Which of the following best describes a vertical pipe?

A vertical pipe is indeed best described as one that is positioned at an angle of 45° or more with respect to the horizontal plane. This description captures the essence of what defines a vertical orientation in plumbing contexts. When installing plumbing systems, maintaining the proper orientation of pipes is crucial for ensuring effective drainage, pressure management, and overall system performance.

In plumbing, vertical pipes are used in various applications, such as venting or in vertical risers. Their alignment affects the flow of fluids and gas, which is why understanding their orientation in relation to horizontal planes is key for any plumbing professional.

The other descriptions do not adequately capture the characteristics of a vertical pipe. A pipe running parallel to the ground would be horizontal, while a pipe that is bent to curve does not specifically relate to its vertical orientation. Lastly, a pipe with no slope is typically horizontal and would not be classified as vertical in any context. Thus, the identification of a vertical pipe as one set at an angle of 45° or more recognizes its critical role in plumbing configurations.