Description
Factory-Direct Carbon Steel SHS/RHS — Q235B and Q345B square and rectangular tubes rolled to ASTM and JIS standards, shipped with original mill test certificates from our Jinan production base.
Technical Specifications
| Parameter | Value |
|---|---|
| Designation | Q235B/Q345B Carbon Steel Square/Rectangular Tube |
| Product Type | Square / Rectangular Steel Tube (SHS/RHS) |
| Steel Grade | Q195, Q235, Q235B, Q345, Q345B, SS400, SS330, SS540, DC51D+Z, DC52D+Z, DC53D+Z, SGC, SGHC |
| Standard | ASTM / JIS |
| Section Shape | Square / Rectangular / Round |
| Wall Thickness | 0.5–200 mm |
| Length | 12 m |
| Technique | Cold Rolled / Hot Rolled |
| Surface Treatment | Hot Rolled / Consumer’s Requirement |
| Tolerance | ±1% |
| Ends | As per customer requirement |
| Application | Fluid Pipe / Boiler Pipe / Drill Pipe / Hydraulic Pipe / Gas Pipe / Construction / Petrochemicals |
| MOQ | 5 Tons |
| Origin | Shandong, China |
Application Suitability
| Industry | Typical Applications |
|---|---|
| Construction & Infrastructure | Building column frames, roof trusses, scaffolding uprights, bridge support piers |
| Petrochemical & Energy | Hydraulic pipeline manifolds, gas distribution headers, boiler support structures |
| Machinery & Equipment | Conveyor frame members, crane boom sections, equipment base platforms |
| Fluid Transport | Water supply mains, irrigation channels, drainage culverts |
When ASTM and JIS Grade Labels Mask the Same Steel
A Q235B tube stamped as SS400 on the mill certificate is not a different product — it is the same chemistry under a different national standard, and mixing them on one purchase order creates traceability gaps.
Global buyers sourcing an ASTM JIS carbon steel square rectangular tube supplier often receive mixed documentation because Chinese mills cross-reference GB, JIS, and ASTM designations inconsistently. A shipment labeled SS400 may arrive with a mill test certificate referencing Q235B chemistry, leaving the importer unable to prove compliance to the project engineer. [NEED_CITE: steel grade equivalence between ASTM A500 and JIS G3466 standards] Without side-by-side chemical composition tables in the original mill paperwork, customs brokers in destination ports may hold the container pending clarification — a delay that compounds into demurrage charges and idle crane time at the job site.
Matching Wall Thickness to Structural Load Paths
Square and rectangular tubes in the 0.5–200 mm wall thickness range cover everything from light-gauge curtain wall mullions to heavy-duty column sections in industrial warehouses. For fluid and gas pipeline applications in petrochemical plants, the Q345B grade provides the higher yield tier needed to withstand internal pressure cycles, while Q235B remains the cost-effective default for non-pressurized structural frames. Hot rolled finish suits thick-wall sections where surface scale is acceptable, whereas cold rolled delivers tighter dimensional control for machinery bases requiring precise bolt-hole alignment. An ASTM JIS carbon steel square rectangular tube supplier with in-house cutting and bending capability can ship project-ready lengths, eliminating secondary fabrication at the destination yard.
Engineering Compliance Across ASTM, JIS, and GB Frameworks
Structural frames designed to AISC or EN 1993 require documented proof that the supplied steel grade meets the specified yield and tensile thresholds. [NEED_CITE: EN 10219 cold-formed structural hollow section dimensional tolerances] When the project specification calls for ASTM A500 Grade B, the mill test certificate must explicitly reference that designation — a generic “carbon steel” label will not pass the inspector’s review. For European market shipments, CE certification under EN 10210 (hot finished) or EN 10219 (cold formed) is mandatory for structural hollow sections, and the factory must hold FPC (Factory Production Control) approval. Our production lines carry both CE marks and ISO 9001:2015 registration, with every heat number traceable from slab to finished tube.
Decoding Q-Series, JIS, and ASTM Grade Systems
The Q-series (Q195 through Q345B) follows the Chinese GB standard, where the number after “Q” indicates the minimum yield strength in MPa. Q235B corresponds roughly to ASTM A36 and JIS SS400 in chemistry, though impact testing requirements differ — Q235B mandates room-temperature Charpy testing, while SS400 does not. For buyers specifying an ASTM JIS carbon steel square rectangular tube supplier, understanding these equivalences prevents over-specification: ordering Q345B when SS400 suffices adds material cost without structural benefit. The DC51D+Z through DC53D+Z grades listed in our catalog are hot-dip galvanized forming steels, selected when post-forming corrosion resistance is required without a separate galvanizing step. [NEED_CITE: comparison of Q235B SS400 and A36 mechanical property requirements]
The Hidden Cost of Tolerance Drift on 12-Meter Lengths
A ±1% wall thickness tolerance sounds tight on paper, but across a 12-meter length with 200 mm outer dimension, the cumulative weight variance per bundle can shift theoretical tonnage by several hundred kilograms. If the supplier ships on theoretical weight while the actual weight falls below the invoiced quantity, the buyer absorbs the shortfall — or worse, the structural engineer rejects the batch because the load-bearing capacity no longer matches the design calculation. [NEED_CITE: theoretical vs actual weight calculation methods for structural steel tubes] Certification gaps compound the problem: a missing or altered mill test certificate means the steel grade cannot be verified, triggering full-batch rejection at the port or costly third-party re-testing after arrival.
Why Project Buyers Return to Our Production Lines
We operate three simultaneous production lines in Jinan with monthly capacity exceeding 20,000 tons, allowing us to fulfill both trial orders and full-container bulk shipments from the same quality-controlled inventory. Our in-house理化实验室 issues original mill test certificates for every heat, and we accommodate SGS or BV third-party inspection at the factory before container sealing — eliminating the surprise of rejected cargo at destination. With over 2,800 specifications in ready stock, we consolidate multi-product orders (square tubes, round pipes, H-beams, plates) into single shipments, reducing the coordination burden on procurement teams managing fragmented supplier lists. Professional export documentation handling ensures that CE certificates, packing lists, and bills of lading align with destination-country customs requirements.
Documentation & Compliance
- Mill test certificate documenting Q235B or Q345B chemical composition and mechanical properties per ASTM A500 or JIS G3466
- CE certificate under EN 10210 (hot finished) or EN 10219 (cold formed) for European structural compliance
- ISO 9001:2015 quality management certificate covering the full production and inspection process
- SGS or BV third-party inspection report available upon request, conducted before container sealing
- Heat number traceability linking each tube bundle to its original slab chemistry and rolling record
- Customs documentation package including packing list, bill of lading, and certificate of origin
Packaging, Loading & Delivery
- Q235B and Q345B square and rectangular tubes bundled with steel strips and edge protectors to prevent coating damage during ocean transit
- Hot rolled surfaces coated with rust-preventive oil before bundling; galvanized options (DC51D+Z series) shipped with plastic sleeve wrapping to preserve zinc layer integrity
- 12-meter standard lengths loaded into 20ft and 40ft containers with optimized nesting for rectangular sections, maximizing payload per shipment
- Custom cutting to project-specified lengths available before packing, with cut ends deburred and marked per bundle
- Each bundle labeled with heat number, steel grade (Q235B/Q345B/SS400), wall thickness, and length for on-site identification
- FOB, CIF, and DDP terms available with professional container loading supervision and real-time shipment tracking
Starting Your Procurement Cycle
Submit your specification sheet — including steel grade preference (Q235B, Q345B, SS400, or equivalent), section dimensions, wall thickness, quantity, and destination port — and receive a detailed quotation with volume-based pricing within 12 hours. We provide original mill test certificates and CE documentation upfront, so your project engineer can verify compliance before the deposit is released. For non-standard dimensions or custom processing (cutting, bending, punching), our technical team confirms feasibility and lead time before contract signing.
Frequently Asked Questions
Q: How do Q235B, SS400, and ASTM A36 compare for square and rectangular tubes?
A: These three grades share similar carbon and manganese chemistry, making them interchangeable for many structural applications. However, impact testing requirements and sulfur/phosphorus limits differ slightly between standards. We supply mill test certificates that clearly state the tested standard so your engineer can confirm equivalence.
Q: Can you provide third-party inspection before shipment?
A: Yes. We accommodate SGS, BV, or other accredited third-party inspectors at our Jinan factory. Inspection covers dimensional checks, surface quality, wall thickness verification, and witness testing. The inspection report is issued before container sealing.
Q: What is the minimum order quantity for custom-cut lengths?
A: Our standard MOQ is 5 tons. For custom cutting, bending, or punching services, the same 5-ton minimum applies, though lead time extends slightly to accommodate processing scheduling.
Q: Do you supply galvanized square and rectangular tubes?
A: Yes. Our catalog includes DC51D+Z, DC52D+Z, and DC53D+Z hot-dip galvanized forming steels, as well as SGC and SGHC grades. Galvanized tubes are bundled with protective wrapping to preserve the zinc coating during transit.
Q: How do you handle mixed-product container loading?
A: We consolidate square tubes, rectangular tubes, round pipes, H-beams, and steel plates into single containers, optimizing space utilization. Each product type is separately bundled and labeled, with a consolidated packing list provided for customs clearance.
Request Your ASTM JIS Carbon Steel Square Rectangular Tube Quotation
Send your specification sheet — steel grade, section size, wall thickness, quantity, and destination port — to receive factory-direct pricing and original mill test certificates within 12 hours.
Contact: 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
