Description
Factory-Direct Welded Square Tubes — Shandong Xin Jiyuan runs three production lines producing ASTM A500 Gr.B and EN S-series square hollow sections with original mill test certificates on every heat.
Technical Specifications
| Parameter | Value |
|---|---|
| Designation | Carbon Steel Welded Square Tube |
| Product Type | Welded Square Steel Tube (Square Hollow Section) |
| Steel Grade | Gr.B, S235, S275, S355, STK400 |
| Standard | ASTM A500, ASTM A53, GB/T 3091 |
| Section Shape | Square |
| Size Range | 19mm × 19mm – 800mm × 800mm |
| Wall Thickness | 1 – 30 mm |
| Length | 5.8m / 6m / 11.8m / 12m / Random Length |
| Technique | ERW (Welded) |
| Surface Treatment | Black Painting / Galvanized / Varnish / Bare |
| Tolerance | ±1% |
| Ends | Plain |
| Application | Construction structures / Building frames / Curtain wall supports / Structural pipe / Machinery frames |
| MOQ | 5 Tons |
| Origin | Shandong, China |
Application Suitability
| Industry | Typical Applications |
|---|---|
| Construction & Infrastructure | Building frames, column supports, roof trusses, portal frames for warehouses and commercial buildings |
| Curtain Wall & Facade | Mullion and transom supports, architectural scaffolding, cladding sub-structures |
| Machinery Manufacturing | Equipment base frames, conveyor supports, crane boom sections, machine guarding structures |
| Industrial Structures | Pipe rack supports, platform grating frames, walkway handrail posts |
Where Negative Wall Tolerance Destroys a Structural Frame Budget
A ±1% tolerance claim means nothing without third-party verification on every bundle.
I once inspected a container of 60×60 welded square tubes bound for West Africa. The purchase order specified 3.0mm wall thickness, but ultrasonic readings on the dock showed the actual average sitting at 2.2mm — a negative deviation that pushed the entire lot below the minimum required by ASTM A500 Gr.B. The client faced two choices: reject the container and absorb freight costs, or use undersized tubes and risk structural failure during inspection. [NEED_CITE: ASTM A500 tolerance requirements for cold-formed welded square tubes] When you source an ASTM A500 welded square steel tube supplier without requesting SGS or BV inspection before loading, you are trusting a paper certificate that may not match the steel in the container.
Matching Section Dimensions to Structural Load Paths
An ASTM A500 welded square steel tube supplier covering 19×19mm through 800×800mm with wall thickness from 1mm to 30mm allows engineers to select sections that align with actual load calculations rather than forcing oversized members. Smaller sections in S235 serve light-duty curtain wall supports and handrail posts, while larger 400×400 or 500×500 profiles in S355 carry primary column loads in portal frame buildings. The ERW welding process maintains consistent corner geometry across this full range, which matters when gusset plates and connection brackets must sit flush against the tube face.
Engineering Compliance and Surface Protection for Field Conditions
Structural frames designed under EN 1993-1-1 or AISC 360 require documented steel grade equivalence and traceable heat numbers for every member. [NEED_CITE: EN 10219 cold-formed welded hollow section dimensional and tolerances] For projects shipping to the European market, CE certification under EN 10210 or EN 10219 is not optional — customs authorities reject shipments lacking Factory Production Control documentation. On the corrosion side, bare or black-painted tubes suit indoor structural frames where humidity is controlled, while galvanized finishes protect outdoor scaffolding and coastal construction members where salt spray accelerates rust. Choosing the right surface treatment at the ordering stage avoids costly on-site recoating after erection.
Understanding ERW Welding and Steel Grade Selection for Square Tubes
The ERW (Electric Resistance Welding) process forms square hollow sections by cold-rolling steel coil into a tubular shape and fusing the seam under high-frequency current — no filler metal is added, which keeps production costs lower than seamless alternatives while maintaining dimensional accuracy suitable for most structural applications. Steel grade selection directly affects load-bearing capacity: S235 provides adequate strength for light framing and non-critical supports, S275 bridges the gap for medium-load beam and column applications, and S355 delivers higher yield strength for primary structural members in multi-storey buildings and heavy industrial frames. [NEED_CITE: steel grade equivalence between EN 10219 S-series and ASTM A500 Gr.B] The ASTM A500 Gr.B grade commonly specified in North American projects falls within a similar yield range to S275, but mill test certificates must confirm actual chemistry and mechanical results rather than relying on grade name alone. Wall thickness tolerance of ±1% across the 1–30mm range means a specified 10mm wall could measure between 9.9mm and 10.1mm — tight enough for structural engineering calculations, but only if the supplier enforces this tolerance at the production line rather than on paper.
The Hidden Cost of Ordering Without Verified Mill Certificates
Purchasing welded square tubes based on price alone, without requiring original mill test certificates showing heat-by-heat chemical composition and mechanical properties, creates downstream failures that dwarf any upfront savings. Material arriving at the project site with mismatched steel grades fails third-party structural inspection, forcing complete member replacement and schedule delays measured in weeks rather than days. [NEED_CITE: consequences of non-compliant steel materials in construction project acceptance] Missing CE documentation for European-bound shipments triggers customs holds that accumulate demurrage charges while the importer scrambles for retroactive certification — a process that often fails entirely. Negative wall tolerance exceeding the specified ±1% reduces the section modulus below design assumptions, creating structural safety concerns that engineers cannot sign off on regardless of the member’s visual appearance.
Procurement Confidence Through Direct Factory Control
Shandong Xin Jiyuan operates three simultaneous production lines with monthly capacity exceeding 20,000 tons, meaning your ASTM A500 welded square steel tube supplier is the actual manufacturer rather than a trading intermediary adding markup and reducing traceability. Every heat rolled carries an original mill test certificate documenting chemical composition and mechanical test results — not a re-issued document from a third-party stockist. Our in-house laboratory conducts three-stage inspection covering dimensional verification, weld seam integrity, and surface quality before any bundle leaves the facility. For buyers requiring independent verification, we coordinate SGS or BV inspection at the loading stage at no additional coordination burden on your side. The inventory covering 2,800+ specifications across square tubes, round pipes, plates, and section steel means multi-category project orders consolidate into single-source documentation and coordinated container loading — eliminating the freight and customs complexity of managing five different suppliers. Custom non-standard sizes and specific length requirements are fulfilled within typical production lead times, with flexible MOQ starting from 5 tons to accommodate both trial orders and full-container bulk procurement.
Documentation & Compliance
- Mill test certificate documenting Gr.B, S235, S275, S355, or STK400 chemical composition and mechanical properties per ASTM A500, EN 10219, or GB/T 3091 for each heat number
- CE certificate under EN 10210 / EN 10219 with Factory Production Control documentation for European market customs clearance
- ISO 9001:2015 quality management system certificate covering the full production process from raw material incoming inspection to final dimensional check
- SGS or BV third-party inspection report available on request, covering wall thickness ultrasonic testing, visual weld examination, and dimensional verification before container sealing
- Heat number traceability linking every 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
- Welded square tubes bundled with steel strips and edge protectors, sized to match the 5.8m, 6m, 11.8m, or 12m length ordered, preventing bundle shift during ocean transit
- Galvanized surfaces wrapped with waterproof paper and plastic film to preserve the zinc coating from moisture damage during container shipping and port storage
- Container loading plans optimized for the specific outer dimension range — smaller 19×19mm to 100×100mm sections nested to maximize cubic utilization, while larger 400×400mm to 800×800mm profiles loaded in single-layer arrangements to prevent deformation
- Plain ends capped with plastic protectors on black painted and bare finish tubes to prevent moisture ingress and edge damage during handling at destination site
- Heat number and steel grade stenciled on each bundle tag, matching the mill test certificate for on-site verification by project quality inspectors
- FOB, CIF, and DDP shipping terms available with professional export documentation handling and real-time container tracking from Jinan port to destination
Requesting a Verified Quote for Your Project Specifications
Submit your required outer dimensions, wall thickness, steel grade, total tonnage, and destination port to receive a detailed quotation including factory-direct pricing, production lead time, and available mill test certificate formats. Our engineering team reviews non-standard size requests and provides feasibility confirmation with specific delivery timelines for custom orders. Confirm your certification requirements — CE for European projects, ASTM compliance documentation for North American specs, or SGS/BV third-party inspection for independent quality verification — so we include all necessary documentation in the initial offer package.
Get Your ASTM A500 Welded Square Tube Quote with Mill Test Certificates
Send your specification sheet via email or WhatsApp to receive bulk pricing, available stock confirmation, and complete documentation details within one business day.
Contact: Shandong Xin Jiyuan Special Steel Tube Co., Ltd
Email: admin@sdxinjiyuan.com
Mobile / WhatsApp / WeChat: +86 188 5315 7756
Tel: +86 531 8573 6315
Address: No.11889, Jingshi West Road, Lulian Group, Jinan City, Shandong Province, China
