Description
Direct Mill Supply — Full traceability from raw coil to finished Q235 Q345 round ERW welded steel pipe under one quality system.
Technical Specifications
| Parameter | Value |
|---|---|
| Designation | Q235/Q345 Round ERW Welded Steel Pipe |
| Product Type | Round Welded Steel Pipe (ERW / LSAW) |
| Steel Grade | Q195, Q235, Q235B, Q345, S235JR, S275JR, S355JR, SS400, St37, St52, ASTM A53, ASTM A36, ASTM A500, ASTM A106, 20#, 10#, 16Mn |
| Standard | GB/T 3091, GB/T 13912, BS 1387, ASTM A53, ASTM A500, ASTM A106, JIS, BIS, KS, API, GS |
| Section Shape | Round |
| Size Range | Outer Diameter 10–1000 mm |
| Wall Thickness | 1–80 mm |
| Length | 1–12 m (standard 6 m / 6.4 m / 12 m; customized available) |
| Technique | ERW / Hot Rolled |
| Surface Treatment | Hot Rolled, Oiled or Non-oiled; optional galvanizing, plastic coating, painting |
| Tolerance | ±1% |
| Ends | Plain / Beveled / Threaded |
| Application | Fluid transport, hydraulic systems, structural support, construction, machinery, greenhouse, fencing, curtain walls |
| Invoicing | By Actual Weight |
| Origin | Shandong, China |
Application Suitability
| Industry | Typical Applications |
|---|---|
| EPC / Industrial Plant | Process water lines, cooling water circuits, chemical fertilizer pipelines |
| Construction & Infrastructure | Column casings, scaffold tubes, curtain wall mullions, pile sleeves |
| Machinery Manufacturing | Hydraulic cylinder barrels, conveyor rollers, crane boom sections |
| Agriculture & Greenhouse | Greenhouse frame arches, irrigation mainlines, fencing posts |
| Oil & Gas Support | Low-pressure gathering lines, vent stacks, utility conduits |
Where Negative Tolerance Turns a Pipe Order into a Customs Rejection
Dimensional accuracy on ERW welded round pipe decides whether your shipment clears site inspection or gets held at the port.
When buyers source Q235 Q345 round ERW welded steel pipe from trading agents rather than integrated mills, wall thickness often drifts below the −1% tolerance band. Third-party inspectors at destination ports — SGS, BV, TÜV — measure every heat, and a single out-of-tolerance bundle triggers full-container hold. I once watched a Middle East shipment of LSAW line pipe get stuck for eleven days because the wall thickness negative tolerance was not controlled at the rolling stage; the entire lot failed re-inspection. [NEED_CITE: EN 10219 dimensional tolerance requirements for welded hollow sections]
Fragmented procurement makes this worse. The trader buys black pipe from one mill, sends it to a separate galvanizing yard, and ships without unified documentation. Material certificates do not match heat numbers. Coating thickness reports are missing. The buyer absorbs rework cost, schedule delay, and sometimes outright rejection.
Matching OD and Wall Thickness to Structural and Fluid Service
A Q235 Q345 round ERW welded steel pipe with OD 10–1000 mm and WT 1–80 mm covers both thin-wall fluid conveyance and heavy-wall structural columns. For greenhouse arches and fencing, the lower end of the diameter range with oiled black finish keeps cost down. For industrial platform columns and pile sleeves, the thicker-wall sections in Q345 or S355JR carry higher axial loads and accept bolted or welded connections without local buckling. Our own steel mill produces the raw coil, so the chemical composition in the MTC traces directly back to the heat — no gap between material supplier and pipe fabricator.
Engineering Compliance Across GB, EN, and ASTM Frameworks
Structural frames designed to EN 1993 or AISC require welded pipe that conforms to recognized hollow-section standards. Our Q235 Q345 round ERW welded steel pipe is produced under GB/T 3091 and GB/T 13912, with equivalent grades S235JR, S275JR, S355JR meeting EN 10219 requirements, and ASTM A53 / A500 / A106 covering North American projects. [NEED_CITE: steel grade equivalence mapping between GB Q-series, EN S-series, and ASTM A53] Surface treatment selection — oiled black, hot-dip galvanized, or 3PE coating — depends on the corrosion environment: indoor structural use needs only oil film, while coastal industrial plants require galvanized or 3PE for long-term protection. Fixed-length cutting to 6 m, 6.4 m, or 12 m reduces on-site welding joints and speeds erection.
Understanding the Steel Grade Ladder and ERW Weld Integrity
The Q-series (Q195, Q235, Q345) follows the Chinese yield-strength designation system, where Q235 indicates a minimum yield point of 235 MPa class. European equivalents S235JR, S275JR, S355JR follow EN 10025, and ASTM A53 Grade B / A500 Grade B cover similar mechanical ranges for American-spec projects. Moving from Q235 to Q345 or from S235JR to S355JR increases yield strength, allowing thinner walls for the same load — reducing weight and cost per meter.
ERW (Electric Resistance Welding) forms the pipe from hot-rolled coil and welds the seam through electrical resistance without filler metal. The process suits medium-diameter, medium-wall pipe efficiently and keeps cost lower than seamless for non-high-pressure service. Online ultrasonic flaw detection and hydrostatic testing per standard requirements verify weld integrity before shipment. For corrosive environments, hot-dip galvanizing adds a zinc layer that sacrifices itself to protect the base steel, while 3PE coating provides a mechanical barrier for buried or submerged service. [NEED_CITE: ERW weld quality inspection methods per API and EN standards]
The Hidden Cost of Buying ERW Pipe Without Verified MTC
Ordering Q235 Q345 round ERW welded steel pipe without a valid Mill Test Certificate tied to heat numbers creates downstream risk. If the chemical composition does not match the declared grade, structural calculations become invalid — the engineer cannot sign off, and the building inspector will reject the assembly. If the wall thickness exceeds negative tolerance, the theoretical weight invoiced does not match actual weight, and the buyer overpays. If the pipe lacks third-party inspection clearance, customs at destination may hold the container until re-testing is completed — adding weeks and storage fees. [NEED_CITE: EN 10204 3.1 inspection document requirements for structural steel]
Why Integrated Mill-to-Pipe Supply Reduces Procurement Risk
Our production starts from our own steel mill with three rolling lines and over 2,800 raw material specifications, so the coil that becomes your Q235 Q345 round ERW welded steel pipe carries full chemical and mechanical traceability from the first heat. Welding procedures are qualified per WPS/PQR, and welders hold AWS and EN certifications. Every order ships with a complete documentation package — dimensional inspection reports, coating thickness records, NDT results — prepared under one quality system. We handle shop drawing review, material optimization, and fabrication sequencing for medium-to-large projects across the EU, Middle East, Southeast Asia, and Africa. Professional loading plans for oversized and heavy pipe bundles prevent transit damage and simplify site receiving.
Documentation & Compliance
- Mill Test Certificate documenting Q235/Q345 chemical composition and mechanical properties per heat number, conforming to EN 10204 3.1
- CE certificate for EN 10219 hollow sections when supplying S235JR/S275JR/S355JR grades to European projects
- ISO 9001 quality management certificate covering the full production line from coil to finished pipe
- SGS or BV third-party inspection report available at any production stage — ultrasonic testing, dimensional check, coating thickness
- Full material traceability from heat number on pipe marking through MTC to shipping documents
- Export customs documents including packing list, bill of lading, and certificate of origin
Packaging, Loading & Delivery
- Q235/Q345 round ERW welded steel pipe bundled with steel strips and edge protectors, seaworthy packaging for ocean transit
- Oiled black pipe surfaces protected with plastic end caps; galvanized pipes wrapped to preserve zinc coating during handling
- OD 10–1000 mm pipes loaded with optimized nesting in 20ft and 40ft containers; 6 m / 6.4 m / 12 m lengths maximize cubic utilization
- Custom cut-to-length available within 1–12 m range to match project erection sequences and reduce on-site welding
- Heat number, steel grade, and size marked on each pipe bundle; shipping marks per buyer requirement
- FOB, CIF, and DDP terms available; professional loading plans for heavy-wall and large-diameter bundles
Starting Your Q235 Q345 ERW Pipe Inquiry
Share your project drawings or specification sheet — including OD, wall thickness, length, steel grade, quantity, and destination port — and we respond within 24 hours with a detailed quotation covering material, fabrication, coating, packing, and shipping. We include the shop drawing timeline, production schedule, and Mill Test Certificate format in the initial offer. For non-standard dimensions or custom surface treatment, we confirm feasibility and lead time before contract.
Frequently Asked Questions
Q: How do Q235, S235JR, and ASTM A36 compare in chemical and mechanical properties?
A: Q235 (GB), S235JR (EN), and ASTM A36 are all carbon structural grades with similar yield strength ranges. Q235 follows the Chinese standard GB/T 700, S235JR conforms to EN 10025-2 with specified impact energy at room temperature, and ASTM A36 follows the American standard for structural steel. We supply all three and provide grade equivalence mapping in the quotation.
Q: Can you arrange third-party inspection before shipment for EU or Middle East projects?
A: Yes. SGS, BV, and TÜV inspection is available at any production stage — raw material check, in-process welding inspection, dimensional verification, coating thickness measurement, and final visual inspection. The third-party report ships with the MTC and forms part of the customs clearance document set.
Q: What is the MOQ for non-standard OD or wall thickness?
A: Standard sizes in Q235/Q345 have no strict MOQ. For custom OD, wall thickness, or length outside the 10–1000 mm × 1–80 mm × 1–12 m range, we confirm minimum tonnage per heat based on the rolling schedule. Share your specification and we advise within 24 hours.
Q: Should I choose oiled black, hot-dip galvanized, or 3PE coating for my project?
A: Oiled black pipe suits indoor structural and temporary applications where corrosion risk is low. Hot-dip galvanized coating protects outdoor and moderately corrosive environments for decades. 3PE coating is specified for buried or submerged pipelines in aggressive soil or water conditions. We guide the selection based on your service environment and project standard.
Q: How is invoicing calculated — theoretical weight or actual weight?
A: All Q235 Q345 round ERW welded steel pipe is invoiced by actual weight. The ±1% tolerance on wall thickness means actual weight may differ slightly from theoretical weight. We provide the theoretical weight estimate in the quotation and confirm actual weight on the final MTC and packing list.
Get Your Q235 Q345 ERW Pipe Quotation with Full MTC
Send your specification — OD, wall thickness, length, grade, quantity, and destination — and receive a detailed offer with Mill Test Certificate format and production timeline within 24 hours.
Tel: +86 531 8573 6315 | Mobile/WhatsApp/WeChat: +86 188 5315 7756 | Email: admin@xjystructure.com
