Tianjin Brisk Steel is one of the manufacturers of S355JRH Seamless Square Box Section / Seamless SHS / Seamless square tube / solid drawn square hollow section / Seamless Square Hollow Section in China. Our products are mainly exported to the Middle East, Southeast Asia, Europe, New Zealand, and other regions.If you would like to learn more about our products, feel free to contact us and send your purchase list.
Basic Definition & Standard
Applicable standard for seamless sections: EN 10210
- EN 10210-1: Technical delivery conditions, mechanical properties, and chemical composition for hot-finished hollow sections
- EN 10210-2: Dimensions, sectional properties, and tolerances
Manufacturing process: Hot rolling + hot extrusion or cold-rolling forming; seamless (no weld seam); suitable for pressure-bearing and fatigue-resistant applications
Standard for welded cold-formed square hollow sections: EN 10219
While S355JRH square hollow sections on the market are typically welded, specifying "seamless" requires the use of the EN 10210 seamless manufacturing process.
Detailed Comparative Table
| Comparison Item | Seamless S355JRH (EN 10210) | Welded S355JRH (EN 10219) |
|---|---|---|
| Weld Joint | No seam, uniform metal texture | One welding seam; potential internal defects (porosity, incomplete fusion) |
| Fatigue Resistance | Excellent, anti-crack under cyclic load | Poor; seam cracks easily with long-term vibration |
| Bearing Capacity | Higher tensile, compression & bending strength | Lower overall strength, strength drops at weld position |
| Wall Thickness Range | 3mm–40mm, thick-wall options available | Mostly thin & medium wall (1.5mm–12mm); thick wall production limited |
| Dimensional Tolerance | Class A / Class C high precision optional | Standard Class A tolerance only, harder to control seam flatness |
| Impact Toughness Consistency | Consistent impact value on all four faces | Unstable impact toughness at weld area |
| Unit Cost | Higher (complex hot extrusion process) | Lower (efficient strip rolling & welding) |
| Standard Application Field | Heavy machinery, bridge, offshore, high-rise main load-bearing parts | Light civil construction, decoration, static low-load frames |
| Certification Suitability | CE machinery certification, offshore engineering inspection | General building civil projects without strict dynamic load test |
- Pick seamless square tube if: your structure bears vibration, heavy impact, cyclic load, requires full UT inspection or long service safety guarantee.
- Pick welded square tube if: the component only bears steady static light load, no frequent shaking, and cost control is the top priority.
Scenarios to Choose Seamless SHS/RHS
- Structures bearing dynamic, cyclic or vibrating loads: Crane booms, forklift chassis, truck & trailer frames, lifting platforms, tower crane sections - Reason: Weld seams are weak points prone to fatigue cracking under repeated shaking and stress; seamless tube has uniform full-section strength.
- Heavy static load components with high compression & bending demand: Main building columns, large-span bridge supports, heavy-duty warehouse rack uprights
- Parts requiring pressure resistance or high structural safety margin: Offshore port support frames, mechanical base frames under heavy impact
- Projects with strict non-destructive testing (UT ultrasonic inspection required): EU machinery equipment certified with CE standard
- Machining parts with full perimeter force distribution: Components that need drilling, tapping or bending across all four sides
- Harsh high-stress long-service-life engineering: Wind power auxiliary supports, large mechanical equipment brackets
Scenarios to Choose Welded SHS/RHS
- Light static load structures without vibration: Factory partition frames, ordinary guardrails, billboard brackets, simple sunshades
- Cost-sensitive civil construction with low load requirement: General steel structure secondary beams, low-load municipal landscape frames
- Decorative & light architectural frames: Curtain wall keels, indoor decorative steel frames, bus stop light auxiliary supports
- Short-term temporary structures: Construction temporary scaffolding frames, temporary stage supports
- Projects with tight budget and no fatigue load risk: Small ground photovoltaic brackets under static wind load only
Diverse surface finish options to meet various needs
-
Black as-rolled: Lowest cost; suitable for subsequent painting
-
Pickled & Oiled: Smooth surface finish; preferred for machining
-
Hot-dip galvanized: Corrosion protection for outdoor use; zinc coating ≥ 85 μm
-
Pre-galvanized, clear-coated, or black-painted
FAQ
Q: What standard for S355JRH seamless square box section?
A: Seamless hollow sections comply with EN 10210, cold welded SHS follows EN 10219.
Q: What does H stand for in S355JRH?
A: H = Hollow section, specially designed for structural tube & profile.
Q: Difference between seamless and welded S355JRH square tube?
A: Seamless has no welding line, better fatigue resistance & pressure resistance for heavy dynamic loads. Welded is cheaper for light static construction.
Q: Minimum yield strength of S355JRH?
A: Min 355MPa for wall thickness ≤16mm.
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