bundle to its heat number, steel grade, and production date
- Full customs document package: commercial invoice, packing list, bill of lading, and certificate of origin
Packaging, Loading & Delivery
- ERW square tubes bundled with galvanized steel strips, padded at contact points to protect galvanized or painted surfaces during ocean transit
- 5.8m and 6m lengths loaded in 20ft containers; 11.8m and 12m lengths in 40ft open-top or flat-rack for oversized sections up to 800×800mm
- Black painted or bare tubes coated with anti-rust oil at mill ends to prevent edge corrosion before arrival
- Heat number and steel grade stenciled on each bundle tag, matching the mill test certificate for site verification
- FOB Jinan/Qingdao, CIF destination port, or DDP door-to-door terms available based on buyer’s import license and project timeline
- Custom cut-to-length and bevel-end preparation available for orders requiring direct welding without on-site cutting
Start Your ASTM A500 Welded Square Steel Tube Inquiry
Submit your specification list — size range, wall thickness, steel grade, surface finish, quantity, and destination port — to receive a detailed quotation with volume pricing and mill test certificate samples within 12 hours. For non-standard dimensions or custom lengths outside the 19×19mm to 800×800mm range, our engineering team provides a feasibility and lead-time assessment.
Request Your Quotation and Mill Test Certificate
Send your ASTM A500 welded square steel tube requirements to admin@sdxinjiyuan.com or reach us via WhatsApp at +86 188 5315 7756.
Frequently Asked Questions
Q: How do ASTM A500 Gr.B, EN S355JR, and GB Q345B compare for structural use?
A: These grades belong to different international standards but serve similar structural roles. ASTM A500 Gr.B is the North American specification for cold-formed welded tubing; EN S355JR covers cold-formed hollow sections under EN 10219; GB Q345B is the Chinese standard for low-alloy high-strength structural steel. We supply all three and provide cross-reference documentation so your engineer can verify equivalence.
Q: Can I request third-party inspection before shipment?
A: Yes. SGS, BV, and Intertek inspections are arranged on request. The inspector verifies dimensional tolerance, surface finish, weld-seam quality, and reviews the mill test certificate against the physical bundle. The inspection report is issued before the container is sealed.
Q: What is the MOQ for custom sizes outside your standard range?
A: Standard sizes from 19×19mm to 800×800mm with 1–30mm wall thickness are available from stock with a 5-ton MOQ. Non-standard dimensions or custom lengths require production scheduling, and lead times depend on the specification complexity and order volume.
Q: How do you calculate invoicing weight — theoretical or actual?
A: Invoicing follows the agreement in the proforma invoice. Most bulk orders use theoretical weight based on standard density and nominal dimensions, with the ±1% tolerance applied. For projects requiring actual-weight invoicing, we weigh each bundle on calibrated scales before loading and provide the weight certificate.
Q: Which surface finish suits coastal construction projects?
A: Hot-dip galvanized finish provides long-term corrosion resistance in salt-spray environments and is recommended for curtain wall supports, sound barriers, and outdoor structural frames near the coast. Black painted or bare finish suits indoor applications or projects where the buyer applies a custom coating system on site.
