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    2. ASTM A453 Grade 660 Class B
    3. 12 Point Screws

    ASTM A453 Grade 660 Class B 12 Point Screws

    Marked A2B Drawing No.N733D Item Code C1F19A2

    ASTM A453 Grade 660 Class B twelve point Screws often refered as 12 point flange bolts offered at TorqBolt are manufactured in accordance with IFI 115 standard in metric and imperial coarse and fine thread sizes with UNC, UN, UNF, UNEF, UNJF & ISO threads.
    DESCRIPTION: (C1F19A2) Flanged twelve-point, external wrenching screw.
    MATERIAL: Precipitation hardening steel conforming to ASTM A453 Grade 660 Class B, 130 ksi tensile strength.
    SCREW THREADS: Class 2A UNC, UNF or 8 UN series.
    HARDNESS : BRINELL 248 - 341 HB.
    SURFACE TEXTURE: Threads, body under head fillet and bearing area 63 microinch.
    HEAD MARKING: A2B as indicated and registered source ID.
    FOR USE IN TEMPERATURE UP TO 1200 °F.
    All dimensions are in inches unless otherwise indicated.

    ASTM A453 Grade 660 Class B 12 Point Screws

    DIMENSIONS








    THREAD SIZE A
    Flange diameter    		 H
    Head height    		 J
    Width across flats    		 C
    Width across corners    		 K
    Chamfer    		 M
    Flange thickness    		 R
    Fillet    		 D
    Body diameter
    max min max min max min min max max min max min max min
    1/4 (0.250) 0.375 0.365 0.250 0.244 0.253 0.249 0.284 0.008 0.088 0.068 0.015 0.010 0.2500 0.2435
    5/16 (0.312) 0.469 0.457 0.312 0.306 0.316 0.311 0.356 0.008 0.119 0.099 0.015 0.010 0.3120 0.3053
    3/8 (0.375) 0.562 0.550 0.375 0.368 0.378 0.370 0.422 0.008 0.166 0.146 0.020 0.015 0.3750 0.3678
    7/16 (0.438) 0.656 0.642 0.438 0.430 0.440 0.432 0.493 0.010 0.197 0.177 0.030 0.020 0.4380 0.4294
    1/2 (0.500) 0.750 0.735 0.500 0.492 0.503 0.495 0.565 0.010 0.228 0.208 0.030 0.020 0.5000 0.4919
    5/8 (0.625) 0.938 0.921 0.625 0.616 0.628 0.620 0.707 0.010 0.275 0.255 0.030 0.020 0.6250 0.6163
    3/4 (0.750) 1.125 1.107 0.750 0.740 0.753 0.745 0.850 0.010 0.338 0.318 0.040 0.030 0.7500 0.7406
    7/8(0.875) 1.312 1.293 0.875 0.864 0.879 0.868 0.990 0.015 0.353 0.333 0.045 0.035 0.8750 0.8647
    1(1.000) 1.500 1.479 1.000 0.988 1.004 0.993 1.134 0.015 0.416 0.396 0.050 0.040 1.0000 0.9886
    1 1/8(1.125) 1.684 1.665 1.125 1.111 1.129 1.117 1.276 0.015 0.448 0.428 0.055 0.045 1.125 1.109
    1 1/4(1.250) 1.871 1.852 1.250 1.236 1.254 1.241 1.418 0.015 0.494 0.474 0.060 0.050 1.250 1.234
    1 3/8(1.375) 2.058 2.038 1.375 1.360 1.379 1.366 1.561 0.015 0.541 0.521 0.065 0.055 1.375 1.357
    1 1/2(1.500) 2.245 2.224 1.500 1.485 1.505 1.491 1.705 0.015 0.604 0.584 0.070 0.060 1.500 1.482
    1 5/8 (1.625) 2.430 2.408 1.625 1.611 1.630 1.615 1.848 0.015 0.651 0.631 0.070 0.060 1.625 1.605
    1 3/4 (1.750) 2.620 2.597 1.750 1.734 1.755 1.740 2.009 0.015 0.760 0.740 0.080 0.070 1.750 1.730
    2 (2.000) 2.995 2.970 2.000 1.983 2.005 1.990 2.268 0.015 0.885 0.865 0.090 0.075 2.000 1.980
    2 1/4 (2.250) 3.375 3.344 2.250 2.232 2.255 2.200 2.480 0.030 1.010 0.990 0.125 0.100 2.250 2.227
    2 1/2 (2.500) 3.750 3.717 2.500 2.481 2.505 2.455 2.760 0.030 1.119 1.099 0.150 0.110 2.500 2.477
    THREAD/INCH 20 UNC 28 UNF 18 UNC 24 UNF 16 UNC 24 UNF
    T (1) Thread length min 1 1.12 1.25
    L Length Tol PART NO. (For other lengths, last three digits are lengths in 16ths.)
    Preferred Lengths 3/8 (0.375)
    1/2 (0.500)
    5/8 (0.625)    		 - 0.03 21006
    21008
    21010    		 20006
    20008
    20010    		 23006
    23008
    23010    		 22008
    22010    		 25008
    25010    		 24008
    24010
    3/4 (0.750)
    7/8 (0.875)
    1 (1.000)    		 21012
    21014
    21016    		 20012
    20014
    20016    		 23012
    23014
    23016    		 22012
    22014
    22016    		 25012
    25014
    25016    		 24012
    24014
    24016
    1 1/4 (1.250)
    1 1/2 (1.500)    		 - 0.04 21020
    21024    		 20020
    20024    		 23020
    23024    		 22020
    22024    		 25020
    25024    		 24020
    24024
    1 3/4 (1.750) 21028 20028 23028 22028 25028 24028
    2 (2.000)
    2 1/4 (2.250)
    2 1/2 (2.500)    		 21032
    21036
    21040    		 20032
    20036    		 23032
    23036
    23040    		 22032
    22036
    22040    		 25032
    25036
    25040    		 24032
    24036
    24040
    2 3/4 (2.750)
    3 (3.000)
    3 1/4 (3.250)    		 - 0.06 21044
    21048    		   23044
    23048
    23052    		   25044
    25048
    25052    		 24048
    3 1/2 (3.500)
    4 (4.000)
    4 1/2 (4.500)
    5 (5.000)    		     23056   25056
    25064
    25072
    25080    		  
    THREAD/INCH 14
    UNC    		 20
    UNF    		 13
    UNC    		 20
    UNF    		 11
    UNC    		 18
    UNF    		 10
    UNC
    T (1) Thread length min 1.38 1.50 1.75 2.00
    L Length Tol PART NO. (For other lengths, last three digits are lengths in 16ths.)
    Preferred Lengths 1/2 (0.500)
    5/8 (0.625)
    3/4 (0.750)
    7/8 (0.875)    		 - 0.03 27008
    27010
    27012
    27014    		   29008
    29010
    29012
    29014    		          
    1 (1.000)
    1 1/4 (1.250)
    1 1/2 (1.500)
    1 3/4 (1.750)    		 - 0.06 27016
    27020
    27024
    27028    		 26016
    26020
    26024    		 29016
    29020
    29024
    29028    		 28016
    28020
    28024
    28028    		 33016
    33020
    33024
    33028    		 32016
    32020
    32024
    32028    		 35020
    35024
    35028    		 34020
    34024
    34028
    2 (2.000)
    2 1/4 (2.250)
    2 1/2 (2.500)    		 27032
    27036
    27040    		 26032 29032
    29036
    29040    		 28032
    28036
    28040    		 33032
    33036
    33040    		 32032

    32040    		 35032
    35036
    35040    		 34032

    34040
    2 3/4 (2.750)
    3 (3.000)
    3 1/4 (3.250)
    3 1/2 (3.500)    		 - 0.08 27044
    27048
    27052
    27056    		   29044
    29048
    29052
    29056
    28048    		 33044
    33048
    33052
    33056    		   35044
    35048
    35052
    35056    		  
    4 (4.000)
    4 1/2 (4.500)
    5 (5.000)
    5 1/2 (5.500)
    6 (6.000)    		 27064   29064
    29072
    29080
    29088
    29096    		   33064
    33072
    33080
    33088    		   35064
    35072
    35080
    35088
    35096    		  
    THREAD/INCH 9
    UNC    		 8
    UNC    		 7
    UNC    		 8
    UN    		 7
    UNC    		 8
    UN    		 6
    UNC    		 8
    UN    		 6
    UNC    		 8
    UN
    T (1) Thread length min 2.25 2.50 2.82 3.12 3.44 3.75
    L Length Tol PART NO. (For other lengths, last three digits are lengths in 16ths.)
    Preferred Lengths 2 (2.000)
    2 1/4 (2.250)
    2 1/2 (2.500)    		 - 0.10 37032
    37036
    37040    		 39032
    39036
    39040    		 42032
    42036
    42040    		 41032
    41036
    41040    		 45032
    45036
    45040    		 44032
    44036
    44040    		 48032
    48036
    48040    		 47032
    47036
    47040    		 51032
    51036
    51040    		 50032
    50036
    50040
    2 3/4 (2.750)
    3 (3.000)
    3 1/4 (3.250)    		 - 0.14 37044
    37048
    37052    		 39044
    39048
    39052    		 42044
    42048
    42052    		 41044
    41048
    41052    		 45044
    45048
    45052    		 44044
    44048
    44052    		 48044
    48048
    48052    		 47044
    47048
    47052    		 51044
    51048
    51052    		 50044
    50048
    50052
    3 1/2 (3.500)
    4 (4.000)
    4 1/2 (4.500)    		 37056
    37064
    37072    		 39056
    39064
    39072    		 42056
    42064
    42072    		 41056
    41064
    41072    		 45056
    45064
    45072    		 44056
    44064
    44072    		 48056
    48064
    48072    		 47056
    47064
    47072    		 51056
    51064
    51072    		 50056
    50064
    50072
    5 (5.000)
    5 1/2 (5.500)
    6 (6.000)    		 37080
    37088
    37096    		 39080
    39088
    39096    		 42080
    42088
    42096    		 41080
    41088
    41096    		 45080
    45088
    45096    		 44080
    44088
    44096    		 48080
    48088
    48096    		 47080
    47088
    47096    		 51080
    51088
    51096    		 50080
    50088
    50096
    Greater than (6.000) - 0.20  
    THREAD/INCH 8 UN 8 UN 8 UN 8 UN 8 UN
    T (1) Thread length min 4.07 4.38 5.00 5.62 6.25
    L Length Tol (For other lengths, last three digits are lengths in 16ths.)
    Preferred Lengths 2 (2.000)
    2 1/4 (2.250)
    2 1/2 (2.500)    		 - 0.18 98032
    98036
    98040    		 52032
    52036
    52040    		 54032
    54036
    54040    		 56032
    56036
    56040    		 58032
    58036
    58040
    2 3/4 (2.750)
    3 (3.000)
    3 1/4 (3.250)    		 - 0.20 98044
    98048
    98052    		 52044
    52048
    52052    		 54044
    54048
    54052    		 56044
    56048
    56052    		 58044
    58048
    58052
    3 1/2 (3.500)
    4 (4.000)
    4 1/2 (4.500)    		 98056
    98064
    98072    		 52056
    52064
    52072    		 54056
    54064
    54072    		 56056
    56064
    56072    		 58056
    58064
    58072
    5 (5.000)
    5 1/2 (5.500)
    6 (6.000)    		 98080
    98088
    98096    		 52080
    52088
    52096    		 54080
    54088
    54096    		 56080
    56088
    56096    		 58080
    58088
    58096
    Greater than (6.000) -0.24  
    Specifications
    • ASTM A453
    • ASTM A638
    • EN 10269
    • EN 10083-3
    • ISO 3506-5
    • DIN 267
    Surface Treatments
    • Xylan 1070 / 1014 / 1400 / 1424
    • Xylar 2 / 101
    • SermaGard 1105 / 1280
    • Dacromet 320 / 500
    • TakeCoat 1000 Ceramic
    • Magnigard
    • MolyKote
    Certifications
    • ISO 9001 - 2015 Certified
    • PED 2014/68/EC
    • NACE MR0175/ISO 15156-2
    • NORSOK M-650
    • DFAR
    • MERKBLATT AD 2000 W2/W7/W10
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