Description
Factory-Direct Q235 Q355 Round Pipe Supply — Seamless and ERW welded round steel pipes in OD 10–700mm, shipped with EN 10210/10219 and ASTM A53 mill test certificates from our in-house physical and chemical laboratory.
Technical Specifications
| Parameter | Value |
|---|---|
| Designation | Q235 Q355 Seamless Welded Round Steel Pipe |
| Product Type | Round Steel Pipe / Seamless & Welded Round Hollow Section |
| Steel Grade | Q195, Q235, Q355, Q345, 10#, 20#, 45#, 16Mn, SS400, ST35–ST52, ASTM A53 (Grade A/B/C), ASTM A106, ASTM A500, API 5L |
| Standard | API 5L, ASTM A53, ASTM A106, ASTM A500, ASTM A252, ASTM A450, ASTM A671, ASME B36.10M, BS EN 10219, BS EN 10210, 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 / 6.4 m / 12 m) |
| Technique | Seamless (Hot Rolled / Cold Drawn) & Welded (ERW / Hot Rolled) |
| Surface Treatment | Hot Rolled / Oiled / Zinc Coated (200–700 g/m² Hot Dip Galvanized) / Black |
| Tolerance | ±1% |
| Ends | Plain / Beveled |
| Application | Fluid transport / Boiler & heat exchanger / Structural frames / Scaffolding / Machinery manufacturing / Construction / Pipeline engineering |
| MOQ | 1 Ton |
| Origin | Shandong, China |
Application Suitability
| Industry | Typical Applications |
|---|---|
| Construction & Infrastructure | Building frames, scaffolding systems, pile casings, bridge handrails |
| Fluid & Pipeline Engineering | Water supply mains, gas distribution lines, oil transport pipelines, chemical fertilizer feed lines |
| Machinery Manufacturing | Hydraulic cylinder barrels, conveyor rollers, agricultural equipment frames |
| Boiler & Heat Exchanger | High-temperature steam lines, heat exchange tube bundles, pressure vessel nozzles |
| Steel Structure Fabrication | Column sections, truss members, purlin supports for warehouses and industrial sheds |
What Wall-Thickness Tolerance Costs on a Structural Frame Order
A ±1% tolerance on a 10mm wall Q355 pipe means the difference between passing SGS inspection at destination and having an entire container held at Jebel Ali.
I learned this the hard way. A batch of Q355 seamless pipes I shipped to a Saudi client got flagged during SGS复检 at the port because the wall thickness negative tolerance exceeded the allowable limit. The entire container was held. The root cause was not the mill — it was the lack of real-time dimensional verification before loading. Since then, every Q235 Q355 seamless welded round steel pipe leaving our facility goes through in-house dimensional, mechanical, and chemical testing against EN 10219 and ASTM A500 tolerances before a single piece is staged for container loading [NEED_CITE: EN 10219 cold-formed hollow section dimensional tolerance requirements]. The cost of re-sorting at the factory is a fraction of the cost of demurrage, re-inspection, and reputational damage at destination.
How OD 10–700mm Coverage Matches Structural and Pipeline Applications
A single project often requires both small-diameter precision tubes for machinery and large-diameter heavy-wall pipes for structural columns or pipeline sections. Sourcing these from separate suppliers creates grade mismatch risks and certification gaps. Our Q235 Q355 seamless welded round steel pipe range covers OD 10–700mm with wall thickness from 1mm cold-rolled precision up to 20mm hot-rolled heavy wall, allowing EPC contractors and steel traders to consolidate fluid transport, structural framing, and boiler applications under one purchase order with consistent mill test documentation.
Engineering Compliance Across EN, ASTM, and GB Standards
Structural frames designed to EN 1993 require hollow sections conforming to EN 10210 or EN 10219 with CE marking for EU market entry. Pipeline projects following API 5L or ASTM A53 demand specific chemical composition limits and hydrostatic test records. Our Q235 Q355 seamless welded round steel pipe production covers all three standard systems, with in-house laboratory testing verifying chemical composition and mechanical properties per the relevant standard before shipment. Third-party inspection by SGS or BV is arranged on request to satisfy destination customs and project owner requirements [NEED_CITE: steel grade equivalence mapping between GB Q-series and EN S-series standards].
Steel Grade Selection and Process Differences Explained
Q235 and Q355 represent the most widely specified structural grades in the Chinese standard system, with Q355 offering higher yield strength for load-bearing columns and heavy-duty scaffolding. In the European system, S235JR and S355JR serve equivalent roles under EN 10219. ASTM A53 Grade B and A500 Grade B fulfill similar structural functions in North American projects. Seamless pipes produced by hot rolling or cold drawing are preferred for high-pressure fluid transport and boiler applications where internal integrity is critical. ERW welded pipes offer cost efficiency for structural framing, scaffolding, and low-pressure fluid conveyance where dimensional accuracy and surface quality matter more than pressure rating. Surface treatment selection — oiled for short-term corrosion protection, black for indoor structural use, or hot dip galvanized at 200–700 g/m² for outdoor or marine environments — is determined by the service environment and project specification.
Hidden Costs of Wrong Grade or Missing Certification
Ordering Q235 when the structural drawing specifies Q355 means the pipe will not meet the design load requirement — a failure discovered only during third-party inspection or, worse, during structural loading. Missing CE marking on EN 10219 pipes blocks customs clearance in EU member states. Negative wall thickness beyond the ±1% tolerance triggers rejection at destination port, regardless of whether the pipe passes visual inspection. These are not theoretical risks. They are recurring issues in international steel procurement that trace back to inadequate mill test documentation and the absence of pre-shipment dimensional verification [NEED_CITE: consequences of steel grade mismatch in structural engineering projects].
Why Procurement Teams Consolidate Round Pipe Orders With Us
Our production facility operates three dedicated lines covering over 2,800 specifications in round, square, and rectangular hollow sections, allowing a single order to include seamless Q355 boiler tubes, ERW welded Q235 scaffolding pipes, and galvanized structural rounds in one shipment. Every Q235 Q355 seamless welded round steel pipe is tested in our in-house physical and chemical laboratory, with mill test certificates issued per EN 10204 3.1 showing actual chemical composition and mechanical test results. We hold CE certification under EN 10210 and EN 10219, ISO 9001:2015, and Singapore FPC, with SGS and BV verification available for every shipment. Custom non-standard sizes outside the OD 10–700mm range are available with low minimum order quantities. Professional container loading with anti-damage measures ensures pipes arrive without bending or surface coating damage. We export to over 50 countries, with established logistics routes to the EU, North America, Middle East, and Southeast Asia.
Documentation & Compliance
- Mill test certificate documenting Q235 or Q355 chemical composition, yield strength, and tensile properties per EN 10204 3.1 or ASTM A53 requirements
- CE certificate confirming EN 10210 seamless or EN 10219 welded hollow section compliance for EU market customs clearance
- ISO 9001:2015 quality management system certificate covering the full production and testing process
- SGS or BV third-party inspection report verifying dimensional tolerance, wall thickness, and surface coating weight before shipment
- Material traceability documentation linking each pipe to its heat number for project-specific quality audits
- Complete customs documentation including packing list, bill of lading, and certificate of origin for destination port clearance
Packaging, Loading & Delivery
- Seamless and ERW welded Q235 Q355 round pipes bundled with steel strips and edge protectors to prevent surface damage during ocean transit
- Hot dip galvanized pipes packed with protective separators to preserve the 200–700 g/m² zinc coating without scratching or peeling
- Standard 6m and 12m lengths optimized for 20ft and 40ft container loading, with custom cut lengths available to maximize container utilization
- Oiled black pipes wrapped in waterproof cloth for humidity protection during transit to tropical and coastal destinations
- Heat number and steel grade stenciled on each pipe end for on-site identification and traceability verification
- FOB, CIF, and DDP shipping terms available with door-to-door logistics coordination to major construction ports worldwide
How to Request a Quotation With Full Mill Documentation
Submit your specification including outer diameter, wall thickness, steel grade, surface treatment, quantity, and destination port. We respond within 12 hours with a detailed quotation including unit price, lead time, and shipping terms. Mill test certificates and third-party inspection reports are confirmed at the quotation stage so there are no documentation surprises at customs.
Get Your Q235 Q355 Round Pipe Quote With Mill Test Certificate
Send your dimensions, grade, and quantity to receive a factory-direct quotation with full EN 10210/10219 or ASTM A53 documentation.
Company: Shandong Xin Jiyuan Special Steel Tube Co., Ltd
Tel: +86 531 8573 6315
Mobile/WhatsApp/WeChat: +86 188 5315 7756
Email: admin@sdxjypipe.com
Frequently Asked Questions
Q: How do Q235 and Q355 map to European and American steel grades?
A: Q235 corresponds approximately to S235JR in EN 10219 and ASTM A53 Grade A. Q355 maps to S355JR/S355J2 in the EN system and ASTM A500 Grade B or Grade C. We provide cross-standard equivalence documentation with every quotation to prevent ordering errors.
Q: What is the difference between seamless and ERW welded round pipes for my application?
A: Seamless pipes produced by hot rolling or cold drawing are suited for high-pressure fluid transport, boiler tubes, and applications requiring uniform internal integrity. ERW welded pipes are cost-effective for structural framing, scaffolding, and low-pressure conveyance where dimensional accuracy and surface finish are the primary requirements.
Q: What mill test certificates and inspection documents are provided?
A: Every shipment includes a mill test certificate per EN 10204 3.1 showing actual chemical composition and mechanical properties. Third-party inspection by SGS or BV is available before shipment. CE certification under EN 10210/10219 is provided for EU market compliance.
Q: Can you produce non-standard outer diameters or wall thicknesses outside the listed range?
A: Yes. Custom non-standard sizes are available with low minimum order quantities. Our 2,800+ specification range and three production lines allow us to accommodate special dimensional requirements for machinery and structural projects.
Q: What surface treatment options are available and how do I choose?
A: Hot rolled oiled pipes suit short-term indoor storage and transport. Black pipes are used for indoor structural applications. Hot dip galvanized pipes with 200–700 g/m² zinc coating are specified for outdoor, marine, or corrosive environments where long-term corrosion resistance is required.
