New Mexico Pipe Fitter Journeyman (JPF) Practice Exam

In terms of pipe sizes above 12 inches, what does the outer diameter (OD) correspond to?

1. The nominal size

2. The internal diameter

3. The standard gauge

4. The wall thickness

The correct answer is: The nominal size

The outer diameter (OD) of a pipe that is larger than 12 inches directly corresponds to the nominal size of the pipe. Nominal size is a standardized designation that provides a reference for the dimensions of the pipe, which typically includes the outer diameter for larger pipes. This is especially relevant in contexts where pipes are often referred to by their nominal sizes, reflecting their intended use and standardization across various applications. For pipes above 12 inches, the nominal size generally aligns closely with the OD, making it easier for professionals in the industry to identify and select the correct pipe fittings and components without needing to measure every individual pipe. The concept is fundamental in plumbing and piping systems, where consistency in dimensions allows for efficient planning and installation. The other choices, such as internal diameter and wall thickness, represent different aspects of pipe dimensions and serve specific purposes, but they do not define the relationship of the outer diameter to the nominal size, particularly in larger pipes. Thus, understanding that the OD reflects the nominal size is crucial for accurate identification and implementation in piping systems.