Description
Factory-Direct Pre-Galvanized RHS — ASTM A53 GrB welded rectangular tubes produced in-house with full mill test certificates and third-party inspection support.
Technical Specifications
| Parameter | Value |
|---|---|
| Designation | ASTM A53 GrB Pre Galvanized Welded Rectangular Steel Tube |
| Product Type | Welded Rectangular Steel Tube / RHS |
| Steel Grade | Gr.B, S235, S275, S355, STK400, A53-A369 |
| Standard | ASTM A500, ASTM A53, GB/T 3091 |
| Section Shape | Rectangular |
| Size Range | 15mm×20mm – 700mm×800mm |
| Wall Thickness | 1 – 30 mm |
| Length | 5.8m / 6m / 11.8m / 12m / Random Length |
| Technique | ERW / Welded |
| Surface Treatment | Pre Galvanized / Black Painting / Varnish / Bare |
| Tolerance | ±10% |
| Ends | Plain End |
| Application | Steel structures, Construction frames, Curtain wall framing, Support tubes, Building structures |
| MOQ | 1 Ton |
| Origin | China |
Application Suitability
| Industry | Typical Applications |
|---|---|
| Commercial Construction | Building frames, curtain wall supports, roof trusses |
| Infrastructure | Scaffolding systems, bridge handrails, sign gantries |
| Industrial Facilities | Machinery frames, conveyor structures, equipment supports |
| Steel Fabrication | Column sections, beam-to-column connections, purlin systems |
Zinc Coating Consistency Determines Whether Your Shipment Passes Site Inspection
Pre-galvanized ERW rectangular tubes must deliver uniform zinc thickness across every face — corners included — or the entire batch fails acceptance testing.
Buyers sourcing pre galvanized welded rectangular steel tube products often discover coating inconsistencies only after the container reaches the job site. A coating gauge reading below contract specification triggers full-batch rejection, and replacing 20 tons of RHS means weeks of delay on a tight construction schedule. Beyond coating thickness, weld seam quality on ERW tubes directly affects zinc adhesion — poor seam preparation leads to peeling within months of installation. Dimensional tolerance drift on wall thickness compounds the problem: tubes arriving at the lower end of ±10% may technically pass but reduce load-bearing margin on structural frames. [NEED_CITE: pre-galvanized vs hot-dip galvanized coating thickness comparison]
Matching Wall Thickness and Grade to Structural Load Requirements
Pre galvanized welded rectangular steel tube in Gr.B through S355 grades covers the full spectrum from light-duty curtain wall framing to primary structural columns. The 1–30mm wall thickness range across 15×20mm to 700×800mm sections means a single supplier can furnish both secondary purlins and main load-bearing members under one purchase order. For curtain wall contractors, smaller sections with thinner walls provide the sharp aesthetic lines required for architectural facades while maintaining corrosion resistance from the pre-galvanized surface. Heavy-wall sections in S355 grade serve machinery manufacturers building equipment frames that must withstand dynamic loading without deflection.
Engineering Compliance and Certification for Cross-Border Procurement
Structural hollow sections exported to EU markets require CE marking under EN 10210 or EN 10219 — a documentation gap that blocks customs clearance regardless of physical quality. ASTM A53 GrB tubes destined for North American projects must conform to dimensional and chemical requirements specified in the standard, with mill test certificates traceable to heat numbers. [NEED_CITE: EN 10219 cold-formed structural hollow section compliance requirements] Fabricators in Southeast Asia and the Middle East frequently request dual-certified material meeting both ASTM and EN grade equivalences, reducing the need for separate procurement streams. Plain-end delivery allows on-site cutting and welding without end-preparation delays, while the ±10% tolerance band aligns with standard fabrication allowances for bolted and welded connections.
Understanding ERW Welding and Pre-Galvanized Surface Treatment
ERW (Electric Resistance Welding) forms rectangular sections by rolling steel strip into shape and welding the seam through electrical resistance — a process that delivers consistent wall thickness and tight dimensional tolerance across long production runs. Pre-galvanizing applies the zinc coating to the steel strip before forming and welding, ensuring uniform coverage on all surfaces including the interior bore. This differs from hot-dip galvanizing, where formed tubes are immersed in molten zinc, creating a thicker but less uniform coating that can pool at corners. [NEED_CITE: pre-galvanized strip coating uniformity vs post-galvanizing] Steel grade selection follows project engineering specifications: Gr.B and S235 serve general construction, S275 provides intermediate strength for loaded frames, and S355 delivers higher yield capacity for heavy structural applications. STK400 meets JIS requirements for Japanese-specification projects across Southeast Asia.
Hidden Costs of Incorrect Grade Selection and Missing Documentation
Ordering S235 when the structural engineer specified S355 means the tubes cannot carry the design load — and replacement requires demolishing installed sections, not just swapping stock. Missing CE certificates on a pre galvanized welded rectangular steel tube shipment to Rotterdam means the container sits at port while the buyer scrambles for retroactive documentation, incurring demurrage charges that exceed the material cost. [NEED_CITE: steel grade equivalence between ASTM and EN standards] Coating thickness below contract minimum passes mill inspection but fails site testing, forcing the buyer to either reject the shipment or accept reduced corrosion life — neither option avoids project delay.
Why Buyers Source ASTM A53 GrB RHS from Xin Jiyuan
Our 3 production lines cover 2,800+ specifications, meaning your 700×800mm heavy-wall section and your 15×20mm curtain wall tube ship from the same facility under one quality system. The in-house physical and chemical laboratory tests every heat for composition and mechanical properties before release, with results documented on EN 10204 3.1 mill test certificates. Full CE certification under EN 10210 and EN 10219 supports EU customs clearance, while SGS and BV third-party inspection is arranged on request for projects requiring independent verification. Our patented sharp-corner rectangular tube technology — holding 41 invention patents — delivers true right-angle corners for architectural applications where standard rounded-corner RHS creates visible gaps at connections. Professional container loading with anti-damage measures prevents the bending and surface scratches that plague improperly stowed tube shipments.
Documentation & Compliance
- Mill test certificate documenting Gr.B chemical composition and mechanical properties per ASTM A53, traceable to heat number
- CE certificate under EN 10210/EN 10219 for pre galvanized welded rectangular steel tube exported to EU member states
- ISO 9001:2015 quality management certificate covering ERW welding, galvanizing, and dimensional inspection processes
- SGS or BV third-party inspection report verifying coating thickness, dimensional tolerance, and surface quality
- Material traceability by heat number linking each tube to its original steel coil test results
- Customs documentation including packing list, bill of lading, and certificate of origin for destination clearance
Packaging, Loading & Delivery
- Pre galvanized rectangular tubes bundled with steel strips and edge protectors to preserve zinc coating during ocean transit
- 5.8m and 6m lengths loaded in stacked tiers with timber separators to prevent contact damage between layers
- 11.8m and 12m lengths shipped in open-top containers or flat racks with lashing points secured at four corners
- Custom cutting to project-specified lengths available, with cut ends deburred and touched up with zinc-rich paint
- Heat number and steel grade stenciled on each tube for site identification and traceability verification
- FOB, CIF, and DDP shipping terms available with professional container loading plans optimized for 20ft and 40ft units
Start Your Procurement with Complete Technical Documentation
Submit your dimension schedule, steel grade requirement, quantity, and destination port to receive a detailed quotation including unit pricing, production lead time, and available mill test certificates. For non-standard sizes outside the 15×20mm to 700×800mm range, our engineering team provides custom fabrication options with confirmed delivery schedules.
Request Your ASTM A53 GrB RHS Quotation
Send your specifications to admin@sdxjypipe.com or contact us via WhatsApp at +86 188 5315 7756 for pricing and certification details.
Frequently Asked Questions
Q: What is the difference between pre-galvanized and hot-dip galvanized rectangular tubes?
A: Pre-galvanized tubes receive zinc coating on the steel strip before forming, resulting in uniform thickness across all surfaces including the interior. Hot-dip galvanized tubes are coated after forming, producing thicker but less uniform coverage that may pool at corners. Pre-galvanized offers better dimensional accuracy and smoother surface finish for architectural applications.
Q: Can you supply ASTM A53 GrB tubes with CE certification for EU projects?
A: Yes. Our pre galvanized welded rectangular steel tube production carries CE marking under EN 10210 and EN 10219, meeting EU construction product regulation requirements. We provide both ASTM and EN documentation for projects requiring dual compliance.
Q: What is the minimum order quantity for custom non-standard sizes?
A: Standard sizes from 15×20mm to 700×800mm with 1–30mm wall thickness are available from 1 Ton MOQ. Custom non-standard dimensions require production runs with higher minimum quantities depending on section size and wall thickness.
Q: How do you ensure zinc coating thickness meets contract requirements?
A: Every tube undergoes coating thickness measurement using calibrated gauges at multiple points per piece. Results are documented in the mill test certificate and available for third-party verification by SGS or BV before shipment.
Q: Do you provide third-party inspection before shipment?
A: Yes. SGS and BV inspection services are arranged on request, covering dimensional verification, coating thickness measurement, visual surface inspection, and documentation review prior to container loading.
