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Nominal Size ("DN")

Nominal Size ("DN")

Nominal Size is a numerical designation of size that is common to all components in a piping system, other than components, designated by outside diameters or by thread size.

NOTE: The nominal size is designated by DN followed by a number. The nominal size cannot be measured, and should not be used for the purposes of calculation. It should be noted that not all piping components are designated by nominal size; for example, steel tubes are designated and ordered by outside diameter and thickness. It is a convenient round number for reference purposes and is loosely related to manufacturing dimensions.


In preparing this definition, we have drawn from various sources including Legislation, Codes, Standards and industry information, research and knowledge.  Like the english language, these definitions may subtly change from time to time. As such these definitions are provided solely on the basis that users will be responsible for making their own assessment of the definition and and are advised to verify all relevant representations, statements and information.