Note 1: For facings types B, D, F and G, the transition from the edge of the raised face to the flange shall be radius,
or chamfer at the choice of the flange manufacturer.
Note 2: B1 and B2 are raised face (type B) for different applications.
For flanges and collars (except types 33, 36 and 37) with facing types A, B1, E and F, turning shall be
carried out with a round nosed tool in accordance with Table as hereunder.
Surface finish for jointing faces
Facing types Method of
machining
Radius of tool nose
mm
Raa
μm
Rza
μm
Min. Min. Max. Min. Max.
A, B1 b, E, F Turning c 1.0 3.2 12.5 12.5 50
B2 b, C, D, G, H Turning c - 0.8 3.2 3.2 12.5
For certain applications, e.g. low temperature gases, it may be necessary to stipulate closer control to the surface
finish.
a} Ra and Rz are defined in EN ISO 4287.
b) Types B1 and B2 are raised face (type B) flanges with different specified surface roughness values.
B1 : Standard facing for all PN numbers.
B2 : Only if agreed between the purchaser and the flange manufacturer.
c) The term 'turning' includes any method of machine operation producing either serrated concentric or serrated
spiral grooves.
Flanges type 05 up to PN 40 and collars (except types 33, 36 and 37) shall have type A facing, other
flanges shall have type B1 facings; unless type B2 facing is agreed between the purchaser and the supplier

Wall thickness and end preparation EN 1092-1
Weld-end preparation for flanges types 11 and 34
Unless otherwise specified, for flanges in accordance with this European Standard the welding end connections
given in A1 to A3 shall be used. Additional types of welding ends are specified in EN ISO 9692-2 and example
of designs in EN 1708-1 and may be used by agreement between the component or pressure equipment
manufacturer and the flange manufacturer.
● Wall thickness S ≦ 3 mm: Flanges/collars may be delivered with square cut ends.
● Wall thickness 3 < S < 22: Bevelled ends with an angle of 30° +5°
−0 and root face of (1,6 ± 0,8) mm.
● If flange wall thickness (S) > pipe wall thickness (T), the inner diameter shall be chamfered with an angle of
15°+5°
−0 to match (see A3).