What is the outside diameter (O.D.) of a nominal 6" pipe?

The outside diameter (O.D.) of a nominal 6-inch pipe is accurately described as 6 5/8 inches. This measurement reflects the standardized sizing used in the pipe industry, where the nominal size refers to a category that does not directly correlate to the actual physical dimensions of the pipe. Instead, the nominal size is a label that represents the approximate internal diameter, while the O.D. is influenced by the wall thickness, which changes based on the type and schedule of the pipe.

In the case of a nominal 6" pipe, it is common within the industry to standardize the outside diameter at 6 5/8 inches. This standardization ensures compatibility with fittings, flanges, and other components designed for this pipe size, enabling a consistent and reliable approach when working on piping systems.