Description
Factory-direct pricing, no middlemen — Q235 and Q345 ERW welded square steel tubes shipped from Jinan with original mill test certificates for every heat.
Technical Specifications
| Parameter | Value |
|---|---|
| Designation | Q235/Q345 ERW Welded Square Steel Tube |
| Product Type | Welded Square and Rectangular Steel Tube (ERW) |
| Steel Grade | Q195, Q215, Q235, Q345, GR.A, GR.B, S235, S355 |
| Standard | ASTM, ISO 9001, CE, BIS, JIS, GS |
| Section Shape | Square |
| Size Range | 10×10 – 600×600 mm |
| Wall Thickness | 0.8 – 30 mm |
| Length | 5.7 – 6 m |
| Technique | Welded ERW |
| Surface Treatment | Pre-galvanized / Hot-dipped galvanized / Bare / Oiled |
| Tolerance | ±1% |
| Ends | Plain / Beveled (per customer request) |
| Application | Steel structures / Construction frames / Machinery / Scaffolding / Furniture / Fluid transport / Pipeline |
| MOQ | 1 Ton |
| Origin | Shandong, China |
Application Suitability
| Industry | Typical Applications |
|---|---|
| Construction & Infrastructure | Building frames, column supports, warehouse portal structures |
| Machinery Manufacturing | Equipment bases, conveyor frames, hydraulic support structures |
| Scaffolding & Access | Scaffold tower uprights, cross braces, working platform frames |
| Furniture & Interior | Display rack frames, shelving uprights, industrial table legs |
| Fluid & Pipeline | Low-pressure fluid conveyance lines, drainage channels |
What Negative Tolerance Really Costs on a Structural Frame Order
A wall thickness running 8% under nominal turns a routine delivery into an expensive customs hold and air-freight replacement.
Global buyers ordering ERW welded square steel tube batches regularly discover that paper certificates do not match physical measurements on site. When negative tolerance exceeds the allowed range, entire containers get flagged at destination ports, project timelines slip, and replacement material must be air-freighted at the supplier’s cost. Specification gaps for non-standard sizes force buyers to source from multiple mills, multiplying coordination overhead and delivery risk. [NEED_CITE: EN 10219 dimensional tolerance requirements for cold-formed welded hollow sections]
Matching Wall Thickness to Structural Load Paths
ERW welded square steel tube in the 10×10 to 600×600 mm range with wall thickness from 0.8 to 30 mm covers both light-gauge furniture frames and heavy-duty structural columns. The ±1% tolerance ensures that section modulus calculations hold true during engineering verification, while the ERW process produces a consistent longitudinal weld seam tested under water pressure. Pre-galvanized and hot-dipped galvanized surface options address corrosion exposure from mild indoor environments to outdoor coastal conditions.
Engineering Compliance and Certification Pathways
Structural applications require compliance with EN 10219 for cold-formed welded hollow sections or ASTM A500 for North American projects. Q235 and Q345 grades meet Chinese GB/T standards, while S235 and S355 equivalents serve European and international specifications. CE certification under EN 10210/10219 and Lloyd’s FPC approval enable customs clearance across EU member states without additional testing delays. [NEED_CITE: steel grade equivalence tables between GB, EN, and ASTM systems]
Steel Grade Selection and ERW Weld Integrity
Q235 provides adequate yield strength for general construction frames and scaffolding, while Q345 delivers higher load-bearing capacity for heavy machinery bases and multi-story building columns. The ERW welding process creates a continuous longitudinal seam with 100% water pressure testing, ensuring weld integrity matches the base metal. Surface treatment selection depends on service environment: bare or oiled tubes suit indoor or painted applications, pre-galvanized offers moderate corrosion protection, and hot-dipped galvanized provides long-term resistance for outdoor or aggressive atmospheres.
Hidden Costs of Unverified Material Sources
Purchasing ERW welded square steel tube without original mill test certificates or third-party inspection creates downstream risk. Material traceability gaps mean failed heat numbers cannot be linked to production batches, blocking project acceptance. Negative tolerance exceeding specification limits reduces actual load capacity below design assumptions, triggering structural safety concerns and costly rework. Missing CE or ISO documentation causes customs holds at destination ports, delaying project timelines and incurring demurrage charges. [NEED_CITE: importance of mill test certificates for structural steel traceability]
Why Project Buyers Source From Jinan
Factory-direct pricing eliminates trading company markups, with volume discounts available for long-term partners placing recurring orders. Every batch ships with original mill test certificates documenting chemical composition and mechanical properties, verified by our in-house laboratory before release. Third-party inspection through SGS or BV is available upon request for buyers requiring independent verification. Our 2,800+ specification inventory enables consolidated multi-product container loading, reducing freight cost per ton for mixed orders combining square tubes, round pipes, and section steel. Professional export documentation and container loading optimization ensure efficient port clearance and delivery.
Documentation & Compliance
- Mill test certificate documenting Q235 and Q345 chemical composition and yield strength per GB/T standards
- CE certificate confirming compliance with EN 10210/10219 for European market structural applications
- ISO 9001:2015 quality management certificate covering production and inspection processes
- SGS or BV third-party inspection report available for independent material verification before shipment
- Full material traceability by heat number linking each batch to original production records
- Complete customs documentation including packing list, bill of lading, and certificate of origin
Packaging, Loading & Delivery
- ERW welded square steel tubes bundled with steel strips and edge protectors to prevent surface damage during transit
- Hot-dipped galvanized tubes packed with waterproof wrapping to preserve zinc coating integrity during ocean shipping
- Container loading optimized for 5.7–6 m lengths to maximize CBM utilization and reduce freight cost per ton
- Plain or beveled ends protected with plastic caps to prevent deformation and facilitate on-site welding
- Heat number and steel grade stenciled on each bundle for site identification and traceability verification
- FOB, CIF, and DDP terms available with professional logistics coordination from Jinan to destination port
Start Your Procurement With Verified Specifications
Submit your ERW welded square steel tube requirements including size range, wall thickness, steel grade, quantity, and destination port to receive competitive factory-direct pricing within 12 hours. Request original mill test certificates and third-party inspection reports for quality verification before production begins. Our team will confirm certification compliance, container loading optimization, and delivery timelines for your project schedule.
Frequently Asked Questions
Q: What is the difference between Q235 and S235 steel grades for square tubes?
A: Q235 follows Chinese GB/T standards while S235 meets European EN specifications. Both offer similar yield strength for general structural applications, but certification requirements differ by destination market. We supply both grades with original mill test certificates documenting compliance.
Q: Can you provide third-party inspection before shipment?
A: Yes, SGS and BV third-party inspection is available upon request. The inspection covers dimensional verification, wall thickness measurement, surface quality, and material traceability before container loading.
Q: What surface treatment options are available for corrosion protection?
A: We offer pre-galvanized, hot-dipped galvanized, bare, and oiled surface treatments. Pre-galvanized suits indoor environments, hot-dipped galvanized provides long-term outdoor protection, while bare or oiled tubes work for painted or indoor applications.
Q: How do you optimize container loading for mixed-size orders?
A: Our export team calculates optimal loading plans combining different square tube sizes to maximize CBM utilization. This reduces freight cost per ton and enables consolidated shipments of multiple specifications in a single container.
Q: What is the minimum order quantity for custom sizes?
A: MOQ starts from 1 ton for both standard and custom specifications. We maintain ready stock for common sizes while custom orders typically require typical production lead times depending on specification complexity.
Ship Verified ERW Welded Square Steel Tube Direct From Jinan
Submit your specifications, steel grade, and quantity requirements to receive factory-direct pricing and original mill test certificates within 12 hours.
Contact: Shandong Xin Jiyuan Special Steel Tube Co., Ltd
Mobile/WhatsApp/WeChat: +86 188 5315 7756
Email: admin@sdxinjiyuan.com
Website: www.sdxinjiyuan.com
