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    ASME B18.2.3.1M Hex Cap Screws Dimensions

    Metric hex cap screws manufactured according to ASME B18.2.3.1M fastening specifications.

    ASME B18.2.3.1M Hex Cap Screws are widely used in machinery, automotive systems, industrial assemblies, and metric fastening applications. These metric cap screws provide precise threading, dependable fastening performance, and accurate dimensional tolerances for metric industrial systems.

    ASME B18.2.3.1m Metric Hex Cap Screws

    ASME B18.2.3.1m Metric Hex Cap Screws Dimensions

    Nominal Dia.,D,and Thread Pitch Body Dia., D s Width Across Flats, S Width Across Corners, E Head Height, K Wrenching Height, K1 1 Washer Face Thick., C Washer Face Dia., DW
    Max Min. Max Min. Max Min. Max Min. Min. Max Min. Min.
    ANSI B18.2.3.1M - M5 5 4.82 8 7.78 9.24 8.79 3.65 3.35 2.4 0.5 0.2 7
    ANSI B18.2.3.1M - M6 6 5.82 10 9.78 11.55 11.05 4.15 3.85 2.8 0.5 0.2 8.9
    ANSI B18.2.3.1M - M8 8 7.78 13 12.73 15.01 14.38 5.5 5.1 3.7 0.6 0.3 11.6
    ANSI B18.2.3.1M - aM10 10 9.78 15 14.73 17.32 16.64 6.63 6.17 4.5 0.6 0.3 13.6
    ANSI B18.2.3.1M - M10 10 9.78 16 15.73 18.48 17.77 6.63 6.17 4.5 0.6 0.3 14.6
    ANSI B18.2.3.1M - M12 12 11.73 18 17.73 20.78 20.03 7.76 7.24 5.2 0.6 0.3 16.6
    ANSI B18.2.3.1M - M14 14 13.73 21 20.67 24.25 23.35 9.09 8.51 6.2 0.6 0.3 19.6
    ANSI B18.2.3.1M - M16 16 15.73 24 23.67 27.71 26.75 10.32 9.68 7 0.8 0.4 22.5
    ANSI B18.2.3.1M - M20 20 19.67 30 29.16 34.64 32.95 12.88 12.12 8.8 0.8 0.4 27.7
    ANSI B18.2.3.1M - M24 24 23.67 36 35 41.57 39.55 15.44 14.56 10.5 0.8 0.4 33.2
    ANSI B18.2.3.1M - M30 30 29.67 46 45 53.12 50.85 19.48 17.92 13.1 0.8 0.4 42.7
    ANSI B18.2.3.1M - M36 36 35.61 55 53.8 63.51 60.79 23.38 21.62 15.8 0.8 0.4 51.1
    ANSI B18.2.3.1M - M42 42 41.38 65 62.9 75.06 71.71 26.97 25.03 18.2 1 0.5 59.8
    ANSI B18.2.3.1M - M48 48 47.38 75 72.6 86.6 82.76 31.07 28.93 21 1 0.5 69
    ANSI B18.2.3.1M - M56 56 55.26 85 82.2 98.15 93.71 36.2 33.8 24.5 1 0.5 78.1
    ANSI B18.2.3.1M - M64 64 63.26 95 91.8 109.7 104.65 41.32 38.68 28 1 0.5 87.2
    ANSI B18.2.3.1M - M72 72 71.26 105 101.4 121.24 115.6 46.45 43.55 31.5 1.2 0.6 96.3
    ANSI B18.2.3.1M - M80 80 79.26 115 111 132.72 126.54 51.58 48.42 35 1.2 0.6 105.4
    ANSI B18.2.3.1M - M90 90 89.13 130 125.5 150.11 143.07 57.74 54.26 39.2 1.2 0.6 119.2
    ANSI B18.2.3.1M - M100 100 99.13 145 140 167.43 159.6 63.9 60.1 43.4 1.2 0.6 133
    • (a) This size with width across flats of 15 mm is not standard. Unless specifically ordered, M10 hex
    • cap screws with 16 mm width across flats will be furnished.
    • All dimensions are in millimeters.
    • Basic thread lengths, B, are the same as given in .
    • Transition thread length, X, includes the length of incomplete threads and tolerances on grip gaging
    • length and body length. It is intended for calculation purposes.
    • For additional manufacturing and acceptance specifications, reference should be made to the
    • ASME B18.2.3.1M-1979 (R1995).
    ASME B18.2.3.1m Metric Hex Cap Screws

    Nominal
    Screw Diameter
    and
    Thread Pitch
    Fillet Transition Diameter,
    Da
    Fillet Length, Lf Fillet
    Radius for
    Short and
    Long
    Screws,
    R, Min.
    Body
    Diameter
    for Short
    Screws,
    Dsi, Min.
    For Short
    Screws,
    Min.
    For Short
    and Long
    Screws,
    Max.
    For Long
    Screws,
    Max.
    For Short
    Screws, Max.
    M5 5.1 5.7 1.2 0.7 0.2 4.36
    M6 6.2 6.8 1.4 0.9 0.25 5.21
    M8 8.3 9.2 2.0 1.1 0.4 7.04
    M10 10.2 11.2 2.0 1.2 0.4 8.86
    M12 12.2 13.7 3.0 1.3 0.6 10.68
    M14 14.1 15.7 3.0 1.4 0.6 12.50
    M16 16.5 17.7 3.0 1.6 0.6 14.50
    M20 20.7 22.4 4.0 2.1 0.8 18.16
    M24 24.5 26.4 4.0 2.3 0.8 21.80
    M30 30.8 33.4 6.0 3.0 1.0 27.46
    M36 36.6 39.4 6.0 3.1 1.0 33.12
    M42 . . . 45.6 8.0 3.4 1.2 38.78
    M48 . . . 52.6 10.0 4.0 1.6 44.43
    M56 . . . 63.0 12.0 4.8 2.0 52.09
    M64 . . . 71.0 13.0 5.0 2.0 59.74
    M72 . . . 79.0 13.0 5.0 2.0 67.74
    M80 . . . 87.0 13.0 5.0 2.0 75.74
    M90 . . . 97.0 13.0 5.0 2.5 85.74
    M100 . . . 107.0 13.0 5.5 2.5 95.72

    ASME B18.2.3.1m Metric Hex Cap Screws Thread Length

    Nominal Screw Diameter and Thread Pitch Thread Length, B, Ref Transition Thread Length, X, Ref Screws Threaded Full Length
    Screw Lengths, L ≤ 125 Screw Lengths, L > 125 & ≤ 200 Screw Lengths, L > 200 Screw Lengths, L, Under Unthreaded Length Under Head, A, Max. [Note (1)] Screw Lengths, L Unthreaded Length Under Head, A,
    Max.
    At Least Under
    M5 16 22 35 4.0 10 1.2 10 25 2.4
    M6 18 24 37 5.0 12 1.5 12 30 3.0
    M8 22 28 41 6.25 16 1.9 16 40 4.0
    M10 26 32 45 7.5 20 2.2 20 45 4.5
    M12 30 36 49 8.75 24 2.6 24 50 5.3
    M14 34 40 53 10.0 28 3.0 28 60 6.0
    M16 38 44 57 10.0 32 3.0 32 65 6.0
    M20 46 52 65 12.5 40 3.8 40 80 7.5
    M24 54 60 73 15.0 ... ... ... 90 9.0
    M30 66 72 85 17.5 ... ... ... 110 10.5
    M36 ... 84 97 20.0 ... ... ... 140 12.0
    M42 ... 96 109 22.5 ... ... ... 160 13.5
    M48 ... 108 121 25.0 ... ... ... 180 15.0
    M56 ... ... 137 27.5 ... ... ... 220 16.5
    M64 ... ... 153 30.0 ... ... ... 260 18.0
    M72 ... ... 169 30.0 ... ... ... 280 18.0
    M80 ... ... 185 30.0 ... ... ... 300 18.0
    M90 ... ... 205 30.0 ... ... ... 340 18.0
    M100 ... ... 225 30.0 ... ... ... 360 18.0

    ASME B18.2.3.1m Metric Hex Cap Screws Length Tolerance

    Nominal Length Nominal Screw Diameter
    Over Thru M5 M6 M8 M10 M12 M14 M16-M24 >M24
    6 10 ±0.29 ±0.29 ±0.29 ±0.29 ... ... ... ...
    10 18 ±0.35 ±0.35 ±0.35 ±0.35 ±0.35 ±0.35 ±0.35 ...
    18 30 ±0.42 ±0.42 ±0.42 ±0.42 ±0.42 ±0.42 ±0.42 ±1.05
    30 50 ±0.50 ±0.50 ±0.50 ±0.50 ±0.50 ±0.50 ±0.50 ±1.25
    50 60 ±1.50 ±0.60 ±0.60 ±0.60 ±0.60 ±0.60 ±0.60 ±1.50
    60 80 ±1.50 ±1.50 ±0.60 ±0.60 ±0.60 ±0.60 ±0.60 ±1.50
    80 100 ±1.75 ±1.75 ±1.75 ±0.70 ±0.70 ±0.70 ±0.70 ±1.75
    100 120 ±1.75 ±1.75 ±1.75 ±1.75 ±0.70 ±0.70 ±0.70 ±1.75
    120 140 ±2.00 ±2.00 ±2.00 ±2.00 ±2.00 ±0.80 ±0.80 ±2.00
    140 150 ±2.00 ±2.00 ±2.00 ±2.00 ±2.00 ±2.00 ±0.80 ±2.00
    150 180 ±2.00 ±2.00 ±2.00 ±2.00 ±2.00 ±2.00 ±2.00 ±2.00
    180 250 ±2.30 ±2.30 ±2.30 ±2.30 ±2.30 ±2.30 ±2.30 ±2.30
    250 315 ±2.60 ±2.60 ±2.60 ±2.60 ±2.60 ±2.60 ±2.60 ±2.60
    315 400 ±2.85 ±2.85 ±2.85 ±2.85 ±2.85 ±2.85 ±2.85 ±2.85
    400 500 ±3.15 ±3.15 ±3.15 ±3.15 ±3.15 ±3.15 ±3.15 ±3.15

    Frequently Asked Questions

    What grades of nonferrous metal does ASTM F468 cover for din 933?

    ASTM F468 covers copper (C11000), brass (C26000, C27000, C46200, C46400), bronze (C51000 phosphor, C61300/C61400/C63000 aluminum, C64200, C65100/C65500/C66100 silicon, C67500 manganese), cupro-nickel (C71000, C71500), nickel-base alloys (N04400 Monel 400, N04405, N05500 Monel K-500, N06059 Alloy 59, N06625 Inconel 625, N06686, N10001 Hastelloy B-2, N10276 Hastelloy C-276), aluminum (A92024, A96061, A97075), and titanium (R50250 Gr 1, R50400 Gr 2, R50700 Gr 4, R56400 Gr 5, R56401 Gr 23 ELI, R52400 Gr 7, R58640 Gr 19, R55111 Gr 32) - all available for this product family at TorqBolt.

    What is the dimensional standard for these din 933?

    This product follows ASME B18.2 3 1M, the dimensional standard for din 933. Material chemistry, mechanical properties, and acceptance criteria follow ASTM F468 / F468M for nonferrous bolting. TorqBolt supplies both inch-series and metric sizes per the applicable ASME or ISO drawing.

    Which F468 grades are best for marine and seawater service?

    For seawater bolting per F468: Monel 400 (N04400) and Monel K-500 (N05500) resist chloride stress-corrosion cracking and HF acid; nickel-aluminum bronze C63000 is the standard high-strength marine fastener; cupro-nickel C71500 is preferred for condenser tube-sheet bolting; naval brass C46400 is the lower-cost option for routine marine hardware; titanium Grade 2 (R50400) is the premium choice for severe chloride + chemical service.

    Are F468 din 933 NACE MR0175 acceptable for sour service?

    Most F468 nickel and titanium grades are NACE MR0175 / ISO 15156-listed: Monel 400 (N04400), Monel K-500 (N05500) conditional, Inconel 625 (N06625), Hastelloy B-2 (N10001), Hastelloy C-276 (N10276), Alloy 59 (N06059), Alloy 686 (N06686), and all titanium grades (R50400, R52400, R56400, R56401). Aluminum bronzes are generally not preferred for sour service. TorqBolt provides NACE-compliant heat-treat and hardness reports on request.

    References & Standards

    • ASTM F468 / F468M - Standard Specification for Nonferrous Bolts, Hex Cap Screws, and Studs for General Use
    • ASTM F467 / F467M - Companion specification for Nonferrous Nuts (mate with F468 for matched-alloy assemblies)
    • ASTM F436 / F436M - Hardened steel washers (ferrous washer companion when nonferrous washers are not specified)
    • NACE MR0175 / ISO 15156 - Sour-service hardness limits for petroleum and natural gas industries
    • ASME B18.2.1 / B18.2.3 series / B18.3 / B18.6.7M / B18.31 / B16.5 - Dimensional standards referenced by F468
    • DIN 912 / 933 / 931 - Metric hex socket head and hex head cap screw dimensional standards