Applies to face-to-face and centre-to-face dimensions and their permitted deviations and is a basic standard for dimensional standard for flanged values. Defines the face-to-face and centre-to-face dimensions and specifies series from which the face-to-face and centre-to-face dimensions required in the individual dimensional standards are to be selected. When standardizing the individual type of valves, face-to-face and centre-to-face dimensions shall be taken from only one series.