If a stay exceeds 120 times its diameter, what support requirement applies?

When a stay exceeds 120 times its diameter, it indicates that the length of the stay is significantly greater than its cross-sectional size. In such situations, engineering principles dictate that support is needed to ensure structural integrity and prevent potential issues such as sagging or bending due to load and other external forces.

The guideline specifying support every 120 diameters originates from best practices in mechanical engineering standards. When stays are very long relative to their diameter, it is essential to maintain their stability and prevent deformation. Therefore, providing support at intervals of every 120 diameters is a precautionary measure that helps distribute loads evenly, thereby avoiding excessive stress concentrations on the stay.

This standard aligns with practices established within codes and guidelines that dictate how to manage the support of structural components, specifically those that are elongated in nature. By adhering to this requirement, engineers can ensure the longevity and reliability of the systems they are designing. The other choices do not align with these established guidelines, which is why the interval of support is specifically set at 120 diameters in this case.