What is the most vital step when installing a process valve?

The most vital step when installing a process valve is ensuring proper alignment and sealing of the valve with the piping system. This involves checking the flange faces for cleanliness and flatness, using appropriate gaskets, and ensuring the valve is oriented correctly for its intended flow direction. Additionally, it's crucial to torque the bolts to the manufacturer's specifications to prevent leaks and ensure optimal performance. Proper installation helps maintain system integrity and safety.