Description
Factory-direct pricing, no middlemen markup — Q235B and Q345B ASTM carbon steel square and rectangular hollow sections ship directly from our Jinan production lines to your project site across 50+ countries.
Technical Specifications
| Parameter | Value |
|---|---|
| Designation | Q235B / Q345B Carbon Steel Square & Rectangular Pipe |
| Product Type | Square / Rectangular Steel Tube (Hollow Section) |
| Steel Grade | Q195, Q235, Q235B, Q345, Q345B, SS400, SS330, SS540 |
| Standard | ASTM |
| Section Shape | Square, Rectangular, Round |
| Wall Thickness | 0.5–200 mm |
| Length | 12 m |
| Technique | Cold Rolled, Hot Rolled |
| Surface Treatment | Hot Rolled / Customized per requirement |
| Tolerance | ±1% |
| Ends | As per customer requirement |
| Application | Fluid transport, Boiler, Drill pipe, Hydraulic systems, Gas pipeline, Construction, Petrochemicals, Marine industries |
| MOQ | 5 Tons |
| Origin | Shandong, China |
Application Suitability
| Industry | Typical Applications |
|---|---|
| EPC Contractors | Structural frames and pipeline systems for industrial plants and infrastructure projects |
| Construction Companies | Building frames, scaffolding systems, and marine structural supports |
| Machinery Manufacturers | Hydraulic cylinders, fluid transport lines, and precision equipment frames |
Where ASTM Compliance Decides Customs Clearance on Hollow Section Orders
An ASTM carbon steel square rectangular hollow section supplier without proper mill documentation will delay your shipment at port — regardless of product quality.
Global buyers routinely face customs holds because certificates don’t match the declared steel grade or standard. When Q345B tubes arrive at EU ports with only a domestic test report instead of EN 10219 compliance documentation, the entire container sits in bonded warehouse until supplementary inspection clears [NEED_CITE: EN 10219 cold-formed hollow section certification requirements]. Fragmented sourcing makes this worse — pipes from one mill, plates from another, fabrication from a third — each with inconsistent paperwork that triggers separate compliance reviews.
How Wall Thickness Range Matches Structural Load Requirements
The 0.5–200 mm wall thickness range of this ASTM carbon steel square rectangular hollow section supplier inventory covers everything from light-gauge scaffolding to heavy-duty industrial columns. Thin-wall sections below 3 mm serve non-load-bearing enclosures and conduit systems, while 10 mm and above handle primary structural frames in petrochemical plants and marine platforms. The ±1% tolerance ensures dimensional consistency across 12 m lengths, preventing alignment issues during on-site welding and bolting.
Engineering Compliance and Steel Grade Selection for Load-Bearing Frames
Structural engineers specifying these tubes must verify that Q235B or Q345B meets the yield strength requirements of their design code — whether AISC for North American projects or Eurocode 3 for European construction [NEED_CITE: steel grade equivalence between Chinese GB and ASTM standards]. SS400 and SS540 Japanese grades serve machinery manufacturers exporting to Southeast Asia, where JIS G3466 recognition simplifies local inspection. Hot rolled surfaces accept welding and painting directly, while customized surface treatment options address corrosive environments in gas pipelines and marine applications. Third-party certification through SGS or BV validates chemical composition and mechanical properties before shipment, preventing rejection at destination port.
Steel Grade Hierarchy and Rolling Process Impact on Tube Performance
Q235B offers moderate yield strength suitable for general construction frames and scaffolding, while Q345B delivers higher load capacity for industrial structures and bridge components. The cold rolled process produces tighter dimensional tolerance and smoother surface finish, ideal for precision machinery frames where fit-up matters. Hot rolled tubes handle thicker walls above 20 mm and serve high-pressure applications in boiler systems and petrochemical pipelines. Surface treatment selection depends on service environment — hot rolled finish works for indoor structural frames, while galvanized or oiled coatings protect outdoor installations and marine structures from atmospheric corrosion.
Hidden Costs of Incorrect Steel Grade and Missing Certification
Ordering Q235B when the structural drawing specifies Q345B means the entire batch fails load testing — demolition and replacement cost multiples of the original material price. Missing CE marking on tubes destined for EU construction sites triggers customs rejection, forcing air freight of replacement stock while the original container decays in port storage. Negative tolerance abuse — where actual wall thickness falls below the specified minimum — reduces load capacity without visible indication, creating structural safety hazards that only surface during inspection or failure [NEED_CITE: consequences of negative tolerance in structural steel hollow sections].
Why Source Your ASTM Carbon Steel Square Rectangular Hollow Section From Us
Our Jinan facility operates three dedicated production lines covering 2,800+ specifications, eliminating the need to coordinate multiple suppliers for pipes, plates, and fabrication services. Every batch passes through our in-house physical and chemical laboratory before release — you receive mill test certificates documenting actual chemical composition and mechanical properties, not generic templates. The 41 invention patents include proprietary sharp-corner rectangular tube technology that fills gaps in global supply for architectural and structural applications. CE certification under EN 10210/EN 10219, ISO 9001:2015 registration, and Singapore FPC approval ensure compliance across EU, North American, and Asian markets. Professional loading plans optimize container utilization for 12 m lengths, reducing freight cost per ton compared to LCL shipments.
Documentation & Compliance
- Mill test certificate documenting Q235B and Q345B chemical composition and mechanical properties per ASTM standards
- CE certificate confirming EN 10210/EN 10219 compliance for European construction market access
- ISO 9001:2015 quality management system certificate covering production and inspection processes
- SGS or BV third-party inspection report available for projects requiring independent verification
- Material traceability by heat number linking each tube to its production batch and test results
- Complete customs documentation including packing list, bill of lading, and certificate of origin
Packaging, Loading & Delivery
- Q235B and Q345B tubes bundled with steel strips and edge protectors to prevent surface damage during ocean transit
- Hot rolled surfaces coated with anti-rust oil for 12 m lengths shipped in open-top containers or breakbulk vessels
- Container loading plans optimized for 12 m standard lengths, maximizing payload while respecting port weight restrictions
- Custom cutting to project-specific lengths available, reducing on-site waste and handling for construction teams
- Heat number and steel grade marked on each tube end for site identification and traceability verification
- FOB, CIF, and DDP delivery terms to 50+ countries with door-to-door logistics coordination
Submit Specifications for Quote and Mill Test Certificate
Send your required dimensions, steel grade, quantity, and destination port — we respond within 12 hours with pricing, production timeline, and available mill test certificates. Non-standard sizes and custom surface treatment requests receive technical evaluation and feasibility confirmation before order placement.
Get Your ASTM Hollow Section Quote with Full Certification Package
Submit specifications via email or WhatsApp to receive detailed quotation and mill test certificate samples.
Email: admin@sdxjysteel.com
Mobile/WhatsApp: +86 188 5315 7756
Frequently Asked Questions
Q: What is the difference between Q235B and Q345B for structural applications?
A: Q235B provides moderate yield strength suitable for general construction frames, scaffolding, and non-critical structural elements. Q345B delivers higher load capacity for primary structural frames, bridge components, and industrial structures requiring greater strength-to-weight ratio. Selection depends on your engineering design specifications and local building code requirements.
Q: Can you supply non-standard sizes outside your catalog range?
A: Yes, our production lines cover 2,800+ specifications including custom non-standard dimensions. MOQ for non-standard sizes depends on wall thickness and section complexity — contact us with your drawing for feasibility evaluation and pricing.
Q: What surface treatment options are available for corrosion protection?
A: Hot rolled finish suits indoor structural applications. We also provide galvanized coating for outdoor exposure, oiled surface for temporary protection during transit and storage, and customized treatment per your project specification. Each option addresses different service environments from mild indoor conditions to marine atmospheric corrosion.
Q: Which certifications do you provide for EU and North American markets?
A: We hold CE certification under EN 10210 and EN 10219 for European construction compliance, ISO 9001:2015 for quality management, and Singapore FPC approval. Mill test certificates follow EN 10204 3.1/3.2 format. Third-party inspection through SGS or BV is available for projects requiring independent verification.
Q: How do you optimize container loading for 12 m tubes?
A: Our logistics team prepares detailed loading plans maximizing payload within port weight restrictions. Standard 12 m lengths fit 40ft open-top containers efficiently. For heavier wall thickness sections, we calculate optimal bundle weight to avoid overweight charges while minimizing shipping cost per ton.
