Description
Direct Mill Supply for S235/S275/SS400 Galvanized Square Steel Tube — Hot-dip galvanized ERW square tubes in 40×40 mm and up, produced in-house with full SGS/BV inspection and EN 10219 compliance for EU customs clearance.
Technical Specifications
| Parameter | Value |
|---|---|
| Designation | S235 / S275 / SS400 Galvanized Square Steel Tube |
| Product Type | Galvanized Square Steel Tube |
| Steel Grade | 20#, S235, S275, SS400 |
| Standard | JIS G3466, ASTM A53 |
| Section Shape | Square |
| Size Range | 40×40 mm (2×2 inch / 4×4 inch available) |
| Wall Thickness | 3 mm (12 Gauge) |
| Length | 6 m / 12 m (customizable: 5.8 m, 6 m, 11 m) |
| Technique | ERW + Hot-dip Galvanizing |
| Surface Treatment | Hot-dip Galvanized |
| Tolerance | ±1% |
| Ends | Plain / Beveled / Threaded / Grooved |
| Processing Service | Welding / Punching / Cutting / Bending |
| Application | Machine parts / Structural frames / Scaffolding / Furniture / Construction frames |
| MOQ | 1 Ton |
| Origin | Shandong, China |
Application Suitability
| Industry | Typical Applications |
|---|---|
| Construction & Infrastructure | Structural frames for low-rise buildings, scaffolding uprights, conveyor support structures |
| Machinery Manufacturing | Equipment base frames, guardrail posts, material handling racks |
| Furniture & Interior | Industrial-style shelving, display rack frames, workshop workbench legs |
| EPC & Modular Projects | Prefabricated module frames, temporary site structures, solar panel mounting supports |
Negative Wall Tolerance Turns a 1-Ton Shortfall Into a Full Container Rejection
Actual weight deviation beyond acceptable limits triggers on-site measurement disputes and container-level returns.
I watched a Middle East client pull a caliper off the truck and measure every single tube at the unloading bay. The 40×40×3 mm galvanized square tubes had wall thickness negative tolerance running past 15%, creating a two-ton gap between theoretical and actual weight. The entire container went back. That kind of loss doesn’t happen because someone wanted to cheat — it happens because the mill didn’t control the ERW forming pass and the galvanizing bath temperature wasn’t logged. When you order a Galvanized Square Steel Tube Supplier with no in-house dimensional lab, you inherit that risk. [NEED_CITE: ERW square tube dimensional tolerance requirements per EN 10219]
Matching Load Paths and Corrosion Exposure in Structural Frame Applications
Hot-dip galvanized ERW square tubes in S235 and S275 grades carry structural frame loads while the zinc coating handles atmospheric corrosion at exposed joints and welded connections. The 40×40×3 mm profile fits standard gusset plate detailing and bolted end-plate connections used in scaffolding and machinery bases. As a Galvanized Square Steel Tube Supplier, we hold the ±1% wall tolerance across the full 6 m and 12 m lengths so that cutting and welding at the fabrication shop doesn’t reveal thin-wall sections at mid-span.
Structural Code Compliance and Certification for Cross-Border Delivery
Load-bearing frames designed to EN 1993 or AISC require documented yield strength and weldability — both confirmed through mill test certificates referencing the original heat number. Hot-dip galvanizing adds corrosion resistance but also requires the steel grade to respond predictably to zinc bath immersion without silicon-induced excessive coating growth. For EU-bound shipments, the Galvanized Square Steel Tube Supplier must carry Lloyd’s CE certification under EN 10219, and customs brokers will reject the container without it. [NEED_CITE: EN 10219 cold-formed structural hollow section certification requirements]
Steel Grade Selection and Hot-dip Galvanizing Process Fundamentals
S235 and S275 follow the EN structural steel designation where the number indicates minimum yield strength in MPa — S275 delivers higher load capacity than S235 for the same cross-section, reducing member weight in heavily loaded frames. SS400 under JIS G3466 and 20# under GB standards serve as functional equivalents in Asian-specification projects, though chemical composition limits differ slightly and substitution requires engineer approval. ERW welding forms the square profile from strip steel with a longitudinal seam, then the hot-dip galvanizing process immerses the formed tube in molten zinc at approximately 450°C, creating a metallurgical zinc-iron alloy layer bonded to the steel substrate. This coating provides barrier protection and sacrificial cathodic protection at scratches or cut edges. The ±1% tolerance on the 3 mm wall means actual thickness stays between 2.97 mm and 3.03 mm — tight enough that theoretical weight calculations match delivered weight within acceptable commercial margins.
What Unverified Material Certificates Cost at the Inspection Gate
A Galvanized Square Steel Tube Supplier shipping without proper mill test certificates creates three failure points: customs holds the container for missing EN 10219 documentation, the site engineer rejects tubes that don’t match the specified grade on the drawing, and the zinc coating thickness fails third-party inspection because pre-galvanized material was substituted for hot-dip. Each failure adds demurrage, re-shipment cost, or — worst case — structural rework after installation. [NEED_CITE: steel grade equivalence verification between EN ASTM and JIS standards]
Why Project Procurement Teams Source From Our Mill
We produce the ERW forming and hot-dip galvanizing in the same facility, so wall tolerance and zinc coating thickness are controlled in one production sequence rather than across two separate vendors. Our in-house physical and chemical laboratory tests every heat for dimensional accuracy, tensile properties, and coating weight before release. The mill holds 41 invention patents including China’s original sharp-corner rectangular tube technology, and covers 2,800+ specifications across square, rectangular, and round profiles. Lloyd’s CE certification under EN 10210 and EN 10219 clears EU customs without supplementary testing. Third-party inspection through SGS or BV is arranged pre-shipment at the buyer’s request. Custom lengths — 5.8 m, 6 m, 11 m — are cut to order, and container loading follows a documented anti-damage protocol that prevents zinc coating abrasion during ocean transit.
Documentation & Compliance
- Mill test certificate documenting S235/S275/SS400 chemical composition and mechanical properties per JIS G3466 and ASTM A53
- Lloyd’s CE certificate confirming EN 10219 compliance for hot-dip galvanized cold-formed structural hollow sections
- ISO 9001:2015 quality management certificate covering ERW welding and hot-dip galvanizing process control
- SGS or BV third-party inspection report verifying zinc coating thickness, dimensional tolerance, and surface quality
- Full heat number traceability linking each bundle to its original steel coil test results
- Export customs documentation including packing list, bill of lading, and certificate of origin
Packaging, Loading & Delivery
- Hot-dip galvanized S235/S275 square tubes bundled with steel strips and edge protectors to preserve the zinc coating during handling and ocean transit
- 6 m and 12 m lengths loaded in standard 20ft and 40ft containers with anti-sway bracing to prevent bundle shift and surface abrasion
- Custom cut lengths at 5.8 m and 11 m optimized for specific container dimensions to maximize payload per shipment
- Each bundle tagged with heat number, steel grade (S235/S275/SS400), size 40×40×3 mm, and production date for site traceability
- FOB, CIF, and DDP shipping terms available with full container tracking until port arrival
- Professional loading crew trained in galvanized tube handling to avoid forklift tine damage to the zinc surface
Submit Specifications for Quotation and Mill Test Review
Send your required steel grade, dimensions, wall thickness, total tonnage, and destination port — we return a detailed quotation with unit pricing, production lead time, and shipping terms within 12 hours. Mill test certificates and SGS/BV inspection arrangements are confirmed before the deposit is processed.
Request Your Galvanized Square Steel Tube Quote Today
Submit your specifications and destination to receive pricing, mill test certificates, and third-party inspection confirmation.
Company: Shandong Xin Jiyuan Special Steel Tube Co., Ltd
Website: www.sdxjypipe.com
Tel: +86 531 8573 6315
Mobile/WhatsApp/WeChat: +86 188 5315 7756
Email: admin@sdxjypipe.com
Address: No.11889, Jingshi West Road, Lulian Group, Jinan City, Shandong Province, China
Frequently Asked Questions
Q: What is the difference between S235, S275, and SS400 for galvanized square steel tubes?
A: S235 and S275 follow the European EN designation where the number indicates minimum yield strength in MPa — S275 provides higher load capacity than S235 for the same cross-section. SS400 is the Japanese JIS G3466 equivalent commonly specified in Asian projects. All three grades are hot-dip galvanized in our facility and available in 40×40 mm square profiles with 3 mm wall thickness.
Q: How does hot-dip galvanizing differ from pre-galvanizing for square tubes?
A: Hot-dip galvanizing immerses the fully formed tube in molten zinc, creating a metallurgical zinc-iron alloy coating that provides both barrier and sacrificial cathodic protection. Pre-galvanizing coats the flat strip before forming, leaving the weld seam with a thinner zinc layer. For structural frames exposed to outdoor or industrial corrosion, hot-dip galvanized tubes deliver longer service life and more uniform coating coverage.
Q: Can you produce non-standard sizes and lengths for galvanized square steel tubes?
A: Yes. Beyond the standard 40×40×3 mm in 6 m and 12 m lengths, we produce custom lengths at 5.8 m, 11 m, and other project-specific dimensions. Our mill covers 2,800+ specifications across square, rectangular, and round profiles with wall thicknesses up to 40 mm. The MOQ is 1 Ton for custom orders.
Q: What certifications are required for importing galvanized square tubes into the EU?
A: EU customs and project engineers require Lloyd’s CE certification under EN 10219 for cold-formed structural hollow sections, along with mill test certificates per EN 10204 3.1. Our facility holds full CE certification under both EN 10210 and EN 10219, and third-party inspection through SGS or BV is arranged pre-shipment at the buyer’s request.
Q: How is weight calculated and invoiced for galvanized square steel tubes?
A: Weight is calculated based on the theoretical dimensions and the specified wall thickness with ±1% tolerance. We control the ERW forming process to keep actual wall thickness within this tolerance band, ensuring that delivered weight matches the invoiced weight. Third-party inspection can verify dimensional accuracy and coating weight before shipment.
