Description
Factory-Direct Pricing, No Middlemen — Every S235JR A36 S355 SS400 square steel tube ships from our Jinan production lines at bulk volume pricing, with original mill test certificates attached to each heat number.
Technical Specifications
| Parameter | Value |
|---|---|
| Designation | S235JR / A36 / S355 / SS400 Square Steel Tube |
| Product Type | Square Steel Tube (Welded) |
| Steel Grade | S235JR, A36, S355, SS400, Q235B |
| Standard | ASTM A500, EN10219, EN10210, JIS G3466, GB/T 6728 |
| Section Shape | Square |
| Size Range | Customized width and thickness |
| Length | Customized |
| Technique | Welded (ERW) |
| Surface Treatment | Cold Rolled / Galvanized (Normal spangle, Minimized spangle, Spangle-free) |
| Tolerance | ±1% |
| Processing Service | Welding, Punching, Cutting, Bending, Decoiling |
| Application | Building structures, machinery manufacturing, infrastructure, vehicle manufacturing, home decor |
| Origin | Shandong, China |
Application Suitability
| Industry | Typical Applications |
|---|---|
| Construction & Infrastructure | Factory building frames, stadium roof trusses, commercial center columns, auxiliary bridge structures, stage trusses, greenhouse frames |
| Machinery Manufacturing | Machine tool frames, conveyor support frames, automation equipment bases |
| Vehicle Manufacturing | Trailer chassis, RV structural frames |
| Home Decor & Furniture | Stair handrails, security window frames, furniture structural frames |
What Wall-Thickness Tolerance Costs on a Custom Size S355 S235JR Square Steel Tube Supplier Order
A ±1% tolerance on a structural frame order is the difference between passing third-party inspection and scrapping an entire container.
I once watched a shipment of square tubes get rejected at a Middle Eastern port because the wall thickness ran negative beyond acceptable limits — the theoretical weight and actual weigh-in differed by nearly a ton per container. The buyer’s SGS inspector flagged every piece. The entire lot had to be reworked at the supplier’s expense. When you source a Custom Size S355 S235JR Square Steel Tube Supplier, tolerance control is not a spec sheet detail — it determines whether your steel clears customs or sits in a bonded warehouse for weeks. [NEED_CITE: EN 10219 cold-formed structural hollow section dimensional tolerance requirements]
Matching Structural Tubes to Engineering Load Paths
A Custom Size S355 S235JR Square Steel Tube Supplier that understands load path requirements will match the steel grade to the structural demand — S355 for primary load-bearing columns and trusses where higher yield strength reduces section size, S235JR or A36 for secondary framing and non-critical bracing where cost efficiency matters. The ERW welding process produces a consistent longitudinal seam suitable for the square section geometry used in building frames and machinery bases, while the ±1% tolerance ensures that connection plates and gusset joints fit without on-site grinding or reaming.
Structural Compliance and Surface Protection for Field Conditions
Engineering specifications for steel structures typically reference EN 1993 or AISC design codes, which require verified material properties and dimensional accuracy. [NEED_CITE: EN 10219 and ASTM A500 compliance requirements for structural hollow sections] For outdoor infrastructure applications such as bridge auxiliary structures and greenhouse frames, galvanized surface treatment with normal or minimized spangle coating provides corrosion resistance without additional field painting. Cold rolled finish suits indoor machinery frames and furniture applications where surface appearance matters. Steel grade selection directly affects load-bearing capacity — S355 delivers higher yield strength than S235JR, allowing lighter sections for the same structural demand. CE certification under EN10210 and EN10219 is mandatory for European market customs clearance, while ASTM A500 compliance serves North American project specifications.
Steel Grade Systems and Welding Process Fundamentals
The S-series (S235JR, S355) follows the European EN standard designation where the number indicates minimum yield strength in MPa for thickness under 16mm. A36 follows the ASTM system used across North America, while SS400 is the Japanese JIS G3466 equivalent for general structural use. Q235B is the Chinese GB/T standard grade widely accepted across Southeast Asian and African markets. [NEED_CITE: steel grade equivalence mapping between EN 10025, ASTM A36, and JIS G3101 standards] These grades overlap in mechanical properties but differ in chemical composition requirements and impact testing conditions — S235JR requires room-temperature Charpy impact testing, while S355JR demands the same at elevated energy levels. The ERW (Electric Resistance Welding) process forms the square tube from rolled steel coil, passing through forming rollers and welding the seam through electrical resistance heat. This method produces tight dimensional tolerances suitable for structural applications, with the weld seam running along the tube length. For galvanized variants, the formed tube undergoes hot-dip galvanizing after welding, coating both exterior and interior surfaces with a zinc layer that sacrificially protects the base steel from corrosion.
The Hidden Cost of Unverified Material Claims
Ordering square tubes without original mill test certificates creates a chain of risk: unverified chemical composition means the steel may not meet the specified grade, unconfirmed mechanical properties mean structural calculations are based on assumptions rather than data, and missing traceability by heat number means failed inspection results cannot be traced back to the production batch. [NEED_CITE: material traceability requirements for structural steel in construction projects] Customs authorities in the EU and Middle East increasingly require CE documentation and EN-compliant test reports — shipments without proper certification face rejection or bonded warehouse storage. The cost of re-inspection, rework, or replacement far exceeds the price difference between verified and unverified supply sources.
Why Procurement Teams Source Structural Tubes from Xin Jiyuan
Our Jinan facility operates three production lines running simultaneously, producing square and rectangular tubes in over 2,800 specifications from a single source — eliminating the need to coordinate multiple suppliers for different steel grades and sizes. Every batch ships with original mill test certificates documenting chemical composition and mechanical properties, and we welcome SGS or BV third-party inspection at any production stage. The factory-direct pricing model removes intermediary margins, with volume discount programs reviewed every six months for long-term partners. Custom sizes outside standard catalogs are available with typical production lead times, and our professional export team handles container loading optimization to maximize weight utilization for heavy structural tubes. We hold ISO 9001:2015, CE EN10210/EN10219, and FPC certifications, ensuring documentation compliance across European, North American, and Middle Eastern markets.
Documentation & Compliance
- Mill test certificate documenting S235JR, A36, S355, SS400, or Q235B chemical composition and mechanical properties per EN10219, ASTM A500, or JIS G3466
- CE certificate confirming EN10210/EN10219 compliance for European Union customs clearance and structural project approval
- ISO 9001:2015 quality management system certificate covering the full production process from raw material intake to finished tube inspection
- SGS or BV third-party inspection report available upon request, covering dimensional verification, visual weld inspection, and coating thickness measurement for galvanized tubes
- Full material traceability by heat number linking each tube bundle to its original mill test certificate and production batch record
- Complete customs documentation package including packing list, bill of lading, and certificate of origin formatted for destination port requirements
Packaging, Loading & Delivery
- Square steel tubes bundled with high-tensile steel strips at regular intervals, with wooden or rubber edge protectors preventing surface damage to galvanized coatings during transit
- Galvanized S235JR and S355 tubes wrapped in waterproof plastic sheeting within each bundle to prevent white rust formation during ocean freight in humid climates
- Container loading plans optimized for custom-length square tubes, maximizing weight utilization within 20ft and 40ft containers while maintaining safe weight distribution for port handling equipment
- Custom cutting to project-specified lengths available before shipment, reducing on-site waste and cutting labor costs for construction and machinery assembly applications
- Each bundle marked with heat number, steel grade (S235JR/A36/S355/SS400/Q235B), section dimensions, and wall thickness for immediate identification at the construction site
- FOB, CIF, and DDP shipping terms available with professional export documentation handling and real-time container tracking from Jinan inland depot to destination port
How to Request a Structural Tube Quotation with Full Traceability
Submit your required steel grade (S235JR, A36, S355, SS400, or Q235B), section dimensions, wall thickness, total quantity, surface treatment preference, and destination port — we respond within hours with factory-direct pricing, typical production lead times, and confirmation of available mill test certificates. For non-standard sizes or custom processing requirements including cutting, bending, or punching, our technical team provides fabrication drawings and lead time confirmation before contract signing.
Request Factory-Direct Pricing with Mill Test Certificates
Send your specifications and quantity requirements to receive a bulk quotation with full material traceability documentation.
Email: admin@sdxinjiyuan.com
WhatsApp: +86 188 5315 7756
