HEX HEAD TRANSMISSION TOWER BOLTS
IS 12427 : 2001
Steel Hardness: 5.8 , 8.8
Finish: Hot Dip Galvanized
| Dimensions of Hexagon Head Transmission Tower Bolts | ||||||
| Nom. Dia. (d) | M12 | M16 | M20 | (M22) | M24 | |
| Thread Pitch | 1.75 | 2 | 2.5 | 2.5 | 3 | |
| b (ref) | 20 | 23 | 26 | 28 | 30 | |
| C | Max. | 0.6 | 0.8 | 0.8 | 0.8 | 0.8 |
| Da | Max. | 14.7 | 18.7 | 24.4 | 26.4 | 28.4 |
| Ds | Max. | 12.7 | 16.7 | 20.84 | 22.84 | 24.84 |
| Min. | 11.3 | 15.3 | 19.16 | 21.16 | 23.16 | |
| Dw | Max. | 18 | 24 | 30 | 34 | 36 |
| Min. | 16.47 | 22 | 27.7 | 31.35 | 33.25 | |
| e | Min. | 19.85 | 26.17 | 32.95 | 37.29 | 39.55 |
| k | Nom. | 7.5 | 10 | 12.5 | 14 | 15 |
| Max. | 7.95 | 10.75 | 13.4 | 14.9 | 15.9 | |
| Min. | 7.05 | 9.25 | 11.6 | 13.1 | 14.1 | |
| k’ | Min. | 4.95 | 6.48 | 8.12 | 9.17 | 9.87 |
| r | Min. | 0.6 | 0.6 | 0.8 | 0.8 | 0.8 |
| s | Max. | 18 | 24 | 30 | 34 | 36 |
| Min. | 17.57 | 23.16 | 29.16 | 33 | 35 | |
Length — Size Combinations and Grip Ranges IS 12427 | |||||||||||||||
| Thread | M12 | M16 | M20 | M22 | M24 | ||||||||||
| Size d | ls | Lg | Grip | ls | Lg | Grip | ls | Lg | Grip | ls | Lg | Grip | ls | Lg | Grip |
| Min. | Max. | Range | Min. | Max. | Range | Min. | Max. | Range | Min. | Max. | Range | Min. | Max. | Range | |
| 30 | 65 | 10 | 6-10 | – | – | – | – | – | – | – | – | – | – | – | – |
| 35 | 11.5 | 15 | 11-15 | 8 | 12 | 8-12 | – | – | – | – | – | – | – | – | – |
| 40 | 16.5 | 20 | 16-20 | 13 | 17 | 13-17 | 9 | 14 | 11-14 | 7 | 12 | 8-12 | – | – | – |
| 45 | 21.5 | 25 | 21-25 | 18 | 22 | 18-22 | 14 | 19 | 15-19 | 12 | 17 | 13-17 | 9 | 15 | 11-15 |
| 50 | 26.5 | 30 | 26-30 | 23 | 27 | 23-27 | 19 | 24 | 20-24 | 17 | 22 | 18-22 | 14 | 20 | 16-20 |
| 55 | 31.5 | 35 | 31-35 | 28 | 32 | 28-32 | 24 | 29 | 25-29 | 22 | 27 | 23-27 | 19 | 25 | 21-25 |
| 60 | 36.5 | 40 | 36-40 | 33 | 37 | 33-37 | 29 | 34 | 30-34 | 27 | 32 | 28-32 | 24 | 30 | 36-30 |
| 65 | 41.5 | 45 | 41-45 | 38 | 42 | 38-42 | 34 | 39 | 35-39 | 32 | 37 | 33-37 | 29 | 35 | 31-35 |
| 70 | 46.5 | 50 | 46-50 | 43 | 47 | 43-47 | 39 | 44 | 40-44 | 37 | 42 | 38-42 | 34 | 40 | 36-40 |
| 75 | 51.5 | 55 | 51-55 | 48 | 52 | 48-52 | 44 | 49 | 45-49 | 42 | 47 | 43-47 | 39 | 45 | 41-45 |
| 80 | 56,5 | 60 | 56-60 | 53 | 57 | 53-57 | 49 | 54 | 50-54 | 47 | 52 | 48-52 | 44 | 50 | 46-50 |
| 85 | 61.5 | 65 | 61-65 | 58 | 62 | 58-62 | 54 | 59 | 55-59 | 52 | 57 | 53-57 | 49 | 55 | 51-55 |
| 90 | 66.5 | 70 | 66-70 | 63 | 67 | 63-67 | 59 | 64 | 60-64 | 57 | 62 | 58-62 | 54 | 60 | 56-60 |
| 95 | 71.5 | 75 | 71-75 | 68 | 72 | 68-72 | 64 | 69 | 65-69 | 62 | 67 | 63-67 | 59 | 65 | 61-65 |
| 100 | 76.5 | 80 | 76-80 | 73 | 77 | 73-77 | 69 | 74 | 70-74 | 67 | 72 | 68-72 | 64 | 70 | 66-70 |
| 105 | 78 | 82 | 78-82 | 74 | 79 | 75-79 | 72 | 77 | 73-77 | 69 | 75 | 71-75 | |||
| 110 | 83 | 87 | 83-87 | 79 | 84 | 80-84 | 77 | 82 | 78-82 | 74 | 80 | 76-80 | |||
| 115 | 88 | 92 | 88-92 | 84 | 89 | 85-89 | 82 | 87 | 83-87 | 79 | 85 | 81-85 | |||
| 120 | 93 | 97 | 93-97 | 89 | 94 | 90-94 | 87 | 92 | 88-92 | 84 | 90 | 86-90 | |||
| 125 | 98 | 102 | 98-102 | 94 | 99 | 95-99 | 92 | 97 | 93-97 | 89 | 95 | 91-95 | |||
| 130 | 103 | 107 | 103-107 | 99 | 104 | 100-104 | 97 | 102 | 98-102 | 94 | 100 | 96- I00 | |||
| 135 | 108 | 112 | 108-112 | 104 | 109 | 105-109 | 102 | 107 | 103-107 | 99 | 105 | 101-105 | |||
| 140 | 113 | 117 | 113-117 | 109 | 114 | 110-114 | 107 | 112 | 108-112 | I04 | 110 | 106-110 | |||
| 145 | 118 | 122 | 118-122 | 114 | 119 | 115-119 | 112 | 117 | 113-117 | 109 | 115 | 111-115 | |||
| 150 | 123 | 127 | 123-127 | 119 | 124 | 120-124 | 117 | I22 | 118-122 | 114 | 120 | 116-120 | |||
| 155 | I28 | 132 | 128-132 | 124 | 129 | 125-129 | 122 | I27 | 123-127 | 119 | 125 | 121-125 | |||
| 160 | 133 | 137 | 133-137 | 129 | I34 | 130-134 | 127 | 132 | 128-132 | 124 | 130 | 126-130 | |||
Transmission Tower Line Bolts as per Indian Standard IS 12427 : 2020
This Indian Standard (First Revision) was adopted by the Bureau of Indian Standards, after the draft finalized by
the Bolts, Nuts and Fasteners Accessories Sectional Committee and approved by the Basic and Production
Engineering Division Council. This standard was originally published in 1988; subsequently need is felt to revise it to incorporate the changes taken place at various levels.
In this revision, following major changes have been made:
a) The range of sizes has been enlarged to cover sizes upto M24;
b) The range of nominal lengths has been extended upto M24;
c) The use of property classes 5.8 and 8.8 are also permitted subject to the agreement between the manufacturers
and the users; and
d) The length—size combinations have been suitably extended.
The other type of transmission tower bolt known as step bolt is covered in IS 12427:2020 / IS 10238:2001 ‘Fasteners —
Threaded steel fasteners — Step bolts for steel structures — Specification @rst revision)’. The hexagon head
bolts intended for fabrication of general steel structures are covered in IS12427:2020 IS 6639:1972 ‘Hexagon bolts for steel structures’.
For the purpose of deciding whether a particular requirement of this standard is complied with, the final value, observed or calculated, expressing the result of a test or analysis, shall be rounded off in accordance with 1S 2:1960, IS 12427:2020 ‘Rules for rounding off numerical values (revised)’. The number of significant places retained in the rounded off value should be the same as that of the specified value in this standard.