What is the O.D (outside diameter) of a 14" nominal pipe size?

The outside diameter (O.D.) of a 14" nominal pipe size is actually 14 inches. In plumbing and piping, "nominal" sizes refer to standardized dimensions that may not reflect the actual physical measurements of the pipe. For a 14-inch nominal pipe, the O.D. is designated at 14 inches to maintain consistency with other nominal sizes within the piping system.

Understanding nominal sizes is crucial for pipefitters and installers, as it allows for compatibility with flanges, fittings, and other components that are designed to match nominal pipe sizes. It's important to note that while the O.D. of some nominal sizes does match the nominal inch measurement, it doesn't apply to most other nominal sizes, such as those less than 14 inches, which often have a smaller O.D. than their nominal size would suggest.