Description
Vertically integrated ERW tube production — Q195/Q235/Q345 grades manufactured and fabricated under one roof from raw coil to finished square and rectangular sections.
Technical Specifications
| Parameter | Value |
|---|---|
| Designation | Q235/Q345 ERW Square/Rectangular Steel Tube |
| Product Type | Square and Rectangular Steel Tube (SHS/RHS) |
| Steel Grade | Q195, Q235, Q345 |
| Standard | ASTM |
| Section Shape | Square / Rectangular |
| Size Range | 10×10 – 1000×1000 mm |
| Wall Thickness | 0.5 – 40 mm |
| Length | 1 – 12 m |
| Technique | ERW (Electric Resistance Welded) |
| Surface Treatment | Galvanized |
| Tolerance | ±1% |
| Ends | Plain (default) |
| Application | Steel structures / Construction frames / Machinery / Scaffolding / Furniture |
| MOQ | 25 Tons |
| Origin | Shandong, China |
Application Suitability
| Industry | Typical Applications |
|---|---|
| Commercial & Industrial Construction | Building column and beam frames, mezzanine platforms, warehouse portal frames |
| Machinery Manufacturing | Equipment support bases, conveyor structure frames, crane boom sections |
| Scaffolding & Temporary Works | Scaffold uprights, ledger braces, shoring tower components |
| Infrastructure & EPC Projects | Pipe rack supports, cable tray structures, equipment skid frames |
What Negative Tolerance Really Costs on a Galvanized ERW Tube Order
Theoretical weight looks clean on paper; actual measured thickness decides whether the frame passes inspection at site.
When buyers source a Q235 Q345 ERW square rectangular steel tube supplier without verifying wall thickness against the purchase order, the gap between calculated weight and measured weight becomes a customs or acceptance dispute. Galvanized coating adds surface layer that masks slight under-thickness during visual checks, but ultrasonic testing at the project site reveals the truth. [NEED_CITE: EN 10219 dimensional tolerance requirements for cold-formed hollow sections]
How Wall-Thickness Range Matches Structural Load Paths
A Q235 Q345 ERW square rectangular steel tube supplier covering 0.5–40 mm wall thickness serves both light-gauge purlin systems and heavy-load column sections from a single procurement source. The ERW process with ±1% dimensional tolerance ensures that connection plates and bolt holes align without on-site reaming, which matters when galvanized surfaces cannot be re-drilled without touching up the zinc layer. Our own mill produces the raw coil, so heat-number traceability runs from slab to finished tube without third-party material gaps.
Meeting ASTM Compliance for North American and International Projects
ASTM-standard galvanized ERW tubes require documented chemical composition and mechanical property alignment, which determines whether customs authorities accept the shipment or hold it for re-inspection. [NEED_CITE: ASTM A500 structural tubing grade requirements] The galvanized surface treatment provides corrosion resistance for outdoor scaffolding and industrial frames, while the plain ends allow field welding with proper pre-treatment of the zinc zone. Cut-to-length services from 1–12 m reduce on-site waste and welding joints in frame assembly.
Understanding Q-Grade Steel and ERW Weld Integrity
Q195, Q235, and Q345 represent a Chinese steel grade series where yield strength increases progressively, making Q345 suitable for primary structural members while Q195 serves non-load-bearing applications. The ERW welding process creates a longitudinal seam that, when properly controlled and inspected, delivers weld integrity comparable to the parent metal — critical for galvanized tubes where coating adhesion depends on surface uniformity. Galvanizing after ERW formation ensures full zinc coverage including the weld zone, unlike pre-galvanized strip where the weld area may show coating thinning.
Hidden Costs of Unverified Material Certification
Procuring from a trader rather than a Q235 Q345 ERW square rectangular steel tube supplier with in-house testing means the mill test certificate may not match the actual heat batch delivered. Missing heat-number traceability triggers project rejection during structural steel acceptance audits, and re-inspection by SGS or BV at the destination port adds cost and delays that exceed the original price saving. [NEED_CITE: material traceability requirements in structural steel construction codes]
Why Procurement Teams Choose Our Integrated Mill and Fabrication Facility
We produce the raw steel coil, form the ERW tubes, and apply galvanized coating within the same facility, eliminating the material-handoff gap where certification chains break. Over 2,800 specifications in stock mean standard sizes ship without waiting for mill rolling schedules, while custom sizes outside the 10×10 to 1000×1000 mm range are rolled to order with the same heat-number documentation. Every bundle carries the heat number stenciled on the tube end, matching the mill test certificate that travels with the shipment. Our loading team plans container stowage around the 1–12 m length range to maximize payload without exceeding port weight limits, and we provide full export documentation including certificate of origin for preferential tariff treatment.
Documentation & Compliance
- Mill test certificate documenting Q235/Q345 chemical composition and mechanical properties per ASTM, with heat-number traceability from raw coil to finished tube
- Galvanized coating thickness measurement report confirming zinc layer uniformity across the tube surface and weld seam
- SGS or BV third-party inspection report available for pre-shipment verification of dimensions, surface quality, and coating adhesion
- Certificate of origin issued for preferential customs treatment in destination countries
- Packing list and bill of lading matching heat numbers and bundle counts for site receiving verification
Packaging, Loading & Delivery
- Galvanized Q235/Q345 ERW square rectangular steel tube bundles secured with steel strips and edge protectors to prevent zinc coating damage during ocean transit
- Container loading plans optimized for 1–12 m tube lengths to maximize payload within 25-ton MOQ while respecting port weight restrictions
- Heat number and steel grade stenciled on each tube end for site identification and traceability matching the mill test certificate
- FOB, CIF, and DDP shipping terms available with full export documentation including certificate of origin for customs clearance
- Cut-to-length services available within the 1–12 m range to reduce on-site cutting waste and welding joints for scaffold and frame assembly
Start Your Procurement with Verified Specifications
Submit your project drawings or specification list including steel grade (Q195/Q235/Q345), section size, wall thickness, length, and destination port to receive a detailed quotation with mill test certificate preview and production lead time. We confirm ASTM compliance documentation, galvanized coating standards, and container loading plans before contract signing.
Request Quotation with Mill Test Certificate
Send your specification sheet to admin@xjystructure.com or contact us via WhatsApp at +86 188 5315 7756 for a response within 24 hours including material availability and shipping options.
Frequently Asked Questions
Q: Can you provide mill test certificates for Q235 and Q345 grades with ASTM equivalence?
A: Yes, every shipment includes a mill test certificate documenting chemical composition and mechanical properties, with heat-number traceability from our own steel production facility. We can provide grade equivalence documentation showing Q235/Q345 alignment with ASTM standards upon request.
Q: What is the minimum order quantity for custom sizes outside your standard range?
A: Our standard MOQ is 25 tons, which applies to both stock sizes within the 10×10 to 1000×1000 mm range and custom rolled sizes. Non-standard dimensions require production scheduling based on coil width optimization.
Q: Do you offer third-party inspection before shipment?
A: Yes, we accommodate SGS, BV, or other nominated third-party inspection agencies for pre-shipment verification of dimensions, wall thickness, galvanized coating quality, and surface condition.
Q: How do you handle negative tolerance on wall thickness?
A: We produce to ±1% dimensional tolerance as specified, and can provide actual measured thickness reports alongside theoretical weight calculations. Our mill test certificates include both values for transparent verification.
Q: Can you provide cut-to-length services for specific project requirements?
A: Yes, we offer cut-to-length services within the 1–12 m range to match your project’s structural module sizes, reducing on-site cutting waste and welding joints.
Get Your Q235 Q345 ERW Square Rectangular Steel Tube Quote Today
Share your project specifications including steel grade, section dimensions, wall thickness, quantity, and destination port to receive a comprehensive quotation with material certification preview and delivery timeline.
