Seamless square and rectangular tubes are long steel bars with hollow cross-sections that have no seams along their perimeters. The interior is hollow, with a specified cross-sectional area, and are extensively used as pipelines for conveying fluids, such as oil, gas, water, and certain solid materials. The circular cross-section distributes stress more evenly when subjected to internal or external radial pressure, which is why the vast majority of steel tubes are circular. However, circular tubes also have limitations, particularly under plane bending conditions, where they are not as strong as square or rectangular tubes. As a result, square and rectangular tubes are commonly used in structures like agricultural machinery frames and steel-wood furniture.