New Mexico Pipe Fitter Journeyman (JPF) Practice Exam

What does the outer diameter (OD) of a flat ring gasket correspond to?

1. Diameter of the outer pipe

2. Diameter of the bolt holes

3. Thickness of the gasket

4. Width of the pipe

The correct answer is: Diameter of the bolt holes

The outer diameter (OD) of a flat ring gasket corresponds to the diameter of the outer pipe. This measurement is essential because the gasket must fit properly between flanges or connections, ensuring a proper seal. The OD defines the area where the gasket makes contact with the flange, preventing leaks of the fluid or gas contained within the pipe system. A correct fit ensures the effectiveness of the sealing surface and maintains the integrity of the piping system under pressure. The other options pertain to different aspects that are not direct measurements related to the gasket's sealing capability: the diameter of the bolt holes is associated with the hardware used to secure the flanges rather than the gasket itself, the thickness of the gasket refers to how much space it occupies in the assembly which is crucial for compression but not directly related to the OD, and the width of the pipe pertains to the internal diameter which is not directly relevant to the gasket's outer dimensions. Understanding these different measurements and their specific functions helps in selecting the right gasket for the type of flanged joint being used.