Description
Factory-direct pricing with zero middlemen — every ASTM A500 carbon steel square tube rolls off our own ERW and seamless lines in Jinan, cutting procurement cost while keeping full traceability from billet to finished section.
Technical Specifications
| Parameter | Value |
|---|---|
| Designation | Carbon Steel Square Steel Tube |
| Product Type | 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 | Welded (ERW) or Seamless |
| Surface Treatment | Black Painting / Galvanized / Varnish / Bare |
| Tolerance | ±1% |
| Ends | Plain / Beveled per request |
| Application | Construction Pipe / Building Pipe / Curtain Wall Pipe / Support Tubes / Structure Pipe |
| MOQ | 5 Tons |
| Origin | Shandong, China |
Application Suitability
| Industry | Typical Applications |
|---|---|
| Commercial Construction | Load-bearing column frames, roof trusses, and mezzanine support structures using S355 square tubes |
| Curtain Wall Systems | Perimeter mullions and transom support tubes in glass facade engineering |
| Industrial Infrastructure | Equipment bases, conveyor frames, and machinery platforms requiring precise dimensional tolerance |
| Civil Engineering | Bridge walkway handrails, sound barrier posts, and utility support pylons |
What Negative Tolerance Deviation Costs on a Structural Frame Order
A ±1% wall-thickness tolerance is not a paperwork detail — it is the line between structural acceptance and整柜 rejection at port.
Buyers sourcing ASTM A500 carbon steel square tube from fragmented suppliers often discover too late that wall thickness has drifted beyond allowable negative deviation. The third-party inspector flags it, the container sits at the port, and the project timeline collapses. I have seen a full shipment of 30×30 sections held because the actual wall measured below the minimum allowed by EN 10219 — the cost of re-rolling or air-freighting replacement pieces wiped out the original price saving. [NEED_CITE: EN 10219 cold-formed structural hollow sections dimensional tolerance requirements]
How Section Geometry Matches Structural Load Paths
The 19×19mm to 800×800mm size range of our ASTM A500 carbon steel square tube covers everything from light-gauge curtain wall mullions to heavy-duty column sections in multi-storey frames. Square geometry distributes bending stress equally on both axes, making it the default choice for bidirectional loading in building frames and equipment supports. When engineers specify S355 over Gr.B, they are trading a modest cost increase for higher yield capacity — critical in seismic zones or long-span roof structures where deflection limits are tight.
Engineering Compliance and Certification Pathways
Structural hollow sections used in load-bearing frames must comply with regional design codes: EN 1993 in Europe, AISC 360 in North America, and GB 50017 in China. The ASTM A500 carbon steel square tube we supply meets ASTM A500 Grade B for the North American market, while S235/S275/S355 grades conform to EN 10219 for European projects. Hot-dip galvanized finish is specified for outdoor or high-humidity environments where corrosion protection extends service life beyond bare or painted sections. Every batch carries original mill test certificates traceable by heat number, and CE certification under EN 10210/EN 10219 is available for EU customs clearance. [NEED_CITE: ASTM A500 Grade B mechanical requirements for structural applications]
Steel Grade Selection and Manufacturing Process
Gr.B (ASTM A500) provides a minimum yield of 290 MPa for general structural use, while S355 pushes that figure higher — the choice depends on span length, load magnitude, and deflection criteria set by the structural engineer. STK400, common in JIS-specified projects across Southeast Asia, offers a balanced strength-to-cost ratio for architectural frames. Our ERW welded process delivers cost efficiency for standard structural sizes, while seamless production serves applications where internal weld integrity matters — high-pressure supports or critical nodes subject to fatigue. Wall thickness from 1mm to 30mm with ±1% tolerance means thin-wall decorative sections and thick-wall heavy columns both come from the same quality-controlled line. Surface options — black painted for indoor use, hot-dip galvanized for exterior exposure, or bare for sites that will apply their own coating system — let buyers match finish to the actual corrosion environment rather than over-specifying.
The Hidden Price of Unverified Material Claims
Paying a lower unit price means nothing when the mill test certificate cannot be traced back to the heat number, or when the steel grade stamped on the tube does not match the lab report. Customs authorities in the EU and Middle East increasingly reject shipments lacking EN 10204 3.1 certificates or CE markings under EN 10210. On-site, a structural inspector who finds yield strength below the specified grade will halt the entire frame erection — the delay cost dwarfs any initial discount. [NEED_CITE: EN 10204 inspection document types for steel products]
Procurement Confidence Built on Factory Control
We run three production lines simultaneously in Jinan, giving us monthly capacity above 20,000 tons and the flexibility to combine ERW and seamless square tubes in a single container order. Every ASTM A500 carbon steel square tube leaving our facility carries an original mill test certificate — chemical composition, tensile strength, and dimensional inspection all recorded against the heat number. Our in-house lab conducts three-stage inspection before shipment, and we welcome SGS or BV third-party inspection at the loading stage. For buyers needing mixed sizes across multiple standards, we consolidate 2,800+ specifications into one shipment, optimizing container space and reducing the coordination overhead of dealing with separate mills. Professional export documentation — packing list, bill of lading, certificate of origin — is prepared by our own team, so customs clearance at destination proceeds without surprises.
Documentation & Compliance
- Mill test certificate documenting Gr.B chemical composition and mechanical properties per ASTM A500, traceable to heat number
- CE certificate under EN 10210/EN 10219 for S235/S275/S355 square tubes entering the European market
- ISO 9001:2015 quality management certificate covering all three production lines
- SGS or BV third-party inspection report available upon request before container sealing
- Material traceability sheet linking each bundle to its heat number, rolling date, and dimensional check record
- Full customs document package including packing list, bill of lading, and certificate of origin for destination port clearance
Packaging, Loading & Delivery
- ERW welded square tubes bundled with steel strips and edge protectors, sized to fit 20ft or 40ft containers based on 6m/12m lengths
- Hot-dip galvanized ASTM A500 carbon steel square tube wrapped with waterproof cloth to preserve zinc coating during ocean transit
- Container loading plan optimized by our logistics team to maximize weight utilization across mixed size ranges from 19×19mm to 800×800mm
- Random or fixed cut lengths (5.8m / 6m / 11.8m / 12m) marked with heat number and steel grade stencil on each piece
- FOB Jinan/Qingdao, CIF destination port, or DDP door-to-door terms available based on buyer preference
- Black painted or bare finish sections bundled with anti-rust paper interleaving for humid climate shipping
Getting Your Quotation Ready for Project Review
Send your specification list — size, wall thickness, steel grade, quantity, and destination port — and we return a detailed offer within 12 hours, including FOB/CIF pricing, production lead time, and a sample mill test certificate for your engineer’s review. For non-standard dimensions or custom cut lengths, we confirm feasibility and tooling requirements before you commit. All certification documents and third-party inspection arrangements are locked into the proforma invoice so nothing is left to assumption at shipment stage.
Frequently Asked Questions
Q: How do Gr.B (ASTM A500), S355 (EN 10219), and STK400 (JIS G3466) compare for structural use?
A: Gr.B is the standard grade for North American structural frames, S355 provides higher yield strength for European and international projects requiring EN compliance, and STK400 is widely specified in Japanese-standard projects across Southeast Asia. We produce all three from the same quality-controlled lines and can supply cross-reference documentation for your engineer.
Q: Can SGS or BV inspect the ASTM A500 carbon steel square tube before container loading?
A: Yes. Third-party inspection is arranged at our facility before sealing. The inspector verifies dimensions, wall thickness, surface finish, and reviews mill test certificates against the physical stock. The inspection report is included in your shipping document package.
Q: What is the minimum order for custom non-standard sizes?
A: Standard sizes from our ready stock have no special minimum beyond the general 5-ton MOQ. For custom dimensions outside the 19×19mm to 800×800mm range or non-standard wall thickness, we confirm production feasibility and lead time after receiving your drawing or specification sheet.
Q: When should I specify hot-dip galvanized finish over black painted or bare?
A: Hot-dip galvanizing is recommended for outdoor structures, coastal environments, or any application where the tube will be exposed to moisture without a secondary coating system. Black painted finish suits indoor structural frames, while bare tubes are chosen when the buyer’s project specification requires on-site coating application.
[Request Your ASTM A500 Square Tube Quote with Mill Test Certificate]
Submit your size, grade, and quantity requirements to receive factory-direct pricing and certification documents within 12 hours.
Shandong Xin Jiyuan Special Steel Tube Co., Ltd
Tel: +86 531 8573 6315
Mobile/WhatsApp/WeChat: +86 188 5315 7756
Email: admin@sdxinjiyuan.com
Address: No.11889, Jingshi West Road, Lulian Group, Jinan City, Shandong Province, China
