How are mechanical components tested against requirements in critical systems? What is the process for changing those components, like upgrading pipes to a fanc

How are mechanical components tested against requirements in critical systems? What is the process for changing those components, like upgrading pipes to a fancy new composite? In my mind, we'll start treating silicon the same way... formal verification, rigorous real-world testing, trusted suppliers, and an expectation that change is slow, expensive, and risky.