Types of Square and Rectangular Tubes

Square pipe classified by production process: hot rolled seamless square pipe, cold drawn seamless square pipe, extruded seamless square pipe, welded square pipe.

Welded square pipe classification by welding process:

1. By Process:

- Arc-welded square tubes

- Resistance welded square tubes (high-frequency, low-frequency)

- Gas-welded square tubes

- Furnace-welded square tubes

2. By Weld Seam:

- Straight seam welded square tubes

- Spiral welded square tubes

Classification by Material:

- Plain carbon steel square tubes: Q195, Q215, Q235, SS400, 20# steel, 45# steel, etc.

- Low alloy steel square tubes: Q345, 16Mn, Q390, ST52-3, etc.

Classification by Production Standard:

- National Standard (GB)

- Japanese Standard (JIS)

- British Standard (BS)

- American Standard (ASTM)

- European Standard (EN)

- Non-standard

Classification by Production Process:

- Hot-rolled seamless square tubes

- Cold-drawn seamless square tubes

- Extruded seamless square tubes

- Welded square tubes

Classification by Cross-Section Shape:

1. Simple Cross-Sections:

- Square tubes

- Rectangular tubes

2. Complex Cross-Sections:

- Flower-shaped tubes

- Open-shaped tubes

- Corrugated tubes

- Special-shaped tubes

Classification by Surface Treatment:

- Hot-dip galvanized square tubes

- Electro-galvanized square tubes

- Oiled square tubes

- Pickled square tubes

Classification by Usage:

- Decorative square tubes

- Square tubes for machine tool equipment

- Square tubes for the machinery industry

- Square tubes for the chemical industry

- Square tubes for steel structures

- Square tubes for shipbuilding

- Square tubes for automobile manufacturing

- Square tubes for steel beams and columns

- Special-purpose square tubes

Classification by Wall Thickness:

- Ultra-thick wall square tubes

- Thick wall square tubes

- Thin wall square tubes

Mechanical Properties:

- Plasticity: The ability of a metal material to undergo plastic deformation without damage under load.

- Hardness: A measure of a metal material's resistance to deformation. Common methods include Brinell hardness (HB), Rockwell hardness (HRA, HRB, HRC), and Vickers hardness (HV).

- Fatigue: The mechanical property of metals under cyclic loads.

- Impact Toughness: The ability of a metal to resist damage under impact loads.

- Strength: The ability of a metal to resist failure (excessive plastic deformation or fracture) under static loads, including tensile strength, compressive strength, bending strength, and shear strength. Tensile strength is commonly used as a basic indicator.

This overview provides a detailed classification of square and rectangular tubes, their production processes, materials, standards, cross-sections, surface treatments, and mechanical properties.