Description
Factory-Direct Welded Tube Supply — Shandong Xin Jiyuan runs three ERW lines producing Q235 and Q345 square and rectangular tubes in wall thickness from 0.8 to 30 mm, shipped with original mill certificates under CE and ISO frameworks.
Technical Specifications
| Parameter | Value |
|---|---|
| Designation | Q235/Q345 Welded Square and Rectangular Steel Tube |
| Product Type | Welded Square / Rectangular Steel Tube (SHS / RHS) |
| Steel Grade | Q195, Q215, Q235, Q345, GR.A, GR.B, S235, S355 |
| Standard | ASTM A213, DIN EN 10217-1 |
| Section Shape | Square / Rectangular |
| Size Range | Customizable per drawing |
| Wall Thickness | 0.8–30 mm |
| Length | 0.5 m – 11.8 m |
| Technique | ERW (Welded) |
| Surface Treatment | Bare / Pre-galvanized / Hot-dip galvanized / Oiled |
| Tolerance | ±1% |
| Ends | Plain / Beveled |
| Application | Steel structures, fences, posts, warehouse and building construction |
| MOQ | 10 Tons |
| Origin | Shandong, China |
Application Suitability
| Industry | Typical Applications |
|---|---|
| Industrial Construction | Warehouse portal frames, mezzanine beams, column bracing |
| Infrastructure | Highway guardrail posts, lighting pole bases, signage gantries |
| Agricultural Structures | Greenhouse skeleton tubes, equipment shed frames |
| Commercial Building | Curtain wall sub-frames, interior partition supports |
What Negative Tolerance Does to a Structural Frame Budget
A wall-thickness deviation beyond ±1% shifts theoretical weight and load calculations off-spec before the first beam is welded.
I once inspected a batch of 50×50×3.0 ERW square tubes where the actual wall ran over 8% below nominal. The theoretical weight and the weighbridge reading diverged by nearly two tons per container. The buyer’s structural engineer in Lagos could not reconcile the load table with the as-delivered sections, and the entire shipment sat at the port awaiting re-inspection. That kind of mismatch does not just delay a project — it forces redesign, reordering, and sometimes scrap. When you source a Q235 Q345 ERW welded square rectangular steel tube supplier, the tolerance claim on paper means nothing unless the mill runs inline ultrasonic checks and issues certificates tied to each heat number. [NEED_CITE: EN 10219 cold-formed hollow section dimensional tolerance requirements]
How Wall-Thickness Range Covers Structural and Decorative Loads
The 0.8 to 30 mm wall range on a Q235 Q345 ERW welded square rectangular steel tube supplier’s line means one procurement channel can cover light-gauge fence posts and heavy-load warehouse columns at the same time. Thin-wall sections (0.8–2.0 mm) serve non-structural cladding supports and decorative framing where weight matters. Mid-range walls (3.0–8.0 mm) handle standard building frames and scaffolding. Thick-wall sections above 10 mm carry point loads in crane runways and heavy equipment bases. Xin Jiyuan’s three ERW lines run these ranges simultaneously, so a single order mixing fence posts and column sections ships in one container set rather than three separate supplier batches.
Engineering Compliance Across GB, EN, and ASTM Frameworks
Structural frames designed under EN 1993 require hollow sections conforming to EN 10219 for cold-formed or EN 10210 for hot-formed profiles, with CE marking and factory production control certificates. Projects in North America reference ASTM A500 Grade B or C for structural tubing. The Q235 and Q345 grades in this product line map to S235 and S355 under EN standards, giving buyers a single material source that satisfies both Chinese GB and European EN specifications on mixed-standard projects. Every batch carries original mill test certificates showing chemical composition and mechanical test results per heat number, and SGS or BV third-party inspection is available for projects requiring independent verification. [NEED_CITE: steel grade equivalence between EN 10219 and ASTM A500 standards]
ERW Welding, Grade Selection, and Surface Treatment Trade-offs
ERW welded tubes form from coil through continuous rolling and high-frequency electric resistance welding, producing a longitudinal seam that is forge-welded under pressure. This process delivers tight dimensional tolerance at lower cost than seamless, making it the standard choice for structural framing where internal pressure is not a factor. The Q235 grade offers adequate strength for general construction and fencing at competitive pricing. Q345 provides higher yield strength for load-bearing frames and bridge supports. For corrosive environments — coastal structures, chemical plant walkways, agricultural buildings — hot-dip galvanizing adds a zinc coating that outlasts pre-galvanized finish in wet or saline conditions. Bare or oiled finish suits indoor applications or sites where field welding and painting follow installation.
The Real Cost of Unverified Mill Certificates
Buying on price alone without certificate verification creates three failure modes at project stage. First, customs authorities in the EU, Middle East, and Africa increasingly demand CE marks and EN-compliant mill test certificates; missing documents mean container hold at port with daily storage charges. Second, structural inspectors comparing as-built sections against design calculations will reject material where actual wall thickness falls outside the tolerance band stated on the certificate. Third, field welding on tubes with unverified chemical composition risks weld cracking when carbon equivalent exceeds the range assumed in the welding procedure specification. A Q235 Q345 ERW welded square rectangular steel tube supplier who issues heat-number-traceable certificates and accepts third-party inspection before shipment removes all three risks from the project timeline. [NEED_CITE: customs clearance requirements for structural steel with CE marking in EU markets]
Why Buyers Return to Xin Jiyuan for Repeat Orders
Xin Jiyuan operates three ERW production lines running simultaneously, producing over 20,000 tons monthly across 2,800+ standard and custom specifications. Factory-direct pricing eliminates trading-company margins, and volume discount programs reward long-term partners with quarterly price reviews. The in-house metallurgical lab tests every heat for chemical composition and mechanical properties before release, and original mill test certificates ship with each batch — not photocopies, not templates. CE certification under EN 10210 and EN 10219, ISO 9001:2015 registration, and FPC certification mean the documentation package clears EU, Middle Eastern, and African customs without supplemental letters. For non-standard dimensions or custom lengths beyond the 11.8 m standard range, the production team provides technical drawings and lead-time confirmation within 48 hours. Professional export crews optimize container loading plans to maximize payload per shipment, reducing per-ton freight cost on long-distance ocean routes.
Documentation & Compliance
- Mill test certificate documenting Q235 or Q345 chemical composition and yield strength per heat number, issued from Xin Jiyuan’s in-house lab
- CE certificate covering EN 10210 and EN 10219 hollow section production, required for EU market customs clearance
- ISO 9001:2015 quality management certificate validating production process control and inspection records
- SGS or BV third-party inspection report available on request for projects requiring independent material verification
- Heat-number traceability linking each tube bundle to its original coil test report and production log
- Full customs document package including packing list, bill of lading, and certificate of origin formatted per destination-country requirements
Packaging, Loading & Delivery
- Hot-dip galvanized Q235 and Q345 tubes bundled with steel strips and edge protectors to preserve the zinc coating during ocean transit and crane handling
- Bare and oiled tubes packed in seaworthy bundles sized to match 20-foot and 40-foot container payloads, with length segments from 0.5 m to 11.8 m optimized for maximum fill
- Custom-cut lengths prepared per project drawing, with cut ends deburred and marked with heat number, steel grade, and section dimensions for site identification
- Container loading plans drafted by Xin Jiyuan’s export team to balance weight distribution and maximize tons per shipment, reducing per-unit freight on FOB and CIF terms
- Each bundle labeled with weather-resistant tags showing steel grade (Q235/Q345), section size, wall thickness, length, and heat number for traceability at destination port
- Delivery terms available include FOB Tianjin/Qingdao, CIF destination port, and DDP door-to-door for projects requiring full logistics coordination
How to Start a Bulk Inquiry for Welded Square and Rectangular Tubes
Send your specification list — section size, wall thickness, length, steel grade, surface treatment, quantity, and destination port — and Xin Jiyuan’s team returns a detailed quotation within 12 hours, including volume pricing, production lead time, and certification scope. For non-standard dimensions or mixed-size container orders, the technical team provides drawing confirmation and loading optimization before contract signing. Request sample sections and original mill test certificates for quality verification before committing to full production runs.
Frequently Asked Questions
Q: What is the difference between Q235, Q345, S235, and S355 steel grades?
A: Q235 and Q345 follow the Chinese GB standard system, where the number indicates minimum yield strength in MPa. S235 and S355 follow the European EN standard system with the same yield-strength naming logic. Q235 roughly corresponds to S235, and Q345 corresponds to S355 in mechanical properties, though chemical composition ranges differ slightly. Xin Jiyuan supplies all four grades and provides mill test certificates showing the exact composition and test results for each heat.
Q: Can you provide mill test certificates and third-party inspection reports for customs clearance?
A: Yes. Every shipment includes original mill test certificates documenting chemical composition and mechanical properties per heat number. For projects requiring independent verification, SGS or BV third-party inspection is available at the production stage before shipment. CE certificates under EN 10210 and EN 10219, ISO 9001:2015 registration, and full customs documentation (packing list, B/L, certificate of origin) ship with every order.
Q: What is the MOQ for custom sizes and non-standard dimensions?
A: The standard MOQ is 10 tons. For non-standard section sizes, custom lengths beyond the 11.8 m range, or special surface treatment requirements, Xin Jiyuan’s production team reviews the specification and confirms feasibility, lead time, and minimum quantity within 48 hours. Trial orders starting from 1 ton are accepted for new customers testing material quality before committing to bulk procurement.
Q: How do you choose between bare, pre-galvanized, and hot-dip galvanized surface treatment?
A: Bare or oiled finish suits indoor structural applications or projects where field painting follows installation. Pre-galvanized tubes offer moderate corrosion resistance at lower cost, suitable for sheltered outdoor structures. Hot-dip galvanized tubes provide the thickest zinc coating and longest service life in corrosive environments — coastal construction, chemical plants, agricultural buildings, and infrastructure exposed to weather. The choice depends on the service environment, design life, and maintenance access at the installation site.
Q: What are the delivery terms and production lead time for bulk orders?
A: Xin Jiyuan offers FOB, CIF, and DDP delivery terms. Standard-size Q235 and Q345 tubes ship from ready stock within days of deposit receipt. Custom orders and non-standard dimensions typically require typical production lead times depending on specification complexity and order volume. The export team provides a confirmed shipping schedule at the quotation stage, and real-time tracking updates are available during ocean transit.
Start Your Q235 Q345 ERW Welded Square Rectangular Steel Tube Order
Submit your specification list — section size, wall thickness, length, steel grade, surface treatment, quantity, and destination port — to receive a detailed quotation with volume pricing, mill test certificate scope, and confirmed production lead time within 12 hours.
Contact: Shandong Xin Jiyuan Special Steel Tube Co., Ltd
Tel: +86 531 8573 6315
Mobile/WhatsApp/WeChat: +86 188 5315 7756
Email: admin@sdxinjiyuan.com
Website: www.sdxinjiyuan.com
