Description
Factory-direct round steel pipe supply — XJY Structure operates its own steel mill producing Q235 and Q355 grades across OD 10–700mm, eliminating third-party sourcing gaps from raw coil to finished pipe.
Technical Specifications
| Parameter | Value |
|---|---|
| Designation | Q235 Q355 Seamless Welded Round Steel Pipe |
| Product Type | Round Steel Pipe / Circular Hollow Section |
| Steel Grade | Q195, Q235, Q345, Q355, SS400, 10#, 20#, 45#, 16Mn, A53, A106, A369, ST35, ST52 |
| Standard | API 5L, ASTM A53, ASTM A106, ASTM A252, ASTM A500, ASTM A671, ASME B36.10M, BS EN10219, BS EN10296, BS 1387, BS 6323, BS 6363, GB/T 3091, GB/T 13793, GB/T 9711, JIS G3466 |
| Section Shape | Round |
| Outer Diameter | 10–700 mm |
| Wall Thickness | Cold rolled 1–4.0 mm / Hot rolled 4–20 mm |
| Length | 1–12 m (standard 6 m / 12 m) |
| Technique | Hot Rolled / Cold Rolled / Cold Drawn |
| Surface Treatment | Hot Rolled / Slightly Oiled / Zinc Coated (200–700 g/m²) |
| Tolerance | ±1% |
| Ends | Plain / Beveled (per standard) |
| Application | Fluid transport / Structural applications / Construction building material / Boiler / Hydraulic system / Gas & Oil pipeline / Chemical fertilizer / Scaffolding / Machinery |
| MOQ | 1 Ton |
| Origin | Shandong, China |
Application Suitability
| Industry | Typical Applications |
|---|---|
| EPC & Industrial Projects | Oil & gas pipeline systems, hydraulic conveyance lines, chemical plant process piping |
| Construction & Infrastructure | Structural columns, scaffolding frameworks, building frame assemblies |
| Mechanical & Manufacturing | Machinery shafts, boiler tubes, fluid transport systems |
What Wall-Thickness Tolerance Costs on a Structural Frame Order
Negative tolerance beyond specification limits triggers third-party rejection at destination port.
Overseas buyers sourcing Q235 Q355 seamless welded round steel pipe from fragmented suppliers face material traceability gaps that surface only during on-site inspection. When wall thickness drifts below the lower tolerance limit, entire shipments get held at customs warehouses — storage fees alone can consume the margin on that order. The root cause often traces back to fabricators sourcing raw materials from multiple mills without unified quality control, creating certification chain breaks that fail EN 10219 or ASTM A500 compliance audits. [NEED_CITE: EN 10219 cold-formed hollow section dimensional tolerance requirements]
How OD 10–700mm Range Matches Structural and Fluid Applications
The 10–700mm outer diameter coverage spans from small-bore fluid lines to large structural columns, with cold rolled walls (1–4mm) serving precision machinery applications and hot rolled walls (4–20mm) handling load-bearing structural duty. Q235 Q355 seamless welded round steel pipe in this range supports both pressure-containing systems per API 5L and structural frameworks per EN10219, allowing single-source procurement for mixed-scope EPC projects. Our integrated mill produces the full diameter range under one quality management system, so heat numbers trace consistently from coil to finished pipe — no certification gaps between size segments.
Engineering Compliance Across International Standards
Structural applications require Q235 Q355 seamless welded round steel pipe to meet specific dimensional and mechanical criteria depending on the governing code. EN 10219 governs cold-formed welded hollow sections for European projects, while ASTM A500 covers structural tubing in North American construction — both demand documented chemical composition and yield strength verification. For pressure-containing duty in oil and gas pipelines, API 5L and ASTM A106 specifications apply, requiring hydrostatic testing and certified welding procedures. Surface treatment selection between hot rolled finish, slight oiling, or zinc coating (200–700 g/m²) depends on corrosion environment and project design life. [NEED_CITE: steel grade equivalence between Q235/Q355 and S235/S355 systems]
Steel Grade Selection and Process Considerations
Q235 and Q355 represent the workhorse grades for general structural and fluid applications, with Q355 offering higher yield strength for load-critical members. The Q-series (Chinese GB standard) corresponds roughly to S-series (EN standard) and ASTM A36/A572 (US standard), though exact equivalence requires cross-reference per project specification. Hot rolled process produces thicker walls (4–20mm) suitable for structural columns and heavy-duty piping, while cold rolled and cold drawn methods achieve tighter tolerances and thinner walls (1–4mm) for precision machinery and hydraulic systems. Welded versus seamless construction depends on pressure rating and diameter — seamless pipe handles higher pressures in oil and gas applications, while welded pipe offers cost efficiency for structural and low-pressure fluid duty. Surface treatment choice between black oiled, hot rolled finish, or hot-dip galvanized (200–700 g/m² zinc coating) balances corrosion protection against project budget and environmental exposure. [NEED_CITE: hot-dip galvanized coating thickness standards for structural steel]
Hidden Costs of Sourcing Without Verified Certification
Purchasing Q235 Q355 seamless welded round steel pipe from suppliers without complete mill test certificates creates downstream risks that surface during project inspection or customs clearance. Material without traceable heat numbers fails third-party verification requirements, triggering shipment holds and re-inspection costs at destination. Negative tolerance exceeding specification limits compromises structural load capacity, forcing costly rework or member replacement after installation. Certification gaps between material supplier and fabricator break the quality chain that EN 10219 and ASTM A500 require for project acceptance. [NEED_CITE: material traceability requirements in EN 10204 inspection documents]
Why Project Teams Source From XJY Structure
Our vertically integrated operation combines raw steel production with fabrication capability, producing Q235 Q355 seamless welded round steel pipe under unified quality control from coil to finished product. The mill maintains 2,800+ specifications in inventory, covering the full OD 10–700mm range across hot rolled, cold rolled, and welded processes — eliminating the need to coordinate multiple suppliers for mixed-scope projects. Every shipment includes complete mill test certificates with heat number traceability, chemical composition, and mechanical properties per the specified standard. Third-party inspection by SGS, BV, or TÜV is available before shipment for projects requiring independent verification. Professional loading and lashing plans handle oversized components up to 700mm OD, with export documentation prepared for smooth customs clearance at destination ports.
Documentation & Compliance
- Mill test certificate documenting Q235/Q355 chemical composition and mechanical properties per GB/T 1591 or equivalent EN/ASTM standard
- CE certificate per EN10219 for cold-formed welded hollow sections supplied to European construction projects
- ISO 9001 quality management system certification covering the integrated steel production and fabrication process
- SGS or BV third-party inspection report verifying dimensional tolerance, surface treatment thickness, and coating adhesion
- Material traceability by heat number from raw coil through finished pipe, included in the complete quality documentation package
- Customs documents including packing list, bill of lading, and certificate of origin prepared per destination country requirements
Packaging, Loading & Delivery
- Q235 and Q355 round steel pipe bundled with steel strips in seaworthy packaging, with edge protectors preserving zinc coating on galvanized products during ocean transit
- Hot rolled and slightly oiled finish pipes receive rust-preventive treatment before bundling, suitable for container or bulk vessel shipment depending on order quantity
- Container loading optimized for 6m and 12m standard lengths, with oversized 700mm OD pipes requiring flat rack or breakbulk arrangements
- Custom cutting to project-specified lengths within the 1–12m range available, reducing on-site waste and handling
- Heat number and steel grade marked on each pipe end, with bundle tags matching the mill test certificate for traceability verification
- FOB, CIF, and DDP terms available, with door-to-door logistics coordination for project sites requiring complete delivery service
How to Initiate Your Q235 Q355 Round Steel Pipe Inquiry
Submit your project specifications including outer diameter, wall thickness, steel grade, quantity, and destination port to receive a detailed quotation with production schedule and mill test certificate timeline. For projects requiring EN10219 or ASTM A500 compliance, specify the governing standard and any third-party inspection requirements in your initial inquiry. Our engineering team reviews shop drawings and provides material optimization recommendations before contract signing, ensuring the Q235 Q355 seamless welded round steel pipe specification matches your structural and fluid application requirements.
Frequently Asked Questions
Q: What is the difference between Q235 and Q355 steel grades for round steel pipe?
A: Q235 offers standard yield strength suitable for general structural and fluid applications, while Q355 provides higher yield strength for load-critical structural members. Both grades are available across the full OD 10–700mm range with complete mill test certification.
Q: Can you provide third-party inspection before shipment?
A: Yes, we accept SGS, BV, and TÜV third-party inspection for dimensional verification, surface treatment thickness measurement, and coating adhesion testing. The inspection report is included in the complete quality documentation package.
Q: What surface treatment options are available for corrosion protection?
A: We offer hot rolled finish, slightly oiled for temporary rust prevention, and hot-dip galvanized with zinc coating thickness of 200–700 g/m² depending on project corrosion requirements and design life.
Q: How do you handle negative tolerance on wall thickness?
A: We maintain ±1% tolerance on wall thickness per standard requirements. Every batch undergoes dimensional inspection before shipment, with results documented in the mill test certificate to ensure compliance with EN10219 or ASTM A500 specifications.
Q: What is the minimum order quantity for custom sizes?
A: The minimum order quantity is 1 Ton. For custom lengths within the 1–12m range or non-standard diameters, we review your specifications and provide production feasibility assessment within 24 hours.
Get Your Q235 Q355 Round Steel Pipe Quote With Complete Certification
Send your project drawings, steel grade requirements, and quantity to receive a detailed quotation including material cost, fabrication services if needed, surface treatment, and shipping to your destination port. Our team responds within 24 hours with preliminary assessment and mill test certificate timeline.
Contact XJY Structure
Website: www.xjystructure.com
Tel: +86 531 8573 6315
Mobile/WhatsApp/WeChat: +86 188 5315 7756
Email: admin@xjystructure.com
Address: No.11889, Jingshi West Road, Lulian Group, Jinan City, Shandong Province, China
