Description
Direct Mill Supply for ZAM Coated Tubes — Vertically integrated production from raw steel coil to finished Q235B and Q355 ZAM coated square rectangular steel tube, with full material traceability and mill test certificates for every heat number.
Technical Specifications
| Parameter | Value |
|---|---|
| Designation | Q235B / Q355 ZAM Coated Galvanized Magnesium Aluminum Square & Rectangular Steel Tube |
| Product Type | Square and Rectangular Steel Tube (SHS / RHS) |
| Steel Grade | Q195, Q235, Q355 (equivalent to S235JR / S355JR) |
| Standard | ASTM, JIS, GB, EN |
| Section Shape | Square / Rectangular / Flat Oval |
| Size Range | Flat Oval 20×60 mm – 40×75 mm; Round OD 20 mm – 500 mm; Square/Rectangular as required |
| Wall Thickness | 0.5 mm – 1.0 mm (ZAM coated); 1 mm – 30 mm (general range); 0.3 mm – 100 mm (as required) |
| Length | 5.8 m – 12 m (standard 6 m / 5.8 m / 6.4 m / 12 m) |
| Technique | ERW (Electric Resistance Welded) |
| Surface Treatment | ZAM Coating (Zinc-Aluminum-Magnesium) / Hot Dip Galvanized (Zinc coating 30 g – 275 g) |
| Coating Grade | AZ61 – AZ80 (Aluminium content 55%) |
| Spangle Type | Zero Spangle |
| Ends | Plain / with or without end caps |
| Processing Service | Welding, Punching, Cutting, Bending |
| Application | Structure Pipe / Steel structures / Construction frames / Machinery / Scaffolding / Furniture / Greenhouse / Fencing |
| Origin | Shandong, China |
Application Suitability
| Industry | Typical Applications |
|---|---|
| Industrial Construction | Steel frame structures for warehouses, logistics centers, and factory buildings |
| Renewable Energy | Solar mounting structures and support frames in coastal or high-humidity environments |
| Infrastructure | Scaffolding systems, fencing, and greenhouse structures requiring long-term corrosion protection |
| Machinery & Equipment | Machinery frames, conveyor structures, and equipment support bases |
Where Coating Traceability Decides Whether Your Shipment Clears Customs
A ZAM coated square rectangular steel tube supplier without full heat-number documentation creates customs and inspection risks that no amount of price negotiation can fix.
I have seen entire container loads held at destination ports because the mill test certificate could not trace back to the original coil heat number. When buyers source from traders who aggregate tubes from multiple small mills, the material certification chain breaks somewhere in the middle. Third-party inspectors flag incomplete documentation, customs officers delay clearance, and project timelines collapse. The ZAM coating itself — Zinc-Aluminum-Magnesium alloy with AZ61 to AZ80 grade and 55% aluminium content — delivers corrosion resistance that outperforms conventional hot dip galvanizing by a significant margin [NEED_CITE: ZAM coating corrosion resistance performance versus hot dip galvanized]. But none of that matters if the paperwork cannot prove what is inside the bundle.
How ZAM Coating Matches Structural Frame Requirements in Aggressive Environments
For steel structure frames in industrial buildings, warehouses, and logistics centers, the ZAM coated square rectangular steel tube provides a corrosion protection layer that forms a dense, self-healing zinc-aluminum-magnesium hydroxide film when exposed to moisture. This makes it particularly suitable for coastal construction sites, chemical plant perimeters, and agricultural structures where salt spray or high humidity accelerates conventional zinc degradation. The zero spangle finish delivers a smooth, uniform surface that accepts powder coating or direct architectural exposure without additional surface preparation. Our vertically integrated supply chain — from raw coil production through ERW welding to ZAM coating — ensures that every tube in your order carries consistent coating thickness and adhesion properties, verified through in-line testing and documented in the mill test certificate.
Engineering Compliance and Standard Alignment for Global Procurement
Structural hollow sections used in load-bearing frames must conform to dimensional and mechanical requirements defined by EN 10219 for cold-formed welded structural hollow sections or EN 10210 for hot-finished sections, depending on the manufacturing route. For European market projects, CE certification under these standards is mandatory for customs clearance and structural approval [NEED_CITE: EN 10219 cold-formed hollow section compliance requirements]. The Q235 and Q355 grades supplied here correspond to S235JR and S355JR under the EN system, and equivalence documentation can be provided upon request to satisfy engineering consultants reviewing material substitutions [NEED_CITE: steel grade equivalence between GB Q series and EN S series]. Wall thickness ranges from 0.5 mm for light-gauge ZAM coated sections to 30 mm for heavy structural tubes, all produced via ERW welding with dimensional tolerance controlled to ±1%. For projects in North America, ASTM A500 compliance can be confirmed through third-party testing arranged at the mill stage.
Understanding ZAM Coating Technology and ERW Welding for Square and Rectangular Tubes
The ZAM coating process applies a Zinc-Aluminum-Magnesium alloy layer onto the steel substrate, with aluminium content typically at 55% (AZ61 to AZ80 grades). This alloy composition creates a corrosion protection mechanism fundamentally different from pure zinc galvanizing — when the coating surface is scratched or cut during fabrication, the magnesium component activates a self-healing reaction that prevents red rust formation at the exposed edge. This property is critical for square and rectangular tubes that undergo cutting, punching, and welding on site, as the cut edges remain protected without requiring touch-up painting. The ERW welding technique used to form these tubes produces a clean, consistent weld seam suitable for structural applications, with the weld zone fully covered by the ZAM coating in the post-coating process. Wall thickness selection directly affects both load-bearing capacity and weight — thinner walls in the 0.5 mm to 1.0 mm range suit non-structural applications like fencing and greenhouse frames, while heavier sections in the 1 mm to 30 mm range serve as primary structural members in steel frames.
Hidden Costs When Coating Quality and Grade Certification Fall Short
Specifying Q355 steel but receiving material that tests as Q235 means the structural frame carries lower yield strength than the engineer calculated — a discrepancy that may not surface until load testing or, worse, until service. Similarly, ZAM coating thickness below the specified AZ61 to AZ80 range reduces corrosion protection life, particularly at cut edges and weld zones where the self-healing mechanism depends on sufficient magnesium content. When third-party inspectors at destination ports measure coating weight below specification, the entire shipment faces rejection or costly renegotiation [NEED_CITE: third-party inspection rejection rates for coating thickness non-compliance]. Missing or incomplete mill test certificates create additional risk — without heat number traceability linking the finished tube back to the original steel coil, customs authorities in strict markets may refuse entry regardless of the physical product quality.
Why Procuring from a Vertically Integrated Mill-Fabricator Reduces Supply Chain Risk
Our production facility operates three steel production lines with over 2,800 specifications of raw material in stock, meaning the steel coil used to form your ZAM coated square rectangular steel tube originates from our own mill — not from a third-party supplier whose certification we cannot fully verify. This vertical integration eliminates the material traceability gap that plagues transactions between traders and end buyers. Every heat number on the mill test certificate traces directly to our coil production records, and our in-house laboratory conducts chemical composition and mechanical property testing before any tube leaves the facility. For projects requiring third-party validation, we arrange SGS, BV, or TÜV inspections for coating thickness, adhesion, and dimensional accuracy at the production stage — not after the container has been sealed. Our welding procedures and welder qualifications are certified to AWS and EN standards, and complete quality documentation packages including WPS, PQR, weld maps, and dimensional inspection reports accompany every shipment.
Documentation & Compliance
- Mill test certificate documenting Q235B or Q355 chemical composition and mechanical properties per GB/T 13793 or EN 10219, with full heat number traceability to raw coil
- CE certificate for EN 10219 cold-formed structural hollow sections, required for European market customs clearance and structural approval
- ISO 9001 quality management system certificate covering the complete production process from coil slitting through ERW welding to ZAM coating
- SGS or BV third-party inspection report verifying ZAM coating thickness (AZ61–AZ80), adhesion performance, and dimensional tolerance
- Material traceability documentation linking each bundle’s heat number to coil production records, chemical analysis, and mechanical test results
- Export customs documents including packing list, bill of lading, and certificate of origin formatted for destination port requirements
Packaging, Loading & Delivery
- ZAM coated square and rectangular tubes bundled with steel strips and edge protectors to preserve the zinc-aluminum-magnesium coating surface during ocean transit and handling
- Bundles sized to match standard 20ft and 40ft container internal dimensions, with 5.8 m and 6 m lengths optimized for full container loading without overhang
- Zero spangle ZAM coating surface protected by anti-scratch interleaving materials at contact points between tubes within each bundle
- Custom cut-to-length service available for 6.4 m and 12 m requirements, with cut ends capped to prevent moisture ingress during storage and transport
- Each bundle labeled with heat number, steel grade (Q235B/Q355), coating grade (AZ61/AZ80), dimensions, and production date for site identification
- Shipping terms available as FOB, CIF, or DDP with professional oversized cargo loading plans and complete export documentation tracking until site delivery
How to Initiate Your Procurement Process
Submit your project drawings, required steel grades, coating specifications, and quantity to receive a detailed quotation including material cost, ZAM coating treatment, packaging, and shipping within 24 hours. Our engineering team will review shop drawings, confirm standard compliance (EN 10219, ASTM A500, or GB/T 13793), and provide a production schedule with third-party inspection milestones. Confirm your certification requirements and destination port documentation needs before contract signing to ensure smooth customs clearance.
Start Your ZAM Coated Tube Inquiry Today
Share your specifications, steel grade requirements, and target quantity to receive a quotation with mill test certificate samples and production timeline.
Contact: Shandong Xin Jiyuan Special Steel Tube Co., Ltd
Website: www.xjystructure.com
Tel: +86 531 8573 6315
Mobile/WhatsApp/WeChat: +86 188 5315 7756
Email: admin@xjystructure.com
Address: No.11889, Jingshi West Road, Lulian Group, Jinan City, Shandong Province, China
Frequently Asked Questions
Q: What is ZAM coating and how does its corrosion resistance compare to conventional hot dip galvanized coating?
A: ZAM coating is a Zinc-Aluminum-Magnesium alloy layer with aluminium content around 55% (AZ61 to AZ80 grades). The magnesium component enables a self-healing effect at cut edges and scratches, providing corrosion resistance significantly higher than pure zinc hot dip galvanizing, particularly in coastal and high-humidity environments.
Q: Can you provide material equivalence documentation between GB grades (Q235/Q355) and EN standards (S235JR/S355JR)?
A: Yes, we provide grade equivalence documentation confirming that Q235 corresponds to S235JR and Q355 corresponds to S355JR in terms of chemical composition and mechanical properties, supported by mill test certificates and third-party verification when required.
Q: What third-party inspection and export documentation do you provide for international shipments?
A: We arrange SGS, BV, or TÜV inspections for coating thickness, adhesion, and dimensional accuracy. Export documentation includes mill test certificates with heat number traceability, packing lists, bills of lading, certificates of origin, and CE certificates for European market compliance.
Q: What is the production lead time and how do you handle container loading for different tube lengths?
A: Typical production lead times apply after drawing approval and deposit receipt. We optimize bundle sizes for 5.8 m and 6 m standard lengths to maximize container utilization, and provide professional loading plans for 6.4 m and 12 m lengths to prevent overhang damage during transit.
Q: Do you offer custom processing services such as cutting, punching, and bending for ZAM coated tubes?
A: Yes, we provide welding, punching, cutting, and bending services for ZAM coated square and rectangular tubes. All processing is performed with procedures that preserve coating integrity at cut edges, leveraging the self-healing properties of the ZAM alloy layer.
