What is the definition of the Factor of Safety?

The Factor of Safety (FoS) is a crucial concept in engineering, particularly in fields involving pressure vessels and structural engineering. It serves as a measure of how much stronger a system is than it needs to be for an intended load.

The correct answer emphasizes the relationship between the bursting pressure, the maximum internal pressure a vessel can withstand before failure occurs, and the working pressure, which is the maximum pressure that is intended to be experienced during normal operation. This ratio helps ensure that systems are designed with a sufficient margin to avoid failure even in adverse conditions or unexpected loads.

In practice, a high Factor of Safety indicates that the design has a significant buffer beyond its normal operating conditions, thereby enhancing reliability and safety. The other definitions listed either do not address this critical boundary of safe operational limits or focus on different aspects of design and performance that are not directly comparable to the concept of the Factor of Safety. By understanding this ratio, engineers can make informed choices about materials, design, and operational parameters, ensuring safety and longevity in their engineering projects.