Mild steel rectangular tube that is designated as “structural” typically refers to rectangular tubes that are used for structural purposes, such as in building and construction applications where strength and stability are critical. These structural mild steel rectangular tubes are commonly made from low carbon steel and are designed to support heavy loads and resist deformation under various loads and stresses.

Some key features of mild steel rectangular tubes used for structural purposes include:

1. High Strength: Structural mild steel rectangular tubes are designed to have high strength properties to withstand heavy loads and resist deformation.
2. Structural Stability: Mild steel rectangular tubes used for structural applications are designed to provide stability and support to the structures they are used in, such as building frames, bridges, and other load-bearing structures.
3. Ductility: Mild steel rectangular tubes used for structural purposes typically have good ductility, allowing for easy bending, forming, and shaping to meet specific design requirements.
4. Versatility: Structural mild steel rectangular tubes can be used in a wide range of applications, such as in building frames, bridges, infrastructure, and other structural applications.
5. Cost-effective: Mild steel rectangular tubes used for structural purposes are generally more cost-effective compared to other higher alloy steels, making them a practical choice for many structural applications.
6. Weldability: Mild steel rectangular tubes used for structural purposes typically have good weldability properties, allowing for easy welding using common welding methods, such as MIG, TIG, or stick welding.
7. Machinability: Mild steel rectangular tubes used for structural purposes usually have good machinability, making them easy to machine into desired shapes and sizes for different structural applications.
8. Availability: Mild steel rectangular tubes used for structural purposes are readily available in various sizes, wall thicknesses, and lengths, making them convenient for use in different structural projects.

It’s important to note that proper engineering and design considerations, including load calculations and adherence to local building codes, should be taken into account when specifying and using mild steel rectangular tubes for structural applications to ensure the safety and performance of the overall structure. Additionally, depending on the application and environmental conditions, surface treatment or coating may be required to provide additional corrosion resistance.