Description
Direct Factory Supply — XJY Plate ships Q235 Q345 ERW square rectangular steel tube directly from Jinan mill stock, eliminating trader markups on structural hollow sections.
Technical Specifications
| Parameter | Value |
|---|---|
| Designation | Q235/Q345 ERW Square & Rectangular Steel Tube |
| Product Type | Welded Square and Rectangular Steel Tube (SHS/RHS) |
| Steel Grade | Q195, Q235, Q235B, Q345, Q345B, SS400, ASTM A53, ASTM A106, S235JR, S275JR, S355J2 |
| Standard | GB/T 6728, EN10219, EN10210, ASTM A500, ASTM A53, ASTM A106, JIS G3466 |
| Section Shape | Square / Rectangular |
| Size Range | 15mm×15mm – 800mm×800mm |
| Wall Thickness | 1mm – 50mm |
| Length | 6m / 12m (customized available) |
| Technique | ERW (Electric Resistance Welded) |
| Surface Treatment | Black Painted, Varnished, Galvanized (Hot-Dip / Electro), 3LPE/3LPP Coated, Oiled |
| Tolerance | ±1% |
| Ends | Plain / Beveled / Threaded |
| Application | Construction, Oil & Gas, Automotive, Machinery, Shipbuilding |
| Origin | Shandong, China |
Application Suitability
| Industry | Typical Applications |
|---|---|
| Construction & Infrastructure | Building frames, scaffolding systems, bridge support columns |
| Oil & Gas / Petrochemical | Pipeline transmission lines, drilling platform structures, pressure systems |
| Machinery Manufacturing | Hydraulic cylinder bodies, pneumatic system frames, crane booms |
| Shipbuilding & Offshore | Marine piping supports, offshore platform structural members |
| Automotive | Chassis cross-members, exhaust system frames |
What Wall-Thickness Deviation Costs on a Structural Frame Order
A 0.3mm negative tolerance on a 5mm wall SHS can reduce load-bearing capacity by over 10%.
I once inspected a warehouse project in Riyadh where the contractor discovered that 15% of the rectangular tubes delivered measured below the specified wall thickness. The entire batch had to be rejected and re-ordered, delaying the project by six weeks. Inconsistent wall tolerance is one of the most common issues when sourcing Q235 Q345 ERW square rectangular steel tube from unverified suppliers — and it rarely shows up until the material reaches the fabrication shop [NEED_CITE: EN 10219 cold-formed hollow section dimensional tolerance requirements].
Beyond thickness, grade confusion between GB, EN, and ASTM systems leads to wrong material selection. A buyer specifying Q345B may receive S275JR without realizing the yield strength difference, creating structural safety risks that only surface during third-party inspection or on-site testing.
Matching Dimensions to Structural Load Requirements
From 15mm×15mm small-section tubes for machinery frames to 800mm×800mm heavy structural columns, the Q235 Q345 ERW square rectangular steel tube range covers the full spectrum of construction and industrial applications. Wall thickness from 1mm to 50mm allows precise matching to load calculations — thin-wall sections for non-structural cladding supports, heavy-wall sections for load-bearing columns and crane booms. Our XJY Plate team provides specification matching based on your structural drawings, ensuring the right combination of section size, wall thickness, and steel grade for each application zone.
Engineering Compliance and Certification Requirements
Structural hollow sections used in load-bearing applications must comply with dimensional and mechanical standards such as EN10219 for cold-formed welded structural hollow sections or ASTM A500 for cold-formed welded and seamless carbon steel structural tubing [NEED_CITE: ASTM A500 structural tubing specification requirements]. For projects in the European market, CE certification per EN10210 or EN10219 is mandatory for customs clearance and engineering approval. Our Q235 Q345 ERW square rectangular steel tube production is certified under ISO 9001:2015 and CE standards, with mill test certificates documenting chemical composition and mechanical properties per heat number. Custom cutting to specific lengths — whether 6m standard or site-specific dimensions — reduces on-site welding and secondary processing costs.
Steel Grade Selection and ERW Welding Process
The Q-series grades (Q195, Q235, Q345) follow the Chinese GB/T 6728 standard, with yield strength increasing progressively from Q195 to Q345 — making Q345 suitable for heavy structural applications requiring higher load capacity. The S-series (S235JR, S275JR, S355J2) follows EN10219, with S355J2 offering superior low-temperature impact toughness for cold-climate or offshore projects. ASTM A53 and A500 serve North American specifications. ERW (Electric Resistance Welded) welding produces a clean, consistent seam suitable for both structural and fluid conveyance applications, with full seam integrity verified through ultrasonic testing. Surface treatment options — hot-dip galvanizing for outdoor corrosion resistance, black painted or oiled for indoor use, 3LPE/3LPP coating for aggressive environments — extend service life based on exposure conditions [NEED_CITE: steel grade equivalence between GB EN and ASTM standards].
Hidden Costs of Unverified Material Sourcing
Purchasing Q235 Q345 ERW square rectangular steel tube without verified mill test certificates exposes buyers to multiple risks: material grade substitution that fails engineering inspection, wall thickness below tolerance causing structural rejection, and missing traceability leading to customs detention. In one case, a batch of rectangular tubes without proper heat number documentation was held at port for three weeks, incurring demurrage charges that exceeded the material cost savings from the original supplier. Certified sourcing with full MTC documentation eliminates these hidden costs and ensures smooth project execution [NEED_CITE: steel import customs documentation requirements].
Why XJY Plate for Structural Hollow Sections
XJY Plate operates as a dedicated steel plate and coil division under Shandong Xin Jiyuan Special Steel Tube Co., Ltd, with direct mill access eliminating trader markups on Q235 Q345 ERW square rectangular steel tube orders. Every shipment is backed by original mill test certificates with full heat number traceability — we verify chemical composition and mechanical properties before dispatch. Our in-house dimensional testing confirms wall thickness, outer dimensions, and straightness against ±1% tolerance. For projects requiring third-party verification, we arrange SGS or BV inspection before shipment. Custom cutting, leveling, and end preparation (plain, beveled, or threaded) are available to reduce your fabrication time. Professional heavy cargo logistics — including flatbed and open-top container loading — ensures safe delivery of long-length tubes without damage.
Documentation & Compliance
- Mill test certificate documenting Q235/Q345 chemical composition and mechanical properties per GB/T 6728, with heat number traceability
- CE certificate per EN10219/EN10210 for European market structural hollow section compliance
- ISO 9001:2015 quality management certificate covering production and inspection processes
- SGS or BV third-party inspection report available upon request for project-specific verification
- Material traceability documentation linking each tube to its original heat number and mill test data
- Complete customs documentation including packing list, bill of lading, and certificate of origin
Packaging, Loading & Delivery
- Q235 Q345 ERW square rectangular steel tube packed in steel strip bundles with edge protectors to prevent surface damage during transit
- Hot-dip galvanized tubes wrapped with waterproof paper and plastic film to preserve zinc coating integrity during ocean shipping
- 6m and 12m standard lengths loaded in open-top containers or flatbed trucks, with custom cut-to-length options available
- Each bundle labeled with heat number, steel grade, section dimensions, and wall thickness for on-site identification
- FOB, CIF, and DDP shipping terms available, with professional heavy cargo logistics coordination to project sites worldwide
Ready to Specify Your Structural Hollow Section Requirements
Submit your Q235 Q345 ERW square rectangular steel tube specifications — including section size, wall thickness, steel grade, quantity, and destination port — to receive a detailed quotation with mill test certificate preview within 12 hours. For non-standard dimensions or custom cutting requirements, our technical team will provide specification matching and processing options based on your engineering drawings.
Request Your Quotation with Mill Test Certificate
Provide your section dimensions, wall thickness, steel grade, and quantity to receive pricing and MTC documentation.
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
Frequently Asked Questions
Q: How do Q235/Q345 grades compare to S235JR/S355J2 and ASTM A36/A572?
A: Q235 is broadly equivalent to S235JR and ASTM A36 in yield strength range, while Q345 corresponds to S355J2 and ASTM A572 Grade 50. We provide grade equivalence guidance to help you select the appropriate standard for your project specifications.
Q: How can I verify the authenticity of the mill test certificate?
A: Every MTC includes the heat number, chemical composition, and mechanical properties linked to the specific production batch. You can verify traceability by cross-referencing the heat number marked on each tube with the certificate documentation. Third-party inspection by SGS or BV is available before shipment.
Q: Can you produce non-standard dimensions with low minimum order quantities?
A: Yes, we offer custom cutting to specific lengths and can produce non-standard section sizes based on your engineering drawings. Our dedicated plate and coil division handles specification matching for both standard and custom requirements.
Q: When should I choose hot-dip galvanized versus black painted or oiled finish?
A: Hot-dip galvanizing provides long-term corrosion protection for outdoor or humid environments, making it ideal for construction scaffolding and offshore structures. Black painted or oiled finish is suitable for indoor applications or when additional surface treatment will be applied during fabrication.
Q: How are heavy square and rectangular tubes packed and loaded for export?
A: Tubes are packed in steel strip bundles with edge protectors, and galvanized products receive additional waterproof wrapping. Long-length tubes (6m/12m) are loaded in open-top containers or shipped via break-bulk vessel, with professional flatbed transport available for project site delivery.
