Product Introduction
Seamless Stainless Steel Rectangular Tube are specialized structural components engineered for superior mechanical strength, corrosion resistance, and dimensional precision. These sections, available in square and rectangular configurations, are formed by cold drawing or extruding seamless steel billets, resulting in a homogenous structure without weld lines—a critical advantage over welded alternatives for high-pressure and heavy-load applications.
Austenitic stainless steel grades like 304, 316, and 310 form the core material, offering a unique combination of ductility, formability, and corrosion resistance. The seamless manufacturing process eliminates weak points, ensuring uniform wall thickness and structural integrity, while the austenitic microstructure provides inherent non-magnetic properties and excellent low-temperature toughness. These tubes are ideal for applications requiring both aesthetic appeal and functional reliability, from architectural supports to industrial machinery.
Key to their versatility is the ability to withstand diverse environmental conditions, from atmospheric corrosion in outdoor structures to chemical exposure in industrial processes. The square and rectangular geometries maximize load-bearing capacity while minimizing material usage, making them efficient choices for structural frameworks, mechanical components, and architectural elements.
Key Product Parameters
Material Grades
Dimensions & Tolerances
Mechanical Properties
| Grade | Tensile Strength | Yield Strength | Elongation | Hardness (HRB) |
| 304 | ≥515 MPa | ≥205 MPa | ≥35% | ≤90 |
| 316 | ≥515 MPa | ≥205 MPa | ≥35% | ≤90 |
| 310S | ≥515 MPa | ≥205 MPa | ≥35% | ≤90 |
| 2205 | ≥655 MPa | ≥450 MPa | ≥25% | ≤290 HBW |
Surface Finishes
Standard Finishes:
Pickled & Annealed: Removes scale, ideal for general corrosion resistance.
Brushed: Uniform matte surface for architectural applications.
Special Finishes:
Polished (Grit 120–600): Smooth surface for aesthetic or hygienic needs.
Mirror Polished: Ra ≤0.2 μm for high-gloss architectural elements.
Electropolished: Enhanced corrosion resistance for medical/ food-grade use.
Manufacturing & Testing
Process Flow:
Hot-rolling of billets into hollow shells.
Cold-drawing/extrusion to achieve precise dimensions.
Solution annealing to restore ductility.
Surface treatment (pickling, polishing).
Quality Control:
100% dimensional inspection (OD, wall thickness, straightness).
Non-destructive testing (Eddy Current, Ultrasonic) for internal defects.
Hydrostatic pressure testing (1.5× design pressure) for pressure-bearing tubes.
Application Scenarios
Architectural & Structural
Building Frames: Columns, beams, and trusses in commercial buildings, bridges, and stadiums.
Decorative Elements: Handrails, balustrades, and facade supports in architectural designs.
Interior Design: Furniture frames, partition systems, and decorative accents.
Industrial Machinery
Mechanical Components: Machine supports, guide rails, and structural frames in manufacturing equipment.
Conveyor Systems: Rollers and support structures in material handling systems.
Agricultural Equipment: Frames for tractors, harvesters, and processing machinery.
Marine & Offshore
Offshore Platforms: Structural supports and walkways in coastal and offshore installations.
Marine Vessels: Hull frames, deck structures, and railing systems.
Desalination Plants: Seawater-resistant components in desalination equipment.
Transportation
Automotive Industry: Chassis frames, exhaust systems, and structural components.
Railway Vehicles: Train car frames, bogie supports, and interior structures.
Aerospace: Non-magnetic brackets and lightweight structural parts.
Energy & Utilities
Renewable Energy: Wind turbine support structures and solar panel frames.
Power Plants: Cooling system components and structural supports in thermal plants.
Pipeline Infrastructure: Support frames for above-ground pipelines.
FAQ (Frequently Asked Questions)
Q: What is the difference between seamless and welded square pipes?
A: Seamless pipes are formed from a single billet, eliminating weld lines for uniform strength and corrosion resistance. Welded pipes have a seam that may require additional treatment, making seamless pipes preferable for high-pressure or critical applications.
Q: Can rectangular tubes be customized for specific dimensions?
A: Yes, rectangular tubes can be custom-fabricated to specific width-to-height ratios and wall thicknesses, including non-standard sizes not listed in standard specifications.
Q: How do austenitic stainless steel tubes perform in marine environments?
A: Grades like 316L offer good resistance to seawater, but for extreme marine conditions, duplex stainless steels (e.g., 2205) or nickel alloys (e.g., Monel 400) are recommended for superior chloride resistance.
Q: What surface finishes are suitable for outdoor architectural applications?
A: Brushed or pickled finishes are ideal for outdoor use, as they balance corrosion resistance with aesthetic appeal. Mirror-polished finishes require more maintenance but offer a premium look.
Q: Can these tubes be used in high-temperature applications?
A: Yes, grades like 310S and nickel alloys withstand temperatures up to 1200°C, making them suitable for furnace components and high-temperature structural parts.
Q: What is the lead time for custom-sized orders?
A: Standard sizes are available within 2–4 weeks. Custom dimensions or special finishes typically require 6–8 weeks, including manufacturing, testing, and certification.
