A correspondence table inches ” / millimeter (mm) is of interest in the case of mechanical coupling of different piping elements (PE water irrigation pipes, pvc pipes, steel pipes, brass or copper ducts, meters, etc) via plumbing elements (flexible captive nut, nipple pipe fitting, fittings, etc..)
The table below allows you to obtain the correspondence between the name – or common name – in inches (conventionally used in the field of plumbing), name in millimeters (∅ inside x ∅ outside) or even the the DN designation – Nominal Diameter – (inside or outside diameter of a tube in mm depending on the case).
The most common are mentioned in bold. For specific dimensions see the detailed table.
The most common dimensions for individual housing are the 12 x 17, le 15 x 21, le 20 x 27.
(*) NB: the « DN » must be distinguished from the normative and commercial sense that sometimes differ. According to the EN ISO 6708 standard the DN corresponds to the inside diameter of a pipe expressed in mm (ex: DN10 = inside ∅ of 6 mm). However, in retail, wholesale and distribution, the DN is often used to indicate the outside diameter of the pipes. As it is confusing it’s better to know if we are talking about the inside or outside diameter.
>> See the applicable sealing types according on the types of fittings