Description
Factory-Direct Round Pipe Supply — We roll and ship Q235 and Q355 seamless and welded round steel pipes from Jinan with original mill certificates, cutting out trader markups on every ton.
Technical Specifications
| Parameter | Value |
|---|---|
| Designation | Q235 Q355 Seamless/Welded Round Steel Pipe |
| Product Type | Round Steel Pipe (Seamless & Welded) |
| Steel Grade | Q195, Q235, Q355, SS400, 10#, 20#, 45#, 16Mn, A53, A106, A369, ST35, ST52 |
| Standard | API 5L, ASTM A53, ASTM A106, ASTM A252, ASTM A450, ASTM A523, ASTM A671, ASME B36.10M, BS 1387, BS EN 10219, BS EN 10296, BS 6323, BS 6363, GB/T 3091, GB/T 13793, GB/T 9711 |
| Section Shape | Round |
| Size Range | Outer Diameter 10–700 mm |
| Wall Thickness | Cold Rolled 1–4.0 mm; Hot Rolled 4–20 mm |
| Length | 1–12 m |
| Technique | Hot Rolled / Cold Rolled / Cold Drawn |
| Surface Treatment | Hot Rolled / Galvanized (Zinc Coated 200–700 g/m²) / Slightly Oiled |
| Tolerance | ±1% |
| Ends | Plain / Beveled (per standard) |
| Application | Fluid transport / Boiler / Drill pipe / Hydraulic pipe / Gas & oil pipeline / Chemical fertilizer / Structure pipe / Construction building material |
| MOQ | 1 Ton |
| Origin | Shandong, China |
Application Suitability
| Industry | Typical Applications |
|---|---|
| Oil & Gas EPC | Transmission pipelines, gathering lines, and process piping using API 5L and ASTM A106 grades |
| Power & Boiler | Superheater tubes, water-wall pipes, and steam lines in utility and industrial boilers |
| Construction & Infrastructure | Structural columns, trusses, scaffolding, and bridge handrails with Q355 and SS400 |
| Chemical & Fertilizer | Process piping, heat exchanger tubes, and corrosion-resistant conveyance lines |
| Mechanical & Hydraulic | Hydraulic cylinder barrels, drill rods, and machined components in 10#, 20#, 45# |
When Grade Equivalence Tables Cause Customs Holds
Mismatched EN-ASTM-GB designations delay clearance more often than dimensional non-conformance.
Project specifiers routinely call out S235JR on drawings, then receive Q235B mill certificates from Chinese suppliers — and customs agents in the EU or Middle East flag the shipment because the heat number traceability does not map to an EN 10219 designation. Buyers sourcing a Q235 Q355 seamless welded round steel pipe supplier for structural or pressure work face the same headache when ASTM A53 Grade B is specified but GB/T 3091 material is shipped without a formal equivalence statement. The pipe passes the yard inspection, fails the site audit, and sits in a bonded warehouse for weeks. [NEED_CITE: steel grade equivalence between EN, ASTM, and GB standards for structural hollow sections]
Matching Pipe Metallurgy to Pressure, Structure, and Corrosion Environments
A Q235 Q355 seamless welded round steel pipe supplier who understands application context will route API 5L X42 or ASTM A106 Grade B to oil and gas lines where internal pressure and sour-service resistance matter, while steering Q355 or SS400 toward building frames where yield strength and weldability dominate the selection. For boiler and pressure vessel work, ST35 through ST52 grades meet the elevated-temperature creep requirements that carbon structural grades cannot satisfy. We verify each heat against the intended service environment before releasing the mill test certificate, because a pipe that tests fine for scaffolding may fail a hydrostatic proof-pressure test on a process line.
Engineering Codes, Surface Protection, and Certification Pathways
Structural frames designed to EN 1993 or AISC 360 require certified yield and tensile values on the mill test certificate — not just a grade stamp on the pipe end. When the project sits in a coastal or industrial atmosphere, galvanized coating at 200–700 g/m² extends service life far beyond oiled or bare hot-rolled finish, but the zinc layer must be specified before rolling, not added as an afterthought. CE marking under EN 10219 is mandatory for structural hollow sections entering the EU, while ASTM A53 and A106 govern North American pressure and mechanical applications; mixing the two without documented equivalence creates rejection risk at the port. [NEED_CITE: EN 10219 cold-formed welded structural hollow sections certification requirements]
Decoding Seamless, ERW, and Cold-Drawn Process Choices
Seamless pipe, produced by hot piercing a solid billet, handles higher internal pressures and is preferred for oil country, boiler, and hydraulic applications where through-wall integrity cannot be compromised. Electric-resistance welded (ERW) pipe, formed from coil and welded along the longitudinal seam, offers tighter dimensional tolerance and lower cost for structural and low-pressure fluid conveyance — and it is the dominant process for Q235 and Q355 round pipe in construction. Cold-drawn pipe adds a final sizing pass that improves surface finish and holds ±1% tolerance on OD and wall, making it suitable for machined components and hydraulic cylinders. Wall thickness selection directly affects weight-per-meter and load capacity; specifying hot-rolled 4–20 mm for structural columns versus cold-rolled 1–4.0 mm for light framing changes both the unit price and the tonnage per container.
The Real Cost of Accepting Sub-Tolerance or Forged Certificates
A pipe that measures 3.8 mm instead of the specified 4.0 mm wall may pass a caliper check at the mill gate but fails the structural engineer’s load calculation, triggering rework or replacement after erection. Missing or altered heat numbers on the mill test certificate mean the pipe cannot be traced back to its chemical composition and mechanical test results — a deal-breaker for pressure vessel inspectors and EU notified bodies. [NEED_CITE: consequences of missing mill test certificates in pressure equipment directives]
Why Procurement Teams Choose Our Mill-Direct Channel
We operate from Jinan with direct access to rolling schedules at multiple Shandong and Hebei mills, which means we quote Q235 and Q355 round pipe at mill-level pricing without a trading company’s margin layered on. Every bundle ships with an original mill test certificate showing heat number, chemical composition, and mechanical properties — not a re-typed commercial invoice. Our in-house quality team checks wall thickness with ultrasonic gauges before container loading, catching negative-tolerance drift that third-party inspectors sometimes miss. For projects requiring third-party validation, we coordinate SGS or BV inspection at the mill before dispatch. We hold ISO 9001:2015 and CE certification, and we routinely load open-top containers and flatbed trailers for pipes up to 12 m long, avoiding the damage and overweight penalties that standard 20-foot containers cause with heavy-wall pipe.
Documentation & Compliance
- Mill test certificate documenting Q235B or Q355B chemical composition, yield strength, and tensile properties per GB/T 3091 or GB/T 9711, with traceable heat number
- CE certificate confirming EN 10219 compliance for structural round pipe entering EU markets
- ISO 9001:2015 quality management certificate covering the full supply and inspection chain
- SGS or BV third-party inspection report verifying OD, wall thickness, and surface coating before shipment
- Material traceability sheet linking each pipe bundle to its heat number, rolling date, and test batch
- Full customs document set including packing list, bill of lading, and certificate of origin for destination-country clearance
Packaging, Loading & Delivery
- Q235 and Q355 round pipes bundled with steel strip ties and edge protectors to prevent coating damage and bundle deformation during ocean transit
- Galvanized pipes wrapped with waterproof paper and plastic sleeves to preserve the 200–700 g/m² zinc layer against salt spray and condensation
- Seamless and hot-rolled pipes lightly oiled to prevent surface rust during storage and transport, with oil type specified per destination climate
- Open-top containers and flatbed trailers used for pipes exceeding 6 m in length or heavy-wall sections, avoiding mid-span bending and end damage
- Each bundle marked with heat number, steel grade, size, and length for site identification and inspection traceability
- FOB, CIF, and DDP terms available, with door-to-door logistics planned for project sites in Southeast Asia, the Middle East, Africa, and South America
Starting Your Procurement with Accurate Specifications
Send us the steel grade, outer diameter, wall thickness, length, quantity, and destination port, and we return a detailed quotation with material cost, processing fees, and shipping terms within 12 hours. If your drawing calls for a grade not listed in our standard range, we source it from partner mills and provide the equivalence documentation your inspector needs. Confirm your certification requirements — CE, SGS, BV, or mill-only — and we lock the inspection plan before the first pipe leaves Jinan.
Frequently Asked Questions
Q: What is the difference between Q235 and Q355 for structural round pipe?
A: Q235 offers lower yield strength and is suited for light structural frames, scaffolding, and general conveyance, while Q355 provides higher yield strength for load-bearing columns, trusses, and bridge components where structural capacity is critical.
Q: Can you supply seamless and welded round pipe in the same order?
A: Yes. We supply both seamless (hot-rolled, cold-drawn) and welded (ERW) round pipe from OD 10 mm to 700 mm, and we consolidate them into a single shipment with separate mill test certificates for each process type.
Q: How do you verify wall thickness before shipment?
A: Our quality team uses ultrasonic thickness gauges to check every bundle against the specified tolerance of ±1%, and we record the measurements in the pre-shipment inspection report available to the buyer.
Q: What surface treatment options are available for round pipe?
A: We offer hot-rolled (bare), galvanized with zinc coating from 200 to 700 g/m², and slightly oiled finish, selected based on the service environment and project specification.
Q: Do you provide third-party inspection?
A: Yes. We coordinate SGS or BV inspection at the mill before loading, covering dimensional checks, visual inspection, and coating thickness measurement, with the report issued directly to the buyer.
Get Your Quotation with Mill Test Certificate
Submit your round pipe specifications — grade, OD, wall, length, quantity, and destination — and receive a detailed offer with original mill test certificate and shipping plan within 12 hours.
Contact: Shandong Xin Jiyuan Special Steel Tube Co., Ltd
Website: www.xjyplate.com
Tel: +86 531 8573 6315
Mobile/WhatsApp/WeChat: +86 188 5315 7756
Email: admin@xjyplate.com
Address: No.11889, Jingshi West Road, Lulian Group, Jinan City, Shandong Province, China
