Flange Dimensions

Allowable pressure by material, class and temperature, and flange tables of ASME B16.5, B16.47, EN 1092-1, GB/T, HG/T and NB/T

Flange Dimensions

Look up data for pipe flanges and pressure vessel flanges. Every table shows the standard, its year and the table it comes from. The library covers:

  • ASME B16.5-2025 (NPS ½ to 24, Class 150 to 2500): material groups and bolting materials, pressure-temperature ratings for each material group, facings and ring grooves, drilling templates and flange dimensions
  • ASME B16.47-2025 (NPS 26 to 60, Series A and Series B, Class 75 to 900): materials and ratings, ring-joint facings, permissible facing imperfections, flange dimensions and recommended bolting
  • EN 1092-1:2018 (DN 10 to 4000, PN 2.5 to 400): flange types, sealing faces, dimensions for each PN, limit deviations, the wall thickness tables of Annex A, material groups and the pressure-temperature ratings of each PN, approximate masses, rings for grooved flanges, fixed bore flanges and connection dimensions for large DN
  • GB/T 9124.1-2019 (DN 10 to 4000, PN 2.5 to 400): pipe outside diameters (series I and II), flange types and sealing faces, the dimensions of each flange type for each PN, flange steels and the pressure-temperature ratings of 12 PN classes in MPa, tolerances, masses and pipe schedules. The standard says its dimensions are interchangeable with EN 1092-1:2018.
  • GB/T 9124.2-2019 (NPS ½ to 24, Class 150 to 2500): sealing faces, the seven flange types, 24 material groups with their pressure-temperature ratings in MPa, tolerances, masses and pipe schedules. There is no Class 400 and no NPS 3½. The standard says its dimensions are interchangeable with ASME B16.5.
  • GB/T 13402-2019 (NPS 26 to 60, Series A and Series B, Class 75 to 900): dimensions, 22 material groups with their ratings in MPa, tolerances, masses and pipe schedules. The standard says its dimensions are interchangeable with ASME B16.47.
  • HG/T 20592-2009 (DN 10 to 2000, PN 2.5 to 160): steel pipe flanges of the PN series — types and sealing faces, materials, pressure-temperature ratings for each PN, connection and flange dimensions, weld joints, tolerances, orifice and jacketed flanges, and masses
  • HG/T 20615-2009 (NPS ½ to 24, DN 15 to 600, Class 150 to 2500): steel pipe flanges of the Class series — types and sealing faces, materials, ratings for each material group in bar, flange dimensions, tolerances, orifice and jacketed flanges, bores, masses and ring-joint distances
  • HG/T 20623-2009 (NPS 26 to 60, DN 650 to 1500, Series A and Series B, Class 150 to 900): large diameter steel pipe flanges — sealing faces, dimensions, tolerances and masses. Its ratings are those of HG/T 20615.
  • NB/T 47020 to 47026-2012 (pressure vessel flanges, DN 300 to 3000, PN 0.25 to 6.4 MPa): Type A and Type B slip-on welding flanges and long weld neck flanges, their materials and maximum allowable working pressures, and the matching nonmetallic, spiral wound and double-jacketed gaskets

Four ways in (switch at the top of the left panel):

  • Allowable pressure — type a material (for example A105, Q345R or P250GH), then pick the standard, the pressure class and the temperature. You get the maximum allowable working pressure at that temperature, with the table it comes from, how the value was found, the temperature limits of the material and a pressure-temperature curve. Values are interpolated only where the standard allows it. Where the standard does not say how to treat a temperature between two table columns, the value at the next higher table temperature is used, and the result says so. For NB/T 47020, also pick the flange type (Type A, Type B or long weld neck). You can add a second flange material; the lower value applies.
  • By standard — pick a standard, then a group of tables (materials, ratings, facings, dimensions, other), then a table. The whole table is shown with the meaning of each column, footnotes and row notes. ASME ratings are chosen by material group, in SI and US customary units. EN 1092-1 has one rating table per PN, so you choose the steel type (non-austenitic, or austenitic and duplex) and then the PN. GB/T 9124.1 also has one rating table per PN; GB/T 9124.2 and 13402 give ratings by material group, in MPa. Each standard page also shows what the standard says about interchangeability with another standard. Pressure vessel flanges (NB/T 47020 to 47026) are listed as a separate group after the pipe flanges.
  • By size — pick the system (Class or PN), the class or pressure, and the size (NPS or DN). You get the rows for that size only: drilling template and dimensions in SI and US customary units, sealing face and ring groove rows, recommended bolting, and the pressure-temperature ratings. For a Class size you pick a material group and the column for your class is highlighted. For a PN size you get the rating tables of that PN (for EN 1092-1: non-austenitic, and austenitic and duplex steels) and can narrow them to one material group. A size that exists in both a European or ASME standard and a Chinese standard shows the tables of both, the Chinese ones after the other, so you can compare them side by side.
  • Search — find ASME B16.5 and B16.47 flange sizes by keyword, pressure class or a minimum outside diameter. Search covers the ASME flanges only.

The values are those of the standard. Only the Allowable pressure page interpolates, and only where the standard allows it.

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