Description
Direct Mill Supply, No Middlemen — Every Q235 Q345 ERW round steel pipe rolls from our own coil-to-pipe production line, with heat numbers traceable back to raw slab.
Technical Specifications
| Parameter | Value |
|---|---|
| Designation | Q235 Q345 ERW Round Steel Pipe |
| Product Type | ERW Welded Round Steel Pipe |
| Steel Grade | Q235, Q345, SS400, A36, A572, S235JR, S355J2 |
| Standard | ASTM, JIS, API, ISO 9001, CE |
| Section Shape | Round |
| Size Range | OD 10–2000 mm |
| Length | 6 m / 6.4 m / 12 m |
| Technique | ERW (Electric Resistance Welded) |
| Surface Treatment | Hot Rolled / Cold Rolled; optional Black, Bright, Galvanized, Painted |
| Tolerance | ±1% |
| Ends | Plain (default) |
| Oiled or Non-oiled | Non-oiled |
| Invoicing | By Theoretical Weight |
| Processing Service | Welding, Cutting, Bending, Punching, Decoiling |
| Application | Water supply and drainage / Fluid transport / Construction structure / Gas pipeline / Oil pipeline / Hydraulic systems / Boiler systems / Chemical fertilizer pipelines |
| MOQ | 10 Tons |
| Origin | Shandong, China |
Application Suitability
| Industry | Typical Applications |
|---|---|
| Water Conservancy & Municipal Infrastructure | Reservoir intake lines, irrigation mains, municipal sewage gravity pipes |
| Oil & Gas Transmission | Onshore gathering lines, chemical fertilizer plant feedstock piping |
| Industrial Construction | Factory column bracing, platform support posts, conveyor gantry legs |
| Boiler & Pressure Systems | Low-pressure steam headers, heat exchanger casings, deaerator piping |
What Negative Tolerance Does to Your Piping Budget
A ±1% OD tolerance sounds tight on paper — until wall thickness drifts past the critical line and a third-party inspector rejects the lot at the port.
Outsourcing ERW round steel pipe procurement across fragmented suppliers creates blind spots: the coil supplier, the pipe mill, and the coating shop each hand off responsibility at different stages. When wall thickness sits on the edge of negative tolerance, theoretical weight invoicing masks real material shortfall. A 6-meter length that weighs three kilos light on paper still needs to pass hydrostatic testing on site — and that gap between spreadsheet and field reality is where project schedules stall. [NEED_CITE: ERW pipe dimensional tolerance standards and inspection protocols]
How This Pipe Matches Structural and Fluid Service Demands
An ERW round steel pipe in Q235 or Q345 grade covers the overlap between structural framing and low-to-medium pressure fluid conveyance. The round cross-section distributes internal pressure uniformly, while the ERW seam — when properly welded and ultrasonically inspected — delivers joint integrity approaching the parent metal. For municipal drainage or irrigation mains, the hot-rolled surface accepts epoxy or bituminous lining directly; for structural columns, the mill-black finish welds clean without pre-grinding. Our vertical integration from raw coil to finished Q235 Q345 ERW round steel pipe means one quality system governs the entire chain.
Engineering Compliance Across Export Markets
Structural applications in the EU require CE marking under EN 10219, while North American projects specify ASTM A53 or A500 — and the steel grade equivalence between these frameworks is not always obvious on a purchase order. Q345 maps roughly to S355J2 in the EN system and A572 Grade 50 in ASTM, but the chemical composition windows differ slightly, and customs authorities in strict jurisdictions will flag mismatches between the mill test certificate and the declared standard. [NEED_CITE: steel grade equivalence mapping between GB, EN, and ASTM systems] Surface treatment selection also drives compliance: galvanized coating meets ISO 1461 for outdoor exposure, while painted systems must match the project’s corrosion category (C3, C4, or C5 per ISO 12944). Fixed lengths of 6 m or 12 m reduce on-site welding joints, but site conditions sometimes demand custom cut-to-length — a service we handle in-house before shipping.
Steel Grade Selection and ERW Process Fundamentals
Q235 and Q345 represent the two most widely specified Chinese structural grades, with Q345 offering higher yield strength for load-bearing frames and heavier wall requirements. When international buyers encounter these designations alongside S235JR, S355J2, A36, and A572, the underlying principle is consistent: the numeric suffix indicates minimum yield strength in MPa (or ksi for ASTM), and higher grades allow thinner walls for the same design pressure. The ERW process forms the round profile from hot-rolled coil and fuses the seam through electrical resistance heating — no filler metal, no flux — producing a clean, narrow weld zone suitable for ultrasonic inspection. [NEED_CITE: ERW welding metallurgy and seam integrity testing methods] For corrosive environments, galvanizing adds a zinc sacrificial layer; for buried pipelines, 3PE coating combines epoxy primer with polyethylene wrap; for indoor structural use, mill-black or shop-prime paint suffices.
The Hidden Cost of Getting the Grade Wrong
Specifying Q235 on a drawing that structurally demands Q345 — or accepting a mill test certificate that lists a commercial grade instead of the ordered standard — creates cascading failures: the inspector rejects the material, the contractor tears out installed sections, and the project absorbs not just replacement cost but crane time, welding crew idle hours, and schedule liquidated damages. Certification gaps compound the problem: a pipe without proper CE documentation cannot clear EU customs, while missing API paperwork blocks delivery to oil and gas sites. [NEED_CITE: consequences of material certification non-compliance in international construction projects]
Why Procurement Teams Source This Pipe From Us
Our mill operates three production lines covering over 2,800 raw material specifications, so when your project calls for Q345 in OD 406 mm × 12 m length, we pull the coil from our own inventory rather than brokering a third-party order. Every heat number traces back to the slab chemistry, and our in-house laboratory issues mill test certificates conforming to EN 10204 3.1 — no waiting for an external lab to schedule testing. For EU-bound shipments, we hold CE certification under EN 10219 and ISO 9001 registration; for projects requiring independent verification, we coordinate SGS or BV inspection at any production stage. Custom cut-to-length, end preparation, and surface treatment all happen under one roof, which eliminates the coordination gaps that arise when pipe, coating, and loading come from separate vendors.
Documentation & Compliance
- Mill test certificate documenting Q235 or Q345 chemical composition and mechanical properties per GB/T 700 and GB/T 1591, with heat number traceability to raw coil
- CE certificate confirming EN 10219 compliance for structural hollow sections exported to European markets
- ISO 9001 quality management system certificate covering the full ERW pipe production process
- SGS or BV third-party inspection report available for wall thickness, OD tolerance, and weld seam ultrasonic testing
- Material traceability sheet linking each pipe bundle to its heat number, coil certificate, and production date
- Export customs documents including packing list, bill of lading, and certificate of origin
Packaging, Loading & Delivery
- Q235 Q345 ERW round steel pipes bundled with steel strip ties and edge protectors to prevent coating damage during ocean transit
- Galvanized pipes wrapped with waterproof cloth and separated by rubber spacers to preserve the zinc layer
- 6 m and 12 m lengths loaded with optimized container stowage plans to maximize TEU utilization for OD 10–2000 mm range
- Cut-to-length pipes marked with heat number and steel grade stencil on both ends for site identification
- FOB, CIF, and DDP terms available with professional oversized cargo lashing for OD above 600 mm
How to Move From Drawing to Mill Test Certificate
Share your project specifications — steel grade, OD, wall thickness, length, surface treatment, and destination port — and we return a detailed quotation with production timeline and mill test certificate sample within 24 hours. For non-standard dimensions or custom coating requirements, our engineering team reviews your drawings and proposes a fabrication sequence before you commit to a purchase order.
Frequently Asked Questions
Q: How do Q235 and Q345 map to international steel grades like A36 or S355JR?
A: Q235 corresponds roughly to ASTM A36 and EN S235JR in yield strength category, while Q345 aligns with ASTM A572 Grade 50 and EN S355J2. Exact equivalence depends on chemical composition and testing requirements specified in your project standard.
Q: Can you arrange third-party inspection before shipment?
A: Yes, we coordinate SGS, BV, or TÜV inspection at any production stage — from coil raw material testing through final dimensional and coating checks — and include the inspection report in the shipping documentation package.
Q: When should I specify galvanized versus painted surface treatment?
A: Galvanizing suits outdoor exposure and buried applications where sacrificial zinc protection extends service life. Painted systems work for indoor structural use or when the project specifies a particular color or corrosion protection scheme per ISO 12944.
Q: How does theoretical weight invoicing work with ±1% tolerance?
A: We invoice by calculated weight based on ordered OD, wall thickness, and length using standard steel density. Actual production stays within ±1% dimensional tolerance, and the mill test certificate confirms measured values for each heat.
Q: What documentation do you provide for EU customs clearance?
A: Every EU-bound shipment includes CE certificate per EN 10219, EN 10204 3.1 mill test certificate, packing list, bill of lading, and certificate of origin — sufficient for customs clearance across European member states.
Request Your Quotation and Mill Test Certificate
Send your drawing specifications, steel grade, quantity, and destination port to receive a detailed offer with production schedule and sample mill test certificate.
Tel: +86 531 8573 6315
Mobile/WhatsApp/WeChat: +86 188 5315 7756
Email: admin@xjystructure.com
