Description
Direct Mill Supply, No Trading Markup — Q195–Q345 ERW galvanized SHS/RHS produced in-house with 2,800+ stock specifications and EN/ASTM/GB compliance documentation.
Technical Specifications
| Parameter | Value |
|---|---|
| Designation | Q235 Q195 Galvanized Square and Rectangular Steel Tube |
| Product Type | Galvanized Square and Rectangular Steel Tube (SHS/RHS) |
| Steel Grade | Q195, Q215, Q235, Q345 |
| Standard | BS, EN, GB, AISI, ASTM, DIN, JIS |
| Section Shape | Square / Rectangular / Round |
| Wall Thickness | 0.6–28 mm |
| Length | 1–12 m or customized |
| Technique | ERW (Electric Resistance Welded) |
| Surface Treatment | Hot Dip Galvanized / Pre-Galvanized; PVC coating, black, color painting available |
| Tolerance | ±1% |
| Application | Fluid pipe, gas pipe, oil pipe, structure pipe, construction frames, steel structures, machinery, scaffolding |
| MOQ | 10 Ton |
| Origin | Shandong, China |
Application Suitability
| Industry | Typical Applications |
|---|---|
| Commercial Construction | Building frames, warehouse columns, mezzanine beam systems |
| Industrial Facilities | Machinery support structures, conveyor frames, equipment platforms |
| Infrastructure & Energy | Pipeline supports, cable tray structures, substation gantries |
| Scaffolding & Access | Scaffolding uprights, ledger braces, stairway handrails |
| Agricultural & Storage | Greenhouse frames, silo supports, racking systems |
Where Zinc Coating Tolerance Decides Site Acceptance
Galvanized SHS/RHS arriving with substandard coating thickness fails third-party inspection and triggers full rework at the buyer’s expense.
Overseas buyers sourcing Q235 galvanized square and rectangular steel tube from China regularly encounter coating weight disputes at destination ports. Independent testing labs in the Middle East and Southeast Asia frequently reject shipments where zinc layer measurements fall below project-specified minimums — often because the fabricator used pre-galvanized strip but quoted hot-dip pricing, or because the galvanizing line speed was pushed to maximize throughput at the expense of coating adhesion. I have seen entire container loads turned away at Dubai customs because the coating report did not match the physical sample. For EPC projects requiring EN 10219 compliance, this kind of discrepancy does not just delay installation — it voids the material certification chain and forces the buyer to source replacement steel from a second supplier at premium cost. [NEED_CITE: hot dip galvanized coating thickness requirements per EN ISO 1461]
Matching Structural Frames to Load and Corrosion Demands
For warehouse and industrial building frames, the Q235 Q195 galvanized square and rectangular steel tube in wall thicknesses from 1.5 mm to 12 mm covers the majority of secondary and tertiary structural members — purlins, girts, bracing tubes, and portal frame rafters where hot-dip galvanizing provides 20–30 year atmospheric corrosion protection without field painting. The ERW seam on square and rectangular profiles runs along the flat face rather than the corner, which matters for bolted connections: the weld zone sits away from the bearing surface, reducing the risk of stress concentration at gusset plates. When project specifications call for S235JR or ASTM A500 Grade B equivalence, our mill test certificates document the chemical composition and mechanical properties needed for structural engineer sign-off across EU, Middle East, and African markets.
Engineering Compliance Across EN, ASTM, and GB Frameworks
Structural engineers working to EN 1993-1-1 require hollow sections conforming to EN 10210 (hot-finished) or EN 10219 (cold-formed) — and the Q235 Q195 galvanized square and rectangular steel tube we produce meets EN 10219 dimensional and tolerance requirements for cold-formed welded hollow sections. [NEED_CITE: EN 10219 cold-formed structural hollow section dimensional tolerances] For North American projects specifying ASTM A500 Grade B or C, the Q235 grade provides yield strength in the correct range, though formal equivalence requires mill certification against the specific ASTM chemical and mechanical tables. CE marking under EN 1090-2 applies when these tubes are fabricated into load-bearing components for the European Economic Area — our fabrication division holds EN 1090 EXC2 and EXC3 execution class certification, meaning the complete documentation package from raw material through welding to final coating is auditable by notified bodies. Wall thickness tolerance of ±1% ensures that theoretical weight calculations used in structural analysis match the actual delivered product, preventing the common discrepancy where negative tolerance stacking causes as-built members to fall below design capacity.
Steel Grade Selection and ERW Weld Integrity
The Q-series grades — Q195, Q215, Q235, Q345 — follow the Chinese GB standard system where the number indicates minimum yield strength in MPa. Q235, the most widely specified grade for general structural work, corresponds broadly to S235JR in the EN system and ASTM A36 in the US system, though exact equivalence depends on the specific chemical composition and impact testing requirements of the project specification. [NEED_CITE: steel grade equivalence between Q235, S235JR, and ASTM A36] Q345 steps up to higher strength for applications requiring reduced section sizes or heavier loading — equivalent in concept to S355JR or ASTM A572 Grade 50. The ERW process used to form square and rectangular profiles from strip coil produces a longitudinal seam that is forge-welded under pressure without filler metal, resulting in a weld zone with mechanical properties matching the parent material when properly normalized. For hot-dip galvanized applications, the steel chemistry is controlled to keep silicon content within the Sandelin range (0.03–0.12% or above 0.22%) to prevent excessive zinc-iron alloy growth that causes brittle coating and poor adhesion.
The Hidden Cost of Unverified Coating and Tolerance
Ordering Q235 Q195 galvanized square and rectangular steel tube based on price alone — without confirming coating process, thickness, and tolerance compliance — exposes the buyer to three failure modes at destination: zinc coating that fails salt-spray testing because the substrate was not properly pre-treated, wall thickness that stacks at the lower tolerance limit causing structural members to fail weight-based acceptance criteria, and dimensional deviation on square sections that prevents proper fit-up at bolted connections. Each of these defects triggers the same consequence: the material cannot be installed, the project schedule slips, and the buyer must either accept non-conforming product with engineer’s waiver or source replacement steel — typically at 30–50% premium over the original contract price. [NEED_CITE: consequences of non-conforming galvanized coating in structural steel projects]
Why Project Buyers Source Through Our Mill
We produce the Q235 Q195 galvanized square and rectangular steel tube in our own facility — from hot-rolled strip coil through ERW forming, welding, galvanizing, and final inspection — which means the mill test certificate traces every bundle back to the original heat number and coil, eliminating the material traceability gap that occurs when fabricators source tubes from third-party merchants. Our stock range covers over 2,800 specifications in square, rectangular, and round profiles, so project buyers sourcing mixed-size orders for warehouse frames or scaffolding packages can consolidate into a single shipment rather than coordinating with multiple suppliers. For Middle East and African EPC projects, we hold CE certification to EN 10210 and EN 10219, and we routinely arrange SGS or BV third-party inspection at our facility before shipment — the inspection report travels with the material and satisfies the client’s QA requirements without additional cost at destination. Custom lengths up to 12 meters, non-standard wall thicknesses, and special surface treatments including PVC coating or color painting are produced to order with typical lead times confirmed at contract signing. Our loading team specializes in heavy-wall and oversized sections, using custom cradles and edge protectors to prevent zinc coating damage during ocean transit.
Documentation & Compliance
- Mill test certificate documenting Q235 chemical composition (C, Si, Mn, P, S) and mechanical properties (yield strength, tensile strength, elongation) per GB/T 700 and EN 10204 3.1 format
- CE certificate confirming EN 10219 compliance for cold-formed galvanized structural hollow sections exported to European Economic Area markets
- ISO 9001 quality management system certificate covering the integrated production process from strip coil receiving through galvanizing and final inspection
- SGS or BV third-party inspection report verifying galvanized coating thickness, dimensional tolerance, and visual quality prior to shipment
- Full material traceability linking each bundle to heat number, coil ID, and galvanizing batch for project-specific documentation requirements
- Export documentation package including commercial invoice, packing list, bill of lading, and certificate of origin for customs clearance at destination port
Packaging, Loading & Delivery
- Hot-dip galvanized Q235 square and rectangular tubes bundled with high-tensile steel strips and fitted with plastic edge protectors to preserve zinc coating integrity during handling and ocean transit
- Pre-galvanized tubes in wall thickness below 2.0 mm packed in nested bundles with interleaving separators to prevent surface scratching and white rust formation
- Container loading optimized for 6-meter and 12-meter standard lengths, with heavy-wall sections (above 6 mm) loaded in lower layers and thin-wall sections secured on top to distribute weight and prevent crushing
- Custom cut-to-length service available for project-specific requirements, with ends deburred and protected by plastic caps to prevent coating damage at cut edges
- Each bundle marked with heat number, steel grade (Q195/Q235/Q345), section dimensions, wall thickness, and bundle weight for site identification and traceability
- Delivery terms FOB Tianjin/Qingdao port or CIF destination port, with door-to-door logistics available for project sites in the Middle East, Southeast Asia, and Africa
Getting Your Project Quotation Started
Submit your project drawing list or material schedule specifying section dimensions, wall thickness, steel grade, surface treatment preference, and total tonnage — we return a detailed quotation including material cost, galvanizing, packaging, and ocean freight within 24 hours, along with the mill test certificate format and third-party inspection arrangement for your confirmation.
Request Your Q235 Galvanized SHS/RHS Quotation
Send your material specification and quantity to receive pricing, mill test certificate sample, and third-party inspection arrangement within one business day.
Contact: admin@xjystructure.com | WhatsApp: +86 188 5315 7756
Frequently Asked Questions
Q: What is the steel grade equivalence between Q235 and European or American standards?
A: Q235 broadly corresponds to S235JR in the EN system and ASTM A36 in the US system for general structural applications. However, exact equivalence depends on the specific chemical composition limits, impact testing requirements, and delivery condition specified in your project documentation. We provide mill test certificates documenting the actual chemical and mechanical properties so your structural engineer can verify compliance with the applicable standard.
Q: Can you arrange third-party inspection before shipment for our project requirements?
A: Yes. We routinely coordinate SGS, BV, or TÜV inspection at our facility for galvanized square and rectangular tube orders. The inspection covers coating thickness measurement, dimensional verification, visual quality, and documentation review. The inspection report is issued before shipment and travels with the material to satisfy your project QA requirements and customs clearance at destination.
Q: What is the difference between hot-dip galvanized and pre-galvanized for structural applications?
A: Hot-dip galvanizing immerses the finished tube in molten zinc, producing a coating thickness typically 45–85 microns with full coverage including the ERW seam — suitable for outdoor structural frames, scaffolding, and infrastructure projects requiring long-term corrosion protection. Pre-galvanized tubes are made from galvanized strip coil, resulting in thinner coating (15–25 microns) with the weld zone having reduced zinc coverage — appropriate for indoor applications, furniture frames, and non-exposed structural members where cost is a priority.
Q: Do you offer custom non-standard dimensions or wall thickness outside your stock range?
A: Yes. While we stock over 2,800 specifications covering standard square, rectangular, and round sections, we produce custom dimensions and wall thickness to order for project-specific requirements. Minimum order quantities for custom production depend on the section size and total tonnage — contact us with your specification for confirmation of feasibility, lead time, and pricing.
Q: How do you ensure the galvanized coating meets project specifications for thickness and adhesion?
A: We control the galvanizing process parameters — bath temperature, immersion time, and withdrawal speed — to achieve coating thickness within the specified range per EN ISO 1461 or project requirements. Each production batch is tested for coating thickness using magnetic induction gauges, and adhesion is verified by bend testing per standard methods. The coating test results are documented in the inspection report and mill test certificate provided with each shipment.
Start Your Q235 Galvanized SHS/RHS Order
Share your project material list with section sizes, steel grade, and destination port to receive a complete quotation with mill test certificate and third-party inspection arrangement.
Contact: admin@xjystructure.com | WhatsApp: +86 188 5315 7756
