Description
Vertically Integrated SHS Mill — From raw steel slab to finished Q355 S355 square hollow section supplier, one quality system controls every step.
Technical Specifications
| Parameter | Value |
|---|---|
| Designation | Q355/S355 Square Hollow Section (SHS) |
| Product Type | Square Hollow Section (SHS) |
| Steel Grade | Q355, S355, Gr.B, S235, S275, STK400 |
| Standard | ASTM A500, ASTM A53, GB/T 3091 |
| Section Shape | Square |
| Size Range | 19mm×19mm – 800mm×800mm |
| Wall Thickness | 1–30mm |
| Length | 5.8m / 6m / 11.8m / 12m / Random Length |
| Technique | Welded (ERW) or Seamless |
| Surface Treatment | Black Painting / Galvanized / Varnish / Bare |
| Tolerance | ±5% / ±10% / ±15% (varies by dimension) |
| Application | Construction Pipe / Building Pipe / Curtain Wall Pipe / Support Tubes / Structure Pipe / Fertilizer Tube |
| MOQ | 5 Tons |
| Origin | Shandong, China |
Application Suitability
| Industry | Typical Applications |
|---|---|
| Commercial Construction | Steel frame structures, building columns, roof trusses for warehouses and logistics centers |
| Industrial EPC Projects | Process pipe racks, equipment support platforms, conveyor structures in petrochemical plants |
| Architectural Facades | Curtain wall mullions, exposed structural elements, canopy frames |
| Infrastructure | Bridge handrail posts, sound barrier support columns, solar panel mounting frames |
Where Wall-Thickness Tolerance Costs More Than the Tube Itself
A batch of Q355 SHS arriving at Jebel Ali with wall thickness below the declared minimum will be rejected on site — and the rework bill dwarfs the original savings.
Outsourcing structural steel fabrication overseas means the buyer cannot walk the production floor. When a fabricator sources raw tubes from a third-party mill, the material certification chain develops gaps: heat numbers do not match, wall thickness drifts into negative tolerance, and the监理 refuses the lot. [NEED_CITE: EN 10219 cold-formed hollow section dimensional tolerance requirements] The cost is not the tube — it is the crane idle time, the re-welding, the rescheduled vessel.
Matching SHS Dimensions to Structural Load Paths
A Q355 S355 square hollow section supplier covering 19×19 mm through 800×800 mm and 1–30 mm wall thickness lets engineers select sections that align with actual load calculations rather than catalog availability. For a warehouse frame in Riyadh, the column might call for 300×300×12 mm S355 in seamless process for higher bearing capacity, while the purlin system uses 100×100×4 mm ERW welded sections where cost efficiency matters more. Our own steel mill produces the raw material, so the same heat number runs through both the seamless and welded lines — traceability stays intact across the full project bill of materials.
Engineering Compliance Across Competing Standard Systems
Structural projects crossing borders often demand simultaneous compliance: EN 1090 for EU-bound components, ASTM A500 for North American specifications, and GB/T 3091 for domestic Chinese engineering. [NEED_CITE: steel grade equivalence between EN 10219 and ASTM A500 standards] The Q355/S355/Gr.B grade range in a single product line eliminates the need to place separate orders for different standard systems. Surface treatment selection — hot-dip galvanized for coastal industrial plants, black painted for indoor structural frames, bare for sections that will receive field-applied fireproofing — is coordinated at the fabrication stage to match the project’s corrosion environment classification.
Steel Grade Selection and Process Route Decisions
The S-series grades (S235, S275, S355) follow the European EN standard system where the number indicates minimum yield strength in MPa. Q355 is the Chinese GB/T 1591 equivalent, offering comparable structural performance to S355JR. ASTM A500 Grade C serves the North American market with a slightly different chemical envelope. [NEED_CITE: structural steel grade equivalence comparison between Chinese, European and American standards] For the process route, ERW welded SHS delivers cost efficiency at high volumes for standard structural applications, while seamless SHS provides uniform wall distribution for heavy-load columns and high-stress connection nodes. Choosing between them depends on the structural engineer’s load calculation and the project’s inspection requirements.
Surface Treatment: Galvanized vs Painted vs Bare
Hot-dip galvanizing provides sacrificial zinc protection suitable for outdoor exposure in industrial and infrastructure environments. Black painting offers short-term corrosion resistance during transit and storage, with the expectation that the structural steel fabricator will apply the final coating system on site. Bare SHS is specified when the component will receive intumescent fireproofing or when the project’s corrosion protection scope is handled entirely by the main contractor after erection. Each option affects the packing and handling procedure — galvanized surfaces require edge protectors to prevent coating damage during ocean transit.
The Hidden Cost of Unverified Material Certification
Ordering a Q355 S355 square hollow section supplier without verified mill test certificates means the buyer absorbs the risk of material substitution. A certificate listing S235 chemistry cannot be used to pass off Q355 — the yield strength gap is structurally significant. [NEED_CITE: EN 10204 inspection document types for structural steel products] When customs authorities at the destination port request EN 10219 compliance documentation and the fabricator cannot produce it, the container sits at the terminal accumulating demurrage charges. The real cost is never the tube price — it is the project delay, the structural re-calculation, and the reputational damage with the end client.
Why Procurement Teams Choose Our Integrated Supply Chain
Our own steel mill with three production lines produces the raw steel that becomes every Q355 S355 square hollow section supplier product we ship. This vertical integration means the heat number on the mill test certificate matches the physical tube in the container — no third-party material sourcing, no certification gaps. The in-house fabrication workshop handles CNC cutting, drilling, welding per approved WPS, and shot blasting, so shop drawing coordination stays under one roof. We maintain over 2,800 specifications in stock, covering the full 19×19 to 800×800 mm range in both welded and seamless processes. Certified welding procedures and qualified welders hold AWS and EN certifications. Every shipment includes a complete quality documentation package: WPS, PQR, weld maps, dimensional inspection reports, and coating reports. International project delivery experience spans the EU, Middle East, Southeast Asia, and Africa.
Documentation & Compliance
- Mill test certificate documenting Q355 and S355 chemical composition and mechanical properties per GB/T 1591 and EN 10219, traceable by heat number
- CE certificate confirming EN 10210 / EN 10219 compliance for structural hollow sections exported to European Union member states
- ISO 9001 quality management system certificate covering the full production process from raw steel melting to finished SHS dispatch
- SGS or BV third-party inspection report available upon request, verifying dimensional accuracy, wall thickness, and surface treatment quality prior to shipment
- Material traceability documentation linking each bundle to its original heat number, steel grade, and production batch
- Complete customs export documentation including packing list, bill of lading, and certificate of origin for destination-country clearance
Packaging, Loading & Delivery
- Q355 and S355 SHS bundled with high-tensile steel strips in seaworthy packaging, with bundle weight optimized for container or bulk vessel loading
- Galvanized square hollow sections packed with edge protectors and waterproof interleave to preserve the zinc coating during ocean transit and port handling
- Container loading plans optimized for 5.8m and 6m lengths in 20ft containers, and 11.8m/12m lengths in 40ft open-top or flat-rack units, maximizing payload per shipment
- Random length and cut-to-order SHS available to match project-specific fabrication requirements, reducing on-site cutting waste
- Each bundle marked with heat number, steel grade (Q355/S355), size specification, and production batch for site identification and traceability
- FOB, CIF, and DDP delivery terms available, with professional oversized cargo loading and lashing planning for 800×800 mm sections
Start Your Procurement with Complete Technical Documentation
Submit your project drawings, steel grade requirements, quantity, and destination port to receive a detailed quotation including material cost, fabrication scope, coating specification, and shipping arrangement. Our engineering team will review your shop drawings and confirm the optimal process route — ERW welded or seamless — based on your structural load requirements and budget. Mill test certificates and third-party inspection arrangements are confirmed before production begins.
Request a Quotation with Full Material Certification
Send your specifications and drawings to receive pricing, mill test certificates, and production scheduling within 24 hours.
Mobile/WhatsApp/WeChat: +86 188 5315 7756
Email: admin@xjystructure.com
Frequently Asked Questions
Q: What is the difference between Q355 and S355 steel grades for square hollow sections?
A: Q355 follows the Chinese GB/T 1591 standard while S355 follows the European EN 10025/EN 10219 system. Both indicate a minimum yield strength of approximately 355 MPa. The chemical composition ranges differ slightly between the two standards, but their structural performance is comparable. We supply both grades from the same integrated production line, allowing buyers to select based on their project’s governing standard.
Q: Can you provide third-party inspection before shipment for overseas buyers?
A: Yes. SGS and BV third-party inspections are available upon request. The inspection covers dimensional accuracy, wall thickness measurement, surface treatment quality, and visual weld inspection. The inspection report is issued before the container is sealed, giving the buyer independent verification of product quality.
Q: How do you handle surface treatment selection for different project environments?
A: We offer hot-dip galvanizing for outdoor and corrosive environments, black painting for short-term transit protection, varnish coating, and bare delivery for sections that will receive field-applied coatings. The selection depends on the project’s corrosion environment classification and the main contractor’s coating specification.
Q: What is the production lead time for welded versus seamless SHS?
A: Typical production lead times vary based on order quantity, size specification, and surface treatment requirements. ERW welded SHS generally has shorter lead times due to higher production throughput. Seamless SHS requires additional processing steps. We confirm the specific production schedule after receiving the order details and drawing approval.
Q: How are oversized square hollow sections loaded for international shipping?
A: Sections up to 6m length are loaded in standard 20ft containers. Sections of 11.8m and 12m require 40ft open-top or flat-rack containers. Sections exceeding container dimensions, such as 800×800 mm SHS, are loaded on bulk vessels or flat-rack containers with professional lashing and securing plans to prevent transit damage.
Get Your Q355 S355 Square Hollow Section Quote Today
Share your project drawings and specifications to receive a complete quotation with mill test certification and production scheduling.
Mobile/WhatsApp/WeChat: +86 188 5315 7756
Email: admin@xjystructure.com
