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F.2.6 Flanges made from steel castingsFor flanges made from steel casting (types no. 21, 34) the current dimension needs to be calculated.The calculation shall be done if a steel flange is combined with a casted flange/valve. p/T ratings are notavailable for these combinations.F.2.7 Rounding of maximum allowable pressure at temperatureThe results of calculated maximum allowable pressure PS at temperature (according to Formula (F.2)respectively (F.3)) shall be rounded downwards to the first decimal place (e.g. value of 15,09 barrounded downwards to 15,0 bar; or 15,19 bar rounded downwards to 15,1 bar).G.1 GeneralG.1.1 p/T ratingsA range of p/T ratings for a selection of commonly used EN materials is indicated in this annex. Thesep/T ratings are prepared to support the user of this European Standard and shall not be understoodeither as a limitation in p/T ratings nor materials. If the user of this European Standard has the need todetermine his own p/T rating for a certain application this can be done under consideration of the basicrules to determine a p/T rating (see Annex F).G.1.2 Basics of determination of p/T ratings (see Annex F)p/T ratings are calculated by using Formulae (F.2) and (F.3).In compliance with Formula (F.3), the calculated pressure values do not exceed PN.Strength values for steel forgings, flat steel products and steel castings are taken from EN materialstandards considering the different range of product thickness. For provisions regarding the referencevalue for thickness vR see F.2.4.p/T ratings are calculated by using the strength values of steel forgings depending on different range ofproduct thickness and are verified for flat steel products of the same group.Nominal design stresses are calculated by using the formulae as defined in Table F.2.Interpolation rules as defined in Annex F have been applied.

At higher temperatures the additional external loads shall be reduced to the same degree as themaximum allowable pressure.NOTE 1 The graduation of vR depends from the product of material from which a flange is manufactured. Forthe different methods of fabrication see Table 1 of this European Standard.NOTE 2 For flanges made from steel casting (type 21) see Table 6, footnote a and definitions stated in F.2.6.NOTE 3 If the flange joint consists of materials with different strength properties (excluding bolts), p/T ratingsneed to be chosen in accordance with the lowest strength values.NOTE 4 The p/T ratings are built by a comparison of a material related term (ft;fCR) and the value of 140 MPa toPN. ft;fCR are a function of the material thickness for a given material. To compare the results of Formulae (F.2) and(F.3) with the thickness of a flange of this European Standard vR is introduced in this European Standard.