Description
Factory-direct welded square tubes — 2,800+ size coverage from 19×19mm to 800×800mm with wall thickness up to 30mm, shipped with full mill documentation.
Technical Specifications
| Parameter | Value |
|---|---|
| Designation | Carbon Steel Welded Square Steel Tube |
| Product Type | Welded Square Steel Tube (Square Hollow Structural Section) |
| 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 | Construction structures / Building frames / Curtain walls / Support tubes / Structural frameworks / Fertilizer transport |
| MOQ | 5 Tons |
| Origin | Shandong, China |
Application Suitability
| Industry | Typical Applications |
|---|---|
| Construction & Building | Columns, beams, and trusses in commercial buildings and industrial warehouses |
| Facade & Curtain Wall | Architectural steel framing for glass curtain wall systems and building exteriors |
| Machinery & Equipment | Structural support frames for industrial machinery and conveyor platforms |
| Infrastructure | Support structures for bridges, walkways, and utility frameworks |
| Agriculture & Transport | Fertilizer transport frames and agricultural equipment structures |
Where ASTM A500 Certification Decides Your Shipment Clears Customs
Missing or incorrect mill certificates block EU and North American imports — we ship every ASTM A500 welded square steel tube with EN 10204 3.1 documentation and CE marking per EN 10219.
Procurement teams ordering welded square tubes for international projects frequently encounter specification mismatches between ASTM, EN, and JIS standards. A shipment labeled Gr.B may arrive without the chemical composition breakdown required by EU customs, or the dimensional tolerance documentation may not reference EN 10219 cold-formed hollow section requirements [NEED_CITE: EN 10219 cold-formed hollow section dimensional tolerance requirements]. The result: containers held at port, re-inspection costs, and project delays.
We produce ASTM A500 welded square steel tube in S235 through S355 grades with full traceability by heat number. Every order includes mill test certificates documenting chemical composition and mechanical properties, with third-party inspection available via SGS or BV before loading.
Precision Dimensions for Curtain Wall and Structural Framing
Our ASTM A500 welded square steel tube maintains ±1% dimensional tolerance across side lengths from 19mm to 800mm, ensuring clean connections in curtain wall framing where misaligned corners create visible gaps in architectural facades. The ERW welding process produces consistent wall thickness from 1mm to 30mm, allowing structural engineers to specify exact load-bearing requirements without over-engineering for tolerance uncertainty.
Structural Compliance and Surface Protection Selection
Engineering specifications for welded square hollow sections must account for both load-bearing requirements and environmental exposure conditions. S235 and S275 grades serve general structural applications where moderate yield strength suffices, while S355 provides higher load capacity for heavy-duty frameworks and crane support structures [NEED_CITE: structural steel grade selection for load-bearing applications]. Surface treatment selection depends on installation environment: hot-dip galvanizing protects against corrosion in outdoor or humid conditions, black painting suits indoor applications with controlled environments, and bare finish works for projects requiring on-site welding or custom coating.
Understanding Grade Equivalence Across International Standards
ASTM A500 Gr.B, EN S235/S275/S355, and JIS STK400 represent different standardization systems but share comparable mechanical properties for structural applications. The ERW welding process joins formed steel strip through high-frequency electric resistance, creating a continuous weld seam suitable for square sections from 19mm to 800mm side length. Wall thickness tolerance of ±1% ensures consistent weight calculation and structural performance across production batches.
Galvanized surface treatment adds zinc coating thickness typically ranging from 40 to 80 microns, providing sacrificial corrosion protection extending service life in outdoor construction applications. Black painting offers cost-effective protection for indoor structural frameworks where aesthetic appearance matters less than corrosion resistance.
The Hidden Cost of Tolerance Drift and Missing Documentation
Ordering welded square tubes without verified dimensional tolerance leads to fabrication problems on-site: corners that don’t align, weld gaps exceeding acceptable limits, and structural connections requiring costly rework. More critically, shipments arriving without proper CE certification or mill test certificates face customs rejection in EU markets, regardless of actual product quality [NEED_CITE: steel import documentation requirements for EU customs clearance].
Material substitution without proper grade equivalence documentation creates liability exposure. A project specified for S355 structural frames cannot accept S235 material without engineering recalculation and client approval, even if the physical dimensions match perfectly.
Why Project Teams Source ASTM A500 Welded Square Steel Tube From Us
Our facility operates three dedicated production lines covering 2,800+ specifications in welded square tubes, eliminating the need to source from multiple suppliers when projects require mixed sizes and grades. Every shipment includes mill test certificates generated from our in-house physical and chemical laboratory, with heat number traceability from raw material to finished product.
We hold CE certification per EN 10210 and EN 10219 for European market compliance, ISO 9001:2015 quality management certification, and facilitate third-party inspection through SGS or BV for clients requiring independent verification. Our loading team uses timber dunnage between every layer and cross-strapping to prevent transit damage — a practice we implemented after early export experience taught us that improper container loading crushes bottom layers and dents corners beyond tolerance.
Documentation & Compliance
- Mill test certificate documenting S235/S275/S355 chemical composition and yield strength per ASTM A500 and EN 10219 standards
- CE certificate per EN 10219 for cold-formed structural hollow sections, required for EU market customs clearance
- ISO 9001:2015 quality management system certificate covering production processes and inspection procedures
- SGS or BV third-party inspection report available upon request, documenting dimensional verification and surface treatment quality
- Material traceability documentation linking each bundle to specific heat numbers and production batch records
- Complete customs documentation including packing list, bill of lading, and certificate of origin for destination country requirements
Packaging, Loading & Delivery
- Welded square tubes bundled with steel strips in seaworthy packaging, with timber dunnage separating each layer to prevent surface damage during ocean transit
- Galvanized ASTM A500 welded square steel tube protected with edge guards to preserve zinc coating integrity at corners and edges
- Container loading optimized for 6m and 12m lengths, maximizing payload while maintaining weight distribution for safe transport
- Custom cutting available to project-specific lengths from standard 5.8m, 6m, 11.8m, and 12m stock, reducing on-site waste
- Heat number and steel grade marked on each tube end for site identification and traceability verification
- FOB, CIF, and DDP shipping terms available with door-to-door logistics coordination to project sites across 50+ countries
Request Your ASTM A500 Welded Square Steel Tube Quotation
Submit your project specifications including side dimensions, wall thickness, steel grade, surface treatment preference, and total quantity to receive detailed pricing with mill test certificate documentation. We respond within 12 hours with complete quotation including production lead time, shipping terms, and certification details for your destination market.
Get Your Welded Square Tube Quote With Full Certification
Send specifications to admin@sdxjypipe.com or contact via WhatsApp at +86 188 5315 7756 for pricing and technical documentation.
Frequently Asked Questions
Q: How do ASTM A500 Gr.B, S235, and S355 grades compare for structural applications?
A: ASTM A500 Gr.B corresponds roughly to S275 in yield strength, while S235 offers lower yield strength for general structural use and S355 provides higher capacity for heavy-duty applications. We supply all five grades — Gr.B, S235, S275, S355, and STK400 — with mill test certificates documenting actual chemical composition and mechanical properties for each heat number.
Q: What documentation do I need for EU customs clearance?
A: EU imports require CE certification per EN 10219 for cold-formed structural hollow sections, mill test certificates per EN 10204 3.1 format, and complete customs documentation including certificate of origin. We provide all required documents with every shipment and can arrange third-party inspection through SGS or BV if your project specifies independent verification.
Q: Can you produce non-standard dimensions with low minimum order quantity?
A: Yes, our production lines cover 2,800+ specifications from 19mm × 19mm to 800mm × 800mm with wall thickness from 1mm to 30mm. Custom non-standard sizes are available with 5-ton minimum order quantity, and we provide detailed production drawings for client approval before manufacturing begins.
Q: When should I specify galvanized versus black painted surface treatment?
A: Hot-dip galvanized finish suits outdoor applications, coastal environments, or projects requiring long-term corrosion protection without maintenance. Black painting works for indoor structural frameworks where appearance matters and environmental exposure is controlled. Bare finish is appropriate when on-site welding or custom coating application is planned.
Q: How do you prevent damage during container shipping?
A: We use timber dunnage between every layer of welded square tubes, cross-strapping to secure loads, and edge protectors for galvanized products to preserve zinc coating. Our loading team personally signs off on every container loading diagram, and we provide loading photos before shipment for client verification.
Get Your ASTM A500 Welded Square Steel Tube Quote With Mill Test Certificates
Submit your project specifications including dimensions, steel grade, quantity, and destination port to receive detailed pricing within 12 hours. Contact admin@sdxjypipe.com or WhatsApp +86 188 5315 7756 for technical consultation and certification documentation.
