This flange rating calculator contains p/T ratings of frequently used austenitic and ferritic-austenitic materials. It is based on Annex G of the harmonised standard EN 1092-1. The temperature-dependent strength values of the forged materials according to EN 10222-5 were taken as a basis (different product thickness ranges of the forged products were also taken into account).

Other flange materials can be calculated on the basis of Annex F of this standard, taking into account temperature-dependent strength values of the material standards.

The p/T ratings  are  calculated  by  using  the  strength  values  of  steel  forgings  and  are  verified  for  flat  steel  products of the same group.

Using standard flanges for pressure vessels and industrial piping without calculation 

EN 13445-3 clause 11.4.2 and EN 13480-3 annex D clause D.4.2  stated: Flanges (but without main pressure bearing flanges) that conform to an European Standard for pipework flanges may be used as pressure vessel components and industrial piping without any calculation,

provided all the following conditions are fulfilled:

• a) Under normal operating conditions, the calculation pressure does not exceed the rating pressure given in the tables of the relevant European Standard, for the flange and material under consideration for the calculation temperature.
• b) Under testing conditions or exceptional conditions, the calculation pressure does not exceed 1,5 times the rating pressure given in the same tables, at appropriate temperature.
• c) The gasket is one of those permitted  for the relevant PN or Class series.
• d) The bolts are of a strength category at least equal to the minimum required by Table 11.4-1 as a function of the gasket type used in the connection.
• e) The vessel is subjected to loadings of predominantly non-cyclic nature, see 5.4.2.
• f) The difference between mean temperatures of bolts and flange does not exceed 50 °C in any condition.
• g) The bolt and flange materials have coefficients of thermal expansion at 20 ° C that differ by more than 10 % (e.g. austenitic steel flanges with ferritic steel bolts) but the calculation temperature is < 120 °C, or the bolt and flange materials have coefficients of thermal expansion at 20 °C which do not differ by more than 10%.