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REFERENCE · EN 1092-1

EN 1092-1 flange tolerances (Table 22)

EN 1092-1 · EN 1092-1:2018 · verified 2026-11-04

Pressure-temperature ratingsMaterial groupsTolerancesMarkingTypes and facings

Reference tables are transcribed from EN 1092-1:2018; table numbers, printed page numbers and cell values keep the standard's original wording.

Clause 5.9 of EN 1092-1:2018 refers all flange and collar dimensional tolerances to Table 22, and sends any dimension without a stated tolerance to the general tolerances of EN 22768-1:1993. Table 22 runs across six pages (77 to 82) and is reproduced here in full.

The table is organised the way the dimensions are: neck and bore first, then wall thickness and weld bevel, outside diameter, hub length, neck diameters, collar and flange thickness, facing geometry, and finally eccentricity and parallelism. Many tolerances depend on the flange type group and on whether a surface is machined, so read the flange-type cell together with the size band before taking the tolerance.

Tolerances in Table 22 are given as an upper and lower limit, as plus-only limits for bores and holes, or as a percentage of the outside diameter or wall thickness. Dimensions for which Table 22 states no tolerance fall back to EN 22768-1:1993.

StandardEN 1092-1:2018
Source tableTable 22 (pp. 77–82)
Clause§5.9 (p. 18)
Unitsmm, %, degrees
General tolerancesEN 22768-1:1993

Neck outside diameter, bore, wall thickness and bevel (p. 77)

Wall thickness S has two tolerance regimes: a neck machined on both faces, and a neck machined on one face only or left unmachined.

Table 22 (p. 77) — tolerances on neck outside diameter, bore, wall thickness and bevel
DimensionFlange typesSizeTolerancemmNeck one face machined, or un-machinedmm
Outside diameter of neck A11, 21, 34≤ DN 125+3,0 / 0—
Outside diameter of neck A11, 21, 34> DN 125 ≤ DN 1200+4,5 / 0—
Outside diameter of neck A11, 21, 34> DN 1200+6,0 / 0—
Outside diameter of neck A35, 36, 37≤ DN 150±0,75 % a, min. ±0,3 mm—
Outside diameter of neck A35, 36, 37> DN 150±1 % a, max. ±3,0 mm—
Bore diameter B1, B2, B301, 02, 04, 12, 32≤ DN 100+0,5 / 0—
Bore diameter B1, B2, B301, 02, 04, 12, 32> DN 100 ≤ DN 400+1,0 / 0—
Bore diameter B1, B2, B301, 02, 04, 12, 32> DN 400 ≤ DN 600+1,5 / 0—
Bore diameter B1, B2, B301, 02, 04, 12, 32> DN 600+3,0 / 0—
Wall thickness S c11, 34 b≤ DN 100+1,0 / 0+2,0 / 0
Wall thickness S c11, 34 b> DN 100 ≤ DN 400+1,5 / 0+2,5 / 0
Wall thickness S c11, 34 b> DN 400+2,0 / 0+3,5 / 0
Wall thickness S c35S ≤ 8+15 % / −10 %—
Wall thickness S c35S > 8+15 % / −5 %—
Wall thickness S c36, 37≤ DN 600−12,5 % a / +15 %—
Wall thickness S c36, 37> DN 600−0,5 mm a / +15 %—
Bevelled wall thickness Sp35, 36, 37S ≤ 6+1,0 / 0—
Bevelled wall thickness Sp35, 36, 37S > 6+2,0 / 0—

Tolerance is given as upper / lower limit in mm unless a percentage is shown. Dimension letters follow the standard's dimension symbols. Wall thickness S has two regimes: a neck machined on both faces, and a neck machined on one face only or unmachined; the second value is in the right-hand column.

  • aTolerance in % of the outside diameter or of the wall thickness, as applicable.
  • bBore tolerance not applicable.
  • cPreparation of ends, see Annex A.

Outside diameter D, hub length and neck diameter N1 (p. 78)

Table 22 (p. 78) — tolerances on outside diameter D, hub length and neck diameter N1
DimensionFlange typesSizeTolerancemm
Outside diameter D21≤ DN 250±4,0
Outside diameter D21> DN 250 ≤ DN 500±5,0
Outside diameter D21> DN 500 ≤ DN 800±6,0
Outside diameter D21> DN 800 ≤ DN 1200±7,0
Outside diameter D21> DN 1200 ≤ DN 1600±8,0
Outside diameter D21> DN 1600 ≤ DN 2000±10,0
Outside diameter DAll other types≤ DN 150±2,0
Outside diameter DAll other types> DN 150 ≤ DN 500±3,0
Outside diameter DAll other types> DN 500 ≤ DN 1200±5,0
Outside diameter DAll other types> DN 1200 ≤ DN 1800±7,0
Outside diameter DAll other types> DN 1800±10,0
Length through hub H1, H2, H3, H4, H511, 12, 13, 34, 35, 36, 37≤ DN 80±1,5
Length through hub H1, H2, H3, H4, H511, 12, 13, 34, 35, 36, 37> DN 80 ≤ DN 250±2,0
Length through hub H1, H2, H3, H4, H511, 12, 13, 34, 35, 36, 37> DN 250±3,0
Neck diameter N111 (machined bearing surface)N1 ≤ 1200 / −1,0
Neck diameter N111 (machined bearing surface)N1 > 120 ≤ 4000 / −1,2
Neck diameter N111 (machined bearing surface)N1 > 400 ≤ 1000+1,6 / 0
Neck diameter N111 (machined bearing surface)N1 > 1000 ≤ 2000+2,5 / 0
Neck diameter N111 (machined bearing surface)N1 > 2000+4,0 / 0
Neck diameter N111 (un-machined bearing surface)N1 ≤ 1200 / −1,0
Neck diameter N111 (un-machined bearing surface)N1 > 120 ≤ 4000 / −2,0
Neck diameter N111 (un-machined bearing surface)N1 > 400 ≤ 1000+4,0 / 0
Neck diameter N111 (un-machined bearing surface)N1 > 1000 ≤ 2000+6,0 / 0
Neck diameter N111 (un-machined bearing surface)N1 > 2000+8,0 / 0

Tolerance is given as upper / lower limit in mm. Neck diameter N1 is toleranced differently depending on whether the bolting bearing surface is machined.

Neck diameters N1, N2 and N3 (p. 79)

Table 22 (p. 79) — tolerances on neck diameters N1, N2 and N3
DimensionFlange typesSizeTolerancemm
Neck diameter N1, N2, N321, 34 (un-machined bearing surface)≤ DN 500 / −2,0
Neck diameter N1, N2, N321, 34 (un-machined bearing surface)> DN 50 ≤ DN 1500 / −4,0
Neck diameter N1, N2, N321, 34 (un-machined bearing surface)> DN 150 ≤ DN 3000 / −6,0
Neck diameter N1, N2, N321, 34 (un-machined bearing surface)> DN 300 ≤ DN 6000 / −8,0
Neck diameter N1, N2, N321, 34 (un-machined bearing surface)> DN 600 ≤ DN 40000 / −10,0
Neck diameter N1, N2, N321, 34 (machined bearing surface)≤ DN 50+1,0 / 0
Neck diameter N1, N2, N321, 34 (machined bearing surface)> DN 50 ≤ DN 150+1,5 / 0
Neck diameter N1, N2, N321, 34 (machined bearing surface)> DN 150 ≤ DN 300+2,0 / 0
Neck diameter N1, N2, N321, 34 (machined bearing surface)> DN 300 ≤ DN 600+2,5 / 0
Neck diameter N1, N2, N321, 34 (machined bearing surface)> DN 600 ≤ DN 4000+3,0 / 0
Neck diameter N2, N312, 13≤ DN 50+1,0 / 0
Neck diameter N2, N312, 13> DN 50 ≤ DN 150+2,0 / 0
Neck diameter N2, N312, 13> DN 150 ≤ DN 300+4,0 / 0
Neck diameter N2, N312, 13> DN 300 ≤ DN 600+8,0 / 0
Neck diameter N2, N312, 13> DN 600 ≤ DN 1200+12,0 / 0
Neck diameter N2, N312, 13> DN 1200 ≤ DN 1800+16,0 / 0
Neck diameter N2, N312, 13> DN 1800+20,0 / 0

Tolerance is given as upper / lower limit in mm.

Collar thickness, flange thickness and facing diameter (p. 80)

Table 22 (p. 80) — tolerances on collar thickness, flange thickness and facing diameter
DimensionFlange typesSizeTolerancemm
Collar thickness F35 (machined on both facings)≤ 18 mm thickness±1,0
Collar thickness F35 (machined on both facings)> 18 mm ≤ 50 mm thickness±1,5
Collar thickness F35 (machined on front face only, or un-machined)≤ 18 mm thickness+2,0 / −1,3
Collar thickness F35 (machined on front face only, or un-machined)> 18 mm ≤ 50 mm thickness+4,0 / −1,5
Collar thickness F36 (machined on front face only, or un-machined)≤ 18 mm thickness±10 %
Collar thickness F37 (un-machined)≤ 5 mm thickness±0,20
Collar thickness F37 (un-machined)> 5 mm thickness±0,30
Collar thickness F32, 34 (machined on both faces)≤ 18 mm thickness+1,0 / −1,3
Collar thickness F32, 34 (machined on both faces)> 18 mm thickness±1,5
Collar thickness F32, 34 (machined on front side only)≤ 18 mm thickness+2,0 / −1,3
Collar thickness F32, 34 (machined on front side only)> 18 mm ≤ 30 mm thickness+3,0 / −1,5
Collar thickness F32, 34 (machined on front side only)> 30 mm thickness+4,0 / −1,5
Flange thickness C1, C2, C3, C4All types (machined on both faces)≤ 18 mm thickness+1,0 / −1,3
Flange thickness C1, C2, C3, C4All types (machined on both faces)> 18 mm ≤ 50 mm thickness±1,5
Flange thickness C1, C2, C3, C4All types (machined on both faces)> 50 mm thickness±2,0
Flange thickness C1, C2, C3, C4All types (machined on front side only); Type 02 and 04 (un-machined)≤ 18 mm thickness+2,0 / −1,3
Flange thickness C1, C2, C3, C4All types (machined on front side only); Type 02 and 04 (un-machined)> 18 mm ≤ 50 mm thickness+4,0 / −1,5
Flange thickness C1, C2, C3, C4All types (machined on front side only); Type 02 and 04 (un-machined)> 50 mm thickness+7,0 / −2,0
Facing diameter d1All types≤ DN 250+2,0 / −1,0
Facing diameter d1All types> DN 250+3,0 / −1,0

Tolerance is given as upper / lower limit in mm unless a percentage is shown.

Facing heights, facing dimensions and bolting (p. 81)

Table 22 (p. 81) — tolerances on facing heights, facing dimensions and bolting
DimensionFlange typesSizeTolerancemm
Facing height f1All types (facing type B, D, F and G)≤ DN 32 (2 mm)0 / −1,0
Facing height f1All types (facing type B, D, F and G)> DN 32 to DN 250 (3 mm)0 / −2,0
Facing height f1All types (facing type B, D, F and G)> DN 250 to DN 500 (4 mm)0 / −3,0
Facing height f1All types (facing type B, D, F and G)> DN 500 (5 mm)0 / −4,0
Facing height f2All types (facing type C, E and G)All DN+0,5 / 0
Facing height f3All types (facing type D and F)All DN+0,5 / 0
Facing height f3All types (facing type H)All DN+0,2 / 0
Facing height f4All types (facing type H)All DN+0,5 / 0
Facing dimension WAll typesAll DN+0,5 / 0
Facing dimension XAll typesAll DN0 / −0,5
Facing dimension YAll typesAll DN+0,5 / 0
Facing dimension ZAll typesAll DN0 / −0,5
Diameter of bolt circle KAll typesBolt size M10 to M24±1,0
Diameter of bolt circle KAll typesBolt size M27 to M45±1,5
Diameter of bolt circle KAll typesBolt size > M45±2,0
Diameter of bolt holes LAll typesBolt size M10 to M24+1,0 / 0
Diameter of bolt holes LAll typesBolt size M27 to M45+2,5 / 0
Diameter of bolt holes LAll typesBolt size > M45+4,0 / 0
Centre-to-centre of adjacent bolt holesAll typesBolt size M10 to M24±1,0
Centre-to-centre of adjacent bolt holesAll typesBolt size M27 to M45±1,5
Centre-to-centre of adjacent bolt holesAll typesBolt size > M45±2,0

Tolerance is given as upper / lower limit in mm. Facing heights f1 to f4 correspond to the facing dimensions in Figure 4; W, X, Y and Z are facing dimensions of the tongue, groove, spigot and recess types.

Eccentricity and parallelism (p. 82)

Table 22 (p. 82) — eccentricity of facing diameters and parallelism of bearing surface
DimensionFlange typesSizeTolerancemm
Eccentricity of machined facing diameters dAll types≤ DN 651,0
Eccentricity of machined facing diameters dAll types> DN 652,0
Parallelism between bolting bearing surface and flange jointing facesAll types (machined bearing surface)All DN1°
Parallelism between bolting bearing surface and flange jointing facesAll types (un-machined bearing surface)All DN2°

Eccentricity is a maximum in mm; parallelism is an angle. Footnote d applies to both dimensions.

  • dBetween bolt circle and facing, and also between bore diameter and facing.

Corner radii and hub radius after back facing (Table 23, p. 82)

Table 23 (p. 82) — corner radii R1 and hub radius R2 after back facing
Flange sizeR1 min.mmR1 max.mmR2 min.mm
Up to and including DN 50351,6
Over DN 50 and up to and including DN 350362,4
Over DN 350583,2

R1 minimum and maximum apply to types 33 and 35 to 37; for types 11, 12, 13, 21 and 34 see the dimension tables (Tables 10 to 21).

FAQ

What tolerance applies to an EN 1092-1 flange outside diameter?
It depends on the type. For type 21 the tolerance is ±4,0 mm up to DN 250, widening to ±10,0 mm above DN 1600 to DN 2000. For all other types it is ±2,0 mm up to DN 150, ±3,0 mm to DN 500, ±5,0 mm to DN 1200, ±7,0 mm to DN 1800 and ±10,0 mm above that.
What is the wall thickness tolerance for a type 11 flange?
With the neck machined on both faces the tolerance is +1,0 / 0 mm up to DN 100, +1,5 / 0 mm over DN 100 to DN 400 and +2,0 / 0 mm above DN 400. If only one face is machined or the neck is unmachined, the corresponding values are +2,0 / 0, +2,5 / 0 and +3,5 / 0 mm.
Is the bore diameter tolerance plus or minus?
It is plus-only: +0,5 / 0 mm up to DN 100, +1,0 / 0 mm over DN 100 to DN 400, +1,5 / 0 mm over DN 400 to DN 600 and +3,0 / 0 mm above DN 600, for types 01, 02, 04, 12 and 32.
What applies to dimensions not listed in Table 22?
Clause 5.9 sends dimensions without a specified tolerance to EN 22768-1:1993. Table 22 tolerances are mandatory only for the dimensions it covers.

Sources

  • EN 1092-1:2018, §5.9 — Tolerances (p. 18)
  • EN 1092-1:2018, Table 22 — Tolerances (pp. 77–82)
  • EN 1092-1:2018, Table 23 — Corner radii R1 and hub radius R2 after back facing (p. 82)
  • EN 22768-1:1993, referred to by §5.9

EN 1092-1:2018 (PDF supplied for this project)