Click any size in the table on the right to jump straight to it.
Pipe and flange dimensions are not universal — they depend on which engineering standard a project follows. ASME/ANSI B36.10M and B36.19M (used mainly in North America and oil & gas projects worldwide) define pipe outside diameters and wall thicknesses by Schedule (SCH 40, SCH 80, XS, XXS, etc.), while EN 10220 (the European/DIN standard) uses DN (nominal diameter) with preferred wall-thickness series instead. The two systems match exactly above DN80/NPS 3", but diverge below that — for example, DN65 measures 76.1 mm while the nearest ASME size, NPS 2½", measures 73.0 mm. Mixing components from both standards on the same line without checking this can cause a misfit at the flange face.
Flanges follow the same split: ASME B16.5 defines pressure ratings by Class (150, 300, 600, 900, 1500), while EN 1092-1 (formerly DIN 2501/2502/2503) rates flanges by PN (nominal pressure in bar). A Class 150 flange and a PN16 flange are not interchangeable — they differ in outside diameter, bolt circle diameter, and bolt pattern, even when the nominal bore is the same.
Choose Pipe Schedule or Flange at the top, then pick your standard (ASME/ANSI or EN/DIN), your nominal size, and your schedule or pressure class. The diagram and spec list update instantly with outside diameter, wall thickness, inside diameter (for pipe) or bolt circle diameter, bolt count and bolt size (for flanges) — all in millimetres, with inch equivalents alongside. The table below the diagram lets you compare every schedule or class for the same nominal size at a glance, and clicking any row jumps straight to it.
NPS (Nominal Pipe Size) is the North American sizing convention, expressed in inches, used with ASME/ANSI standards. DN (Diamètre Nominal) is the metric equivalent used with EN/ISO standards. They are approximately, but not always exactly, related — this tool shows both side by side to avoid mismatches.
Not directly. Even though Class 150 and PN16/PN20 are often quoted as roughly equivalent pressure ratings, their outside diameter, bolt circle diameter, and bolt hole pattern differ, so the bolt holes will not line up. A compatible adapter or spool piece is required to join the two standards.
The values here are drawn from the published ASME B36.10M/B16.5 and EN 1092-1/EN 10220 tables and cross-checked against multiple mill references, but this tool is intended as a quick reference. Always verify against the current edition of the relevant standard before fabrication, procurement, or installation — standards are periodically revised.