Ultimate tensile strength designed into an object must be:

Ultimate tensile strength is a critical property of materials used in engineering applications, especially in contexts such as pressure vessels, structural elements, and machinery components. It represents the maximum amount of tensile (stretching) stress a material can withstand before failure.

When designing an object, the ultimate tensile strength must be greater than the allowable working stress to ensure safety and reliability. The allowable working stress is derived from the ultimate tensile strength, usually using a safety factor to account for uncertainties such as material defects, unexpected loads, or environmental conditions. This safety factor ensures that the material can handle operational demands without undergoing plastic deformation or failure.

By having the ultimate tensile strength be greater than the allowable working stress, engineers create a margin of safety, allowing for unexpected stresses during operation. This practice is crucial in ensuring that components remain functional over their intended lifespan, preventing risks that could arise from material failure. Thus, ensuring that ultimate tensile strength exceeds the allowable working stress is a fundamental aspect of sound engineering design.