Which code section specifies requirements for piping in chemical process plants?

The reference to B31.3 as the correct answer is based on its specific focus on process piping, which includes requirements applicable to piping systems in chemical process plants. The B31.3 code outlines the design, materials, fabrication, assembly, installation, examination, and testing of piping systems that handle various chemicals in a plant setting. This includes providing guidance on safety, operation, and maintenance to ensure that the piping systems function effectively in managing the flow of chemical substances.

In contrast, the other options pertain to different contexts within piping standards. For instance, B31.5 relates to refrigerant piping, while B31.7 addresses piping for nuclear facilities, and B31.9 is focused on the piping for industrial and commercial buildings. Each of these codes has its specific application, making B31.3 the appropriate choice for chemical process plants due to its comprehensive coverage of the unique requirements and considerations relevant to those environments.