Description
Factory-Direct Hot Rolled Seamless Tubes — XJY Plate stocks Q235, Q345, and S355JR seamless square and rectangular tubes in customized sizes, backed by original mill certificates and ready for global shipment.
Technical Specifications
| Parameter | Value |
|---|---|
| Designation | Q235/Q345/S355JR Seamless Square & Rectangular Steel Tube |
| Product Type | Seamless Square and Rectangular Hollow Section |
| Steel Grade | Q195, Q235, Q345, S235JR, S275JR, S355JR |
| Standard | ASTM |
| Section Shape | Square / Rectangular |
| Technique | Hot Rolled Seamless |
| Surface Treatment | Black (Hot Rolled) |
| Tolerance | ±1% |
| Ends | Plain (default) |
| Processing Service | Welding, Punching, Cutting, Bending, Decoiling |
| Size | Customized |
| Application | Fluid transport, Boiler, Drill pipe, Hydraulic systems, Gas pipeline, Oil pipeline, Chemical fertilizer industry, Structural frames, Construction, Machinery |
| MOQ | 1 Ton |
| Origin | China |
Application Suitability
| Industry | Typical Applications |
|---|---|
| Construction & Structural Engineering | High-rise building frames, bridge support columns, industrial platform structures |
| Oil, Gas & Petrochemical | Gas transmission pipelines, oil field transport lines, chemical fertilizer plant piping |
| Machinery & Heavy Equipment | Hydraulic cylinder barrels, drill pipe casings, machinery structural frames |
| Power & Boiler Systems | Boiler superheater tubes, heat exchanger circuits, power plant fluid transport |
Grade Equivalence Across ASTM, EN, and GB Costs More Than You Think
Mismatched grade paperwork is the single most common reason seamless square and rectangular tubes get held at customs or rejected at site inspection.
Procurement teams ordering a High Quality Hot Rolled Seamless Square Rectangular Steel Tube Supplier often specify Q345 on the purchase order, only to receive material labeled S355JR or ASTM A500 Grade B at the port. Without a clear equivalence table signed off before production, the receiving engineer cannot verify whether the chemical composition and yield behavior actually match the structural calculation. [NEED_CITE: steel grade equivalence between EN, ASTM, and GB standards] Wall-thickness tolerance is another silent cost driver — a ±1% tolerance on a hot rolled seamless section means the difference between passing a load test and failing ultrasonic inspection on a pressure application. Buyers who source from multiple traders without traceable heat numbers end up paying twice: once for the material, and again for re-testing or replacement.
Matching Structural Frames and Pressure Lines to the Right Hollow Section
A High Quality Hot Rolled Seamless Square Rectangular Steel Tube Supplier must understand that structural frames for high-rise construction demand consistent corner geometry and weldable chemistry, while boiler and hydraulic lines require uniform wall thickness to withstand internal pressure cycles. Hot rolled seamless production eliminates the weld seam found in ERW alternatives, giving engineers a continuous grain flow around the entire section — critical when the tube will be bent or punched on-site. XJY Plate supplies Q235 for general structural framing where cost efficiency leads, Q345 for heavier load-bearing columns, and S355JR for projects specifying European equivalent grades, all cut to the exact length the fabrication shop needs.
Engineering Compliance From Load Calculation to Customs Clearance
Structural designers working to EN 1993 or AISC specifications need hollow sections that carry documented proof of grade conformity, not just a supplier’s word. [NEED_CITE: EN 10210 hot finished structural hollow section requirements] For projects entering the European market, CE certification and EN-compliant test certificates determine whether the container clears the port or sits in a bonded warehouse accruing demurrage. ASTM-marked material follows a parallel path for North American and Middle Eastern tenders. The black hot rolled surface on these seamless tubes arrives ready for anti-corrosion coating or can be used directly in indoor structural applications, while the ±1% dimensional tolerance ensures that connection plates and gusset joints fit without on-site grinding or reaming.
Why Hot Rolled Seamless Differs From ERW and SSAW in Practice
The hot rolled seamless process pushes a solid billet over a piercing mandrel at high temperature, producing a hollow section with no longitudinal or spiral weld line. This matters for hydraulic systems and gas pipelines where internal pressure fluctuates — a weld seam, even a high-frequency welded one, remains a potential failure plane under cyclic loading. For structural frames carrying static loads, ERW offers cost savings, but when the specification calls for seamless, the uniform wall distribution and consistent mechanical properties around the full circumference justify the premium. Q235 and Q345 belong to the Chinese GB grade system, where the number indicates the minimum yield strength in MPa; S235JR, S275JR, and S355JR follow the European EN system with JR denoting room-temperature impact toughness at 27J. [NEED_CITE: hot rolled seamless versus ERW hollow section manufacturing differences] Selecting between them depends on the design code the project engineer is working under, not on which grade sounds stronger on paper.
Hidden Costs When Grade Papers Do Not Match the Steel
A container of seamless square tubes arriving without a verifiable heat number on the mill test certificate forces the buyer into a choice: pay for independent chemical analysis at the destination port, or risk installing unverified material into a load-bearing frame. [NEED_CITE: mill test certificate verification requirements for structural steel imports] Negative tolerance abuse — where actual wall thickness falls below the stated minimum — reduces load capacity silently and only surfaces when a structural inspector drills into the section. Grade substitution without notification, such as shipping Q235 against a Q345 order, passes visual inspection but fails the moment the engineer checks yield strength test results. These are not theoretical risks; they are the reasons projects across Southeast Asia and the Middle East now require third-party inspection before loading.
Why Procurement Teams Choose XJY Plate for Seamless Hollow Sections
XJY Plate operates as the dedicated plate and coil division of Shandong Xin Jiyuan Special Steel Tube Co., Ltd, meaning every seamless square and rectangular tube ships with full traceability back to the original mill heat — no trading-company guesswork about where the steel was produced. The company maintains ISO 9001:2015 and CE certification, and accepts SGS or BV third-party inspection at the buyer’s request, so the mill test certificate you receive carries weight with customs authorities and site engineers alike. Custom cutting, punching, and bending services mean fabrication shops receive tubes ready to weld, reducing on-site labor and scrap. Professional heavy cargo logistics — including open-top container loading and break-bulk shipping for oversized lengths — prevent the damage and overweight penalties that plague inexperienced shippers. With MOQ starting at 1 Ton and the ability to mix grades and sizes within a single order, smaller fabricators access the same certified supply chain as major EPC contractors.
Documentation & Compliance
- Mill test certificate documenting Q235, Q345, or S355JR chemical composition, yield strength, and tensile properties per ASTM standards, with traceable heat number
- CE certificate confirming conformity for projects entering European markets requiring EN-compliant structural hollow sections
- ISO 9001:2015 quality management certificate covering the full supply chain from mill rolling to final inspection
- SGS or BV third-party inspection report available upon request for buyers requiring independent verification before shipment
- Material traceability by heat number linking each tube to its original billet, chemical analysis, and mechanical test results
- Full customs documentation including packing list, bill of lading, and certificate of origin for smooth port clearance
Packaging, Loading & Delivery
- Seamless square and rectangular tubes bundled with steel strips and edge protectors, preserving the black hot rolled surface from transit abrasion during ocean freight
- Custom cut-to-length tubes separated by size and grade within each bundle, matching the fabrication sequence the buyer provided at order confirmation
- Open-top container or flatbed loading for lengths exceeding standard 6-meter container dimensions, with weight distribution calculated to avoid overweight port penalties
- Heat number and steel grade stenciled on each bundle tag, allowing site receiving teams to verify material against the mill test certificate before unloading
- FOB, CIF, and DDP shipping terms available, with professional break-bulk coordination for project cargo destined for ports without heavy-lift infrastructure
Getting Your Quote and Mill Test Certificate in One Step
Send your required steel grade, section dimensions, wall thickness, length, and destination port, and XJY Plate responds within 12 hours with a detailed quotation including material cost, any processing fees, and shipping terms. For projects requiring grade equivalence confirmation or custom cutting drawings, the technical team provides specification matching before the contract is signed, so the mill test certificate you receive matches the structural calculation your engineer prepared.
Request Your Seamless Tube Quotation With Full Mill Certification
Submit your specification sheet — grade, size, quantity, and destination — to receive a detailed quotation and original mill test certificate within 12 hours.
Contact: admin@xjyplate.com | WhatsApp / WeChat: +86 188 5315 7756 | Tel: +86 531 8573 6315
Frequently Asked Questions
Q: How do Q235, Q345, and S355JR grades compare for structural applications?
A: Q235 and Q345 follow the Chinese GB system where the number indicates minimum yield strength in MPa. S355JR follows the European EN system with JR indicating room-temperature impact toughness. XJY Plate provides a grade equivalence reference during inquiry so your engineer can confirm the correct material before production begins.
Q: Can I receive a mill test certificate before shipment for third-party verification?
A: Yes. XJY Plate provides original mill test certificates documenting chemical composition and mechanical properties, with full heat number traceability. SGS or BV third-party inspection is also available at the buyer’s request before the container is sealed.
Q: What is the minimum order quantity for customized sizes?
A: The MOQ is 1 Ton. XJY Plate accepts mixed orders combining different grades, section sizes, and lengths within a single shipment, supporting both small fabrication workshops and large project procurements.
Q: Do you provide cutting and processing services for seamless square and rectangular tubes?
A: Yes. Processing services include cutting to length, welding preparation, punching, bending, and decoiling. Custom dimensions are available against drawings, and all processed tubes ship with the same mill test certificate traceability as standard-length material.
Q: How does the ±1% tolerance affect actual weight and structural calculations?
A: The ±1% tolerance applies to dimensional measurements on hot rolled seamless sections. XJY Plate provides actual measured dimensions on the mill test certificate so engineers can calculate true weight and verify load capacity against design requirements, avoiding discrepancies between theoretical and delivered weight.
Get Certified Seamless Tubes Delivered to Your Project Site
Share your grade, dimensions, and destination to receive a quotation with original mill test certificate and shipping plan within 12 hours.
Contact: admin@xjyplate.com | WhatsApp / WeChat: +86 188 5315 7756 | Tel: +86 531 8573 6315
