BS 4882

ASTM A193 Grade B87 Specifications

Dimensions for Tap-End Studs

metric countersunk socket head capscrews asme b18.3.5m

Dimensions of metric countersunk socket head cap screws

Nominal Size or Basic Screw Diameter Thread Pitch D A H J T G F M
Body Diameter Head Diameter Head Height Hexagon Socket Size Key Engagement Socket Wall Fillet Extension Above D Drill Allow.
Max. Min. Theoretical Sharp
Max.		 Absolute
Min.		 Reference Flushness Tolerance Nom. Min. Min. Max. Max.
3 0.5 3.0 2.86 6.72 5.35 1.86 0.30 2.0 1.1 0.25 0.25 0.3
4 0.7 4.0 3.82 8.96 7.80 2.48 0.30 2.5 1.5 0.45 0.35 0.4
5 0.8 5.0 4.82 11.20 9.75 3.10 0.35 3.0 1.9 0.66 0.40 0.5
6 1 6.0 5.82 13.44 11.70 3.72 0.35 4.0 2.2 0.70 0.50 0.6
8 1.25 8.0 7.78 17.92 15.60 4.96 0.40 5.0 3.0 1.16 0.60 0.8
10 1.5 10.0 9.78 22.40 19.50 6.20 0.50 6.0 3.6 1.62 0.80 0.9
12 1.75 12.0 11.73 26.88 23.40 7.44 0.60 8.0 4.3 1.80 0.90 1.2
14 (1) 2 14.0 13.73 30.24 26.13 8.12 0.70 10.0 4.7 1.62 1.00 1.5
16 2 16.0 15.73 33.60 28.96 8.80 0.80 10.0 4.8 2.20 1.00 1.5
20 2.5 20.0 19.67 40.32 34.60 10.16 1.00 12.0 5.6 2.20 1.20 1.8

NOTE:(1) Not recommended for new design.

Body and grip Lengths

Nominal Diameter M3 M4 M5 M6 M8 M10 M12 M14 M16 M20
Nominal length LGH LBH LGH LBH LGH LBH LGH LBH LGH LBH LGH LBH LGH LBH LGH LBH LGH LBH LGH LBH
35 17 14.5 15 11.5
40 22 19.5 20 16.5 18 14
45 27 24.5 25 21.5 23 19 21 16
50 32 29.5 30 26.5 28 24 26 21 22 15.7
55 37 34.5 35 31.5 33 29 31 26 27 20.7
60 40 36.5 38 34 36 31 32 25.7 28 20.5
65 45 41.5 43 39 41 36 37 30.7 33 25.5 29 20.2
70 50 46.5 48 44 46 41 42 35.7 38 30.5 34 25.2 30 20
80 60 56.5 58 54 56 51 52 45.7 48 40.5 44 35.2 40 30 36 26
90 68 64 66 61 62 55.7 58 50.5 54 45.2 50 40 46 36
100 78 74 76 71 72 65.7 68 60.5 64 55.2 60 50 56 46
110 86 81 82 75.7 78 70.5 74 65.2 70 60 66 56 58 45.5
120 96 91 92 85.7 88 80.5 84 75.2 80 70 76 66 68 55.5
130 102 95.7 98 90.5 94 85.2 90 80 86 76 78 65.5
140 112 105.7 108 100.5 104 95.2 100 90 96 86 88 75.5
150 122 115.7 118 110.5 114 105.2 110 100 106 96 98 85.5

Dimensions of metric hexagon sockets

Forged Hexagon Socket
Broached Socket
Nominal Socket Size j c
Socket Width Across Flats Socket Width Across Corners
Max. MIn. MIn.
2 2.045 2.020 2.30
2.5 2.560 2.520 2.87
3 3.071 3.020 3.44
4 4.084 4.020 4.58
5 5.084 5.020 5.72
6 6.095 6.020 6.86
8 8.115 8.025 9.15
10 10.127 10.025 11.50
12 12.146 12.032 13.80

Tolerance ON Length. The tolerance on length shall be bilateral as tabulated below:

Nominal Screw length, mm Tolerance on length, mm
up to 16, incl. ± 0.3
Over 16 to 60, incl. ± 0.5
Over 60 to 150, incl. ± 0.8

ASTM A193 Grade B8T Fastener Coatings

PTFE Coated B8T Fasteners
PTFE Coated
Black Phosphated B8T Fasteners
Black Phosphated
Zinc Plated B8T Fasteners
Zinc Plated
Hot Dip Galvanized B8T Fasteners
Hot Dip Galvanized
Cadium Plated B8T Fasteners
Cadium Plated
Ceramic Coated B8T Fasteners
Ceramic Coated
Zinc Nickel B8T Fasteners
Zinc Nickel
Zinc Flake Coated B8T Fasteners
Zinc Flake Coated