Which of the following is NOT a required characteristic of pipe ends?

The characteristic that is NOT required for pipe ends is undercut edges. In mechanical construction, and specifically within the context of piping systems, pipe ends must typically ensure proper flow and connectivity. A full-bore opening is essential for allowing maximum flow through the system, while being free of burrs and obstructions prevents any hindrance to fluid movement and helps in maintaining system integrity. Chamfered ends are often preferred to facilitate easier joining of pipes and to ensure a smooth transition, which helps in maintaining fluid flow and minimizing turbulence.

On the other hand, undercut edges, while they might serve certain purposes in specific applications, are not generally a required characteristic for pipe ends. Instead, the primary focus is on ensuring that the pipe ends allow for smooth connections and efficient fluid transport. Thus, the absence of a requirement for undercut edges aligns with standard practices in piping, which prioritize optimal flow characteristics and ease of installation.