Final answer:
The American Society of Mechanical Engineers (ASME) governs the metal specification of steam piping in power plants, setting codes and standards to ensure safety in the engineering field.
Step-by-step explanation:
The regulatory body that governs the metal specification of steam piping used in a power plant is the American Society of Mechanical Engineers (ASME). ASME is renowned for developing codes and standards for the mechanical engineering profession, including the construction of boilers and pressure vessels, to ensure safety and efficiency in power plants. The ASME codes and standards are considered a leading authority for mechanical and multidisciplinary engineering practices globally. Established in the late nineteenth century, the ASME played a crucial role in enhancing the status of the engineering profession and establishing educational standards in collaboration with colleges and universities. Today, ASME's commitment continues in the promotion of the art, science, and practice of mechanical engineering.