What is the purpose of small holes drilled in the ends of stay bolts?

The small holes drilled in the ends of stay bolts serve the purpose of detecting leaks or cracks. These holes allow for the inspection of potential failures in the bolt or the surrounding structural components. By enabling visual or physical checks for signs of leakage, such as moisture or air escaping, maintenance personnel can identify issues before they lead to more significant problems. This preventative measure is crucial in high-pressure or high-temperature systems, where the integrity of the bolts and the structures they support is vital for safe operation.

In contexts where other options are considered, increasing airflow or enhancing structural integrity does not directly apply since these functions are not the primary intent of having holes in stay bolts. Additionally, while maintenance may benefit indirectly from this design, the main role of the holes is related to monitoring the condition of the bolts and the structures they secure.