BS 4504 Standard Flanges Dimensions and Tolerances
PDF: BS 4504 Standard Flanges Dimensions and Tolerances
BS 4504 Standard Flanges Dimensions and Tolerances
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Dimension |
Range |
Tolerance |
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mm |
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Flange Facings |
Eccentricity of machined facing diameters |
< DN 100 |
1.0 |
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> DN 100 |
2.0 |
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a (type B facing height) |
2 mm |
+0, -1.0 |
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3 mm |
+0, -2.0 |
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4 mm |
+0, -3.0 |
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5 mm |
+0, -4.0 |
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6 mm |
+0, -5.0 |
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b (type C and E facing height) |
All |
+0.5, -0 |
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b (type G facing height) |
All |
+0, -0.5 |
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b (type H facing height, outer) |
All |
+0.2, -0 |
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c (type D and F facing height) |
All |
+0, -0.5 |
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d (type H facing height, inner) |
All |
+0.5, -0 |
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B and E (facing diameters) |
All |
+0, -0.5 |
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C and D (facing diameters) |
All |
+0.5, -0 |
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Surface Finish |
Facing types A, B, E and F |
All, turning |
Ra = 3.2 µm min 12.5 µm max |
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All, other than turning |
Ra = 3.2 µm min 6.3 µm max |
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Facing types C, D, G and H |
All |
Ra = 0.8 µm min 3.2 µm max |
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Flange Drilling Details |
B (diameter of bolt circle) |
Bolt sizes M10 to M24 |
±0.9 |
|
Bolt sizes M27 to M45 |
±1.4 |
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Centre to centre of adjacent bolt holes |
Bolt sizes M10 to M24 |
±0.45 |
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Bolt sizes M27 to M45 |
±0.7 |
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All |
A (outside diameter) |
< DN 150 |
±2.0 |
|
> DN 150 < DN 500 |
±3.0 |
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> DN 500 < DN 1200 |
±5.0 |
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> DN 1200 < DN 1800 |
±7.0 |
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> DN 1800 |
±10.0 |
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C (flange thickness, machined on both faces) |
< 18 mm thickness |
±1.0 |
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> 18 mm < 50 mm thickness |
±1.0 |
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> 50 mm thickness |
±1.0 |
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C (flange thickness, machined on front face) |
< 18 mm thickness |
+2.0, -1.0 |
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> 18 mm < 50 mm thickness |
+4.0, -1.5 |
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> 50 mm thickness |
+7.0, -2.0 |
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Weld Neck Flanges, Code 111 |
B (outside diameter of hub at welding end) |
< DN 125 |
+3.0, -0 |
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> DN 125 < DN 1200 |
+4.5, -0 |
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> DN 1200 |
+6.0, -0 |
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F (hub diameter) |
< DN 50 |
+0, -2.0 |
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> DN 50 < DN 150 |
+0, -4.0 |
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> DN 150 < DN 300 |
+0, -6.0 |
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> DN 300 < DN 600 |
+0, -8.0 |
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> DN 600 < DN 1200 |
+0, -10.0 |
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D (length through hub) |
< DN 80 |
±1.5 |
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> DN 80 < DN 250 |
±2.0 |
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> DN 250 |
±3.0 |
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Slip on, Code 112 and Threaded,Code 113 |
E (slip on flange hub diameter)B (threaded flange hub diameter) |
< DN 50 |
+1.0, -0 |
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> DN 50 < DN 150 |
+2.0, -0 |
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> DN 150 < DN 300 |
+4.0, -.0 |
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> DN 300 < DN 600 |
+8.0, -0 |
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> DN 600 < DN 1200 |
+12.0, -0 |
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> DN 1200 < DN 1800 |
+16.0, -0 |
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> DN 1800 |
+20.0, -0 |
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B (slip on bore diameter) |
< DN 100 |
+0.5, -0 |
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> DN 100 < DN 400 |
+1.0, .0 |
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> DN 400 < DN 600 |
+1.5, .0 |
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> DN 600 |
+3.0, -0 |
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D (length through hub) |
Same as Weld Neck D |
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Blank Flanges, Code 105 |
B (flange thickness) |
Same as C for all other flanges |
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C (unmachined centre portion) |
Maximum specified |
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