Description
Factory-Direct Rectangular ERW Tubes — Produced on 3 dedicated lines in Jinan with in-house lab verification, eliminating trading markup on every metric ton shipped.
Technical Specifications
| Parameter | Value |
|---|---|
| Designation | Q235/Q345 Rectangular ERW Welded Steel Tube |
| Product Type | Rectangular ERW Welded Steel Tube (Hollow Section) |
| Steel Grade | Q195, Q215, Q235, Q345 |
| Standard | ASTM A213, DIN EN 10217-1 |
| Section Shape | Rectangular (Square and Round also available) |
| Size Range | 300×300 mm and full range per manufacturer catalog |
| Wall Thickness | Up to 40 mm |
| Length | Custom as per customer request |
| Technique | ERW (Electric Resistance Welded) |
| Surface Treatment | Slightly Oiled / Hot Rolled finish |
| Tolerance | ±1% |
| Ends | Plain |
| Invoicing | By Theoretical Weight |
| Processing Services | Welding, Punching, Cutting, Bending, Decoiling |
| Application | Structure Pipe, Fluid Pipe, Boiler Pipe, Drill Pipe, Gas Pipe, Oil Pipe, Chemical Fertilizer Pipe |
| MOQ | 5 Tons |
| Origin | Shandong, China |
Application Suitability
| Industry | Typical Applications |
|---|---|
| EPC Contractors & Construction | Steel structure frames for industrial warehouses, high-rise building columns, bridge support members |
| Machinery Manufacturers | Conveyor system frames, crane boom sections, equipment base structures requiring precision rectangular profiles |
| Industrial Piping | Fluid transport lines, gas distribution networks, oil field piping, chemical fertilizer plant process piping |
| Infrastructure Developers | Scaffolding systems, solar panel mounting structures, urban utility pole foundations |
What Dimensional Tolerance Costs When Your Frame Won’t Square Up
A ±1% tolerance on a 300 mm rectangular section means the difference between a beam that bolts in clean and one that needs on-site rework.
I have watched project teams burn through their installation budget because the rectangular tubes arrived with wall thickness drifting beyond acceptable limits — the flanges would not align at the gusset plate, and the whole grid had to be re-measured before a single bolt went in. When you are sourcing an ASTM Rectangular ERW Welded Steel Tube Supplier for structural frames, the tolerance claim on a brochure means nothing without an in-house physical and chemical lab backing every heat number. [NEED_CITE: EN 10219 cold-formed hollow section dimensional tolerance requirements] Fragmented sourcing from multiple traders compounds this: each batch carries its own tolerance drift, and by the time the third container arrives on site, your fitters are adjusting connections rather than assembling them.
Matching Rectangular Hollow Sections to Structural Load Paths
The 300×300 mm rectangular profile in Q345 grade delivers higher yield strength than Q235, making it the practical choice for primary load-bearing columns and beam-to-column connections in steel frames. ERW welding produces a consistent longitudinal seam that handles bending moments predictably, while the slightly oiled surface protects against transit corrosion without interfering with field welding or paint adhesion. As an ASTM Rectangular ERW Welded Steel Tube Supplier, we map Q-series grades to their ASTM and EN equivalents so your engineer can specify with confidence across different code jurisdictions.
Engineering Compliance and Certification Requirements
Structural hollow sections destined for EU markets must carry CE marking under EN 10210 or EN 10219, with Factory Production Control certification verified by a notified body — Lloyd’s Register EU CE covers this requirement. For North American projects, ASTM A213 compliance governs the material specification, and your ASTM Rectangular ERW Welded Steel Tube Supplier must provide original mill test certificates showing chemical composition and mechanical properties traceable to each heat number. [NEED_CITE: steel grade equivalence mapping between Chinese GB and ASTM standards] On-site secondary operations — cutting, punching, bending — are handled per customer drawings, and the ±1% tolerance ensures that fabricated connections remain within structural engineering tolerances even after thermal cutting.
Understanding Q235 and Q345 in the ERW Welding Process
Q235 and Q345 belong to the Chinese GB/T 700 and GB/T 1591 carbon and low-alloy structural steel families respectively. Q345 offers higher yield strength than Q235, which translates directly to reduced section weight for the same load capacity — a critical factor when shipping costs are calculated per theoretical weight. The ERW process forms the rectangular profile by cold-bending a hot-rolled coil and welding the seam through electric resistance, producing a clean internal bead suitable for fluid and gas conveyance. [NEED_CITE: ERW welding process characteristics for structural hollow sections] The hot-rolled surface finish retains a mill scale layer that provides short-term corrosion resistance during storage and transit, while the slightly oiled variant adds an additional protective film for extended ocean shipping to Southeast Asia or Middle East destinations.
The Hidden Price of Unverified Mill Test Certificates
Customs authorities in the EU and Gulf states increasingly reject steel shipments lacking properly formatted EN 10204 3.1 or 3.2 certificates — the cargo sits at port accruing demurrage while the buyer scrambles for documentation. [NEED_CITE: EN 10204 inspection document types for steel products] Worse, material that passes customs but fails third-party inspection at the project site triggers full container return shipments, a scenario I dealt with early in my career when negative wall thickness tolerance exceeded the acceptable limit and the client’s SGS inspector flagged the entire batch. Choosing an ASTM Rectangular ERW Welded Steel Tube Supplier who runs incoming, in-process, and final inspections through an in-house laboratory prevents this cascade of delays and financial losses.
Procurement Advantages Directly from the Mill
Every rectangular tube in our 2,800+ specification range rolls off three dedicated production lines in Jinan, meaning you deal with the manufacturer rather than a trading company adding margin and opacity. Our in-house physical and chemical laboratory issues original mill test certificates for every heat, and we hold 41 invention patents — including proprietary sharp-corner rectangular tube technology that eliminates the rounded internal radius typical of standard ERW forming, improving connection fit-up for bolted and welded joints. CE certification under EN 10210/EN 10219, Singapore FPC, ISO 9001:2015, and verification by SGS and BV ensure that your ASTM Rectangular ERW Welded Steel Tube Supplier meets the compliance requirements of regulated markets across 50+ export destinations. Non-standard sizes and custom wall thicknesses are produced to order, and our logistics team designs container loading plans that maximize payload while protecting the slightly oiled surface finish during ocean transit.
Documentation & Compliance
- Mill test certificate documenting Q235/Q345 chemical composition and mechanical properties per GB/T 700 and GB/T 1591, traceable by heat number
- CE certificate under EN 10210/EN 10219 for EU market structural hollow section compliance, issued with Lloyd’s Register notification
- ISO 9001:2015 quality management system certificate covering the full ERW production and inspection process
- SGS or BV third-party inspection report available upon request for projects requiring independent verification
- Material traceability documentation linking each tube bundle to its heat number, chemical analysis, and dimensional inspection record
- Customs document package including packing list, bill of lading, and certificate of origin formatted for destination port requirements
Packaging, Loading & Delivery
- Q235/Q345 rectangular tubes bundled with steel strips and edge protectors to prevent surface damage to the slightly oiled finish during handling
- Seaworthy packaging with waterproof wrapping for ocean shipments to Southeast Asia and Middle East destinations, preserving the hot-rolled surface condition
- Container loading plans optimized for 300×300 mm section dimensions, maximizing payload per 20ft and 40ft containers while maintaining weight distribution
- Custom cut-to-length service available before shipping, reducing on-site waste and welding time for EPC contractors
- Heat number and steel grade markings stenciled on each bundle for site identification and traceability verification
- FOB, CIF, and DDP logistics options with real-time tracking from Jinan factory to project site across 50+ countries
Securing Your Rectangular Tube Supply with Verified Documentation
Submit your specification sheet — including section dimensions, wall thickness, steel grade, quantity, and destination port — and receive a detailed quotation with unit pricing, production lead time, and applicable certification within 12 hours. We will confirm whether your required dimensions fall within our standard 2,800+ specification range or need custom tooling, and provide sample material with original mill test certificate for your quality team’s approval before production begins.
Request Your Quotation and Mill Test Certificate Today
Send your specifications via email to admin@sdxjysteel.com or contact us on WhatsApp at +86 188 5315 7756 to receive pricing, certification details, and container loading plans for your Q235/Q345 rectangular ERW welded steel tube order.
Frequently Asked Questions
Q: How do Q235 and Q345 grades compare to ASTM A500 and S355JR equivalents?
A: Q235 maps broadly to ASTM A500 Grade B and S235JR in terms of yield strength range, while Q345 corresponds to ASTM A500 Grade C and S355JR. We provide formal grade equivalence documentation for your engineer’s review, and our ASTM Rectangular ERW Welded Steel Tube production can be specified to meet multiple standard requirements simultaneously.
Q: Can you provide third-party inspection and original MTC for customs clearance?
A: Yes. Every shipment includes an original mill test certificate issued by our in-house laboratory, and we arrange SGS or BV third-party inspection at the factory before loading. The MTC includes chemical composition, mechanical properties, and dimensional inspection results traceable to each heat number.
Q: What is the MOQ for non-standard rectangular sizes and custom wall thickness?
A: The standard MOQ is 5 tons. For non-standard dimensions outside our 2,800+ specification catalog, we evaluate tooling requirements and confirm the minimum order quantity based on the specific profile and wall thickness requested.
Q: What surface treatment options are available for rectangular ERW tubes?
A: Standard options include slightly oiled and hot-rolled finish as produced. We also offer hot-dip galvanized coating for corrosion-prone environments and can discuss additional protective coatings based on your project’s environmental exposure requirements.
Q: How do you handle container optimization and logistics for heavy steel shipments?
A: Our logistics team designs custom loading plans based on your tube dimensions and order weight, maximizing container payload while ensuring safe weight distribution. We offer FOB, CIF, and DDP terms with real-time tracking to destinations across 50+ countries.
