Description
Factory-direct bulk supply — Galvanized square and rectangular tubes in Q195–Q345, SS400, S235–S355 grades with Z41–Z120 coating, 2,800+ specifications in ready stock, shipped with original mill test certificates for customs and project compliance.
Technical Specifications
| Parameter | Value |
|---|---|
| Designation | Q235 SS400 Galvanized Square Steel Tube |
| Product Type | Galvanized Square and Rectangular Steel Tube |
| Steel Grade | Q195, Q235, Q345, SS400, STK400, STK500, S235, S355, A36, A53, A106, 10#, 20#, 45# |
| Standard | ASTM, JIS, ISO 9001, CE, API |
| Section Shape | Square / Rectangular |
| Size Range | 15×15 mm – 1000×1000 mm |
| Wall Thickness | 0.5 – 20 mm |
| Length | 1 – 12 m |
| Technique | Cold Rolled Based / Hot Rolled Based |
| Surface Treatment | Galvanized (Z41 – Z120 coating) |
| Spangle Type | Zero Spangle / Regular Spangle |
| Hardness | Mid Hard |
| Skin Pass | Yes |
| Oiled or Non-oiled | Non-oiled |
| Tolerance | ±1% |
| Ends | Plain |
| Application | Steel structures, construction frames, fencing, greenhouse, fluid transport, machinery, scaffolding, making pipes, making corrugated sheets, making containers |
| MOQ | 1 Ton |
| Origin | Shandong, China |
Application Suitability
| Industry | Typical Applications |
|---|---|
| Construction & Infrastructure | Building frames, scaffolding structures, column supports for commercial and industrial projects |
| Agriculture | Greenhouse framing, irrigation pipe supports, livestock shelter structures |
| Fencing & Security | Perimeter fencing posts, barrier rails, gate frames for industrial and residential zones |
| Machinery & Equipment | Machine frames, conveyor supports, equipment base structures |
| Fluid Transport | Water supply piping, low-pressure liquid distribution systems, drainage conduits |
| Storage & Logistics | Container frames, warehouse racking supports, pallet base structures |
What Missing Mill Certificates Cost on a Galvanized Tube Shipment
A container of Q235 SS400 galvanized square steel tube without traceable mill test certificates is a container that may never clear customs or pass site inspection.
I have seen importers in the Gulf receive galvanized tubes that looked acceptable on the surface — only to have the entire shipment rejected because the zinc coating thickness was inconsistent and no original mill certificates accompanied the cargo. The buyer had no way to prove chemical composition or mechanical properties to the project consultant. The tubes sat in a yard for weeks, the zinc began to white-rust in the humid coastal air, and the loss was total. For a Q235 SS400 galvanized square steel tube supplier shipping to regulated markets, traceability is not a paperwork detail — it is the baseline requirement. [NEED_CITE: EN 10219 cold-formed hollow section documentation requirements]
How Galvanized Square Tubes Match Structural and Corrosive Environments
The galvanized coating on Q235 SS400 galvanized square steel tube provides a zinc barrier that resists atmospheric corrosion in outdoor and high-humidity environments — greenhouse frames in Southeast Asia, perimeter fencing along coastal sites, and scaffolding exposed to seasonal rain. The Z41 to Z120 coating range lets buyers match protection level to exposure severity: lighter coatings for indoor machinery frames, heavier coatings for structures in tropical or marine climates. The ±1% thickness tolerance and skin-pass treatment ensure dimensional consistency when tubes are cut, welded, or bolted on-site, reducing fit-up gaps in structural connections.
Engineering Compliance and Steel Grade Selection
Structural frames and load-bearing columns require steel grades that meet recognized engineering specifications. Q345 and S355 grades deliver higher yield strength for EPC infrastructure projects, while Q235 and SS400 serve general construction and fencing applications at lower cost. For EU project tenders, CE certification under EN 10210 or EN 10219 is often a mandatory submission requirement — without it, the procurement team cannot pass the consultant’s compliance review. [NEED_CITE: steel grade equivalence between Chinese GB, European EN, and American ASTM standards] Specifying the correct grade from the start avoids the cost of reordering or the risk of structural underperformance under design loads.
Understanding Steel Grades and Galvanizing for Square Tubes
The Q-series (Q195, Q235, Q345) follows the Chinese GB standard system where the number indicates minimum yield strength in MPa — Q235 is the workhorse grade for general structures, while Q345 steps up for heavier load requirements. The S-series (S235, S355) follows the European EN system with a similar yield-strength naming logic, making S355 the direct counterpart to Q345 for projects specifying EN standards. SS400 and STK400/STK500 follow the Japanese JIS system, commonly requested for projects in Southeast Asia and the Middle East where JIS specifications dominate. The galvanized coating — applied in Z41 to Z120 weight classes — determines corrosion resistance life: Z41 suits indoor or sheltered applications, while Z120 extends service life in aggressive outdoor or industrial atmospheres. Zero spangle and regular spangle options address both aesthetic and painting requirements.
The Hidden Cost of Wrong Steel Grade or Coating Class
Specifying S235 when the structural engineer calculated for S355 means the frame may deflect beyond allowable limits under design load — a failure discovered only during loading tests or, worse, during service. Ordering Z41 galvanized tubes for a coastal fencing project when Z80 or Z120 is needed means the zinc depletes within months, white rust appears, and the buyer faces replacement costs that dwarf the original price difference. Missing CE or mill test certificates can hold a container at port for weeks, incurring demurrage charges that exceed the tube cost itself. [NEED_CITE: consequences of non-compliant steel grade selection in structural engineering]
Why Bulk Buyers Source Galvanized Square Tubes from Xin Jiyuan
Xin Jiyuan operates three production lines running simultaneously with monthly capacity exceeding 20,000 tons, meaning large-volume orders for Q235 SS400 galvanized square steel tube are fulfilled from factory floor — no trading company margin added. The ready stock covers over 2,800 specifications across square and rectangular sections, so standard sizes ship within days while custom dimensions run on dedicated schedules. Every production batch undergoes three-stage in-house inspection, and original mill test certificates documenting chemical composition and mechanical properties ship with every container. CE certification under EN 10210 and EN 10219, plus ISO 9001:2015 registration, clears the documentation requirements for EU and international project tenders. Third-party inspection through SGS or BV is arranged on request before loading. The export team handles container loading optimization — critical for galvanized tubes where improper stacking can damage the zinc coating during ocean transit — and prepares complete customs documentation including packing lists, bills of lading, and certificates of origin.
Documentation & Compliance
- Mill test certificate documenting Q235 and SS400 chemical composition and mechanical properties per GB/T and JIS standards, traceable by heat number
- CE certificate under EN 10210 and EN 10219 for galvanized hollow sections, required for EU project tender submissions
- ISO 9001:2015 quality management certificate covering the full production and inspection process
- SGS or BV third-party inspection report available on request, verifying coating thickness, dimensional tolerance, and surface quality before shipment
- Material traceability by heat number on every bundle, linking each tube to its original mill test certificate
- Complete customs documentation package including packing list, bill of lading, and certificate of origin for destination-country clearance
Packaging, Loading & Delivery
- Galvanized square and rectangular tubes bundled with steel strips and edge protectors to preserve the zinc coating from abrasion during handling and ocean transit
- Surface protection maintained through non-oiled, skin-pass treated finish that resists white rust formation during storage and shipping
- Container loading optimized for tube lengths from 1 to 12 meters, with weight distribution planned to prevent shifting and coating damage during rough sea transit
- Custom cutting to project-specific lengths available within the 1–12 m range, reducing on-site waste and labor for fencing and greenhouse framing
- Heat number and steel grade marked on each bundle for site traceability and inspection verification
- FOB, CIF, and DDP shipping terms available with professional export documentation handling for destination-country customs clearance
Starting Your Galvanized Tube Procurement
Submit your specifications — section size, wall thickness, steel grade, coating class, quantity, and destination port — and receive a factory-direct quotation with volume pricing, delivery schedule, and sample mill test certificates within 12 hours. For non-standard dimensions or multi-product container consolidation, the engineering team provides custom loading plans and compliance documentation review before production begins.
Request Factory-Direct Pricing and Mill Test Certificates
Send your specification sheet via email or WhatsApp to receive bulk pricing, coating class recommendations, and delivery confirmation for your next Q235 SS400 galvanized square steel tube order.
Email: admin@sdxinjiyuan.com
Mobile / WhatsApp / WeChat: +86 188 5315 7756
Tel: +86 531 8573 6315
Frequently Asked Questions
Q: How do Q235, SS400, S235, and A36 steel grades compare for galvanized square tubes?
A: These grades belong to different national standard systems — Q235 follows Chinese GB, SS400 follows Japanese JIS, S235 follows European EN, and A36 follows American ASTM. They share similar yield strength ranges and are commonly used for general structural and construction applications. The correct grade depends on your project specification and destination market requirements.
Q: What is the difference between Z41, Z80, and Z120 galvanized coating classes?
A: The Z number indicates zinc coating weight in grams per square meter. Z41 provides basic corrosion protection suitable for indoor or sheltered applications. Z80 offers moderate protection for standard outdoor use. Z120 delivers extended corrosion resistance for aggressive environments such as coastal areas, industrial zones, or high-humidity climates.
Q: Can you provide mill test certificates and arrange third-party inspection before shipment?
A: Every batch ships with original mill test certificates documenting chemical composition and mechanical properties, traceable by heat number. SGS or BV third-party inspection is available on request to verify coating thickness, dimensional tolerance, and surface quality before container loading.
Q: Do you support non-standard dimensions, and what is the minimum order quantity?
A: Custom sizes within the 15×15 mm to 1000×1000 mm section range and 0.5–20 mm wall thickness are available. The minimum order quantity is 1 ton for both standard and custom specifications, with typical production lead times for non-standard orders.
Q: How do you handle container loading for galvanized tubes to prevent coating damage?
A: Tubes are bundled with steel strips and edge protectors, and container loading plans are optimized for weight distribution and secure stacking to prevent shifting and zinc coating abrasion during ocean transit. The export team prepares detailed loading diagrams for multi-product consolidated shipments.
